Rheumatoid Hand Flashcards
A 60-year-old woman with a history of rheumatoid arthritis presents with a boutonnière deformity of the long finger. Which of the following is the most likely cause of the deformity?
A) Destruction of the cartilage of the proximal interphalangeal joint
B) Dorsal subluxation of the lateral bands at the proximal interphalangeal joint
C) Metacarpophalangeal joint subluxation
D) Rupture of the distal extensor tendon
E) Synovitis at the proximal interphalangeal joint
The correct response is Option E.
The posture of a boutonnière is flexion of the proximal interphalangeal (PIP) joint and hyperextension of the distal interphalangeal joint. The common injury for non-rheumatoid patients that suffer traumatic injuries that lead to the deformity is a rupture of the central slip that means no active extension at the PIP joint. Over time, the lateral bands slip volarly and cause hyperextension of the distal joint. Synovitis of the PIP joint leads to subsequent attenuation of the central slip, which leads to the same deformity.
2018
A 64-year-old woman with rheumatoid arthritis is evaluated for abrupt onset of inability to extend the ring and little fingers of the left hand. Surgical exploration confirms attritional tendon rupture and caput ulnae syndrome. In addition to tendon reconstruction, which of the following interventions is most likely to prevent recurrence of this condition?
A) Distal ulna resection
B) Proximal row carpectomy
C) Radiocarpal arthrodesis
D) Scaphoid excision and four-corner fusion
E) Trapeziectomy and ligament reconstruction
The correct response is Option A.
Darrach procedure, or distal ulna resection, is a well-established procedure to treat distal radioulnar joint (DRUJ) arthritis and distal ulnar instability such as in caput ulnae syndrome. A dorsal approach is used to gain access to the DRUJ via dorsal fifth extensor compartment approach. The triangular fibrocartilage complex (TFCC) and extensor carpi ulnaris (ECU) sheath are preserved. Excision of the distal ulnar head is performed proximal to the radial sigmoid notch.
DRUJ arthritis and instability may result in attritional rupture of the extensor tendons due to tendons abrading against the dislocated, eroded ulna head as well as restriction of forearm rotation. Thus, the aims of treatment for DRUJ arthritis are pain relief, prevention of attritional tendon rupture if the patient presents prior to tendon rupture, and improvement of forearm rotation.
These aims are commonly achieved using a Darrach procedure or Sauvé-Kapandji procedure and less commonly by ulnar head replacement arthroplasty. The Sauvé-Kapandji procedure was introduced amid concerns over ulnar translocation of the carpus following resection of the distal ulnar head as done in the Darrach procedure, yet both procedures have shown good outcomes in the treatment of DRUJ arthritis. In fact, a recent systematic review found no significant difference in outcomes between the two procedures in rheumatoid arthritis patients.
Proximal row carpectomy and scaphoid resection and four-corner fusion are both used to treat wrist arthritis, but are usually for osteoarthritis such as with SLAC and scaphoid nonunion advanced collapse (SNAC) wrist, and are not generally used in rheumatoid arthritis patients. Trapeziectomy and ligament reconstruction are procedures used to treat acarpal arthritis of the thumb, not DRUJ arthritis. Radiocarpal arthrodesis is a treatment for radiocarpal arthritis, and not DRUJ arthritis with caput ulnae.
2018
A 56-year-old woman is evaluated for the sudden, painless inability to flex the interphalangeal joint of the right thumb. Medical history includes rheumatoid arthritis. There is no history of antecedent trauma to the hand. Physical examination shows that flexor pollicis longus tenodesis is absent. X-ray studies show an osteophyte along the volar aspect of the scaphoid. Which of the following is the most appropriate next step in management?
A) Anterior interosseous nerve decompression
B) Extensor indicis proprius (EIP) tendon transfer
C) Palmaris longus tendon grafting with osteophyte resection
D) Primary tendon repair
E) Observation
The correct response is Option C.
This patient has an atretic flexor pollicis longus (FPL) tendon rupture due to a scaphoid osteophyte. This is termed a Mannerfelt lesion. FPL ruptures are the most common flexor tendon ruptures in patients with rheumatoid arthritis. The underlying pathophysiology is secondary to osteophyte formation along the volar aspect of the scaphoid. Surgical treatment can include tendon transfer, tendon grafting, or interphalangeal joint fusion to correct the deformity. Treatment should include exploration of the carpal tunnel with resection of the underlying osteophyte to avoid additional attritional tendon ruptures. Due to the fraying of the tendon caused by the osteophyte, primary repair of the FPL tendon is not typically feasible. Treatment options include FDS tendon transfer and palmaris longus tendon graft. EIP tendon transfer is typically employed for extensor tendon ruptures in rheumatoid patients.
