Hand - Extensor and Flexor Tendon Injury Flashcards

Question

A 32-year-old man who works as a carpenter comes to the office for follow-up examination seven days after sustaining a 2-cm laceration to the dorsum of the left thumb proximal to the interphalangeal joint while using a knife. In the emergency department, the laceration was sutured, and the thumb was immobilized with a splint. On physical examination, the wound is clean. No infection is noted. Weak extension of the interphalangeal joint is noted. The patient cannot extend the thumb off the tabletop. Laceration of which of the following tendons is most likely? A) Abductor pollicis longus B) Extensor carpi radialis brevis C) Extensor carpi radialis longus D) Extensor pollicis brevis E) Extensor pollicis longus

Answer 1

Correct answer is option E. The patient described has an injury to the **extensor pollicis longus (EPL) tendon**, which can be difficult to diagnose in the emergency department. Often, a patient will have weak active extension at the interphalangeal joint. The thumb extensor mechanism receives fibers from the abductor pollicis brevis, adductor pollicis, the ulnar head of the flexor pollicis brevis, and the EPL. If the EPL is lacerated, there may be weak extension at the interphalangeal joint; however, the **thumb cannot be actively lifted off a tabletop**. The extensor pollicis brevis, abductor pollicis longus, extensor carpi radialis longus, and extensor carpi radialis brevis do not contribute to the extension of the thumb off a tabletop.

Answer 2

The correct response is Option E. The goal of treatment is to restore normal finger function; prevent pain, stiffness, and traumatic arthritis; and to restore activities of daily living. This patient has a complete tear of the radial collateral ligament of the proximal interphalangeal (PIP) joint of the long finger. Widening of the joint space indicates probable interposition of ligament fibers. Angulation greater than 20 degrees is associated with poor prognosis. Complete tears with subluxation and interposition require surgical repair.Most collateral ligament ruptures occur at the proximal attachment to the middle phalanx. Partial tears can be treated with nonsurgical and conservative methods. Splinting, buddy taping, extension block placement, and temporary fixation with a Kirschner wire would be incorrect.

Answer 3

The correct response is Option A. Increasing the suture caliber has shown to increase the force in static testing and fatigue strength in dynamic testing. The use of 3-0 polyethylene terephthlate fiber suture increased the fatigue strength compared with 4-0 sutures by two to three times. The placement of the suture dorsally has been shown to increase the strength of the repair by two to four times, and is more environmentally favored because of a decreased risk for interference with the synovial fluid. It has been shown that locking loops improve force and gap resistance compared with grasping loops in flexor tendon repair. Statistically significant improvement was observed with the locking loop technique for ultimate and gap strength values using 2-0 core suture and ultimate strength values using 3-0 core suture.

Answer 4

The correct response is Option D. A Boutonnière deformity occurs with injury to the central tendon and injury or attenuation of the triangular ligament. The lateral bands migrate volarly to become proximal interphalangeal (PIP) joint flexors, and their action is on the distal interphalangeal (DIP) joint, extending it. The triangular ligaments are bound by the lateral bands, central slip, and terminal tendon. The sagittal bands of the metacarpophalangeal (MCP) joint originate from the volar plate and anchor the extensor mechanism. The oblique retinacular ligament originates from the volar lateral crest of the proximal phalanx and inserts into the terminal tendon. The volar plates stabilize the MCP and PIP joints. The terminal tendon is the convergence to the lateral bands at the dorsum of the middle phalanx inserting on the distal phalanx.

Answer 5

The correct response is Option C. The flexor tendons are bound within a fibro-osseous sheath, with pulleys essential to prevent bowstringing (and consequent poor force transfer). The pulley system includes both annual and cruciate pulleys. Pulleys A2 and A4 attach to bone. Pulleys A1, A3, and A5 are attached to the volar plates at their respective joints. The strength of pulleys, in order from strongest to weakest, are the A2, A1, and A4 pulleys. The pulleys attached to bone have a higher breaking strength compared with those attached to the volar plates.

Answer 6

The correct response is Option E. A quadriga (from the Latin quadria [four] and jungere [to yoke]) is a four-horse chariot that was raced in the Olympics and other sacred games. The patient described is experiencing weakness caused by the quadriga effect imposed by the fusion of the PIP joint of the long finger. PIP fusion is often well tolerated in the index finger because that finger €™s relatively independent profundus function does not impose a significant quadriga effect on the other fingers during power grasp. PIP fusion of the long finger, however, has been shown to decrease the excursion of all profundus tendons, reducing grip strength. PIP fusion restricts profundus excursion to a greater extent than distal interphalangeal (DIP) or metacarpophalangeal (MCP) joint fusion. A significant decrease in grip strength occurs when the PIP joints of the index and small fingers are fixed at less than 45 degrees and when the long and ring fingers are fused in a position of less than 60 degrees of flexion. Any time there is limitation of profundus excursion in the long through small fingers, some decrease in grip strength is expected. By fusing the PIP joint, excursion of the profundus tendon within the finger is effectively limited. Disuse atrophy would be unlikely in the patient described, as atrophy of the muscle bellies would have to occur in the forearm, which is far away from the site of injury. Extrinsic tightness would be noted in cases where MCP flexion limits PIP flexion. Intrinsic tightness would be noted if the patient was found to have inability to flex the PIP joint with MCP extension. Flexor tendon injury is unlikely if DIP joint and MCP joint motion are normal.

Answer 7

The correct response is Option D. The flexor pollicis longus tendon courses through the vicinity of the scaphoid. Scaphoid fracture malunion or scaphoid arthritic spurs can result in ruptures to the flexor pollicis longus tendon. The other tendons described do not course in the area of the scaphoid and would not be injured with disease in the area of the scaphoid.

Answer 8

The correct response is Option E. Difficult situations such as these often arise, especially in patients who have sustained multiple traumas. This patient has had a delay in the care of a cold hand because of a limb-threatening injury. Because of the threatened limb, closing the skin and performing the repairs on another day is not an option. Continuation of the tourniquet would be dangerous to this patient; the upper limit of time for tourniquet use in the upper extremity is most frequently defined as two hours, after which muscle and nerve damage begins. Performing the surgery without tourniquet control is an option but is not the best option in a true spaghetti-like wrist, for which a bloodless field is best for meticulous preparation and identification of structures. Of the options listed, the best choice is to release the tourniquet for 20 minutes (5 minutes for every 30 minutes the tourniquet was in use) and to finish the case immediately. Release of the tourniquet for only five minutes is not adequate after two hours of tourniquet use. Indeed, revascularization of the hand with closure of the wound, opting to finish the case on another day is an option, but was not offered as a choice for this item. References

Answer 9

The correct response is Option E. There is considerable variability in the anatomy of the first dorsal compartment of the wrist; this is particularly true when considering the presence or absence of a septum in the compartment. The significance of these variations is that they may predict failure of steroid injections to resolve de Quervain disease and must be considered when releasing the compartment surgically to ensure that a complete release of all tendons is performed. While studies vary, based on methodology of imaging, cadaveric dissection, or surgical findings, there is consistency that septa are more common in patients presenting with de Quervain disease than in the general population. Studies have shown no association between the number of APL slips and de Quervain disease.

Answer 10

The correct response is Option E. Disruption of the central slip of the extensor tendon at its insertion into the base of the middle phalanx results in extensor lag at the PIP joint of the finger. If this deformity is left untreated, then a boutonnière deformity may result. This deformity results from subsequent volar subluxation of the lateral bands. Disruption of the terminal extensor tendon does not result in boutonnière deformity; in fact, the use of the extensor tenotomy distal to the triangular ligament may be used for correction of chronic boutonnière deformity. Intrinsic tightness of the lumbricals and sagittal band disruption do not initiate boutonnière deformity. Quadriga effect results from an imbalance of tendon forces between adjacent fingers and is also not responsible for progression to boutonnière deformity. Many surgeons consider the results of surgical treatment for boutonnière deformity unpredictable, and so they try splint immobilization to first regain extension and then allow the central slip to heal, even in delayed presentations. Surgical options include reattachment of the central slip and various reconstructions of the lateral bands including tenotomy, tendon grafting, and tendon transfer. Management strategies vary depending on the time since injury and the degree and ability to correct a PIP joint flexion contracture.

Answer 11

The correct response is Option E. The patient described has a significant wrist injury until proven otherwise. Physical examination will be the most helpful in making a determination regarding what should be done next. Electromyography/nerve conduction study typically does not give actionable information until 3 weeks or more after injury. Ultrasonography may be helpful but would not give more information than one could get from a thorough physical examination and would likely be painful as the probe is pressed on the wound. CT angiography can be critical preoperatively if there was a concern regarding inflow. Magnetic resonance angiography would be revealing but would be expensive and unnecessary in this setting. The patient was taken to the operating room for exploration. Intraoperative and postoperative images are shown.

Answer 12

Correct answer is option B. In patients with zone II flexor tendon injuries, outcome is most dependent on the repair technique and rehabilitation protocol used. Suture techniques that employ locking loops or multiple strands have been shown to be stronger and to provide a better, longer lasting repair than the standard, two-strand modified Kessler technique. Compliance is critical to successful rehabilitation. In general, an immediate, graded early active flexion program has been shown to result in greater total active motion than early passive flexion and/or late motion programs. Repair techniques that use increased strength, combined with a more detailed early, graded active flexion program, have been shown to optimize active flexion while minimizing tendon rupture. In addition, a history of smoking has been shown to correlate with poorer outcomes regardless of the method of rehabilitation

Answer 13

The correct response is Option E. The most appropriate position for splint immobilization of an injury leading to a boutonnière deformity is with the distal interphalangeal (DIP) joint free and the proximal interphalangeal (PIP) joint extended. The patient sustained a central slip disruption of the long finger of the left hand, resulting in an acute boutonnière deformity. Patients with boutonnière deformity have flexion at the PIP joint and hyperextension at the DIP joint. There is tearing of the extensor tendon from its insertion at the base of the middle phalanx, resulting in decreased ability to extend the finger at the PIP joint. As a result, the lateral bands fall volar to the axis of rotation at the PIP joint, changing their force from extension to flexion at the PIP joint. The extensor force of the lateral bands is then directed toward the terminal tendon at the DIP joint, resulting in hyperextension of the DIP joint. Splint immobilization of the PIP joint in extension and the DIP joint free to flex permits healing of the central slip back to the middle phalanx. Flexion of the DIP joint through movement will tend to cause the lateral bands to migrate dorsally again, reversing the effect of the boutonnière deformity. When the lateral bands move dorsal to the axis of rotation at the PIP joint, their extensor force is restored and the DIP hyperextension resolves. Splint immobilization of both joints in extension will not encourage the dorsal migration of the lateral bands. Splint immobilization with the DIP joint in extension and the PIP joint free is recommended in zone 1 extensor tendon injuries (i.e., mallet finger).

Answer 14

Correct answer is option B. The volar border of the anatomic snuff box is comprised of the abductor pollicis longus (APL) and extensor pollicis brevis (EPB) tendons (first dorsal compartment). The dorsal border is comprised of the extensor pollicis longus (EPL) tendon (third dorsal compartment). The above diagram shows the dorsal compartments of the forearm. The abductor pollicis brevis tendon is the most radial component of the thenar musculature; the extensor digitorum communis (EDC) and extensor indicis proprius (EIP) tendons are found in the fourth dorsal compartment. The flexor carpi radialis (FCR) tendon can be found radial to the other tendons within the superficial compartment of the volar forearm at the level of the wrist. The flexor pollicis longus (FPL) tendon lies within the deepest compartment of the volar forearm.

Answer 15

Correct answer is option C. The most important preoperative achievement is the restoration of good passive flexion of the involved digit. This will allow active range of motion in the postoperative period. Preoperative examination clearly shows no function of the flexor digitorum superficialis tendon. Therefore, in the setting of the sharp injury, it would not be expected to be improvable. The location of the proximal FDP stump is not appropriate because it is not a significant factor in timing secondary tendon reconstruction; it would not be reasonable to consider planning a delayed primary repair 3 months out. And with a Zone 2 laceration and no FDP function, the FDP stump will be in the palm, due to tethering by the lumbrical muscle. Confirmation of the presence of a palmaris longus at either forearm is not appropriate because the palmaris is not the only donor tendon for secondary finger flexor reconstruction. The plantaris is a viable option as well, as are the long toe extensors. Preoperative strengthening of grip is not appropriate because it would do nothing to prepare the little finger for reconstruction.

Answer 16

The correct response is Option B. In order for a tendon transfer to be successful, the muscle-tendon unit must be available, of appropriate strength, and able to be spared at the donor site (ie, function of the muscle cannot be critical to the site). The strength of the antagonist muscle must also be opposed, intercalary joints should have appropriate mobility, and the excursion and direction of the muscle should be well matched. In addition, the proposed tendon transfer should demonstrate integrity and synergy. In this 33-year-old man who has developed high median and ulnar nerve paralysis, the extensor indicis proprius is the only tendon of those listed that still has motor innervation. The patient's injuries preclude the use of all muscle-tendon units powered by the paralyzed nerves. However, because the index finger has two independent extensor tendons, the extensor indicis proprius tendon can be used in tendon transfer. A viable abductor digiti quinti muscle-tendon unit can be used for reconstruction in patients with thumb hypoplasia; this is known as the Huber opponensplasty. The flexor digitorum superficialis tendon of the ring finger can be used for opponensplasty when motor innervation is adequate; likewise, the function of the flexor pollicis longus tendon will most likely be restored with a transfer of the brachioradialis tendon. Transfer of the palmaris longus tendon to the abductor pollicis brevis tendon (Camitz transfer) is an abductorplasty, not an opponensplasty.

Answer 17

The correct response is Option E. Swan-neck deformity can occur in the post-traumatic setting as well as in the rheumatoid arthritis population. The PIP joint hyperextends, and the DIP joint flexes. Unlike boutonnière deformity, which is always initiated by a rupture of the central slip of the extensor mechanism, the origin of a swan-neck deformity can be at the DIP, PIP, or MCP joint. Regardless of the initiating problem, a swan-neck deformity can only occur if there is laxity of the volar plate of the PIP joint to allow hyperextension. Flexor digitorum profundus avulsion would lead to inability to flex the DIP joint and would not cause hyperextension of the PIP joint. The oblique retinacular ligament can be used to repair a swan-neck deformity but is not causative of the pathology. Palmar subluxation of the MCP joint can lead to a swan-neck deformity in rheumatoid arthritis patients, but the photograph and x-ray study show this is not present in this patient. Rupture of the central slip of the extensor mechanism would lead to a boutonnière deformity. References

Answer 18

The correct response is Option D. Juncturae tendinum are tendon-like bands that connect the long, ring, and little finger extensor digitorum communis tendons. If the long finger extensor tendon is lacerated proximal to the attachment of the juncturae tendinum between the long and ring fingers, the ring finger extensor digitorum communis tendon will apply extension force to the distal long finger extensor tendon via the juncturae tendinum and produce metacarpophalangeal (MCP) extension. Interossesous and lumbrical muscles produce flexion of the MCP joint. The deep transverse metacarpal ligament stabilized the metacarpal heads relative to each other but does not produce motion at the MCP joint. In this patient, the tendon is visible and noted to be completely lacerated; therefore, the paratenon is not intact.

