Rheumatoid Arthritis — Hand

Rheumatoid arthritis (RA) is a chronic systemic inflammatory autoimmune disease that profoundly affects the hand and wrist. The hand is involved in approximately 90% of RA patients, and the characteristic deformities — ulnar drift, swan neck, boutonnière, Z-deformity of the thumb — result from the combined effects of synovitis, tendon involvement, capsular and ligamentous destruction, and progressive joint erosion. The orthopaedic surgeon must understand both the pathological basis of these deformities and the hierarchy of surgical intervention.

• RA prevalence: approximately 1% of the population; female:male ratio 3:1; peak onset 40–60 years; bilateral and symmetric; serological markers — RF positive in 70–80%, anti-CCP positive in approximately 70% (more specific than RF)
• Pathophysiology: synovitis → pannus formation → enzymatic destruction of cartilage, tendons, and ligaments → instability → deformity; the synovial pannus is driven by TNF-α, IL-1, and IL-6 cytokines — the targets of modern biological DMARDs
• The fundamental principle of RA hand surgery: address the tendon and soft tissue problems before bone and joint problems — synovectomy, tendon repair, and soft tissue balancing should precede joint replacement or fusion; once deformity becomes rigid and fixed, options narrow to fusion or arthroplasty
• Modern DMARD therapy has dramatically reduced the frequency and severity of RA hand deformities — patients requiring surgery today typically have longstanding disease inadequately controlled before the biologic era

• The wrist is involved in approximately 80% of RA patients; radiocarpal, ulnocarpal, and distal radioulnar joint (DRUJ) all affected
• Caput ulnae syndrome: synovitis of the DRUJ causes destruction of the ECU tendon sheath, triangular fibrocartilage complex (TFCC), and DRUJ ligaments → the ulnar head becomes dorsally prominent (Caput ulnae) → ECU tendon subluxes volarly → unstable DRUJ → supination of the carpus relative to the ulna → the prominent ulnar head impinges on the overlying tendons and skin, ultimately causing extensor tendon rupture
• Vaughan-Jackson syndrome: sequential rupture of extensor tendons beginning with EDM and EDC to the small finger, progressing radially; caused by attrition of tendons over the prominent caput ulnae; urgent surgical management — Darrach procedure (distal ulna excision) or Sauvé-Kapandji procedure to remove the mechanical cause + extensor tendon repair/transfer
• Carpal supination deformity: the carpus progressively supinates and the wrist adopts a volar and ulnar translation posture; combined with radial deviation of the metacarpals sets up the forces that produce ulnar drift at the MCPJs
• Wrist surgical options: wrist synovectomy (early); Darrach (distal ulna excision); Sauvé-Kapandji (arthrodesis of DRUJ + pseudoarthrosis of ulna proximal to fusion); total wrist arthroplasty (TWA); wrist arthrodesis (most reliable pain relief but sacrifices motion)

Ulnar drift (ulnar deviation of the fingers at the MCPJs) is the most characteristic deformity of the RA hand. It results from a combination of synovial distension, intrinsic muscle imbalance, tendon subluxation, and the mechanical forces of pinch and grip acting on a destabilised joint.

• Mechanism: MCPJ synovitis → capsular distension → volar plate and radial collateral ligament attenuation → extensor tendons sublux ulnarly → intrinsic muscles (especially ulnar lumbrical and interossei) pull the fingers into ulnar deviation; gravity and pinch forces act in the same direction
• The extensor digitorum communis (EDC) tendon subluxes ulnarly off the metacarpal head as the sagittal band radially weakens — once subluxed, the EDC acts as an ulnar deviator rather than an extensor; this perpetuates ulnar drift and weakens extension; repositioning of the extensor tendon is a key component of MCPJ surgery
• Surgical options for MCPJ ulnar drift: synovectomy + extensor tendon relocation + radial collateral ligament repair (early, passively correctable); silicone arthroplasty (Swanson implant) for established deformity with joint destruction
• Swanson silicone MCPJ arthroplasty: resection of metacarpal head; insertion of silicone spacer (hinge implant); functions as a flexible spacer and space-maintainer, not a true joint; corrects alignment and provides pain relief; approximately 90% patient satisfaction; implant fracture common (30–50% at 10 years) but mostly asymptomatic; revision rarely required

These PIP joint deformities are covered in detail in the Boutonnière & Swan Neck article (article 103). The key points in the context of RA:

• Swan neck in RA: primarily driven by PIP joint synovitis attenuating the volar plate; or intrinsic tightness from interosseous spasm/fibrosis; or FDS rupture; produces PIP hyperextension and DIP flexion; flexible deformities treated with soft tissue procedures; rigid = PIP arthrodesis or arthroplasty
• Boutonnière in RA: PIP joint synovitis attenuates the central slip; the lateral bands displace volarly and the PIP goes into flexion while the DIP goes into hyperextension; progressive and self-perpetuating; early — PIP synovectomy + central slip reconstruction; late rigid — PIP arthrodesis
• Nalebuff classification is used for both deformities in the RA context — stages I (flexible) to III (rigid with joint destruction)

• Z-deformity of the thumb (Type III): CMC joint collapses into adduction and flexion → MCPJ hyperextends to compensate → IPJ flexes to allow tip pinch; the thumb is in the shape of a Z; the most functionally disabling thumb deformity in RA