An incomplete anterior interosseous nerve (AIN) palsy can mimic FPL rupture. Physical examination allows differentiation between AIN palsy and FPL rupture. In the setting of AIN palsy, tenodesis of the IP joint will still be present with MCP hyperextension of the thumb. Initial management of AIN neuropathy consists of observation and splinting. Nerve conduction studies can be of diagnostic as well as prognostic value. Surgical exploration and decompression of the anterior interosseous nerve is a consideration after failure of nonoperative management of a compression neuropathy.
2018
A 60-year-old man comes to the office because of a 20-year history of rheumatoid arthritis. Which of the following is the most likely thumb deformity in this patient?
A) Boutonnière
B) Clinodactyly
C) Gamekeeper’s thumb
D) Swan-neck
E) Thumb-in-palm
The correct response is Option A.
Boutonnière deformity is the most common deformity in rheumatoid arthritis thumbs. Swan-neck deformity is the second most common deformity. The pathophysiology begins with metacarpophalangeal (MCP) joint synovitis which stretches the dorsal joint structures. The extensor pollicis brevis (EPB) tendon insertion is disrupted leading to a flexion deformity. Next, the extensor pollicis longus (EPL) tendon subluxes volar early causing flexion of the proximal phalanx. Early treatment includes synovectomy and extensor reconstruction and late treatment the MCP joint arthrodesis. Swan-neck deformity begins with carpometacarpal (CMC) joint synovitis causing bony erosion of the joint. The CMC joint will dorsiflex and radially subluxate causing an adduction contracture of the first metacarpal leading to hyperextension of the MCP joint. Gamekeeper’s thumb occurs from ulnar collateral ligament weakness. Thumb-in-palm deformity is seen in patients with cerebral palsy. Thumb clinodactyly is a congenital disorder.
2017
A 55-year-old woman is evaluated for continued weakness and deformity of the right thumb 6 months after a ligamentous reconstruction, tendon interposition arthroplasty for carpometacarpal degenerative disease. Which of the following is the most likely reason for her continued symptoms after arthroplasty?
A) Lack of a bone tunnel for the ligamentous reconstruction
B) Metacarpophalangeal hyperextension
C) Not pinning the metacarpal to maintain the joint space
D) Removal of the entire trapezium
E) Use of only half of the flexor carpi radialis for the ligamentous reconstruction
The correct response is Option B.
Hyperextension of the metacarpophalangeal (MCP) joint is part of the progression of the degeneration that affects the thumb basal joint. The hyperextension compensates for the adduction of the thumb base so that the thumb tip can be placed where it is most functional for pinch and grasp. Failure to address hyperextension greater than 30 degrees in MCP joints associated with basal joint arthritis has been shown to lead to weakness and poor hand function.
Multiple procedures have been proposed for treatment of basal joint arthritis. These include metacarpal osteotomy for early-stage conditions, trapeziectomy with or without tendon reconstruction, and interposition and trapeziometacarpal arthrodesis. Little difference in outcomes has been shown when comparing the different procedures that include trapeziectomy and the simple removal of the trapezium as the most critical portion of the procedure.
Taking the whole flexor carpi radialis (FCR) for the suspension has shown a small difference in wrist kinematics. No studies have shown whether the whole or half of the FCR makes a difference in the success of the suspension.
Multiple successful procedures have been described that do not include a bone tunnel for anchoring the suspension to the base of the thumb metacarpal. Removal of the entire trapezium is the most important part of the operative procedure when treating basal joint arthritis surgically. Pin fixation of the metacarpal after trapeziectomy helps to prevent metacarpal subsidence and maintenance of thumb length but is not necessary with a ligamentous reconstruction as in this patient.