Answer 19

The correct response is Option E. Flexion deformity of the distal joint seen in mallet finger will lead to secondary hyperextension of the proximal joint. This occurs in a zigzag fashion because of the imbalance of forces. If the terminal tendon is displaced proximally, the conjoined tendons will slide proximally and become extensors to the proximal joint. A boutonnière deformity is a flexion deformity of the proximal joint from disruption of the central slip. The lateral slips migrate volarly becoming an extensor to the distal joint which then hyperextends. Clinodactyly is a genetic condition in which there is a curvature of the fifth finger toward the fourth finger. A hook nail usually results from loss of nail bed support, usually after amputation. Camptodactyly is also a genetic condition in which there is a fixed flexion deformity of the proximal joint of the little finger.

Answer 20

The correct response is Option D. An anomalous connection between flexor pollicis longus (FPL) and the profundus tendon to the index finger (flexor digitorum profundus-II) was initially described by Linburg and Comstock in 1979. In their initial report, the Linburg-Comstock anomaly was detected on physical examination in one extremity in 31% of patients and in both extremities in 14%. Dissection of 43 cadavers demonstrated the anomaly in at least one extremity of 25% and in both extremities of 6%. This anomalous tendon connection has been described as a source of tenosynovitis, which is alleviated with surgical division of the connection. The connection typically occurs at the level of the distal forearm, proximal to the carpal tunnel. This connection has been blamed for failure of FPL repair due to transmission of inadvertent tension to the repair site.

Answer 21

Correct answer is option B. This patient has a mallet finger deformity. No fracture was involved; therefore, it is considered a Type I mallet injury. Patients are sometimes noncompliant or not well instructed regarding how the splint is to be used. Both the Fowler tenotomy and open repair should be reserved for chronic cases of mallet finger. In fact, open repair with direct suture of the terminal tendon has shown poor results. Fusion of the distal interphalangeal joint is an extreme method of treating this condition and would not be indicated at this time. An additional six-week period of splinting would be appropriate in a compliant patient. One author has shown that mallet fingers that remain untreated for up to 12 weeks can be treated conservatively with six weeks of splinting. However, a noncompliant patient would benefit from transarticular fixation with Kirschner wires, which would be more difficult to manipulate versus splinting alone.

Answer 22

The correct response is Option D. In this child who has a fixed flexion deformity of the thumb, most likely resulting from congenital triggering, the most appropriate management is operative release of the A1 pulley. Trigger thumb is an isolated congenital deformity that is thought to occur in 0.05% of live births; 25% to 33% of patients have bilateral findings. This condition is caused by a proliferation of synovial fluid within the tendon. Because the thumb is often minimally flexed in infants, the deformity is not typically diagnosed until age 6 months. Studies have shown that approximately 30% of children with congenital trigger thumb will experience spontaneous resolution of the deformity by age 3 years. However, because there have been no signs of improvement of the deformity in this 3-year-old girl, simple release of the A1 pulley is indicated. Congenital clasp thumb can produce findings similar to congenital triggering. In children with the clasp thumb deformity, there is absence of the extensor pollicis brevis and/or extensor pollicis longus tendons. This deformity is characterized by extreme flexion of the metacarpophalangeal joint and adduction of the thumb into the palm. Conservative treatment can be ineffective in children younger than 3 years. Splinting is often impractical for compliance reasons, and injection of a corticosteroid is difficult in a 3-year-old child. Excision of a tendon nodule is recommended only to improve recurrent triggering.

Answer 23

The correct response is Option A. The lumbrical muscles are intrinsic muscles of the hand. They arise from the flexor digitorum profundus tendon and insert into the radial lateral band of the extensor mechanism. Their origin and insertion both attach to muscle/tendon rather than bone, which makes them unique compared with other muscles, which typically originate from and insert into bone. No muscles arise from the flexor digitorum superficialis tendon. The interosseous muscles originate from the metacarpal shafts and insert into the proximal phalanges.

Answer 24

The correct response is Option B. This patient has a classic Stener lesion, in which the adductor aponeurosis becomes interposed between the ruptured ulnar collateral ligament and the base of the proximal phalanx. This lesion cannot heal spontaneously because reattachment of the ulnar collateral ligament to the proximal phalanx is blocked by the interposed tendon. It is important to identify this condition at the time of the initial injury so that operative repair can be performed without delay. Without surgical correction, the patient will have painful instability to radial stress of the metacarpophalangeal joint. The abductor tendon, the first dorsal interosseous muscle, and the flexor pollicis longus are not involved because they are not in the vicinity of the ulnar collateral ligament of the metacarpophalangeal joint of the thumb. Tearing of the joint capsule is a potential complication of a Stener lesion, and an unrepaired capsular tear can be associated with relative supination of the proximal phalanx in relation to the metacarpal. Although the joint capsule should always be inspected, and repaired if necessary, at the time of ligament repair, it is not involved with blocking of the ulnar collateral ligament. In this injury, only the adductor aponeurosis becomes interposed between the ulnar collateral ligament and the proximal phalanx.

Answer 25

The correct response is Option E. The oblique retinacular ligament of Landsmeer passes volar to the axis of rotation of the proximal interphalangeal (PIP) joint, and when it is involved in a fibrotic process, it may produce hyperextension of the distal interphalangeal (DIP) joint. Tightness of this ligament can result in contractural deformity resulting in a boutonnière deformity. Inadequate checkrein release would result in persistent flexion deformity at the PIP joint but would not impact the position of the DIP joint. Scar adhesions of the flexor tendons would limit active range of motion of the digit but would not create a hyperextension deformity at the DIP joint. Extensor tendon laxity would limit active extension at the DIP joint, creating a flexion deformity rather than a hyperextension deformity.

Answer 26

The correct response is Option C. This patient has developed Volkmann ischemic contracture, and there has been muscle fibrosis resulting from ischemia of the volar compartment. At this point, there is no functioning flexor muscle. The most appropriate management is thorough debridement of the volar forearm muscles and free functioning muscle transfer to restore extrinsic finger flexion. Flexor digitorum superficialis to flexor digitorum profundus tendon transfer is a useful treatment to open a nonfunctional hand due to severe spasticity. Pronator teres to extensor carpi radialis brevis tendon transfer is a tendon transfer used to restore wrist extension, not flexion. Flexor pronator slide or lengthening of the flexor tendons is only indicated when there is a contracture but still some functioning muscle. Z-lengthening of the flexor tendons also relies on a mild to moderate contracture and the presence of functioning flexor muscle.

Answer 27

The correct response is Option E. An ultrasound will be the most effective way to diagnose a Stener lesion, which would necessitate surgical intervention for this patient. Stener lesions are a unique type of ulnar collateral ligament injury in which the dorsal adductor aponeurosis becomes interposed between the ruptured distal end of the ligament and its insertion at the proximal phalanx. This prevents healing of the ligament, and thus these injuries cannot be treated closed. Ulnar collateral ligament injuries that demonstrate no endpoint on valgus stress testing generally require operative management. Those that demonstrate some laxity with a firm endpoint can be treated with cast immobilization as long as there is no Stener lesion. Stress view x-ray study will show full versus partial disruption of the ligament but will not identify the presence or absence of a Stener lesion. Some consider MRI to be the most sensitive modality for detection of these lesions; however, criticisms of MRI include its cost and delay in availability. Arthrography can be used to identify capsular injury but cannot detect the collateral ligament displacement with high accuracy. CT scan will not be able to resolve the ligament position clearly. Ultrasonography is cost-effective, dynamic, and easy to obtain. Ultrasonography has been shown to have a positive predictive value of 87 to 100% when used to identify Stener lesions. On the imaging examination, an uninjured collateral ligament will appear as a hypoechoic arc. In a Stener lesion, the arc will be disrupted with displacement or a large gap between the two ends, as seen in the image.

Answer 28

The correct response is Option C. This patient has a boutonniere deformity, in which the extensor mechanism (comprised of the central slip, transverse and oblique retinacular ligaments, and lateral bands) becomes imbalanced. In patients with this deformity, the central slip is damaged and the transverse retinacular ligament is stretched. The lateral bands begin to drift volarly, eventually moving anterior to the center of rotation of the proximal interphalangeal (PIP) joint. As a result, the lateral bands flex the PIP joint, and passive extension of the PIP joint becomes impossible. There are three stages of boutonniere deformity. Patients with stage 1 deformities can passively extend the PIP joint. With stage 2, the joint becomes contracted and cannot be extended fully, but the joint itself is not yet involved. Degeneration of the joint is seen in a patient with a stage 3 boutonniere deformity. Because this patient has only a stage 1 boutonniere deformity, the most appropriate management is splinting the PIP joint in extension (ie, at 0 degrees) for a minimum of six to eight months. The distal interphalangeal (DIP) joint should be unencumbered and allowed to flex actively, and an exercise program should be initiated for joint rehabilitation. Buddy taping is only useful for certain types of injuries involving the collateral ligament and volar plate. Splinting of the DIP joint in extension is appropriate for treatment of a mallet finger deformity. Primary repair and open repair are difficult procedures and are not advocated as management options for patients with stage 1 deformities.

Answer 29

The correct response is Option B. This patient has a boutonniere deformity, which results from disruption of the central slip of the extensor tendon at the PIP joint with concomitant volar migration of the lateral bands. This volar migration may not be seen until 10 to 21 days after injury. Patients with boutonniere deformities have persistent flexion of the PIP joint resulting from loss of the central slip and the unopposed forces of the flexor digitorum superficialis tendon. The transverse retinacular ligaments become stretched, and the volarly migrated lateral bands exert direct pull on the DIP joint. This leads to the characteristic findings of hypertension of the DIP joint and worsening flexion of the PIP joint. The most appropriate management is splinting of the PIP joint in extension; this can be performed successfully as late as six weeks after initial injury. The DIP joint should be left unencumbered to allow motion, which will result in dorsal migration of the lateral bands and reestablish the normal relationship of the tendinous structures within the finger.

Answer 30

The correct response is Option E. The sensory branch of the radial nerve arises between the brachioradialis and extensor carpi radialis brevis approximately 8 cm proximal to the styloid process of the radius. It pierces the fascia approximately 5 cm (3 fingerbreadths) proximal to the radial styloid. The nerve then fans out proximal to the wrist and passes superficially to the radial styloid and first dorsal compartment. The flexor carpi radialis tendon and radial artery are located in the volar forearm. The second dorsal extensor compartment and Lister tubercle of the radius are dorsal and ulnar to the radial sensory nerve.

Answer 31

The correct response is Option B. Most of these injuries even after a month will respond to splinting of the DIP joint in extension for 6 weeks. Any residual extension lag is largely an aesthetic concern and rarely will require further treatment. The operative treatment of soft-tissue mallet injury may lead to unacceptable complications while splinting may lead to skin irritation but little else. The preferred treatment at 4 weeks is closed reduction and splinting. Surgical treatment may be considered for more chronic injury greater than 3 months. Pinning in extension may be appropriate for a small subgroup of patients with work-related inability to wear an orthosis (such as surgeons).

Answer 32

The correct response is Option B. Tendon transfers for complete high radial nerve injuries are often performed within weeks after injury and allow restoration of wrist and digital extensor stabilization. If present, the palmaris longus tendon is transferred to the extensor pollicis longus tendon to allow for thumb extension. The flexor carpi radialis is transferred to the extensor digitorum communis for finger extension. The pronator teres is transferred to the extensor carpi radialis brevis to add support for wrist extension. The brachioradialis is not generally a good transfer in a high radial nerve palsy as it is typically weak. The extensor indicis proprius does not usually receive a tendon for transfer as the extensor digitorum communis will provide extension to all digits, including the index. The extensor pollicis brevis does not normally receive a tendon transfer since thumb MP joint extension (in addition to IP joint extension) is normally restored with transfer to the extensor pollicis longus tendon. Pronator quadratus is not used for tendon transfers for wrist extension and cannot reach the extensor carpi radialis brevis.

Answer 33

The correct response is Option C. The palpable mass on the ulnar aspect of the metacarpal head is a Stener lesion, which is formed by interposition of the fascia of the adductor pollicis between the torn ulnar collateral ligament and the metacarpophalangeal (MP) joint. The proximal stump of the ulnar collateral ligament lies superficial and proximal to the fascia of the adductor pollicis. Interposition of the adductor pollicis prevents healing of the ligament. Operative repair is indicated in patients with Stener lesions. The abductor pollicis brevis and flexor pollicis brevis insert into the radial side of the MP joint, and the opponens pollicis inserts into the radial side of the metacarpal shaft. The abductor pollicis longus is not involved with the MP joint.

Answer 34

The correct response is Option C. A free gracilis muscle would provide a good strength and excursion match to the native finger flexors it would replace. Vascular and nerve connections could be performed in the distal upper arm, outside of the zone of resection. While individual finger flexion would not be restored, the patient would be able to make a composite fist after this surgery. The flexor digitorum profundus to superficialis transfer is used to treat flexor spastic contracture, typically with palmar hygiene issues, in a patient who still has some voluntary motor control. It requires the presence of flexor digitorum profundus and superficialis muscles, both of which would be removed as part of the anterior forearm compartment muscles. The Oberlin-Mackinnon nerve transfer transfers branches of the median nerve and ulnar nerve to the brachialis and biceps muscles, respectively. It is used to restore elbow flexion and would not provide finger flexion. A flexor pronator slide detaches the muscles originating from the medial epicondyle of the humerus and advances them distally. It is used to treat contractures of the fingers, often in patients with mild to moderate Volkmann contracture. In this patient, the flexor muscles have been resected, so this procedure is not possible. A latissimus dorsi muscle provides broad soft-tissue coverage for wounds and can also provide a strong flexion force. It cannot reach beyond the distal elbow. It can restore elbow flexion but cannot be used as a pedicled transfer to restore finger flexion.

Answer 35

The correct response is Option D. This patient has an ulnar collateral ligament injury of the thumb metacarpophalangeal (MP) joint. Although the indications for surgical repair are controversial, the pertinent anatomy is consistent. After the skin and subcutaneous tissue are divided, the sagittal bands are encountered. The sagittal bands stabilize the extensor pollicis longus over the MP joints of the thumb and travel from the lateral aspects of the tendon towards the flexor digital sheath. Repair of this structure is important to prevent subluxation of the tendon with thumb motion. The adductor for aponeurosis is readily visible under the sagittal bands. This structure should also be tagged before division to facilitate accurate surgical repair. Once the adductor aponeurosis is divided, the ulnar collateral ligament is readily visible and amenable to repair. The juncturae tendineum are extensor tendon connections on the dorsum of the hand and are not involved with the regional anatomy of the thumb. The extensor pollicis longus is usually dorsal to the area of dissection and does not require surgical manipulation. The ulnar collateral ligament does not exist under the skin. The volar plate may be injured in a gamekeeper=s type of injury and should be assessed. A clue to a significant volar plate injury requiring repair is volar subluxation of the proximal phalanx in relation to the metacarpal. The abductor pollicis, flexor pollicis longus, and first dorsal interosseous are out of the zone of injury and should not be surgically disturbed.

Answer 36

The correct response is Option A. The main rationale for performing early motion exercises is to decrease adhesion formation. During the early phases of tendon healing, large amounts of collagen are deposited and form early scarring. Although this scarring is crucial for the healing of the repaired tendon, scarring will also occur in the tendon sheath and, if allowed to progress, can lead to stiffness in the involved digit. Early passive- and active-motion protocols assist in breaking apart early scarring of the tendon to the surrounding sheath. Early motion has not shown to increase the final strength of the repair and is more likely to cause rupture. Although synovial fluid flow might be increased with tendon excursion, it does not improve outcomes. Postoperative pain is likely increased with therapy.

