How to repair the damage caused by rheumatoid arthritis
Rheumatoid arthritis is an autoimmune systemic condition that affects approximately 1% of the population. The clinical course of the disease is variable; it ranges from mild, self-limited arthritis and/or synovitis, to a progressive, multisystem disease.
Three Main Phases
There are three main phases of rheumatoid arthritis within the joints in the hand:
• proliferative phase;
• destructive phase; and
• fibrosis phase.
Inflammation and proliferation of the synovium in and around the joints are characteristic of the initial phase. Various pro-inflammatory cells migrate into the area of synovial proliferation, and there is an increase in angiogenesis and periarticular swelling.
As the disease progresses, it enters the destructive phase, where the synovium becomes known as a pannus and invades adjacent tissue and joints, perpetuating cartilage erosion and tendon rupture, with swelling and pain. Inflammatory cytokines, such as tumor necrosis factor-alpha and interleukin-1, induce cellular proliferation, matrix metalloproteinase expression, adhesion molecule expression, and secretion of other cytokines and prostaglandins, fostering a cycle of swelling, inflammation, pain, and destruction.
Following the inflammatory phase, fibrosis ensues, resulting in tendon adhesions, stiffness, and fixed joint deformities.
The natural history of rheumatoid arthritis is not entirely predictable, and each of these phases may be halted or prolonged depending on the individual. Classically, synovial hypertrophy precedes joint destruction and, in the more severe cases, significant arthritic damage to the wrist, the metacarpophalangeal (MP) joints, and the interphalangeal (IP) joints. Consequently, there is a disruption of balance between the extrinsic flexor and extensor tendons, as well as the intrinsic mechanism of the fingers. This imbalance results in radial deviation at the wrist, ulnar drift at the MP joints, and/or swan neck and Boutonniere deformities of the fingers and thumb.
Initial Treatment: Medical Management
The initial treatment of rheumatoid arthritis should be medical management. Many of these medications include non-steroidal anti-inflammatories, disease-modifying antirheumatics (hydroxychloroquine, gold derivatives, methotrexate, sulfasalazine, leflunomide, cyclosporine, azothioprine, and penicillamine), biologic response modifiers (infliximab, etanercept, and anakinra), and prednisone.
Many patients, however, are often sent to a hand surgeon in the late stages of this disease, necessitating joint replacements or fusions, because there is little else to offer from a restorative function point of view. It is important to take an adequate history of the patient with rheumatoid arthritis, noting, specifically, functional limitations and symptoms such as pain, stiffness, weakness, and numbness. Ultimately, treatment is determined by the functional limitations the patient has as a result of pain or deformity.
Surgical Options
There are several surgical options for patients with rheumatoid arthritis, depending on the stage of the disease and the level of destruction. Surgical treatments include:
• synovectomies;
• tendon realignment, reconstruction or transfers; and
• joint arthroplasty or arthrodesis.
The goals of surgery remain restoration of function, alleviation of pain, and retardation of the disease’s progress. Functional wrist synovitis is often associated with bogginess, crepitance, and even tenderness on range of motion at the wrist. Synovectomy of the dorsal wrist can improve range of motion, prevent tendon rupture, and decrease wrist pain. Synovectomy of the volar aspect of the wrist can also improve range of motion, decrease pain, and decompress the median nerve. The symptoms of carpal tunnel syndrome may become amplified subsequent to synovial proliferation in the volar wrist. Synovitis in the fibrosseous canal in the fingers can result in decreased range of motion, pain, and triggering.
Access to the diseased tissue in the volar palm and fingers requires zig-zag- or Brunner-type incisions. Care should be taken not to injure the neurovascular bundles and the annular pulley system, with particular attention paid to the A-2 and A-4 pulley.
Tendon Rupture
Tendon rupture can occur with prolonged disease. The two main causes of tendon rupture are:
• chronic attrition of the tendon on bony prominences; and
• synovial invasion of the tendon.
Extensor tendons are more commonly ruptured than flexor tendons. Invasive tenosynovitis of the extensor tendons on the ulnar aspect of the wrist often results from the bony instability of the distal radial ulnar joint and prominence of the distal ulna, with subsequent attritional rupture of the extensor tendons to the little, ring, and possibly long fingers. Characteristically, the patient is unable to extend these digits even if they are passively extended. This common rupture is known as the Vaughn-Jackson lesion.