2016
A 45-year-old woman who has a 15-year history of rheumatoid arthritis comes for evaluation because of the inability to actively extend the metacarpophalangeal (MCP) joints of the right small and ring fingers. On examination today, she has near full passive motion of all fingers and is able to actively extend the thumb, index, and long fingers. Photographs are shown. She is unable to hold the ring and small fingers in extension when they are passively extended. X-ray studies show severe destructive arthropathy of the wrist, MCP, and proximal interphalangeal joints. There is ulnar drift and subtle volar subluxation of the MCP joint in all fingers; the ulnar head is prominent dorsally and is unstable. Which of the following is the most likely cause of her inability to actively extend the MCP joints of the ring and small fingers?
A) MCP joint contracture
B) Posterior interosseous nerve palsy associated with elbow synovitis
C) Rupture of the extensor tendons in zone VII
D) Rupture of the sagittal bands
E) Volar subluxation of the MCP joints
The correct response is Option C.
Extensor lag of the fingers is a common problem in patients with rheumatoid arthritis and severe wrist and finger arthropathy. Persistent synovial inflammation results in periarticular osseous destruction and weakening of the stabilizing ligaments. Any of the choices can potentially cause a restriction of finger extension at the metacarpophalangeal (MCP) joints, but only rupture of the extensor tendons would result in the constellation of findings observed here. This patient has severe wrist arthritis and dorsal prominence of the ulnar head (unstable). This can result in attritional ruptures of the extensor digiti minimi and ulnar-sided extensor digitorum communis tendons; treatment is resection of the ulnar head and tendon transfer to restore extensor function.
Posterior interosseous nerve palsy resulting from synovitis about the radiocapitellar joint is well described in patients with rheumatoid arthritis, but would affect extension of all fingers and the thumb. Rupture and subluxation of sagittal bands would lead to inability to actively extend the MCP but, in contrast to extensor tendon ruptures, full extension can be maintained after the fingers are passively extended. MCP joint contracture would limit active and passive finger motion.
2016
A 57-year-old right-hand–dominant woman with rheumatoid arthritis presents with 10/10 pain of the right thumb that is preventing her from painting, her primary activity. X-ray study shows rheumatoid changes in multiple joints; right thumb carpometacarpal (CMC) joint is consistent with Eaton stage 3-4 disease. On physical examination, the right thumb metacarpal base is prominent. Grind test result is positive. Which of the following is the most appropriate management to help this patient resume her normal activities?
A) Arthrodesis of the thumb CMC joint
B) Pyrocarbon implant arthroplasty of the thumb CMC joint
C) Referral to a rheumatologist for infliximab
D) Regimen of splinting, rest, and ibuprofen 800 mg 3 times daily
E) Trapeziectomy with ligament reconstruction and tendon interposition
The correct response is Option E.
The patient described has a severe case of thumb carpometacarpal (CMC) joint arthritis keeping her from doing her activities of daily living. Given the severity of her disease, splinting, rest, and anti-inflammatory medications may temporize the problem, but will likely not provide her the degree of symptomatic improvement to allow her to return to her desired activities.
Trapeziectomy with ligament reconstruction and tendon interposition is a good option for this patient, since she clearly has advanced CMC disease and seeks function requiring minimal strength with preservation of mobility postoperatively. If she were a laborer or needed significant grip strength, this option would be less acceptable.
Infliximab (Remicade) is a reasonable option when multiple joints are significantly involved. Because this patient primarily has single joint disease, the systemic side effects of infliximab, most commonly infections and rarely malignancy, do not justify its use in this patient.
Arthrodesis would eliminate this patient’s pain, but it would also limit thumb mobility, potentially negatively affecting her fine-motor work. Fusion of that joint would make opposition difficult and may alter the way she holds her paintbrush. Although FDA approved, thumb CMC silicone implants are inferior to trapeziectomy with ligament reconstruction and tendon interposition. Pyrocarbon implant arthroplasty is intended for patients with osteoarthritis but does not provide the soft-tissue stability required in this patient.
2014
In a patient with rheumatoid arthritis with painful, debilitating deformity of the left wrist and hand, which of the following is the most appropriate first step in reconstruction?
A) Intercarpal fusion with ulnar head arthroplasty
B) Proximal interphalangeal joint arthrodesis with terminal extensor tendon release
C) Silicone metacarpophalangeal joint arthroplasty with sagittal band reconstruction
D) Soft-tissue reconstruction of the extensor tendon rupture with tendon transfer
E) Total wrist arthrodesis with ulnar head excision
The correct response is Option E.