Answer 37

Correct answer is option D. In this patient who has a functional deficit involving the interphalangeal (IP) joint of the thumb after sustaining a zone V laceration of the **extensor pollicis longus (EPL) tendon**, repair of the tendon will provide the best functional outcome. The EPL tendon facilitates hyperextension of the IP joint of the thumb, which is no longer possible in this patient. In contrast, the mechanism of action of the intrinsic muscles, via their contributions to the extensor tendon mechanism, allows the patient to extend the IP joint of the thumb only to a neutral position. Control of edema is appropriate for patients who have joint stiffness or loss of motion due to swelling of the soft tissues. Removal of sutures is indicated following wound healing but will not address the functional EPL deficit. Sensory re-education is used to optimize functional outcome in patients with sensory nerve injuries. Arthrodesis of the MP joint can be performed to relieve severe posttraumatic arthritis, not acute tendon lacerations.

Answer 38

The correct response is Option B. Advances in primary flexor tendon repair techniques and postoperative mobilization protocols have improved functional results for Zone II injuries. Repair strength has been shown to be related to the number of strands that cross the repair site. Other factors that contribute to repair strength include suture caliber, adequate core suture purchase (at least 0.7 to 1.0 cm), and the use of an epitendinous repair in addition to core suture placement. A forearm-based dorsal block splint is placed to protect flexor tendon repairs. Compared with passive mobilization protocols, early active mobilization protocols demonstrate better functional outcomes without a significantly increased rate of tendon rupture. A minimum of a four-strand core repair is necessary to tolerate an early active mobilization protocol. In this patient, a six-strand core repair with an epitendinous repair is appropriate for an active motion protocol. Although the flexor repair described in this scenario is strong enough to tolerate protected early active motion, complete absence of a protective splint with unrestricted use of the hand would be inappropriate and risks tendon rupture. The Kleinert splint is a dorsal extension block splint that allows active extension and utilizes rubber bands for passive flexion. This is not considered an early active flexion protocol. A relative motion extension splint with immediate controlled active motion is used following extensor tendon repairs/injuries. Cast immobilization following flexor repair would not be appropriate in this scenario if the goal is to maximize flexor function, but it may have a role in the postoperative management of flexor injuries in children or unreliable adults.

Answer 39

The correct response is Option C. Many techniques for primary flexor tendon repair have been described. All methods involve a core suture to bear the load of the repair with or without an epitendinous suture. Multiple studies have shown that more strands crossing the repair site and/or larger diameter of each strand increases the strength of the repair. Two-strand repairs cannot withstand early active rehabilitation protocols; repairs of four strands or greater, including a cruciate repair as done in the patient above, can tolerate an early active motion rehabilitation protocol. Trumble and Seiler’s studies compare passive motion protocols and active motion protocols to each other for risk of rupture and incidence of deceased range of motion at final measurement. Both studies identified active motion protocols incurred a higher occurrence of rupture but a lower incidence of decreased range of motion compared with the passive protocols.

Answer 40

The correct response is Option C. Low force and moderate excursion therapy protocols continue to be the most effective protocol following flexor tendon repairs. However, increasing the applied force to the repair site during postoperative rehabilitation beyond 5 N does not accelerate accrual of repair site strength after a multistranded repair. In vivo repair, results have shown that early active mobilization may limit tendon end softening and loss of repair strength that generally occurs after the first 7 days. The mode of rehabilitation described was popularized by Strickland and has been shown to improve outcomes of Zone II repairs, probably due to both increased absolute as well as relative tendon excursions. However, in order to reduce the potential increased repair rupture rate, at least four-strand repair is required. This increased excursion leads to fewer tendon adhesions. Because the fingers are flexed by rubber bands, the Kleinert technique predisposes the patient to flexion contractures. A combination of the Duran passive range of motion and the Kleinert technique improves the results.

Answer 41

The correct response is Option C. This patient has findings consistent with intersection syndrome, or tenosynovitis of the second dorsal compartment that involves the extensor carpi radialis longus and brevis tendons at their intersection near the first extensor compartment. Patients have pain and swelling approximately 4 cm proximal to the wrist, at the point where the extensor pollicis brevis and abductor pollicis longus tendons cross the common radial wrist extensors. Erythema and crepitus are also associated. Symptoms are exacerbated with prolonged wrist motion. Appropriate management includes splinting of the wrist in extension and injection of a corticosteroid. Surgical procedures, such as release of the second dorsal compartment and/or synovectomy at the intersection point, may be required in those patients whose symptoms do not improve with conservative measures. Patients with carpometacarpal joint arthritis have pain at the base of the metacarpal of the thumb. Pain is reproduced on a carpometacarpal grind test or axial compression test. De Quervain tenosynovitis is stenosing tenosynovitis of the first dorsal compartment; the extensor pollicis brevis and abductor pollicis longus tendons are affected. This condition is characterized by localized pain, swelling, and tenderness 1 to 2 cm proximal to the radial styloid. Affected patients have pain on ulnar deviation of the wrist with the thumb clasped in the palm (Finkelstein test). Scapholunate ligament injuries are rare in patients who have no history of trauma. In these patients, pain is commonly elicited over the scapholunate interval. Scapholunate instability may also be present. Radiographs may show an increased scapholunate interval. In Wartenberg syndrome, the superficial sensory branch of the radial nerve is entrapped between the brachioradialis and extensor carpi radialis longus tendons. Pain, numbness, and tingling at the dorsoradial aspect of the wrist are characteristic, and symptoms are often exacerbated when the patient wears compressive jewelry, such as a wristwatch.

Answer 42

The correct response is Option E. EPL tendon rupture occurs in 1% of fractures of the distal radius after closed reduction. The incidence of tendon rupture after closed treatment of distal radius fracture is actually greater than that of open treatment and plate fixation. Tendon ruptures may occur early, due to bone spurs, but they also may occur late, years after the fracture. This is believed to be due to an inflammatory synovitis in the area of the third dorsal compartment and a relative ischemia of the EPL tendon in this area. Ultrasound can help establish the diagnosis; the optimal treatment is tendon transfer from the EIP tendon. Arthrodesis of the thumb IP joint can prevent the flexion deformity of a tendon rupture, but it is not a preferred reconstruction method for a young, active person. Unless there is significant pathology at the distal radius, no specific treatment is required for the bone. Delayed primary repair of the EPL tendon is rarely possible.

Answer 43

The correct response is Option C. This patient's deformity is most likely caused by the quadriga effect, which occurs as a result of excess distal pull on one profundus tendon. Because the flexor profundus tendons share a common muscle belly, any excess pull on one tendon will decrease the force and amplitude of all of the tendons. Quadriga can occur secondary to amputations in which the flexor digitorum profundus (FDP) tendon is attached to the extensor tendon or following grafting of excessively short tendons or advancement of the FDP tendon in patients with zone I injuries. Flexor tendon adhesions can occur following injury or prolonged immobilization. Decreased flexion of the affected digit only is a characteristic finding. Lumbrical plus deformity most frequently affects the index finger, which has an independent FDP tendon. Division of the distal tendon results in proximal migration of the tendon and lumbrical muscle, exacerbating tension on the lateral bands. This tension results in paradoxical extension of the proximal interphalangeal joint with attempted finger flexion. A patient with a tendon rupture would be unable to flex the long finger; the other fingers would not be affected. Triggering of the FDP tendon may be seen following tendon repair because of the excess bulk created as a result of the repair; this appears to interfere with the pulley system. Affected patients would have decreased motion of the long finger without any effect on the other fingers.

Answer 44

The correct response is Option C. The most important preoperative achievement is the restoration of good passive flexion of the involved digit. This will allow active range of motion in the postoperative period. Preoperative examination clearly shows no function of the flexor digitorum superficialis tendon. Therefore, in the setting of the sharp injury, it would not be expected to be improvable. The location of the proximal FDP stump is not appropriate because it is not a significant factor in timing secondary tendon reconstruction; it would not be reasonable to consider planning a delayed primary repair 3 months out. And with a Zone 2 laceration and no FDP function, the FDP stump will be in the palm, due to tethering by the lumbrical muscle. Confirmation of the presence of a palmaris longus at either forearm is not appropriate because the palmaris is not the only donor tendon for secondary finger flexor reconstruction. The plantaris is a viable option as well, as are the long toe extensors. Preoperative strengthening of grip is not appropriate because it would do nothing to prepare the little finger for reconstruction.

Answer 45

The correct response is Option A. Early motion protocols are standard for adult tendon repairs but are not generally suitable for very young children due to poor compliance. Children have a remarkable ability to regain motion after tendon injury, especially for repairs or grafts that are outside of Zone II. In this vignette, the reconstruction was in Zone III, and the prognosis for regaining full motion even after a month of immobilization is excellent. Moreover, it is highly unlikely that a child of this age will predictably comply with splint wear and motion restrictions for the duration of tendon healing. Thus, the risk of early rupture outweighs the risk of stiffness. There are advocates of successful early motion protocols in children with Zone II tendon repairs, but most studies have failed to demonstrate an appreciable benefit of such a practice.

Answer 46

The correct response is Option E. The patient described has an injury to the extensor pollicis longus (EPL) tendon, which can be difficult to diagnose in the emergency department. Often, a patient will have weak active extension at the interphalangeal joint. The thumb extensor mechanism receives fibers from the abductor pollicis brevis, adductor pollicis, the ulnar head of the flexor pollicis brevis, and the EPL. If the EPL is lacerated, there may be weak extension at the interphalangeal joint; however, the thumb cannot be actively lifted off a tabletop. The extensor pollicis brevis, abductor pollicis longus, extensor carpi radialis longus, and extensor carpi radialis brevis do not contribute to the extension of the thumb off a tabletop.

Answer 47

The correct response is Option D. Ruptures of repaired tendons usually occur postoperative days 7 through 10. The best way to diagnose the rupture is MRI when active flexion is relatively contraindicated. Early ruptures can be managed with urgent re-repair. Tendon transfers and grafting should be reserved as secondary reconstruction procedures and should not be needed when the native FDP is available and not shortened. Fusion should be reserved for salvage and in patients where shorter recovery times are beneficial, such as laborers. Doing nothing can lead to swan-neck deformities, adhesions, and stiffness.

Answer 48

The correct response is Option D. The patient described has a lumbrical plus deformity. This deformity occurs following amputation when proximal migration of the profundus tendon results in contracture of the lumbrical muscle. This contracture can result in tightness of the lumbricals, which produces paradoxical extension of the PIP joint during active flexion of the MCP joint. The lumbrical muscle is a component of the intrinsic extensor mechanism, which is responsible for MCP flexion and PIP extension. The lumbrical plus deformity is treated most appropriately by division of the lumbrical tendon. Dynamic flexion splinting is occasionally used for extension contractures of the PIP joint caused by joint stiffness. Fusion of the PIP joint is indicated for cases of arthritis. Injection of a corticosteroid is appropriate if the patient has active triggering at the level of the A1 pulley. Tenolysis is used when flexor tendon adhesions are suspected (when passive joint motion is greater than active joint motion).

Answer 49

The correct response is Option D. This patient has sustained a dorsal mid forearm laceration. Common injuries within this location include injuries to the musculotendinous units of the extensors to the wrist, fingers, and thumb. Additionally, the radial sensory nerve and dorsal branch of the ulnar nerve could be injured depending on the location and vector of the object that caused the injury. Passive flexion as demonstrated in the photograph demonstrates the effect of tenodesis. With passive wrist flexion, intact digital extensors should be put under tension and bring the metacarpophalangeal joints into extension. However, in this patient the long and ring fingers do not extend with wrist flexion. In an uninjured hand, when the wrist is passively flexed the fingers and thumb will extend. With wrist extension, the fingers are brought into flexion and the thumb is brought toward the small finger. Bringing the wrist into extension would help with a volar wound as it would help establish injuries to digital flexors. Putting the hand in cold water is a better test for sensory nerve injury as loss of wrinkling will be demonstrated. Passive flexion or extension of the fingers will not reliably demonstrate which specific tendons are injured in this patient.

Answer 50

The correct response is Option E. Of the options listed, the most likely option to result in poor outcome in the setting of delayed tendon repair is stiffness of the interphalangeal joints. Hand therapy directed at achieving passive range of motion of the finger before reconstruction may make repair possible and should be attempted before proceeding with surgery. Although poorly controlled diabetes increases the risk of perioperative infection, it would not impact the ability to perform a reconstruction. Likewise, the amount of time that has passed since the initial injury places the patient outside the range typically accepted for delayed primary repair, but would not directly affect a reconstruction. Digital nerve injury requiring repair/reconstruction has been considered a relative contraindication to repair. The increased two-point discrimination in this patient suggests a prior injury with recovery similar to what might be expected with primary nerve repair. In this setting, the need for concomitant digital nerve repair is unlikely. Although thick, the cutaneous scar is mobile, suggesting that it is not contributing to the lack of motion at the interphalangeal joints. Immature scars or wounds requiring further reconstruction would also be contraindications to reconstruction.

Answer 51

Correct answer is option E. Flexion deformity of the distal joint seen in mallet finger will lead to secondary hyperextension of the proximal joint. This occurs in a zigzag fashion because of the imbalance of forces. If the terminal tendon is displaced proximally, the conjoined tendons will slide proximally and become extensors to the proximal joint. A boutonnière deformity is a flexion deformity of the proximal joint from disruption of the central slip. The lateral slips migrate volarly becoming an extensor to the distal joint which then hyperextends. Clinodactyly is a genetic condition in which there is a curvature of the fifth finger toward the fourth finger. A hook nail usually results from loss of nail bed support, usually after amputation. Camptodactyly is also a genetic condition in which there is a fixed flexion deformity of the proximal joint of the little finger.

Answer 52

The correct response is Option A. This is the basis of the Elson test for central slip disruption of the extensor mechanism of the finger. When the proximal interphalangeal (PIP) joint is maximally passively flexed, the central slip is normally pulled distally, resulting in slack in the terminal tendon. Injury to the central slip eliminates this slack through the lateral band and allows extensor tension to be generated at the distal interphalangeal (DIP) joint. Thus, with central slip injury, the DIP joint can be actively extended with maximal PIP flexion. Swan neck deformity results from terminal extensor tendon disruption and total inability to extend the DIP joint independent of PIP position. Flexor digitorum profundus (FDP) avulsion results in inability to flex the DIP joint. In the Elson test, DIP flexion is always possible. PIP volar plate injury may result in jamming of the volar plate within the PIP joint and paradoxical inability to flex (extension contracture) at the PIP joint. There will also be hyperextension PIP joint pain and laxity. Sagittal band disruption results in inability to actively extend at the metacarpophalangeal joint, but the finger can often maintain extension if passively placed in this position.

Answer 53

The correct response is Option A. Extension of the interphalangeal joints (IP) and extension of the metacarpophalangeal joints (MCP) to the neutral position after an injury to the forearm extensor tendons is possible through the action of the lumbricals and dorsal interossei (intrinsic hand muscles). The extrinsic extensor tendons alone are responsible for extending the metacarpophalnageal joints beyond neutral. The role of the juncturae tendinum is to limit the independent extension of the ulnar three digits. The juncturae tendinum will allow for some finger extension with an isolated single tendon injury at the wrist or dorsal hand but would not maintain extension in all fingers. No meaningful accessory extensor tendon exists. A patient with partial extrinsic tendon lacerations may present with pain on attempted extension but extension beyond neutral would be intact.