• Extensor tendon rupture: most commonly EDM and EDC (Vaughan-Jackson); attrition over Caput ulnae; inability to extend involved fingers; management: Darrach or Sauvé-Kapandji + tendon transfer (EDC ring to EDC middle finger; EIP to EDM; FDS transfer for multiple ruptures); reconstruct lost function with adjacent donor tendons
• Flexor tendon rupture in RA: Mannerfelt lesion — FPL rupture from attrition against a volar bony spur (usually the scaphoid or trapezium) or against a prominent carpal bone through the carpal tunnel; presents as sudden loss of IPJ flexion of the thumb; diagnosis often delayed; management: volar bony spur excision + FPL tendon graft or EIP-to-FPL transfer; IPJ arthrodesis if tendon reconstruction not feasible
• Flexor tenosynovitis: synovial proliferation in the flexor tendon sheath causes triggering, reduced flexion, and occasionally carpal tunnel syndrome; management: corticosteroid injection into the sheath (first-line); flexor tenosynovectomy if persistent or if causing CTS

• Surgical hierarchy in RA hand: (1) Treat soft tissue disease first — synovectomy, tendon repair/transfer, ligament reconstruction; (2) Correct the proximal deformity before the distal — wrist before MCPJs before PIPs; (3) Preserve motion where possible; (4) Arthrodesis for end-stage joint destruction where stability and pain relief are the priorities
• Disease activity: surgery is best performed when RA is in remission or well-controlled with DMARDs; active systemic RA with high CRP and ESR increases wound healing and infection risk; biologics (particularly anti-TNF agents) should be withheld 2–4 weeks perioperatively according to BSRBR/BSR guidelines
• Pre-operative anaesthetic assessment: cervical spine involvement in RA is critical — atlantoaxial instability from odontoid erosion and transverse ligament incompetence is present in approximately 20–30% of RA patients with severe disease; pre-operative lateral flexion-extension cervical radiographs essential before any general anaesthetic; atlantoaxial subluxation (AAS) >3.5 mm = significant; >9 mm = high risk of cord compression; anaesthetist must be informed; awake fibreoptic intubation if significant instability
• Wrist arthrodesis: provides the most reliable long-term pain relief; sacrifices all wrist motion; preferred in young working patients and those with advanced destruction; total wrist arthroplasty (TWA) preserves motion but revision rate is higher than wrist arthrodesis

• Biologic DMARDs and perioperative management: anti-TNF agents (etanercept, adalimumab, infliximab), IL-6 inhibitors (tocilizumab), and JAK inhibitors (baricitinib, tofacitinib) impair immune function and increase infection risk; BSR guidelines recommend stopping most biologics 1–2 dosing intervals before major surgery; restart after wound healing is confirmed (usually 2 weeks); rituximab has a longer effect — delay surgery 6 months after infusion if possible; always coordinate with the patient`s rheumatologist
• Sauvé-Kapandji procedure: arthrodesis of the DRUJ combined with creation of a pseudoarthrosis in the distal ulna proximal to the fusion — preserves some ulnar support of the carpus (unlike Darrach which removes the entire distal ulna); reduces the risk of ulnar translation of the carpus after Darrach in RA patients; preferred over Darrach in younger more active patients and when carpal ulnar translation is a concern
• Atlantoaxial instability in RA: the most important systemic consideration for the orthopaedic surgeon operating on any RA patient; even minor neck manipulation during intubation can cause cord compression or death; all RA patients undergoing general anaesthesia should have cervical spine X-rays (flexion-extension lateral views) to assess for AAS; C1-C2 fusion required for symptomatic AAS or ADI (atlanto-dens interval) >9 mm

• Treat soft tissue before bone; proximal before distal; preserve motion before sacrificing it; arthrodesis for end-stage
• Vaughan-Jackson syndrome: sequential extensor tendon rupture over Caput ulnae; EDM first → EDC ring → radially; Darrach or Sauvé-Kapandji + tendon transfer
• Mannerfelt lesion: FPL rupture on volar bony spur (scaphoid); sudden thumb IPJ flexion loss; FPL graft or EIP transfer + spur excision
• Ulnar drift: EDC subluxes ulnarly → acts as deviator; sagittal band radial attenuation; Swanson silicone arthroplasty for established deformity
• Z-deformity thumb (Type III): CMC adduction → MCPJ hyperextension → IPJ flexion; most functionally disabling RA thumb deformity
• Atlantoaxial instability: present in 20–30% severe RA; ADI >3.5 mm significant; >9 mm = high cord compression risk; flexion-extension cervical X-rays before GA mandatory
• Biologics perioperative: stop 1–2 dosing intervals before surgery; restart after wound healing confirmed; rituximab — delay surgery 6 months post-infusion
• Sauvé-Kapandji preferred over Darrach in young RA patients — preserves ulnar carpal support; reduces carpal ulnar translation risk
• Swanson MCPJ implant: silicone spacer (not a true joint); 90% patient satisfaction; implant fracture 30–50% at 10 years but mostly asymptomatic
• Anti-CCP: more specific than RF for RA diagnosis; useful when RF negative (seronegative RA)