Rheumatoid arthritis is a complex disease, and the treatment for rheumatoid hand deformities remains controversial. Over 70% of rheumatoid patients report hand and wrist dysfunction. In addition, patient concerns over the aesthetic appearance of the hand and wrist can have a significant influence on patient satisfaction following rheumatoid hand surgery. When planning surgery, one must take into account the patient’s symptoms; clinical appearance, including the amount of synovitis; function; and x-ray studies.
Rheumatoid arthritis is a polyarticular disease and deformities of the proximal joints will affect the position of more distal joints. This makes timing and sequence of surgical reconstruction critical. The wrist is the most common joint affected by rheumatoid disease. The accepted strategy is to reconstruct more proximal joints first. This may provide enough stability and motion so that distal surgery is not needed. Surgical treatment of the rheumatoid wrist is usually performed to alleviate wrist pain or to treat deformities that contribute to finger deformities distally. A stable wrist is critical to a successfully reconstructed rheumatoid hand.
Synovitis is the principal pathologic feature of rheumatoid arthritis. Synovitis of the ulnar side of the wrist tends to appear first, resulting in attenuation and rupture of the extensor carpi ulnaris sheath and ligamentous stabilizers of the distal radioulnar joint (DRUJ). This leads to dorsal dislocation of the ulnar head and caput ulna syndrome. Synovitis of the volar and intercarpal ligaments leads to volar and ulnar subluxation of the carpus with supination. The intact radial wrist extensors then contribute to the radial deviation of the metacarpals at the carpometacarpal joint and compensatory ulnar drift at the metacarpophalangeal joint.
Treatment of rheumatoid wrist deformities involves stabilization of the carpus. In this patient, x-ray studies show pancarpal arthritis. This leaves total wrist arthrodesis as the only option presented here. If the mid-carpal joint is unaffected by disease, a limited wrist fusion may be performed such as a radiolunate arthrodesis. Treatment of the DRUJ and ulnar head is accomplished with ulnar head excision when the wrist is stabilized with a fusion. In cases of isolated DRUJ disease, the Sauvé-Kapandji procedure is recommended to prevent further ulnar subluxation of the carpus.
The other answers address pathology distal to the wrist and should not be considered primarily in patients with this degree of wrist pathology.
2014
A 56-year-old man comes to the office because of a 1-year history of deformity, pain, and decreasing range of motion in the proximal interphalangeal (PIP) joint of the right ring finger. History includes a crush injury to the right ring finger 3 years ago treated with splinting and therapy. Active range of motion of the PIP joint is 20 to 40 degrees. X-ray studies show severe joint space narrowing and osteophyte formation. Implant arthroplasty is discussed. Regardless of the type of implant chosen, which of the following is the most likely expected long-term outcome for this patient?
The correct response is Option F.
Several prospective and retrospective studies have shown that proximal interphalangeal (PIP) joint implant arthroplasty provides significant pain relief with no marked change in preoperative range of motion. This finding has been consistent for both silicone, pyrocarbon, and titanium-polyethylene.
Silicone PIP implants have been in use since the late 1960s. The silicone implant acts as a simple spacer following joint resection to allow for the formation of a fibrous capsule of scar tissue that functions as the new joint. The implants can be placed via volar or dorsal approach. PIP arthroplasty is indicated for osteoarthritis, post-traumatic arthritis, rheumatoid arthritis, and other inflammatory arthritic conditions. Complications for silicone arthroplasty are related to implant fracture or degradation; however, this does not guarantee the need for revision surgery. Revision rates for PIP silicone arthroplasty are between 11 to 13%. One long-term study showed greater than 50% of implants were fractured at 16 years. Studies all show significant pain reduction, improvement in functional scores, and good to high patient satisfaction.
Surface replacement PIP implants have been used since the late 1990s. These implants depend on either cementing or osseointegration for stability. Pyrocarbon has an elastic modulus similar to cancellous bone. Short-term studies have shown an increase in joint range of motion that is not maintained in longer-term follow-up studies. In addition, many longer-term outcome studies have shown a significantly higher complication rate with surface replacement implants mostly related to loosening, subsidence, fracture, squeaking, and contracture formation. Reoperation rates for surface replacement implants are as high as 39%. However, studies do show a reduction in pain with good patient satisfaction for these implants as well.