Answer 54

The correct response is Option C. Stenosing tenosynovitis (trigger finger) typically results in pain over the metacarpophalangeal (MCP) joint associated with crepitation, clicking, or locking of the digit with altered motion during the flexion-extension arc. Dislocation of the proximal interphalangeal (PIP) joint could account for the symptoms; however the imaging shows the joint to be congruent and the exam did not reveal any instability. An injury originally identified in rock climbers, rupture of the A2 pulley has been increasingly recognized in other sports and activities. The forceful flexion of the flexor profundus and superficialis tendons with the PIP joint flexed 90 degrees and the distal interphalangeal (DIP) joint extended (the "crimp" position) placed loads exceeding the tolerance of the A2 across the palmar PIP joint, resulting in rupture of the underlying pulley. Treatment for an isolated pulley injury includes rest, ice, anti-inflammatory drugs, and external support through use of a ring splint. Avulsion of the profundus tendon (jersey finger) typically presents with loss of flexion of the DIP joint. Pain may be present both at the avulsion site and over the retracted end of the tendon. This patient's examination shows the profundus function to be intact. Volar (palmar) plate avulsion injuries present with pain and swelling at the PIP joint, but the joint will often be painful to stress in hyperextension and potentially, if the injury extends dorsally into the collateral ligaments, it may exhibit instability. X-ray imaging often demonstrates a small bony avulsion fragment (absent in this patient) along the palmar PIP joint.

Answer 55

The correct response is Option E. Injury to the sagittal band is most likely to account for these findings. The patient has sustained a closed injury to the dorsum of the hand, resulting in a sagittal band rupture. The sagittal bands are responsible for maintaining the position of the extensor tendon dorsally over the metacarpophalangeal (MCP) joint. When this band is ruptured (commonly either via trauma or in rheumatoid arthritis), the extensor tendon can migrate laterally to the MCP joint and fall into the sulcus, causing difficulty in active initiation of extension. However, if the finger is placed in extension passively, the extensor tendon will resume its correct position and will then be able to hold the finger in extension and resist force. Injury to the central extensor tendon will result in loss of active extension as well as an inability to maintain extension and resist force. The juncturae tendinum connect the extensor tendons to each other at the dorsum of the hand. Pull via the juncturae may allow for some degree of extension function even in the presence of extensor tendon laceration, but injury to the juncturae should not create a deficit in extension if the tendon remains intact. The lumbrical muscle is one of the intrinsic hand interosseous muscles. It functions to create flexion at the MCP joint and extension at the interphalangeal joints. Injury to the lumbrical muscle will not cause an extensor deficit at the MCP joint. The oblique retinacular ligament is in the finger, originating at the base of the proximal phalanx and inserting into the distal phalanx. It is believed to coordinate proximal interphalangeal and distal interphalangeal motion but should have no bearing on motion at the MCP joint.

Answer 56

The correct response is Option E. Difficult situations such as these often arise, especially in patients who have sustained multiple traumas. This patient has had a delay in the care of a cold hand because of a limb-threatening injury. Because of the threatened limb, closing the skin and performing the repairs on another day is not an option. Continuation of the tourniquet would be dangerous to this patient; the upper limit of time for tourniquet use in the upper extremity is most frequently defined as two hours, after which muscle and nerve damage begins. Performing the surgery without tourniquet control is an option but is not the best option in a true spaghetti-like wrist, for which a bloodless field is best for meticulous preparation and identification of structures. Of the options listed, the best choice is to release the tourniquet for 20 minutes (5 minutes for every 30 minutes the tourniquet was in use) and to finish the case immediately. Release of the tourniquet for only five minutes is not adequate after two hours of tourniquet use. Indeed, revascularization of the hand with closure of the wound, opting to finish the case on another day is an option, but was not offered as a choice for this item.

Answer 57

The correct response is Option D. Isolated injury to the radial collateral ligament of the index finger occurs with forced ulnar deviation at the metacarpophalangeal (MCP) joint. It can also occur in conjunction with injury to all of the structures surrounding the joint. In isolation, the findings of a complete tear of the ligament will be that of a flail joint. Attempted pinch will result in pain and ulnar deviation. These injuries are often ignored initially and progress to arthritis. Standard radiographs will not show the injury, and MRI is needed for confirmation. Isolated injury to the lumbrical will not be demonstrable on examination, while an injury to the volar plate by itself would not cause instability on key-pinch testing. Injury to the insertion tendon of the first dorsal interosseous muscle will cause a weak pinch, but the joint will not be unstable to radial pressure. Finally, the extensor mechanism does not contribute to the stability of the MCP joint.

Answer 58

The correct response is Option B. Pain in the dorsal radial aspect of the wrist can be caused by a variety of conditions; a thorough history and physical examination are key to elucidating the correct diagnosis. In the scenario presented, the patient has a positive Finkelstein test along with reproduction of the pain with resistance to the extensor pollicis brevis muscle. These are classic findings of de Quervain tenosynovitis. The patient’s physical examination points to the first dorsal compartment of the wrist as a source of pathology rather than basal joint or scaphotrapezial arthritis. Radiographs have not been shown to correlate with symptomatology in basilar joint arthritis. Intersection syndrome is a tendinopathy between the intersection of the tendons of the first and second dorsal compartments. The pain of intersection syndrome is generally found more proximally in the forearm and is also increased with resisted wrist extension. Digital flexor tenosynovitis or trigger finger is an inflammatory tendinopathy of the flexor pollicis longus tendon and pain is generally reproduced with resisted thumb flexion.

Answer 59

The correct response is Option A. The first step in management of this deformity is A1 pulley release. The patient has a congenital trigger thumb, the most common cause of congenital thumb flexion deformity. The flexed position of the thumb can also be seen in patients with congenital clasped thumb, absent or aberrant extensor tendons, arthrogryposis, and spasticity. Patients with congenital trigger thumb commonly have thickening of the tendon, referred to as “Notta’s node.” In patients younger than age 3 years, the spontaneous resolution rate is 30%. Splinting and observation are options when the condition is diagnosed early, but most patients require surgery. During release of the pulley, no attempt is made to excise or reduce the nodule in the tendon. Aspiration is not appropriate for the nodule in the flexor tendon. Aspiration can be used to manage retinacular cysts, which are ganglion cysts on the tendon sheath seen at the volar metacarpophalangeal joint, but patients with such cysts do not have flexion deformity. Biopsy is not necessary for Notta’s node, which is a pathologic thickening of the flexor sheath. Such pathologic changes in the flexor tendon are more common in children than in adults, who more commonly have involvement of the tendon sheath. Trigger digit injection is into the flexor sheath and not the mass. Risk of rupture is higher with direct injection into the mass. Injecting a child would require at least monitored deep sedation if not general anesthesia. Tendon transfer is appropriate for treatment in patients with absent or aberrant thumb extensor tendons.

Answer 60

The correct response is Option D. The thumb metacarpophalangeal (MCP) sesamoid bone(s) may be associated with an irreducible dorsal dislocation. Dorsal dislocation of the thumb at the MCP joint typically occurs with forced hyperextension with resultant volar plate and collateral ligament rupture. Irreducibility usually occurs through interposition of the volar plate in the joint. Extensor expansion interposition, collateral ligaments, bony fragments, sesamoids, and flexor pollicis longus entrapment have also been associated with irreducibility. In these circumstances, open reduction is often necessary. The ulnar neurovascular bundle, extensor pollicis longus, opponens pollicis, and flexor pollicis brevis are not typically associated with an irreducible dislocation.

Answer 61

The correct response is Option C. The flexor digitorum superficialis and flexor carpi radialis musculotendinous units were lacerated in the original injury. They would not be appropriate donor motors due to this. Brachioradialis transfer to the flexor pollicis longus transfer has been reported for patients with cervical spine injuries, but it is not used for transfers to restore intrinsic muscle function. The abductor pollicis brevis cannot be used to correct a claw deformity due to its small size and position in the thenar eminence; in addition, for this patient, its innervation was injured in the original trauma. Both the extensor carpi radialis longus and brevis have been described as a tendon transfer. Neither muscle has been affected by the initial injury. Whichever tendon is not harvested can power wrist extension along with the extensor carpi ulnaris. The tendon does need to be elongated with a graft.

Answer 62

The correct response is Option D. The most appropriate treatment is relative motion extension splint immobilization for 6 weeks. The relative motion extension splint allows immediate controlled active motion. Placing the injured tendon in 15 to 20 degrees less motion than the adjacent tendons results in significantly less force. A splint is fashioned placing the repaired extensor tendon of the long finger in 15 to 20 degrees more metacarpophalangeal extension than the neighboring extensor tendons. Full interphalangeal joint range of motion is permitted. The finger splint is worn with a wrist component for the first 3 weeks (which may not be necessary). The finger component is used for only 3 additional weeks. This allows for earlier recovery of motion and return to work. Without immobilization, the repair is at increased risk for rupture and failure. Extensor tendon injuries have typically been treated with continuous extension splint immobilization for 4 to 6 weeks. Although this would be a reasonable option, use of the relative motion extension splint allows immediate movement and decreases the stiffness that may result from immobilization. This may be preferred in children or noncompliant patients. Dynamic extension splinting is a possibility and may be useful in patients who have an extensor pollicis longus injury or in patients in whom all six finger extensors are severed. Relative motion splinting is not an option in these cases.

Answer 63

The correct response is Option B. Severely contaminated wounds, open fractures, and joint capsule lacerations require emergent and thorough irrigation and debridement. Fractures and skin loss should be treated in the initial procedure when feasible. Fractures should be fixed rigidly enough to allow early dynamic splinting or active motion. For lacerations without associated injury, the extensor tendon can be repaired emergently or in a delayed primary fashion after irrigation, debridement, and loose closure of the wound. If the repair is delayed, it should be performed within 7 days before the tendon ends retract or soften. The results of extensor tendon repair depend on the complexity of trauma and the anatomical zone of tendon injury. In general, results of primary extensor tendon repair are better in Verdan Zones I, II, IV, and V, and worse in Zones III and VI. Tendons should not be repaired under tension as tendon force imbalance and tendon rupture will usually result. Tendon grafting should not be performed in a contaminated wound and probably should be staged in this situation if it is necessary because of tendon loss.

Answer 64

The correct response is Option A. This patient has adhesions after flexor tendon injury and repair. In this scenario, the recommended course of action is to continue hand therapy to improve passive range of motion. A successful functional outcome following tendon injury depends on supple joints with full passive range of motion and tendon gliding. The ultimate goal would be to perform flexor tenolysis; however, the indications are clear that the patient must have minimal soft-tissue edema, minimal scarring, and full or near-full passive range of motion. Active tendon range of motion depends on the flexor digitorum superficialis and flexor digitorum profundus gliding within the flexor tendon sheath. Flexor tendon adhesions are a potential complication any time the flexor tendon sheath is violated, as a result of either surgery or trauma. The literature shows a reoperation rate of 6% after flexor tendon repair and an adhesion rate of 4%. This patient is 4 months post-surgery and reports compliance with supervised hand therapy. Despite this, he has poor active and passive range of motion. Although most authors recommend waiting at least 3 to 6 months before attempting tenolysis, this patient is unlikely to improve with observation alone. Tenolysis is a technically demanding procedure, and all patients must be counseled preoperatively that complications such as neurovascular injury, injury to the pulley system, and tendon rupture are possible outcomes. In cases of tendon rupture or patients requiring pulley reconstruction at the time of tenolysis, two-stage tendon reconstruction with implantation of a silicone rod is indicated. However, this would be a salvage procedure only and not first-line treatment. Proximal interphalangeal (PIP) joint arthrodesis would be limited to a salvage procedure in patients who are unable to undergo tendon repair or reconstruction.

Answer 65

The correct response is Option C. Staged flexor tendon reconstruction is a challenging endeavor that should not be undertaken lightly. To reach a successful outcome, both the patient and the surgeon must make a commitment to extensive surgeries, therapy sessions, and the possibility that the outcome may not be ideal; in fact, the outcome may compromise some existing function (as in cases of secondary quadriga or infection). Prerequisites for attempted surgical intervention include good passive range of motion of all joints involved; a healthy, well-vascularized soft-tissue bed for tendon gliding; and good patient compliance with postoperative therapy and wound care. In such a setting, staged flexor tendon reconstruction can be undertaken with a reasonably good chance of success. Patient range of motion can be controlled with therapy. With good compliance, patient age is not a factor. Uncontrolled pain can become controlled with appropriate medication and therapy.

Answer 66

The correct response is Option C. The most appropriate muscle to transfer for restoration of finger extension is the flexor carpi ulnaris. The radial nerve can be injured as a result of humerus fracture and/or surgery as it crosses the spiral groove of the humerus. The resultant radial nerve palsy will cause inability to extend the wrist, fingers, and thumb. Reinnervation of the muscle ideally should be completed within 12 to 18 months following injury to allow for recovery. In this patient who has radial nerve palsy after humerus fracture, the time following injury has been too long, so nerve repairs or nerve transfers are not a viable option, and tendon transfer is the procedure of choice. Tendon transfer involves the use of a noncritical or expendable donor tendon to provide a missing function. The tendon to be transferred should have adequate strength and range of motion to provide the desired function. Ideally, the tendon used should have synergistic action and allow for tenodesis to facilitate reeducation. Transfer of the flexor carpi ulnaris to the extensor digitorum communis will provide extensor function of the fingers, as it has adequate power and excursion and takes advantage of the linkage between wrist flexion and finger extension. Other typical tendon transfers for finger extension in radial nerve palsy include the flexor carpi radialis and the flexor digitorum superficialis. The brachioradialis is a radial nerve innervated muscle and will not be functioning in this patient who has a high radial nerve palsy. In low radial nerve palsies, it can be used to restore thumb extension. The brachioradialis can also be used to restore finger or wrist extension, as well as finger or thumb flexion in the appropriate patient. The extensor carpi radialis longus is not functional in this patient with radial nerve palsy. It can be used as a transfer for finger flexion in the appropriate patient. The palmaris longus does not have sufficient power to provide finger extension. It can be used as a transfer for thumb extension. The pronator teres has adequate power but less excursion. It is typically used to restore wrist extension rather than finger extension.

Answer 67

The correct response is Option B. The patient described has sustained an injury to the ulnar collateral ligament (UCL) of the MCP joint of his thumb. To select the appropriate therapy, the extent of the injury must be determined (ie, partial versus complete disruption of the UCL). In the patient described, 5 degrees of thumb MCP joint laxity compared to the opposite side indicates that he has sustained a partial tear of his UCL. It is generally accepted that incomplete tears may be treated successfully with immobilization; complete tears require operative treatment. A thumb spica cast provides adequate immobilization to allow healing of a partial tear of this patient €™s UCL; percutaneous pin placement to immobilize the MCP joint would be excessive. A percutaneous approach to MCP immobilization is occasionally used in conjunction with operative treatment of a complete disruption of the UCL. A thumb MCP joint with greater than 30 degrees of laxity, or greater than a 15-degree differential in laxity compared to the contralateral side, demonstrates clinical evidence of a complete disruption of the UCL. With a complete tear of the UCL, a Stener lesion may result whereby the adductor aponeurosis interposes itself between the ends of the completely disrupted UCL, thus preventing ligamentous healing despite prolonged immobilization. Both open suture repair of the UCL and arthroscopic reduction without suture repair of the UCL have been described as operative treatment modalities for Stener lesions. Excessive flexion and premature range of motion have been shown to increase the strain on the healing ligament; thus the patient €™s thumb should be immobilized. However, the splint could be fashioned to leave the interphalangeal (IP) joint free and allow active range of motion in the IP joint to prevent adherence of the extensor tendon to the injured MCP joint capsule.