Another extensor tendon that commonly ruptures is the extensor pollicis longus, which eventually succumbs to the bony prominence of Lister’s tubercle. Although any of the flexor tendons can rupture as a result of attrition, the most commonly involved flexor is the flexor pollicis longus (FPL) tendon. The Mannerfelt lesion describes rupture of the FPL on the tubercle of the scaphoid bone. Tendon transfers are most commonly utilized for repair of the ruptured tendon, as the functional results are considered better then direct end-to-end repair or tendon grafting. Rheumatoid nodules could limit the function of the flexor digitorum profundus (FDP) tendon and produce symptoms similar to the rupture of that tendon.
Rheumatoid Nodules Versus Ruptured Tendons
A careful examination must distinguish between rheumatoid nodules and ruptured tendons. The decision to repair an FDP rupture must be weighed carefully with the overall functional capacity of the patient, as an arthrodesis of the distal interphalangeal (DIP) joint may serve the patient better than risking stiff fingers following FDP repair or reconstruction. This is no more true than in the elderly with significant rheumatoid deformities, where repair and rehabilitation may not be feasible.
Rheumatoid Arthritis of the Wrist
Destructive synovitis and joint degeneration are very common in rheumatoid arthritis of the wrist. The ulnar side of the wrist is most commonly affected, resulting in the destabilization of the distal ulna. The triangular fibrocartilage complex is attenuated, the dorsal wrist capsule is disrupted, and the distal radial ulnar joint is degenerated. The extensor carpi ulnaris tendon migrates volarly as the distal ulna subluxes dorsally. This is often associated with translocation of the proximal carpus.
Collectively, this pathology at the distal ulna is known as the caput ulna syndrome. The extensor tendons to the little, ring, and sometimes long fingers are particularly vulnerable to the proliferative synovitis and malposition of the distal ulna, resulting in attritional rupture. Arthritis and synovitis around the rest of the carpal bones can result in rotary subluxation of the scaphoid, carpal collapse, and significant radial deviation of the wrist.
Interestingly, in the latter stages of rheumatoid arthritis, patients can have significant deformity and joint destruction, yet be relatively pain-free. Patients who reach hand surgeons early in the course of the disease may benefit from early synovectomy in hopes of limiting the amount of bone destruction in the wrist. Reconstruction or resection of the distal radial ulnar joint may be warranted with caput ulna syndrome. Ultimately, in a severely degenerated wrist, total wrist fusion may be needed to restore stability and alignment.
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The MP Joint in Rheumatoid Arthritis
The MP joint is a condylar joint, which permits motion in two planes. This makes the MP joint inherently more unstable than the IP joint. The structure of synovial proliferation results not only in destruction of the cartilage at the MP joint, but also significant attrition of the retaining ligaments around the joint. In this light, the classic deformity associated with rheumatoid arthritis at the MP joint is ulnar drift. Ulnar drift has two components: ulnar shift and ulnar deviation. With time, there is volar subluxation of the proximal phalanx on the metacarpal. The intrinsics become foreshortened and tight. This results in swan neck or Boutonniere deformities.
Deformities at the wrist can also affect the instability and deformity at the MP joint. Weakened radiocarpal ligaments cause radial deviation of the wrist. Because of the forces of the extrinsic tendons, the MP joints are pulled into an ulnar drift position. This phenomenon describes a consequence of an imbalance of opposing forces about a joint. That is, the joints proximal and distal to the affected joint will adopt the opposite position because of extrinsic forces. The weakened capsule of the MP joint, relaxation of the sagittal band, and forces of the extrinsic tendons result in the extensor tendons falling into the ulnar gutters of the MP joints. This subluxation of the extensor tendons accentuates the ulnar drift.
In the early phases of the disease, simple synovectomy and extensor tendon realignment can be performed. In the latter stages, however, joint destruction and volar subluxation of the proximal phalanx mandate joint arthroplasty. Although different types of arthroplasty have been described, the most common type of joint replacement involves silicone implants. During this procedure, the metacarpal is often foreshortened, which helps with the intrinsic tightness. Patients require extensive physical therapy, often with dynamic outrigger splints in the immediate postoperative period.