2014
A 60-year-old woman with rheumatoid arthritis (RA) comes to the office because of the sudden inability to extend the right thumb. The patient reports no pain or swelling before the loss of extension. She notes her RA symptoms have been well controlled for over 10 years with low-dose prednisone and methotrexate. Physical examination shows strong flexion of the right thumb at the interphalangeal joint. The patient is unable to extend the thumb interphalangeal joint against resistance and is unable to lift the thumb off the tabletop when the palm is held flat. Full passive mobility of the thumb is noted. Rupture of which of the following tendons is most likely upon surgical exploration?
A) Abductor pollicis brevis at the metacarpophalangeal joint
B) Abductor pollicis longus at the carpometacarpal joint
C) Extensor pollicis brevis at the metacarpophalangeal joint
D) Extensor pollicis longus at the wrist
E) Flexor pollicis longus near the scaphoid
The correct response is Option D.
One of the more common tendon ruptures in rheumatoid arthritis (RA) is the extensor pollicis longus (EPL) at the level of the wrist. Although spontaneous ruptures with no other known pathology occur, the most common etiologies for rupture center around mechanical or vascular changes in the EPL within the third extensor compartment as the tendon bends around Lister’s tubercle. This appears to be related in part to the proximity of the tendon to an injury (in distal radius fractures) and to the “watershed” zone of perfusion of the EPL at Lister tubercle. In this patient with RA, the rupture is likely a combination of ischemia and direct inflammatory synovial infiltration of the tendon within the third compartment.
Other tendon ruptures may occur in the setting of RA, the common ruptures being the extensor digitorum communis and extensor digiti minimi on the dorsal wrist and the flexor pollicis longus (Mannerfelt lesion) on the volar wrist. The presence of strong flexion of the thumb at the interphalangeal joint rules out flexor pollicis longus (FPL) rupture.
Rupture of the extensor pollicis brevis (EPB) would not result in obvious loss of function as the motion would be compensated for by an intact EPL.
Neither abductor rupture would result in loss of interphalangeal joint extension or retropulsion (lifting the thumb off the table with the palm held flat on the surface).
2019
A 65-year-old woman comes to the office because she is unable to actively extend the left ring and small fingers. Medical history includes rheumatoid arthritis and no marked trauma. On physical examination, the ring and small fingers are held in 45 degrees of flexion with ulnar deviation at the metacarpophalangeal (MCP) joints. Mild swelling around the MCP joints of all fingers and a prominent ulnar head are noted. The patient is able to maintain extension when her fingers are passively extended. X-ray studies show moderate to severe wrist arthritis but minimal arthritic changes of the finger joints. Which of the following best explains the physical examination findings in this patient?
A) Extensor tendon rupture of the ring and small fingers at the ulnar head
B) Incomplete radial nerve palsy
C) Severe ulnar neuropathy at the elbow
D) Ulnar subluxation of the extensor mechanism at the MCP joint
E) Volar subluxation of the MCP joint
The correct response is Option D.
Rheumatoid arthritis (RA) is an autoimmune inflammatory polyarthritis. Immune complex deposition results in inflammation and synovial hypertrophy, joint destruction, and weakening of the ligamentous support structures. This results in a predictable pattern of deformities seen in the hand and wrist related to the inflammatory synovitis.
The wrist is the most commonly affected joint in the upper extremity in RA. Collapse of the carpal height on the radial aspect of the wrist from attenuation of the scapholunate ligament results in weakening of the ulnar collateral ligaments of the wrist, ulnar subluxation and supination of the carpus, and radial deviation of the metacarpals. Along with synovitis of the metacarpophalangeal (MCP) joints, this contributes to the characteristic ulnar drift of the fingers seen in RA.
The loss of active finger extension in rheumatoid patients is because of one of three causes. Attenuation of the radial sagittal band of the MCP joint from inflammation and ulnarly directed forces from pinch and grip may result in ulnar subluxation of the extensor mechanism. The extensor tendons will slide into the valley between the metacarpal heads and the extensor tendon will place a flexion force on the MCP joint. In this case, passive extension of the fingers will centralize the extensor and the patient will be able to maintain the fingers actively in an extended position. This is the critical physical exam maneuver to diagnose this issue and the key to the patient in this question.
Patients with synovitis of the distal radioulnar joint and dorsal subluxation of the ulnar head (caput ulna) may present with spontaneous rupture of the extensor tendons. This occurs in a predictable sequence beginning with the extensor digiti quinti and progressing radially across the hand. Intact junctura may make this difficult to diagnose initially, but these patients will not be able to extend the small finger with the adjacent digits flexed. These patients will not be able to actively maintain finger extension even if the fingers are passively extended.