Answer 68

The correct response is Option E. Flexor tendon injuries in zone 5 have the best prognosis following repair. This zone, one of five in the flexor tendon system, lies proximal to the carpal tunnel. The generous space found proximal to the wrist allows for better tendon gliding following repair. In contrast, zone 2 is an especially tight region that contains both flexor tendons within the fibro-osseous tunnel. There is an increased risk for development of adhesions when flexor tendons are repaired in this zone. Repair of flexor tendon injuries in zones 1, 3, and 4 typically results in intermediate outcomes because of tendon vascularity and gliding potential in these zones.

Answer 69

The correct response is Option D. Extensor indicis proprius (EIP) transfer is the most common procedure for the treatment of chronic ruptures of the extensor pollicis longus (EPL) tendon. The EPL tendon is prone to rupture from synovitis and friction at Listers tubercle. Since these are identified months after the original injury, primary repair is not possible secondary to retraction of the tendon and/or atrophy of the tendon ends. The EIP is the preferred tendon for the transfer because it has an appropriate direction and excursion compared with the EPL. This tendon transfer has demonstrated excellent outcomes in previous studies. Tenorrhaphy of the EPL to the extensor pollicis brevis tendon would not allow full thumb extension. Given the chronicity of this injury, sufficient myostatic contracture has occurred to render tendon interposition grafting inferior to EIP tendon transfer.

Answer 70

The correct response is Option C. Spontaneous rupture of the extensor pollicis longus (EPL) tendon is reported to occur in approximately 0.3 to 5% of nondisplaced or minimally displaced distal radius fractures, but it can also occur without trauma or in patients with inflammatory conditions such as rheumatoid arthritis. This is thought to arise from a loss of vascularity and atrophic changes in the compartment, and, because the tendon substance is usually degenerated, primary repair of the tendon is usually not possible. Tendon transfer using the extensor indicis proprius is the standard of care. Spontaneous rupture of other extensor tendons can occur in association with other conditions (e.g., rheumatoid arthritis), but would be exceedingly uncommon in the clinical scenario presented. The EPL passes through the third extensor compartment. Extensor tendon-compartment relationships include the following: First - abductor pollicis longus, extensor pollicis brevis Second - extensor carpi radialis longus, extensor carpi radialis brevis Third - extensor pollicis longus Fourth - extensor digitorum communis, extensor indicis proprius Fifth - extensor digiti minimi Sixth - extensor carpi ulnaris

Answer 71

The correct response is Option D. In this patient who has a functional deficit involving the interphalangeal (IP) joint of the thumb after sustaining a zone V laceration of the extensor pollicis longus (EPL) tendon, repair of the tendon will provide the best functional outcome. The EPL tendon facilitates hyperextension of the IP joint of the thumb, which is no longer possible in this patient. In contrast, the mechanism of action of the intrinsic muscles, via their contributions to the extensor tendon mechanism, allows the patient to extend the IP joint of the thumb only to a neutral position. Control of edema is appropriate for patients who have joint stiffness or loss of motion due to swelling of the soft tissues. Removal of sutures is indicated following wound healing but will not address the functional EPL deficit. Sensory re-education is used to optimize functional outcome in patients with sensory nerve injuries. Arthrodesis of the MP joint can be performed to relieve severe posttraumatic arthritis, not acute tendon lacerations.

Answer 72

The correct response is Option D. The most appropriate management for the patient described is tendon transfers to restore wrist, finger, and thumb extension. Following closed brachial plexus injuries, patients should receive CT scan or MR myelogram and electrodiagnostic studies at 3 to 4 weeks. This will allow enough time to see pseudomeningoceles and denervation changes. The electromyography and nerve conduction studies are generally repeated at 14 to 16 weeks to look for signs of regenerating axons, and this information is used to help determine the strategy for reconstruction. Surgery is recommended in the absence of clinical or electrical evidence of recovery. The patient described has late symptoms, and any strategy that involves attempting to repair or reconstruct the injured nerves is not recommended. After 12 to 18 months, useful motor recovery is unlikely due to intraneural fibrosis, loss of Schwann cells, muscle atrophy, and motor end-plate degeneration. Tendon transfers may be done at any time assuming that there are suitable donor tendons (at least 4/5 strength and full excursion) and that full passive mobility is present. In this example, the patient has adequate donor tendons from the median and ulnar nerves, and full passive range of motion. Examples of tendon transfers include: palmaris longus to extensor pollicis longus, pronator teres to extensor carpi radialis brevis, and flexor carpi ulnaris to extensor digitorum communis. Early or subacute exploration of the injured plexus with resection and intraplexal nerve grafting can be used with ruptures or neuromas that do not conduct a nerve action potental across the lesion. In adults, grafting is reserved for C5, C6, and C7 to restore shoulder abduction, elbow flexion, elbow extension, and wrist extension. Nerve grafting for lower trunk injuries in adults is generally not successful due to the length and time required for the regenerating axon to reach the distal target muscles. Nerve transfers have become a very useful and versatile tool for reconstruction of brachial plexus and peripheral nerve injuries. A less important distal nerve is sacrificed to replace the function of a more important nerve. Nerve transfers can be performed in preganglionic injuries and to decrease the distance to the target muscle for reinnervation. Ideally, nerve transfers are performed within 6 months of the injury. Studies have shown greater than 70% will achieve M3 function for elbow flexion and shoulder abduction. Common donor nerves include the spinal accessory, intercostals, anterior interosseous, and triceps branch. Other options for late reconstruction include pedicled muscle transfers and neurotized functional free muscle transfers. The latissimus dorsi muscle can be used to restore elbow flexion or elbow extension but will not reach beyond the elbow. Currently, free muscle transfer is the best option to restore hand and wrist function in complete brachial plexus palsy.

Answer 73

The correct response is Option A. Flexor tendon reconstruction in Zone II was originally described by Bassett and Carroll in 1963 and refined by Hunter in 1971. In the first stage, a Dacron-reinforced silicone rod is implanted after excision of the native tendons. It is secured distally to the flexor digitorum profundus stump or directly to the distal phalanx. Proximally, the rod is placed adjacent to the motor tendon but not secured. At this time, pulley reconstruction with tendon or retinacular grafts can be performed as indicated. This allows formation of a pseudosheath around the rod. Once the soft tissue has healed and the patient has regained maximum passive range of motion through therapy, the second-stage tendon grafting is performed. The most commonly reported time frame is 3 months but depends on soft-tissue stability. The most important management decision is to determine if primary repair is possible. If not, one must then decide between single-stage and two-stage tendon reconstruction. The criteria for single-stage reconstruction include a finger with adequate passive motion of all joints, soft tissues with minimal scarring, functional tendon sheath and pulley system, a neurovascularly intact digit, and a compliant patient. If these criteria are not met, the patient should be treated with a staged reconstruction. In this patient, primary repair is not likely with a gap \>1 cm 7 weeks after the initial repair. Myostatic contraction of the proximal stump would be expected. In addition, this patient’s digit has significant internal scarring and poor passive motion— all factors that preclude a single-stage repair. Fractional lengthening might be considered to allow primary repair if the tendon sheath was better quality. If a single-stage repair were indicated, one may consider a flexor digitorum superficialis transfer from an adjacent digit as a motor for the transfer. This requires only one tendon anastomosis, and studies have shown decreased adhesion formation with intrasynovial tendon grafts. However, tensioning of the transfer can be more difficult than traditional tendon grafting. Patients who are unable to tolerate a second-stage procedure can be considered for the implantation of an active silicone rod prosthesis. This device is designed to have both a distal anastomosis to the bone and a proximal anastomosis to the motor muscle-tendon unit with integrated sutures or a loop. This would require meeting the criteria for single-stage reconstruction. Active implants were originally designed for use in two-stage reconstruction, but no studies exist that compare active with passive silicone rods or show any benefit versus a passive implant in a staged reconstruction.

Answer 74

The correct response is Option E. In one large meta-analysis, tendon lacerations up to 90% were managed with early protected range of motion. The only absolute indication for surgery from the list is triggering. There is no evidence that repairing the sheath or pulley without bowstringing is necessary. Isolated A4 laceration would not result in bowstringing. Single digital artery injury in the setting of a perfused digit does not necessitate repair.

Answer 75

The correct response is Option A. The triangular ligament stabilizes the lateral bands dorsally, thereby preventing volar subluxation of the lateral bands to the proximal interphalangeal (PIP) joint rotation of axis, and the boutonnière deformity. The swan-neck deformity occurs when the lateral bands sublux dorsal to the PIP joint rotation of axis. This is prevented by the transverse retinacular ligament, which acts to prevent dorsal migration of the lateral bands at the PIP joint. Neither the mallet, quadriga, or lumbrical plus deformities are caused by volar subluxation of the lateral bands.

Answer 76

Correct answer is option D. Ruptures of repaired tendons usually occur postoperative days 7 through 10. The best way to diagnose the rupture is MRI when active flexion is relatively contraindicated.**Early ruptures** can be managed with **urgent re-repair**. Tendon transfers and grafting should be reserved as secondary reconstruction procedures and should not be needed when the native FDP is available and not shortened. Fusion should be reserved for salvage and in patients where shorter recovery times are beneficial, such as laborers. Doing nothing can lead to swan-neck deformities, adhesions, and stiffness.

Answer 77

The correct response is Option B. The most appropriate management is continuous extension splinting of the distal phalanx. The patient has sustained a mallet injury to the left ring finger. There is tearing of the terminal extensor tendon from its insertion at the base of the distal phalanx, resulting in inability to extend the finger at the DIP joint. On occasion, these injuries may be associated with an avulsion fracture from the dorsal aspect of the distal phalanx. The majority of closed mallet injuries (Type I) in Zone I of the extensor tendon can be treated by continuous extension splinting for 6 to 8 weeks. It is important that the finger not be allowed to flex at the DIP joint during this time period to avoid disruption of healing. Arthrodesis of the DIP joint is reserved for cases of DIP joint arthritis and would not be necessary in this patient. Exploration and suture of the tendon can be performed, but results are no better than closed treatment due to the difficulty of obtaining adequate repair of the thin tendinous substance at this level. Additionally, the patient will still require prolonged immobilization of the DIP joint after open repair. Exploration and suture of the tendon is used to treat Type II (open) mallet injuries. Open repair with reinsertion of tendon into bone is performed in flexor digitorum profundus avulsion injuries. Splinting of the PIP joint in extension with the DIP joint free is used to treat Zone III extensor tendon injuries (central slip avulsion injuries).

Answer 78

The correct response is Option C. The fundamentals of flexor tendon repair are based on primary tendon repair principles, which include easy placement of sutures in the tendon, secure suture knots, smooth juncture of the tendon ends, minimal gapping at the repair site, minimal interference with tendon vascularity, and sufficient strength throughout healing to permit application of early motion stress to the tendon. These fundamentals are best achieved by incorporating a few basic principles. Handling of the tendon should be minimized to decrease the occurrence of adhesion formation. The strength of the repair is proportional to the number of core sutures and the caliber of the sutures that cross the repair site. The core sutures should be placed 7 to 10 mm from the tendon edge; dorsal placement is biomechanically advantageous. The distance of the tendon-suture junctions relative to the level of the tendon cut affects the strength of repairs of cut tendons. Strength of repair decreases significantly with purchase distance of less than 4 mm. No increase in strength is seen with purchase distances of greater than 7 mm, and attempts to increase the purchase distance more significantly (greater than 15 mm) will potentially require unnecessary pulley disruption to achieve and will predispose to bunching at the repair site.

Answer 79

The correct response is Option D. This patient has an ulnar collateral ligament injury of the thumb metacarpophalangeal (MP) joint. Although the indications for surgical repair are controversial, the pertinent anatomy is consistent. After the skin and subcutaneous tissue are divided, the sagittal bands are encountered. The sagittal bands stabilize the extensor pollicis longus over the MP joints of the thumb and travel from the lateral aspects of the tendon towards the flexor digital sheath. Repair of this structure is important to prevent subluxation of the tendon with thumb motion. The adductor for aponeurosis is readily visible under the sagittal bands. This structure should also be tagged before division to facilitate accurate surgical repair. Once the adductor aponeurosis is divided, the ulnar collateral ligament is readily visible and amenable to repair. The juncturae tendineum are extensor tendon connections on the dorsum of the hand and are not involved with the regional anatomy of the thumb. The extensor pollicis longus is usually dorsal to the area of dissection and does not require surgical manipulation. The ulnar collateral ligament does not exist under the skin. The volar plate may be injured in a gamekeeper=s type of injury and should be assessed. A clue to a significant volar plate injury requiring repair is volar subluxation of the proximal phalanx in relation to the metacarpal. The abductor pollicis, flexor pollicis longus, and first dorsal interosseous are out of the zone of injury and should not be surgically disturbed.

Answer 80

The correct response is Option B. The central slip of the extensor mechanism is the terminal direct extension of the extrinsic extensor tendon (extensor digitorum communis and extensor digiti quinti) and is the primary extensor of the proximal interphalangeal (PIP) joint. Injury to the central slip will normally produce flexion of the PIP joint due to unopposed action of the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) tendons and is called a boutonniere deformity. The intrinsic extensor mechanism, via the middle band of the interosseous muscles, also inserts on the dorsal base of the middle phalanx and causes extension of the PIP joint. In an open injury, the central slip may be injured without concurrent injury to the interosseous muscle tendon, allowing the patient to still actively extend the PIP joint even in the presence of a disruption of the central slip. The oblique retinacular ligament connects the flexor tendon sheath volarly to the terminal extensor tendon dorsally. When a patient sustains a laceration to the extensor mechanism over the body of the middle phalanx bone, the oblique retinacular ligament may prevent the occurrence of an extensor lag and a mallet deformity. The lateral conjoined tendon is formed by the lateral bands of the interosseous muscles and the lateral slips of the extrinsic extensor and produces extension of the distal interphalangeal (DIP) joint. The sagittal band keeps the extrinsic extensor tendon centralized over the dorsal metacarpophalangeal (MP) joint by connecting to the volar plate. Disruption of the sagittal band on one side of a finger would allow the extrinsic extensor tendon to dislocate and impair its ability to extend the MP joint.

Answer 81

The correct response is Option D. The superficial location of numerous, tightly packed vital structures at the volar aspect of the wrist/distal forearm makes them susceptible to injury with penetrating trauma. The patient presents with a "spaghetti wrist," a term used to describe these devastating injuries that may result in transection of multiple flexor tendons and neurovascular structures. A thorough knowledge of the anatomy in this region is required in order to appropriately align and repair all transected critical structures. In particular, the flexor digitorum superficialis tendons are arranged such that the middle and ring superficialis tendons are superficial to the index and small finger superficialis tendons. Of note, the flexor digitorum profundus tendons are arranged in a side-by-side fashion deep to the superficialis tendons. The median nerve is located between the superficialis and profundus musculotendinous units at this level. The other options do not describe the correct arrangement of the superficialis tendons at the distal forearm/wrist level. Reference(s) 1. Meals CG, Chang J. Ten tips to simplify the spaghetti wrist. Plast Reconstr Surg Glob Open. 2018;6(12):e1971. 2. Vaughn CJ, Raghavan SS, Hansen SL, Terry MJ. Obstacles to the care of patients with multicomponent volar wrist lacerations at a county hospital. Ann Plast Surg. 2016;76(suppl 3):S238-S240. 3. Yazdanshenas H, Naeeni AF, Ashouri A, Washington ER III, Shamie AN, Azari K. Treatment and postsurgery functional outcome of spaghetti wrist. J Hand Microsurg. 2016;8(3):127-133.