The Proximal and Distal Interphalangeal Joints in Rheumatoid Arthritis
Swan neck and Boutonniere deformities often accompany wrist and MP joint disease in rheumatoid arthritis. The swan neck deformity is characterized by hyperextension of the flexed proximal interphalangeal (PIP) joint and flexion of the DIP joint. Stretching of the volar capsule, in combination with stretching or loss of the terminal tendon, gives the characteristic posture of the swan neck finger. Ruptures of the flexor digitorum superficialis (FDS) tendon can also result in hyperextension at the PIP joint and lead to subsequent swan neck deformity. Volar subluxation of the proximal phalanx accentuates the deformity; and in time the intrinsics become tight and the swan neck becomes a fixed deformity.
Isolated treatment of the swan neck deformity may involve releasing incisions distal to the PIP joint if skin tightness is an issue. Usually, however, more aggressive procedures around the PIP joint are needed. The lateral band or oblique retinacular ligament based distally can be rerouted volarly to prevent the PIP joint from extending beyond neutral. Alternatively, a tendon graft can be used in a similar fashion.
The Boutonniere deformity is characterized by hyperextension at the DIP joint and flexion at the PIP joint. This abnormal finger posture usually starts at the PIP joint. A contracture at this joint results in hyperextension of the MP joint as well as the DIP joint. In the early stages, a three-point splint can be utilized to correct the deformity. As the deformity progresses, however, a surgical intervention may be warranted.
Moderate Boutonniere deformities that are easily reducible and not resolvable with splinting may require reconstruction of the extensor mechanism by shortening the central slip by moving the lateral bands dorsally. Various other procedures have been described for correction of the Boutonniere deformity. Such procedures include:
• crisscrossing the lateral bands over the PIP joint;
• lateral band realignment;
• grafting procedures; and
• skin releases.
The PIP joint that is no longer able to extend passively, is significantly painful, or has evidence of marked degeneration may be best treated with a fusion. Fusions of the PIP joints should increase from 25° to 40° from the index finger to the small finger, respectively. Because of the quality of the soft tissue and bone stock, many of the PIP joints are not amenable to joint arthroplasty.
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Nalebuff described five characteristic deformities of the thumb:
• Type 1 is a Boutonniere deformity, where the pathology originates at the MP joint. The extensor pollicis longus tendon is subluxed in the ulnar direction. The distal phalanx is drawn into extension, and the proximal phalanx subluxes dorsally. This is the most common thumb deformity seen in patients with rheumatoid arthritis.
• In Type 2 deformity, both the MP and IP joints are drawn into extension. The carpometacarpal (CMC) joint is often subluxed as well.
• The Type 3, or swan neck, deformity is the second most common disfigurement of the thumb as a result of rheumatoid arthritis. Destruction of the CMC joint is the initial site of pathology in this deformity. The first metacarpal is often adducted due to the tightness of the lateral bands and the pull of the flexor pollicis longus that draws the distal phalanx into flexion.
• In the Type 4 deformity, there is destruction of the ulnar collateral ligament at the MP joint. While the metacarpal is pulled into adduction, there is radial deviation of the proximal phalanx.
• The Type 5 deformity is similar to the Type 3 deformity. However, there is no adduction of the first metacarpal, and the disease starts at the MP joint rather than the CMC joint. A further deformity has been described that involves isolated IP and MP joint pathology with various levels of destruction.
The treatment of any of the thumb deformities is individualized based on the function and needs of each patient. Because the thumb is needed as a stable post, fusion of the involved joints is often warranted. If the CMC, MP, and IP joints are all involved, an attempt to preserve motion can be made by choosing the IP joint fusion at 0°–20° of flexion, performing an MP joint arthroplasty, and fusing the CMC joint.
Rheumatoid arthritis remains a formidable challenge for all hand surgeons. Early treatment with preservation of joint surfaces and tendon integrity is a high priority in the management of these patients. Combined with medical management by rheumatologists, hand surgeons can restore function, alleviate pain, and return these patients to their activities of daily living and a productive life. n
Michael W. Neumeister, MD, FACS, is associate professor of surgery at Southern Illinois University School of Medicine in Springfield. He can be reached at [email protected].