Finally, volar subluxation or dislocation of the MCP joints from synovitis can be a cause of ulnar drift and loss of digit extension. This may or may not be passively correctable. This can be distinguished easily from extensor tendon subluxation by x-ray evaluation of the hand. Joint malalignment is easily seen on standard x-rays but is not present in this patient. It is important to understand the cause of the deformity because the treatment for each is different.
Radial neuropathy in RA is very rare and would not likely be isolated to extension of the ring and small fingers only. One would expect more global posterior interosseous nerve (PIN) palsy, which is not present in this case.
Severe ulnar neuropathy would result in intrinsic weakness and possibly clawing of the ulnar digits. This would present with hyperextension of the MCP joints and flexion of the interphalangeal joints.
2019
A 65-year-old woman presents with severe osteoarthritis of the proximal interphalangeal (PIP) joint of the nondominant left middle finger. Medical history includes chronic pain and an angular deformity of the joint. Range of motion of the PIP joint is 30 to 60 degrees. Silicone implant arthroplasty is planned. Which of the following is the principle benefit of this procedure?
A) Correction of angular deformity
B) Improved cosmesis
C) Improved range of motion
D) Increased grip strength
E) Pain relief
The correct response is Option E.
Expected outcomes for small joint implant arthroplasty are pain relief with similar range of motion to preoperative values. The procedure involves excision of the arthritic proximal phalanx head and middle phalanx base and replacement with a silicone stemmed implant. The implant acts as a spacer for development of a scar capsule.
Although angular deformity is corrected with this procedure, and many patients report satisfaction with the improved appearance of the alignment of the finger, the primary goal of the procedure is pain relief from underlying arthritis. Outcome studies have not demonstrated improved grip strength or range of motion. Long-term outcome studies show 90% implant survival at 10 years, high patient satisfaction, and a low revision rate despite a relatively high incidence of implant fracture or deformity over time.
2020
In patients with rheumatoid arthritis, the inciting event in development of a boutonniere deformity is which of the following?
A) Central slip attenuation
B) Intrinsic tightness
C) Lateral band volar subluxation
D) Oblique retinacular ligament contracture
E) Proximal interphalangeal (PIP) joint synovitis
The correct response is Option E.
Rheumatoid arthritis is a chronic autoimmune disease characterized by inflammation and deterioration of the joints. Synovial proliferation is the hallmark of rheumatoid arthritis and is often seen early in the course of the disease. There is a progression to synovial pannus formation, periarticular bone demineralization, cartilage destruction, and subchondral osseous erosions. This process is mediated by synovial infiltration of activated T lymphocytes, which promote chronic synovial inflammation.
The boutonniere deformity is extremely common in patients with rheumatoid arthritis. It is characterized by flexion of the proximal interphalangeal (PIP) joint with hyperextension of the distal interphalangeal (DIP) joint.
The causative event of boutonniere deformity in rheumatoid arthritis is synovitis and synovial pannus formation within the PIP joint. This causes the joint capsule to distend, resulting in attenuation of the central slip. Central slip insufficiency results in loss of PIP joint extension and subsequent volar translocation of the lateral bands, which further accentuates the deformity by providing a flexion force across the PIP joint. Extension forces are transferred to the DIP joint. Contraction of the oblique retinacular ligament is associated with a fixed deformity.
Intrinsic tightness would cause the PIP joint to be unable to be flexed when the MP is in extension.
2020
A 75-year-old woman with a medical history significant for rheumatoid arthritis presents with painless loss of extension of the thumb and all digits of the left hand. When she attempts wrist extension, the wrist deviates radially while actively extending. When the examiner passively flexes the wrist, the thumb and fingers extend. Which of the following best describes the likely cause of this patient’s functional deficit?
A) Dorsal ulna prominence; rupture of multiple extensor tendons
B) Ligamentous laxity; subluxation of multiple metacarpophalangeal joints
C) Proliferative synovitis of the radiocapitellar joint; compression of posterior interosseus nerve
D) Scaphoid bone osteophyte; rupture of flexor pollicis longus muscle
E) Weakening of extensor hood; dislocation of extensor tendon
The correct response is Option C.