Answer 82

The correct response is Option B. Functional muscle transfers are a way to restore motion that has been lost. The gracilis muscle is a common option for this kind of transfer. To optimize the outcome, the muscle should be inset at the same tension it was under in the leg. The physiologic basis for this technique is that muscle fibers function best at a particular length/tension relationship. Muscles are typically under ideal tension in their donor position. When transferred, a muscle can be placed under too much or too little tension. If a muscle is overstretched, there is little overlap of the actin and myosin units, and the contractile force is weak. If the muscle is under too little tension, the actin and myosin units aren’t able to achieve maximal contraction. Insetting a muscle under no tension produces the same result as insetting it under less tension.

Answer 83

The correct response is Option D. This patient is presenting with a rupture of the extensor pollicis longus (EPL) tendon, which occurs in as much as 5% of patients with mildly displaced distal radius fractures about 7 weeks after the initial injury. This is thought to be due to attritional rupture secondary to decreased vascularity. The treatment for this problem is a tendon transfer of the extensor indicis proprius to the EPL. Although some surgeons use a tendon graft, a primary repair is not feasible due to fraying of the EPL. Occupational therapy, immobilization, and further diagnostic studies (including electrodiagnostics and x-ray study) are not appropriate.

Answer 84

The correct response is Option A. Traditionally, extensor tendon injuries were treated with 4 to 6 weeks of immobilization that would subsequently lead to decreased flexion and stiffness. More recently, short arc motion protocols with relative motion splints have been utilized and demonstrate improved outcomes. To do this, a thermoplastic yoke splint is constructed by placing the digits of the repaired extensor tendon in approximately 15 to 20 degrees more metacarpophalangeal extension than the adjacent digits for 6 weeks while allowing full interphalangeal joint motion. The wrist is typically placed into an extension splint for 3 weeks at approximately 20 degrees extension to decrease tension on the repair site. Dynamic splinting following extensor tendon repair still limits gliding of the tendon by keeping the digit in a relative static position.

Answer 85

Correct answer is option D. Juncturae tendinum are tendon-like bands that connect the long, ring, and little finger extensor digitorum communis tendons. If the long finger extensor tendon is lacerated proximal to the attachment of the juncturae tendinum between the long and ring fingers, the ring finger extensor digitorum communis tendon will apply extension force to the distal long finger extensor tendon via the juncturae tendinum and produce metacarpophalangeal (MCP) extension. Interosseous and lumbrical muscles produce flexion of the MCP joint. The deep transverse metacarpal ligament stabilized the metacarpal heads relative to each other but does not produce motion at the MCP joint. In this patient, the tendon is visible and noted to be completely lacerated; therefore, the paratenon is not intact.

Answer 86

The correct response is Option A. Patients who have pain disproportionate to the level of injury should be evaluated to exclude a potential diagnosis of osteomyelitis, which in those without open fractures can result from local infection or hematogenous spread. In this patient, the MRI shows an abnormal signal in the proximal phalanx, which is consistent with osteomyelitis. Indium-111-labeled leukocyte scanning can also be used to confirm the diagnosis. Although Staphylococcus aureus is the most likely causal organism, Mycobacterium marinum and anaerobic organisms can also be associated. In cases such as this one, appropriate management includes surgical exploration, decortication to decompress the infected bone, and removal of all involved bone. Antibiotics should be administered intravenously following this procedure, and bone grafting should be performed at a later date. Photographs of the decortication procedure are shown above. Neurectomy is used for repair of neuromas, which manifest as a localized positive Tinel's sign, while neuroplasty would be the procedure of choice in a patient who has an entrapped nerve. Tendon repair is not required because the previous repair is still intact, as shown in the photograph and MRI. Tenolysis will improve the limited tendon excursion seen in patients who have tendon adhesions or scarring.

Answer 87

The correct response is Option E. The patient has a boutonnière deformity that is passively correctable. In most instances, this can be successfully managed with splinting of the PIP joint in extension while allowing active DIP flexion. Splinting of the PIP in extension helps restore central slip continuity; active DIP flexion with the PIP joint extended draws the tight, volarly displaced lateral bands into a more dorsal position while reducing DIP joint hyperextension. Holding the PIP and DIP joints both in extension will not correct the deformity. Open central slip repair is indicated if there is an open wound, but that is not the case in this scenario. Resection of the distal lateral bands only is a reasonable treatment for chronic deformity by relaxing the lateral bands. There is no role for resection of both lateral bands and oblique retinacular ligament in the management of this condition.

Answer 88

The correct response is Option B. Rupture of the flexor digitorum profundus (FDP) tendon from its distal attachment is commonly known as jersey finger. The injury is often overlooked by players and trainers and misdiagnosed as a sprained finger, but it requires more urgent management than these minor injuries. Jersey finger occurs when a flexed distal interphalangeal (DIP) joint is suddenly and forcefully hyperextended, leading to rupture of the FDP tendon at its insertion on the distal phalanx. FDP injuries can be classified based upon the degree of tendon retraction, as described in Leddy and Packer's grading scheme: Type I injuries involve retraction of the profundus tendon all the way to the palm, with associated injuries to the vincula longus and vinculum brevis. Injuries to the vincula disrupt the blood supply to the tendon, necessitating surgical repair within 7 days to avoid necrosis of the tendon and a permanent contracture deformity. Type II injuries involve retraction of the tendon to the proximal interphalangeal (PIP) joint. The tendon stump is held in place by the vincula longus, which are often intact. An avulsion fracture sometimes occurs with type II injuries, and often becomes trapped in the A2 pulley. Without an observable bony fragment on x-ray study, it is impossible to determine the degree of retraction; thus, all type II injuries should be surgically repaired within 7 days. Type III injuries involve a large avulsion fragment that is often intraarticular. The bony fragment prevents retraction past the A4 pulley and holds the tendon in near-anatomic position, obviating the need for urgent repair. Type III injuries are amenable to repair within 2 to 3 months. Type IV injuries are type III lesions with the addition of an avulsion of the FDP tendon from the fracture fragment. Type IV injuries are rare but require urgent repair because of the disruption to the tendon's blood supply.

Answer 89

The correct response is Option E. The most appropriate muscle to transfer for restoration of wrist extension is the pronator teres. The radial nerve can be injured as a result of humerus fracture and/or surgery as it crosses the spiral groove of the humerus. The resultant radial nerve palsy will cause inability to extend the wrist, fingers, and thumb. Reinnervation of the muscle ideally should be completed within 12 to 18 months after injury to allow for recovery. In this patient, who has high radial nerve palsy after humerus fracture, the time following injury has been too long, so nerve repairs or nerve transfers are not a viable option, and tendon transfer is the procedure of choice. Tendon transfer involves the use of a noncritical or expendable donor tendon to provide a missing function. The tendon to be transferred should have adequate strength and range of motion to provide the desired function. Ideally the tendon used should have synergistic action and allow for tenodesis to facilitate reeducation. The pronator teres is a median nerve–innervated muscle that has adequate power and excursion to provide wrist extension. It is typically transferred to the extensor carpi radialis brevis (as opposed to the extensor carpi radialis longus) in these cases to provide for more centrally oriented wrist extension. The brachioradialis is a radial nerve–innervated muscle and will not be functioning in this patient who has a high radial nerve palsy. In low radial nerve palsies, it can be used to restore thumb extension. The brachioradialis can also be used to restore finger or wrist extension, as well as finger or thumb flexion in the appropriate patient. The flexor carpi ulnaris would have adequate power and excursion, but it is not synergistic and it would be difficult to learn to use a wrist flexor to power wrist extension, as it provides an opposite function. This is typically used to restore finger extension, as it would take advantage of the tenodesis effect. The flexor digitorum profundus would be synergistic with wrist extension, but it does not have independent muscle bellies and its use would require sacrifice of important finger flexor activity. The palmaris longus does not have sufficient power to provide for wrist extension. It can be used as a transfer for thumb extension.

Answer 90

The correct response is Option E. The oblique retinacular ligament of Landsmeer passes volar to the axis of rotation of the proximal interphalangeal (PIP) joint, and when it is involved in a fibrotic process, it may produce hyperextension of the distal interphalangeal (DIP) joint. Tightness of this ligament can result in contractural deformity resulting in a boutonnière deformity. Inadequate checkrein release would result in persistent flexion deformity at the PIP joint but would not impact the position of the DIP joint. Scar adhesions of the flexor tendons would limit active range of motion of the digit but would not create a hyperextension deformity at the DIP joint. Extensor tendon laxity would limit active extension at the DIP joint, creating a flexion deformity rather than a hyperextension deformity.

Answer 91

The correct response is Option B. The most appropriate management of the extensor tendon tightness seen in this patient is release of the central slips. Central slip releases can be performed under local anesthesia to immediately improve flexion of the proximal interphalangeal (PIP) joint. This simple maneuver may eliminate the need for extensive soft-tissue reconstruction as long as the scar and tendon contractures are located on the dorsal aspect of the hand and the lateral bands, which supply extensor power to the PIP and distal interphalangeal (DIP) joints, are intact. The risk for subluxation of the intact lateral bands and subsequent development of a boutonierre deformity is minimal. Intratendinous lengthening is performed in patients who have contractures of the extrinsic flexor tendons resulting from cerebral palsy or stroke. Because the metacarpophalangeal (MP), PIP, and DIP joints can all be affected, this technique is primarily recommended to improve the appearance of the hand. Patients who have intrinsic tendon tightness that does not improve with therapy may be considered for release of the lateral bands. In this condition, which is often a sequela of compartment syndrome, the intrinsic tendons of the hand are foreshortened, and flexion of the PIP joint is inhibited when the MP joints are fully extended. Although the scar contractures can be released to relieve some of the stiffness in the PIP joints, the affected area should be covered with full-thickness skin grafts (instead of split-thickness grafts) because they provide superior skin quality and decrease the risk for secondary contractures.

Answer 92

The correct response is Option D. The condition most likely to account for these examination findings is intrinsic tightness. This patient exhibits exam signs consistent with stiffness as a result of intrinsic tightness. The Bunnell test for intrinsic tightness involves comparing flexion at the proximal interphalangeal (PIP) joint with the metacarpophalangeal (MCP) joint extended, to flexion at the PIP joint with the MCP joint flexed. In cases of intrinsic tightness, PIP joint flexion will decrease when the MCP joint is extended, and there is increased flexion of the PIP joint when the MCP joint is flexed. The intrinsic muscles are responsible for flexion at the MCP joints and extension at the PIP joints. When these are tight, PIP joint motion is decreased when the MCP joint is held in extension. There is increased PIP joint flexion possible when the MCP joint is placed in a flexed position because of the decreased tension on the intrinsic muscles that results with MCP flexion, allowing for improved PIP range of motion. In cases of extensor tendon shortening or tightness (extrinsic extensor tendon contracture), the opposite effect is seen. MCP joint flexion will place additional tension on the extensor mechanism, tightening it and resulting in decreased flexor function at the PIP joint, when compared with an extended MCP joint. Flexor tendon adhesions and contractures of the PIP joint capsule can result in stiffness but would give equal limitations to PIP flexion regardless of MCP joint position. Palmar fascia hypertrophy is seen in Dupuytren contracture. This contracture could potentially limit PIP extension, which might vary with MCP position, but would not limit flexion of the PIP joint as described in this item.

Answer 93

The correct response is Option B. Injuries to the ulnar collateral ligament (UCL) of the thumb metacarpophalangeal joint (skier's thumb Injury) can be successfully treated with 4 weeks of immobilization provided that the injury results in either no instability, or limited (\<30 to 35-degree laxity under load, or \<10 to 15-degree difference from the contralateral UCL under load) instability. The photographs provided show 40 to 45 degrees of laxity, which differs substantially from the contralateral (\<10 degrees) thumb. Treatment of this injury requires operative intervention. Incomplete injuries, or injuries with only mild symptomatic laxity, may benefit from occupational therapy. The adductor muscle provides a stabilizing force across the metacarpophalangeal joint and has been a target for treating mild injuries that result in some degree of instability. This would be insufficient for treating this complete rupture. In a similar fashion to strengthening the adductor muscle, addition of another force directed at providing ulnar adduction at the metacarpophalangeal joint has been proposed. As in the case of adductor strengthening, however, this would be inadequate to treat the complete rupture apparent in the clinical photos. When encountered acutely, unstable, complete ruptures of the ulnar collateral ligament of the thumb metacarpophalangeal joint are optimally treated with operative repair. Four to six weeks following the injury, direct repair may be difficult if not impossible. In this patient, the presentation for treatment occurs one year after the initial injury, making repair of the UCL extremely unlikely. On operative exploration in this patient, only a shortened stump of UCL remained attached to the metacarpal head. Chronic unstable injuries of the thumb metacarpophalangeal (MCP) joint ulnar collateral ligament (UCL) may be symptomatic via weakened grip and pinch as well as pain. Treatment in this setting will be dictated by patient needs and by the status of the joint. Patients requiring mobility and lacking arthritic degeneration at the MCP joint are candidates for UCL reconstruction. Reconstruction will typically be accomplished by use of a tendon graft, either palmaris or plantaris, placed through bone tunnels and secured through one of multiple methods (interference screws, periosteal sutures, bone anchors). Given this patient's presentation one year out from the initial injury, reconstruction is the best option.

Answer 94

The correct response is Option A. Several conditions must be met for single-stage tendon grafting to be successful. These include a hand and finger that have good passive motion, a well-healed wound with minimal scarring, and a digit that has intact nerves and arteries. This is a Boyes grade 1 injury. If the grade of injury is greater than 1, two-stage grafting should be considered with implantation of a silicone rod and additional treatment to manage the other conditions to increase motion and function, such as joint release or reconstruction for loss of motion, nerve repair/reconstruction, and pulley reconstruction. A primary repair is not going to be possible in this instance. Two-stage tendon grafting should be considered but a single stage graft can have excellent results with only one procedure. A tendon transfer is not appropriate for this situation.

Answer 95

The correct response is Option D. When patients present with zone II flexor injuries, it is optimal to repair both flexors within 10 days after the injury before the tendons retract excessively preventing primary approximation of the tendon ends. Late flexor injuries (after 2 weeks) in zones I, III, IV, and V can be managed with single-stage tendon grafting. However, when the injury is in zone II, the sheath has collapsed and tendon grafts cannot be easily pulled under intact pulleys, necessitating pulley reconstruction over a silicone rod in the first stage. Then, in a second stage, the tendon rod is replaced with the tendon graft pulled into the sheath in the proximal to distal direction after suturing the graft to the rod. The tendon is repaired first distally to bone, and then the appropriate tension is set on the proximal juncture repair of the graft to the motor tendon (usually the flexor digitorum superficialis to avoid quadriga and lumbrical plus posture). Two-stage tendon grafting in general is recommended for zone II flexor repairs that present late, require simultaneous critical pulley reconstruction (A2, A4), or if volar finger soft-tissue reconstruction is required. Tendon transfer options would not be long enough to span the defect out to the distal phalanx and the flexor digitorum profundus from other fingers should not be sacrificed. Further observation is certainly not warranted.

