Hand/Upper Extremity Flashcards
A 47-year-old woman comes to the office after sustaining an injury to the left wrist after
falling on her outstretched hand. Examination shows pain of the radial aspect of the left
wrist and anatomical snuffbox. Scaphoid fracture is suspected. When obtaining
posterior-anterior x-ray studies, which of the following is the optimal positioning of the
wrist for evaluation of the entire scaphoid?
A ) Wrist in 20 degrees of radial deviation, 20 degrees of wrist extension
B ) Wrist in 20 degrees of radial deviation, 20 degrees of wrist flexion
C ) Wrist in 20 degrees of ulnar deviation, 20 degrees of wrist extension
D ) Wrist in 20 degrees of ulnar deviation, 20 degrees of wrist flexion
E ) Wrist in neutral radial/ulnar position, neutral flexion/extension
The correct response is Option C.
Scaphoid fractures are the most common carpal fracture and frequently occur after a fall
onto an extended and radially deviated wrist. Initial workup often involves plain x-ray
studies, which have a sensitivity of approximately 85%. The optimal position of the wrist when imaging scaphoid fractures includes ulnar deviation and wrist extension, which allows for evaluation of the long axis of the scaphoid. CT scan or MRI may be used as additional imaging if plain x-ray studies do not demonstrate a fracture, yet there is high clinical
suspicion.
A 50-year-old woman comes to the emergency department after sustaining an avulsion
injury of the right ring finger proximal interphalangeal (PIP) joint. A photograph is shown.
Examination shows the central slip is disrupted, and the inside of the PIP joint is visible
through the dorsal wound. The patient is able to actively extend the PIP joint. Which of
the following anatomical structures allows the patient to extend the PIP joint?
A ) Extrinsic extensor tendon
B ) Interosseous muscle tendon
C ) Lateral conjoined tendon
D ) Oblique retinacular ligament
E ) Sagittal band
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.
A 40-year-old man comes to the office because of an 8-month history of intermittent
ischemic change to the right ring finger. The patient reports intermittent coolness, pallor,
pain, and cold sensitivity. Angiogram demonstrates a tortuous ulnar artery at the wrist and faint radial digital artery runoff into the right ring finger. Digital brachial index (DBI) of the ring finger is 0.9. Which of the following is the most appropriate first step in
management?
A ) Botulinum toxin type A injection
B ) Excision and vein grafting of the ulnar artery
C ) Ligation of the thrombosed ulnar artery segment
D ) Thrombectomy and heparin drip
E ) Trial of acetylsalicylic acid and nifedipine
The correct response is Option E.
This patient presents with hypothenar hammer syndrome. The gold standard for establishing
the diagnosis is angiography. Aortic arch and upper extremity arteriography is the study of
choice. In hypothenar hammer syndrome, the pathognomonic angiographic features can
include tortuosity of the ulnar artery with a corkscrew appearance, aneurysm formation,
occlusion of the ulnar artery segment overlying the hook of the hamate, occluded digital
arteries in the ulnar artery distribution, and demonstration of intraluminal emboli at sites of
digital obstruction.
Treatment depends largely on the severity of the ischemia. The therapeutic strategy is
controversial because there are limited studies on this problem. For most patients with
milder or transient/intermittent symptoms, nonsurgical treatment will be sufficient,
particularly in the setting of vasospasm with adequate collateral circulation. Conservative
nonoperative care may include smoking cessation, avoidance of further trauma (may require change of occupation), padded protective gloves, cold avoidance, calcium channel blockers (nifedipine, diltiazem), antiplatelet agents or anticoagulation, local care of fingers with necrosis, and pentoxifylline to reduce blood viscosity.
More severe symptoms (persistent ischemia, soft tissue loss/gangrene, ulnar nerve
symptoms) or symptoms refractory to nonoperative management require consideration of
surgical intervention. Surgical options in this setting include arterial ligation (assuming an
intact radial/palmar arch), resection of thrombosed arterial segment or aneurysm with end-to-end anastomosis, or resection and vascular reconstruction with vein or artery graft. Some argue that best outcomes are seen in those treated with surgical resection and
reconstruction. The benefits of surgical treatment include removal of the source of
embolism, removal of the painful mass, relief of ulnar nerve compression, and creation of a
local periarterial sympathectomy. As this patient has mild and intermittent
symptoms without evidence of soft-tissue loss or gangrene or any evidence of ulnar nerve
irritation, a trial medical management is indicated. Botulinum toxin type A is indicated for vasospasm secondary to Raynaud syndrome or disease and would not be part of the medical
management algorithm.