This patient demonstrates posterior interosseus nerve (PIN) syndrome. She has loss of active thumb and finger extension while maintaining active wrist extension with radial deviation. Proliferative synovitis secondary to rheumatoid arthritis of the radiocapitellar joint or within the radial tunnel is traditionally the culprit at the proximal forearm. Rheumatoid arthritis is characterized by cartilage degradation, synovial expansion, ligamentous laxity, and bony erosion. All joints and tendon sheaths can be involved.
The PIN branch of the radial nerve is a motor nerve. It provides innervation to the extensor carpi radialis brevis (although this can be innervated by the radial nerve proper), supinator, extensor carpi ulnaris, extensor digitorum communis, extensor pollicis longus and brevis, abductor pollicis longus, extensor indicis proprius, and extensor digiti minimi muscles. In compression or entrapment of the PIN nerve, the extensor carpi radialis longus is traditionally spared, as it is innervated by the radial nerve proper, proximal to the level of compression. Thus, active wrist extension with radial deviation is maintained.
Dorsal subluxation of the ulna is secondary to attenuation of surrounding capsular ligaments, and erosion of the distal radioulnar joint leads to dorsal subluxation of the ulna. The dorsally placed ulna can result in attritional rupture of extensors, traditionally affecting the ulnar-most digital extensors first. Multiple extensor ruptures at the level of the wrist would not demonstrate intact extension on tenodesis examination. Attenuation of extrinsic and intrinsic wrist ligaments in rheumatoid arthritis leads to carpal volar subluxation, supination, and ulnar translocation. Wrist collapse leads to metacarpal radial deviation and eventual ulnar drift of the fingers. Further volar and ulnar subluxation of the fingers at the metacarpophalangeal joints (MCPJs) is a result of asymmetry of the metacarpal heads, flexor-extensor-intrinsic imbalance, attenuation of the extensor hood, and attenuation of collateral ligaments. MCPJ subluxation would not result in an intact examination with tenodesis and would not affect wrist extension with radial deviation posture. Weakening of the extensor hood would result in extensor tendon subluxation ulnarly. Classically in the situation of extensor tendon subluxation at the level of the MCPJ, if the joints are not fixed and the examiner passively reduces the joints, the patient is able to maintain active MCPJ extension. Wrist extension should not be impacted.
Scaphoid osteophytes in rheumatoid arthritis can result in attritional rupture of the flexor pollicis longus (FPL), termed the Mannerfelt lesion. FPL rupture should impact the thumb interphalangeal joint with loss of active flexion.
2021
In patients with rheumatoid arthritis, the inciting event in the development of a boutonniere deformity of the thumb is which of the following?
A) Adductor contracture
B) Attenuation of the extensor pollicis brevis
C) Carpometacarpal joint synovitis
D) Extensor pollicis longus subluxation
E) Metacarpophalangeal joint synovitis
The correct response is Option E.
The boutonniere deformity is the most common deformity of the thumb in rheumatoid arthritis (RA). The pathology originates at the metacarpophalangeal (MCP) joint, at which synovitis results in dorsal hood disruption and attenuation of the extensor pollicis brevis with loss of MCP joint extension and volar subluxation of the proximal phalanx. This is accompanied by secondary subluxation of the extensor pollicis longus (EPL) tendon ulnarly.
This results in increased tension on the extensor mechanism with resultant distal phalanx extension and concomitant proximal phalanx dorsal subluxation. Treatment is predicated on status of joint deformity. If the deformity is able to be reduced passively with adequate joint stability and absent radiographic evidence of joint destruction, then reconstruction is achieved by synovectomy and insertion of the EPL tendon into the base of the proximal phalanx. If the contractures are fixed, then MCP arthrodesis is indicated for treatment of symptomatic deformity.
The Nalebuff classification of thumb deformity in RA identifies six types of deformities:
- Type 1: Boutonniere
- Type 2: Boutonniere with carpometacarpal subluxation
- Type 3: Swan-neck deformity
- Type 4: Gamekeeper deformity
- Type 5: Swan-neck with MCP volar plate laxity
- Type 6: Arthritis mutilans
RA is a chronic autoimmune disease characterized by inflammation and deterioration of the joints. Synovial proliferation is the hallmark of RA and is often seen early in the course of the disease. There is a progression to synovial pannus formation, periarticular bone demineralization, cartilage destruction, and subchondral osseous erosions. This process is mediated by synovial infiltration of activated T lymphocytes, which promote chronic synovial inflammation.
2022