Answer 96

The correct response is Option B. For both two-strand and four-strand locking core repair methods, the length of core suture purchase significantly influences both resistance to gapping and also ultimate strength to breaking. The optimal length of purchase is between 0.7 and 1.0 cm. Increased length of purchase from 0.7 to 1.2 cm does not increase the repair strength. Purchase length of 0.4 or less greatly reduces repair strength.

Answer 97

The correct response is Option E. The scenario depicts a classic case of extensor pollicis longus (EPL) tendon rupture following distal radius fracture. The reported incidence of EPL tendon rupture ranges from 0.2 to 3%. Ruptures can occur after internal or external fixation due to impingement of hardware on the tendon or due to ischemic changes in the tendon due to swelling of the tendon and the third dorsal compartment. Reconstruction of the EPL tendon can be accomplished either by tendon transplantation, typically the palmaris interposition between the proximal and distal healthy segments of the EPL tendon, or by transfer of the EIP to the distal segment of EPL tendon. When identified and treated before the EPL muscles retract and shorten, equivalent outcomes can be achieved. Later treatment necessitates tendon transfer. Fusion of the thumb IP joint may be useful in flexor pollicis longus ruptures that cannot be repaired, but this would not restore thumb retropulsion. Fusion of the CMC joint can alleviate pain from basal joint arthritis, but would result in further loss of motion of the thumb. Transfer of the EIP to the abductor pollicis brevis and transfer of the anterior interosseous nerve to the recurrent branch of the median nerve are techniques for restoring thumb palmar abduction/opposition and would not restore retropulsion/extension.

Answer 98

This patient has a boutonniere deformity, in which the extensor mechanism (comprised of the central slip, transverse and oblique retinacular ligaments, and lateral bands) becomes imbalanced. In patients with this deformity, the central slip is damaged and the transverse retinacular ligament is stretched. The lateral bands begin to drift volarly (around days 10-21), eventually moving anterior to the center of rotation of the proximal interphalangeal (PIP) joint. As a result, the lateral bands flex the PIP joint, and passive extension of the PIP joint becomes impossible. There are three stages of boutonniere deformity. Patients with stage 1 deformities can passively extend the PIP joint. With stage 2, the joint becomes contracted and cannot be extended fully, but the joint itself is not yet involved. Degeneration of the joint is seen in a patient with a stage 3 boutonniere deformity. Because this patient has only a stage 1 boutonniere deformity, the most appropriate management is splinting the PIP joint in extension (ie, at 0 degrees) for a minimum of six to eight weeks. This can be performed successfully as late as six weeks after injury. Splinting of the PIP in extension helps restore central slip continuity; active DIP flexion with the PIP joint extended draws the tight, volarly displaced lateral bands into a more dorsal position while reducing DIP joint hyperextension. The distal interphalangeal (DIP) joint should be unencumbered and allowed to flex actively, and an exercise program should be initiated for joint rehabilitation. Holding the DIP joint in extension will not correct the underlying deformity. Open central slip repair is indicated if there is an open wound, but that is not the case in this scenario. Chronic Boutonniere deformity (typically injuries older than 6-8 weeks) treatment depends on how supple the PIP joint is. In cases where full passive extension of the PIP joint is still possible, splinting for longer periods (6-12 weeks) may still result in correction. Alternatively, tendon rebalancing procedures can be performed, possibly with joint replacement if there are arthritic changes.

Answer 99

The correct response is Option D. Zone 7 extensor tendon injuries are those over the dorsal wrist. The extensor indicis proprius tendon typically has the most distal muscle belly and this fact can frequently be used to uniquely identify this tendon. Extensor tendon zones are useful for describing the locations of injuries: Distal interphalangeal (DIP) Central slip to DIP Proximal interphalangeal (PIP) Metacarpophalangeal (MCP) to PIP MCP Carpometacarpal (CMC) to MCP Wrist and proximal

Answer 100

The correct response is Option B. In patients with zone II flexor tendon injuries, outcome is most dependent on the repair technique and rehabilitation protocol used. Suture techniques that employ locking loops or multiple strands have been shown to be stronger and to provide a better, longer lasting repair than the standard, two-strand modified Kessler technique. Compliance is critical to successful rehabilitation. In general, an immediate, graded early active flexion program has been shown to result in greater total active motion than early passive flexion and/or late motion programs. Repair techniques that use increased strength, combined with a more detailed early, graded active flexion program, have been shown to optimize active flexion while minimizing tendon rupture. In addition, a history of smoking has been shown to correlate with poorer outcomes regardless of the method of rehabilitation.

Answer 101

The correct response is Option B. This patient has a mallet finger deformity. No fracture was involved; therefore, it is considered a Type I mallet injury. Patients are sometimes noncompliant or not well instructed regarding how the splint is to be used. Both the Fowler tenotomy and open repair should be reserved for chronic cases of mallet finger. In fact, open repair with direct suture of the terminal tendon has shown poor results. Fusion of the distal interphalangeal joint is an extreme method of treating this condition and would not be indicated at this time. An additional six-week period of splinting would be appropriate in a compliant patient. One author has shown that mallet fingers that remain untreated for up to 12 weeks can be treated conservatively with six weeks of splinting. However, a noncompliant patient would benefit from transarticular fixation with Kirschner wires, which would be more difficult to manipulate versus splinting alone.

Answer 102

Correct answer is option A. The most effective management is profundus and superficialis tendon repair with early passive-motion protocol. Repairing the superficialis tendon not only improves strength and function but also has been shown to increase circulation to the tendon repairs. Many studies have shown that a direct correlation exists between the strength of the tendon repair and the number of core sutures used across the repair (strength is proportional to the number of sutures). Many studies have shown the strength and adhesion-prevention benefits of early passive-motion protocols. Some studies have advocated early flexion active-motion protocols, but none have found the results superior to the early passive-motion protocols. One study has also shown that early passive-motion protocols do not interfere with the outcomes of primary digital nerve repairs when Zone II flexor tendon and digital nerve injuries occur simultaneously.

Answer 103

The correct response is Option D. The most appropriate surgical procedure for the correction of the deformity described is tendon lengthening. Patients with established ischemic forearm contractures are categorized by both the Holden and Tsuge classification systems. In Holden I injuries, the arterial ischemia and venous stasis begin proximal to the forearm fascial compartment. Holden II injuries are from direct trauma, and the ischemia begins at the site of the injury. The Tsuge classification defines the extent of muscle involvement as mild, moderate, or severe. The patient described would be classified as a Holden II, mild type, because his ischemia was caused by direct trauma and his muscle involvement is limited to the deep flexors at the site of the injury. Z-plasty tendon lengthening and possible skin release and limited scarred muscle resection are sufficient. Innervated free muscle transfers are reserved for Holden I or II, severe type, injuries. Often with nerve grafting in an attempt to establish protective distal sensation and other procedures, innervated free muscle transfers are utilized to provide both function and coverage in these patients with complete loss of muscle function after ischemic injury. Muscle slide techniques are reserved for patients with Holden I, moderate injuries. These patients have ischemic changes affecting the entire muscle belly. Some of the muscles €™ contractile units should be intact. Combined with other procedures, the muscle slide permits a reduction of the distal contractures while preserving the muscle €™s residual contractile capabilities. Resection of the dorsal intrinsic muscles and part of the adductor pollicis muscle is reserved for patients with ischemic contracture of the intrinsic muscles. Intrinsic ischemic contractures may accompany any ischemic Volkmann contracture, but this will often present as the hand assuming the intrinsic-plus position following reconstruction of the extrinsic musculature. The patient described is not presenting with an intrinsic-plus deformity. Tendon transfers are used for patients with Holden II, moderate type, injuries. Proximal muscle slides are not usually performed because detachment of these healthy muscles will potentially diminish their functional capacity. Combined with other procedures, tendon transfers are used to augment any residual existing muscle function.

Answer 104

Correct answer is option C. This patient's deformity is most likely caused by the quadriga effect, which occurs as a result of excess distal pull on one profundus tendon. Because the flexor profundus tendons share a common muscle belly, any excess pull on one tendon will decrease the force and amplitude of all of the tendons. Quadriga can occur secondary to amputations in which the flexor digitorum profundus (FDP) tendon is attached to the extensor tendon or following grafting of excessively short tendons or advancement of the FDP tendon in patients with zone I injuries. Flexor tendon adhesions can occur following injury or prolonged immobilization. Decreased flexion of the affected digit only is a characteristic finding. Lumbrical plus deformity most frequently affects the index finger, which has an independent FDP tendon. Division of the distal tendon results in proximal migration of the tendon and lumbrical muscle, exacerbating tension on the lateral bands. This tension results in paradoxical extension of the proximal interphalangeal joint with attempted finger flexion. A patient with a tendon rupture would be unable to flex the long finger; the other fingers would not be affected. Triggering of the FDP tendon may be seen following tendon repair because of the excess bulk created as a result of the repair; this appears to interfere with the pulley system. Affected patients would have decreased motion of the long finger without any effect on the other fingers.

Answer 105

The correct response is Option B. The most appropriate next step in management is repeat operative exploration and repair. This patient has most likely ruptured the flexor tendon. This typically occurs four to six weeks after initial repair and is most commonly caused by excessive grip force or significant devascularization of the tendon. Further occupational therapy is not necessary in a patient who has good passive range of motion following rupture. Staged reconstruction with insertion of a silicone rod and/or delayed tendon grafting is appropriate following tendon rupture if passive range of motion of the finger is significantly limited or there is an insufficient quantity of flexor tendon sheath. Tenolysis is indicated in patients who have tendon adherence or scarring following tendon repair. This procedure is typically delayed for four to six months following the initial repair, and is most effect if the repair is intact and full passive range of motion is maintained. Arthrodesis may be considered if the flexor tendons and flexor sheath cannot be repaired or reconstructed. This procedure provides stability but results in slightly flexed positioning of the finger.

Answer 106

Correct answer is option B. The most appropriate management is continuous extension splinting of the distal phalanx. The patient has sustained a mallet injury to the left ring finger. There is tearing of the terminal extensor tendon from its insertion at the base of the distal phalanx, resulting in inability to extend the finger at the DIP joint. On occasion, these injuries may be associated with an avulsion fracture from the dorsal aspect of the distal phalanx. The majority of closed mallet injuries (Type I) in Zone I of the extensor tendon can be treated by continuous extension splinting for 6 to 8 weeks. It is important that the finger not be allowed to flex at the DIP joint during this time period to avoid disruption of healing. Arthrodesis of the DIP joint is reserved for cases of DIP joint arthritis and would not be necessary in this patient. Exploration and suture of the tendon can be performed, but results are no better than closed treatment due to the difficulty of obtaining adequate repair of the thin tendinous substance at this level. Additionally, the patient will still require prolonged immobilization of the DIP joint after open repair. Exploration and suture of the tendon is used to treat Type II (open) mallet injuries. Open repair with reinsertion of tendon into bone is performed in flexor digitorum profundus avulsion injuries. Splinting of the PIP joint in extension with the DIP joint free is used to treat Zone III extensor tendon injuries (central slip avulsion injuries).

Answer 107

The correct response is Option B. The most appropriate management at this time is division of the lumbrical tendon. This patient has a lumbrical-plus deformity, which occurs following sectioning of the flexor digitorum profundus (FDP) tendon. In patients with this deformity, the independent FDP tendon and lumbrical muscle migrate proximally. With flexion, tension is exerted by the lumbrical via the radial lateral band. During attempted flexion of the digit, this tension transmitted through the radial lateral band results in paradoxical extension of the proximal interphalangeal (PIP) joint. Division of the lumbrical insertion or resection of the lumbrical tendon will restore balanced finger flexion. Therefore, in a patient who has the acute onset of significant intrinsic tightness, the radial lateral band should be released or the lumbrical tendon should be resected. The lumbrical tendons originate from the FDP tendon and insert into the radial lateral band. These tendons pass palmar to the deep transverse intermetacarpal ligament. Division of the central slip of the extensor tendon will result in a permanent flexion deformity of the PIP joint. Division of the superficialis tendon will further weaken index finger flexion. Release of the A1 pulley is appropriate for management of flexor tenosynovitis or trigger finger in a patient who does not have rheumatoid arthritis. Although amputation at the level of the PIP joint would preclude joint hyperextension, this is an extreme measure that does not address the insertion of the lumbrical tendon.

Answer 108

The correct response is Option C. The most effective management is profundus and superficialis tendon repair with early passive-motion protocol. Repairing the superficialis tendon not only improves strength and function but also has been shown to increase circulation to the tendon repairs. Many studies have shown that a direct correlation exists between the strength of the tendon repair and the number of core sutures used across the repair (strength is proportional to the number of sutures). Many studies have shown the strength and adhesion-prevention benefits of early passive-motion protocols. Some studies have advocated early flexion active-motion protocols, but none have found the results superior to the early passive-motion protocols. One study has also shown that early passive-motion protocols do not interfere with the outcomes of primary digital nerve repairs when Zone II flexor tendon and digital nerve injuries occur simultaneously.

Answer 109

The correct response is Option F. The most appropriate description of the location of the tendon at the ankle is medial to the Achilles tendon. The plantaris tendon can present an expendable donor tendon from the lower leg for tendon grafting. The plantaris is a small, thin rudimentary muscle with a long tendon. It acts in plantar flexion at the ankle and flexion at the knee, and harvesting does not leave any donor site deficits. The plantaris originates in the popliteal fossa and travels along the posterior aspect of the calf between the soleus and gastrocnemius muscles to insert in the medial calcaneus. Although there may be some variability in the nature of its insertion, typically the plantaris tendon joins with the Achilles tendon and is found just medial to the Achilles tendon at the ankle in the superficial posterior compartment. It is present in about 90% of people and is found at a higher incidence than the palmaris longus tendon. The plantaris can provide up to double the length of tendon graft compared with the palmaris longus, and it would be a good choice for reconstructing multiple tendon defects where greater length is needed.

Answer 110

The correct response is Option A. The Fowler central slip tenotomy is well known, but seldom used. The central slip or tendon inserts on the base of the middle phalanx and acts on the proximal interphalangeal (PIP) joint. A central slip tenotomy will rebalance the extensor mechanism such that the terminal tendon will be able to extend the distal interphalangeal (DIP) joint in patients with a chronic mallet finger. However, many clinical and anatomical studies have shown that the central slip tenotomy may not restore full extension in patients with a preexisting lag of approximately 36 degrees. Tension on the lateral bands also extends the DIP. Release of the oblique retinacular ligament (ORL) or the lateral bands would, therefore, not assist in extension of the DIP joint. Releasing the terminal tendon will only worsen the mallet finger because this is the structure that is disrupted in an open or closed mallet injury. Release of the triangular ligament would likely create a boutonnière deformity. PIP extension (produced by other tissues in the extensor mechanism) elongates the ORL, creating passive tension that extends the DIP.

Answer 111

The correct response is Option C. The position of safe immobilization (POSI), also called the intrinsic plus position, was described initially by J.I.P. James (British orthopedic surgeon) and is recognized as the correct position in which to immobilize the hand safely following injury or surgery. The wrist is placed in 0 to 30 degrees of extension, metacarpophalangeal (MCP) joints in 70 to 90 degrees of flexion and interphalangeal (IP) joints in full extension. This position creates pretension on the collateral ligaments of the wrist and the MCP and IP joints of the hand, thereby decreasing the risk of stiffness and contracture.