2019
A 17-year-old boy comes to the office because of ongoing pain of the right hand after he
punched a wall 5 days ago. Physical examination demonstrates tenderness of the fifth carpometacarpal joint. Posteroanterior, oblique, and lateral x-ray studies taken at an
urgent care facility were read as negative by the radiologist. Which of the following
additional radiographic views is most likely to help confirm this patient’s diagnosis?
A ) Anteroposterior with 30 degrees of pronation from full supination
B ) Carpal tunnel view with wrist in full extension
C ) Clenched fist lateral in neutral forearm position
D ) Lateral with 15 degrees of supination from neutral forearm position
E ) Posteroanterior with 45 degrees of supination from full pronation
The correct response is Option A.
Injuries to the fifth carpometacarpal joint, including subluxation, dislocation, and fracture
dislocation, are often missed with standard two-view and three-view hand images. Two
views have been suggested to help detect this subtle injury:
- Anteroposterior view with forearm pronated 30 degrees from full supination. This view
shows more clearly the profile of the articulation between the hamate and fifth metacarpal base. (This is similar to the “reverse oblique” view, which is typically done in 45 degrees of pronation and might also be useful.) - Lateral with 30 degrees of pronation. This view is especially helpful for detecting
subluxation of the metacarpal dorsally off of the hamate. In some cases, CT scan may be
warranted if plain films are inconclusive
When considering dislocations of the thumb carpometacarpal (CMC) joint, which of the
following is most correct regarding which vector of dislocation would occur with injury to
the stabilizing ligament?
Injured Ligament Vector of Dislocation
A ) Dorsal intercarpal radial
B ) Dorsoradial dorsal
C ) Intermetacarpal ulnar
D ) Radiocarpal dorsal
The correct answer is B.
The CMCJ is very important for hand function and plays a key role in pinch and grasp. The
increased range of motion inherent to the thumb CMCJ is attributed to the anatomy of the joint. The biconcave saddle shaped articular surface of the CMCJ also provides some inherent stability.
Motion allowed by the joint includes flexion, extension, adduction, abduction, circumduction.
Stabilizing ligaments and joint capsule further reinforce the joint, thus thumb CMCJ dislocations are rare injuries. These injuries account for less than 1% of hand injuries.
There are five major stabilizing ligaments to the CMCJ: anterior (volar) oblique, ulnar collateral,
intermetacarpal, dorsoradial, and dorsal (posterior) oblique. These ligaments are critical stabilizers during motion. The volar oblique ligament and dorsoradial ligaments are considered to be the most
important resistive forces in dislocation in cadaver studies. Reports of traumatic thumb CMCJ dislocation have been in a dorsal vector. The volar oblique ligament was originally thought to be the critical resistive ligament; however, recent literature has supported the dorsal complex (includes the dorsoradial and posterior oblique ligaments) are the most critical for restraint of the joint, thus are injured in dorsal dislocations. Timely recognition is important for these injuries as
immediate reduction and casting or splinting for 4 to 6 weeks may be adequate to prevent
recurrence. However, these injuries are often missed on radiologic examination or may be
persistently unstable. Closed reduction and Kirschner wire fixation may be adequate for treatment in persistently unstable injuries. Some authors advocate for open reduction and ligament reconstruction. Delayed treatment especially beyond three weeks will likely require open reduction
and ligament reconstruction. These injuries are often missed on x-ray examination as they can be subtle especially in the setting of more obvious trauma. Inadequate treatment puts these patients at
increased risk for subsequent posttraumatic osteoarthritis given the joint malalignment.
The radiocarpal and dorsal intercarpal ligaments are wrist stabilizer not thumb CMCJ stabilizers.
2019