Answer 112

The correct response is Option A. This patient has sustained a “jersey finger” injury. The digital cascade is disrupted because there is no flexion force at the distal phalanx of the ring finger. In this patient, the flexor digitorum profundus tendon became avulsed from the distal phalanx (Zone I) when the patient attempted to actively flex the distal interphalangeal joint with the finger in forced extension. Three types of avulsion injuries to the flexor digitorum profundus tendon have been described: Type I: The flexor digitorum profundus tendon retracts into the palm Type II: The flexor digitorum profundus tendon retracts to the proximal interphalangeal joint Type III: The flexor digitorum profundus tendon is entrapped at the A4 pulley The patient is still able to flex the proximal interphalangeal joint, but the joint may be tender if there is blood in the flexor sheath or if he has sustained a Type II injury. The distal phalanx is drawn into extension because of the unopposed pull of the terminal tendon. Rupture of one slip of the flexor digitorum superficialis tendon would not result in loss of function of the flexor digitorum profundus tendon or flexion of the distal interphalangeal joint.

Answer 113

The correct response is Option B. This 40-year-old man has a capillary malformation, or port-wine stain. These lesions are often seen in the distribution of the abducens (VI) and facial (VII) nerves. If left untreated, cobblestoning and progressive darkening may occur due to ectasia of the vessels within the capillary malformation. An arteriovenous malformation is a high-flow lesion often characterized by a palpable thrill or bruit. Compression of the lesion results in occlusion of the associated arteriovenous fistula, causing a baroreceptor response and an increase in blood pressure. This leads to a decrease in heart rate and is known as the Branham sign. Hemangiomas are vascular tumors that appear just after birth and rapidly enlarge during the first year of life. Because spontaneous regression is common, conservative management is suggested for non-life-threatening lesions that do not obstruct the airway or visual axis. Lymphatic malformations, also known as cystic hygromas, occur most frequently in the head and neck region and often enlarge in response to an adjacent infection. Recurrent swelling can lead to scarring, which will significantly decrease the size of the lesion. Venous malformations are low-flow lesions composed of dilated venous channels. These lesions are compressible and have a propensity to fill with blood when the patient changes body positions. When the malformation is associated with thrombosis, pain may result.

Answer 114

The correct response is Option B. The flexor digitorum superficialis (FDS) tendon flexes the proximal interphalangeal (PIP) joint. The flexor digitorum profundus (FDP) tendon can also flex the PIP joint, in addition to flexing the distal interphalangeal (DIP) joint. To confirm that the FDS tendon is flexing the PIP joint, FDP motion must be excluded. The FDP tendons to the long, ring, and little fingers share a common muscle belly. Thus, holding the long and little fingers in extension will prevent the FDP to the long, ring, and little fingers from firing. Any flexion of the PIP joint of the ring finger must then be caused by the FDS tendon. Holding the DIP joint of the ring finger in extension will prevent DIP flexion. It will not, however, prevent the pull of the FDP tendon from being transmitted to the PIP joint. Holding the long, ring, and little fingers flexed at the MCP joint will not exclude FDP motion. Holding the MCP joint of the ring finger extended will not exclude FDP motion. Asking the patient to extend will not assess the integrity of a flexor tendon such as the FDS.

Answer 115

The correct response is Option C. Finger flexion results from the actions of the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) tendons. The FDS tendon inserts into the middle phalanx and provides for flexion at the proximal interphalangeal (PIP) joint. The FDP tendon inserts into the distal phalanx and is the only tendon that provides flexion at the DIP joints. Because it also crosses the PIP joint, the pull of the FDP tendon can result in flexion at the PIP joint as well. To independently examine the flexor tendons, the FDP tendon can be neutralized by holding the remaining fingers in extension. Due to a common muscle belly, the FDP will not act upon the finger, allowing inspection of the FDS tendon function by evaluating PIP joint flexion in this situation. The patient has sustained a flexor tendon laceration in the region of the carpal tunnel. On physical examination, there is absence of flexion function at the index finger of the PIP joint when the remaining fingers are held in extension, indicating laceration to the flexor digitorum superficialis of the index finger. At the level of the carpal tunnel, the flexor tendons travel through a fibro-osseous canal, which contains nine flexor tendons along with the median nerve. The FDS tendons of the middle and ring fingers are most superficial, with the FDS tendons of the index and small fingers deep to them. The FDP tendons lie parallel to each other at the deepest aspects of the carpal tunnel along the bone. The flexor pollicis longus is the most radial structure within the carpal tunnel. The cross-sectional anatomy of the wrist at the level of the carpal tunnel is diagrammed, along with the corresponding tendon locations in the two images shown: A – FDS middle B – FDS ring C – FDS index D – FDS small E – FDP index F – FDP middle

Answer 116

The correct response is Option D. Tendon rupture can occur early or late, up to 6 to 7 weeks, with days 7 to 10 being most common. Reoperation with repair of the previously repaired tendons will yield results similar to primary repair. Therefore, discontinuation of therapy and rod placement are incorrect. Repair should be undertaken before 2 weeks due to tendon shortening. Repair of both tendons will retain independent finger motion with greater power and decreased chance of proximal interphalangeal joint hyperextension. There will also be a better bed for FDP gliding. Therefore, flexor digitorum superficialis transfer is incorrect. Arthrodesis is reserved for failed treatment.

Answer 117

Correct answer is option B. The scenario described provides a classic example of a distal flexor tendon avulsion. Because of several potential factors, the ring finger is the most common finger to present with this type of injury. The flexor digitorum profundus of the ring finger has a less robust insertion at the distal phalanx than the long finger, which is a tip-off in the vignette for this classic injury. Yet the ring finger is similarly involved in the type of hyperextension force, or resisted flexion force, which generates this injury. The little finger does not present as much with this injury either. Flexor tendon reinsertion is correct, because the indicated management is early operation and reinsertion, if possible, of the avulsed tendon. This can be accomplished in a variety of ways, but that discussion is not central to the question. Splinting, followed in 2 weeks by range-of-motion exercises is wrong, because that answer describes how one might treat a sprain, which this is not. If one treated the tendon avulsion conservatively, and incorrectly, by splinting, the surgeon would lose the window for early repair, and the outcome for the patient would be poor. Secondary or delayed reconstruction in these cases is often not possible, and when possible, they often have results inferior to immediate repair. Tendon transfer is wrong because tendon transfers are not used for immediate repair of flexor avulsions. Tendon transfers are useful for secondary reconstruction in nerve palsies, for example. But they are not relevant to this distal and acute injury, confined to a single digit. Open reduction and pin fixation of the middle phalanx is wrong because the injury is not a fracture of the middle phalanx. It is true that one form of the flexor avulsion can involve an avulsion fracture off of the volar aspect of the distal phalanx, and that reinsertion of the fragment is part of the repair. But flexor tendon avulsion does not involve fracture of the middle phalanx. Furthermore, this is not an avulsion of the flexor digitorum sublimis because the patient flexes at the PIP with minimal discomfort, as per the vignette. End-to-end flexor tendon repair is wrong because this injury is a tendon avulsion from a distal bony insertion. There is no distal tendon to which to perform an end-to-end repair. Successful repair of a flexor digitorum profundus (FDP) avulsion really requires some form of anchoring of the distal FDP to distal phalanx bone.

Answer 118

Correct answer is option E. The oblique retinacular ligament of Landsmeer passes volar to the axis of rotation of the proximal interphalangeal (PIP) joint, and when it is involved in a fibrotic process, it may produce hyperextension of the distal interphalangeal (DIP) joint. Tightness of this ligament can result in contractural deformity resulting in a boutonnière deformity. Inadequate checkrein release would result in persistent flexion deformity at the PIP joint but would not impact the position of the DIP joint. Scar adhesions of the flexor tendons would limit active range of motion of the digit, but would not create a hyperextension deformity at the DIP joint. Extensor tendon laxity would limit active extension at the DIP joint, creating a flexion deformity rather than a hyperextension deformity.

Answer 119

The correct response is Option A. Avulsion injury of the flexor digitorum profundus (FDP) tendon represents a flexor tendon injury within zone 1 of the flexor tendon sheath. The anatomy of the pulley and vincular systems affects both the level of FDP tendon retraction and the ultimate prognosis. FDP avulsion injuries were classified into three types by Leddy and Packer in 1977. A type I injury describes tendon retraction into the palm, with the tendon tethered by the lumbrical origin. With this injury, both the vinculum profundus longus (VLP) and brevis (VBP) are ruptured. As a result, there is a substantial loss of both the intrinsic (periosteal) and extrinsic (vincular) vascular supply to the tendon. In type II injuries, the FDP tendon retracts to the level of the proximal interphalangeal joint. In this scenario, the VBP is disrupted, but the VLP remains preserved as it arises at the level of the proximal interphalangeal (PIP) volar plate. In type III injuries, retraction to the level of the A4 pulley of the middle phalanx is seen; these injuries are usually defined by an associated large bony fragment incarcerated within the A4 pulley. In direct contrast with type I injuries, both vincula are usually intact in type III injuries because the VBP originates at the distal portion of the middle phalanx. The Leddy and Packer classification has been expanded to include and better classify distinct injury patterns. Type IV injuries are rare and unique in that they include a large avulsion fragment incarcerated at the A4 pulley, along with rupture of the FDP tendon insertion off this osseous fragment, with secondary tendon retraction into the finger or palm. Type V injuries are complex and defined by the presence of concomitant osseous distal phalanx avulsion and distal phalanx fracture.

Answer 120

The correct response is Option E. No intervention is indicated for this patient. The principles of tendon repair and reconstruction have evolved since the first description of primary tendon repair in Zone II in 1967. Proper patient selection is essential before attempting any reconstruction to restore functional motion. The indications for grafting or reconstructing through an intact flexor digitorum superficialis (FDS) are narrow, and sacrifice of an intact FDS is generally not recommended. Most of the functional arch of motion is maintained with the superficialis tendon, and many patients will function well with an FDS digit alone. Profundus reconstruction through an intact FDS is most often reserved for patients between 10 and 21 years old with high occupational demands for dexterity such as artists or musicians. This patient is beyond the recommended age range for an optimal outcome and is reporting no functional deficits as a result of her injury. In addition, delayed symptoms may give a clue to the patient’s ability to comply with rigorous postoperative therapy. Delayed primary repair can be attempted up to several weeks after a flexor tendon injury, and up to 6 weeks in pediatric patients. However, 9 months is well beyond the time when a primary repair would be possible. The FDS from an adjacent finger can be used as the proximal motor in cases of tendon graft reconstruction or tendon repair rupture. This is a consideration if the native proximal stump of the profundus is significantly damaged or scarred and has poor excursion. In this patient, reconstruction is not indicated, and nothing is mentioned regarding the proximal tendon. A distal interphalangeal (DIP) joint arthrodesis may be indicated if the DIP joint is unstable with a well-functioning proximal interphalangeal (PIP) joint. Tenodesis of the flexor digitorum profundus stump is another option for soft-tissue DIP stabilization. Tendon reconstruction is indicated when a delay in treatment makes primary tendon repair impossible. A healed wound with full passive range of motion, absence of significant scarring, and an intact flexor retinacular pulley system are considered prerequisites for a single-stage reconstruction. In any other situation, a two-stage reconstruction with implantation of a temporary silicone rod is indicated. This would be the reconstructive strategy of choice for this patient if the FDS tendon were also involved in the original injury.

Answer 121

The correct response is Option D. Patients with cerebral palsy typically have cognitive, developmental, and sensory deficits that affect motor function. Cerebral palsy can be characterized as spastic, with fluctuations in muscle tone, or as a motion disorder, involving ataxia, dyskinesia, and tremors. Although improvement is difficult to achieve in those affected by motion disorders, some children with spastic cerebral palsy have enhanced hand function following surgery. Important elements included in the preoperative testing of patients with cerebral palsy are evaluation of cognition, hand placement, and sensibility. In patients who fail to meet the minimum criteria in these areas, the primary goal of surgery is improvement of hygiene and not necessarily of hand function. Cognition is determined by intelligence quotient (IQ) testing; children can be classified as normal (within a standard deviation of the norm), educable (IQ of 50 to 70), and trainable (IQ of 30 to 50). Hand placement is measured by asking the child to place one hand on the head initially and then on the opposite knee. This maneuver tests range of motion, precision of placement, and time required to complete the task. Typically, only those children who can perform this task within five seconds can be expected to benefit from surgery. Sensibility testing varies according to the age of the child. Texture discrimination is the recommended test for children 2 to 3 years of age; object identification is appropriate for those from 4 to 5 years of age, and graphesthesia is tested in children ages 6 to 9 years. In children older than 9 years, sensibility is tested by measuring moving two-point discrimination. Functional improvement following surgery can only be expected in those children who can successfully discriminate texture, identify objects, or exhibit graphesthesia, or those who have moving two-point discrimination of less than 10 mm. Because this 12-year-old boy with spastic cerebral palsy has both poor cognition and sensibility, improvement of hygiene will be the primary goal of any surgical procedure. Therefore, transfer of the flexor digitorum superficialis tendon to the flexor digitorum profundus tendon is recommended to eliminate the clenched fist deformity and relieve the maceration and disintegration of skin that is typically associated with this deformity. This tendon transfer lengthens yet weakens the finger flexors. Transferring the flexor carpi ulnaris to the flexor digitorum profundus will only increase the flexion force and aggravate the deformity. Transfer of the flexor digitorum profundus to the extensor digitorum communis will not resolve the clenched fingers. In patients who have a deformity of this severity, arthrodesis of the wrist is recommended instead of tendon transfers to the wrist extensors.

Answer 122

The correct response is Option B. The Brand transfer uses the extensor carpi radialis longus or brevis as a donor motor to correct clawing of the fingers. It can be used to correct ulnar (ring and small finger) clawing or clawing of all four fingers. In either case, a tendon graft is needed to bridge the gap between the native distal limit of the extensor carpi radialis longus or brevis (on the index or long finger metacarpal base, respectively) to the transfer insertion on the lateral band at the proximal phalanx level. The transfer can be passed through the interosseous membrane in the forearm and then through the carpal tunnel or the intermetacarpal spaces in the hand. The transfer must pass volar to the deep transverse metacarpal ligament to have the correct vector of pull. The extensor digitorum longus provides four tendon slips distally, each with its own paratenon, but has one tendon coming off the muscle proximally. A photograph is shown. There is minimal donor site morbidity in the foot due to the retained function of the extensor digitorum brevis. Palmaris brevus has no tendon and cannot be used as a graft donor. Abductor digiti quinti can be used as a donor muscle for thumb opposition transfer, most commonly in children. It has a very short tendon and cannot be used for anti-claw transfers. In addition, due to this patient’s injury, the abductor digiti quinti is likely denervated and would not be functional for a transfer. Flexor digitorum superficialis (FDS) of the long finger can be used for anti-claw transfers. The tendon can be split along the plane of Camper’s chiasm to create two distal slips for insertion. It is well suited as an anti-claw transfer in patients with isolated ulnar nerve palsy. The FDS tendon cannot be split into four slips for insertion, as would be needed in this patient, and the power of one FDS muscle is insufficient to correct clawing in four fingers. In addition, the FDS resides superficial to the median nerve. In a patient who sustained a forearm laceration with injury to the median nerve, the overlying FDS is also likely to have been injured. Pronator teres is the most common donor motor to restore wrist extension in patients with radial nerve palsy. It has a very short tendon and is not used for anti-claw transfers.