Rheumatoid hand

Ulnar drift or deviation of fingers

Normal anatomical factors contributing to ulnar drift of fingers at MCP joint:

1. Normal mechanical advantage of ulnar intrinsic muscles
2. Asymmetry and ulnar slope of metacarpal heads of index and middle fingers
3. Greater ulnar deviation permitted by radial collateral ligament when MCP joint is flexed
4. Ulnar forces applied during pinch and grasp
5. Flexor tendons enter fibrous sheath at an angle, exerting ulnar and palmar pull that is resisted in normal hand
6. Greater strength of abductor digiti quinti and flexor digiti quinti than of 3rd palmar interossei (adductor)

Pathological factors contributing to ulnar drift of fingers at MCP joint:

1. Z mechanism: Carpal collapse can cause radial deviation of the carpi leading to compensatory MCP joint ulnar deviation
2. Dorsoradial ligament damage from MCP synovitis:
   • Radial sagittal bands: Ulnar subluxation of extensor tendon
   • Accessory collateral ligament: Ulnar displacement of flexor tendons within their tunnels
   • Collateral ligament: Volar displacement of proximal phalanges
3. ECU dysfunction (Caput ulnae): Increased mobility of 4th and 5th metacarpals

Management:

1. Synovectomy, extensor tendon centralization, and intrinsic release arthroplasty
2. Crossed intrinsic transfer: division of the intrinsics on the ulnar side of the wrist and transfer to the radial side
3. Silicon MCP arthroplasty (for late disease)

Swan neck and Boutonniere deformity

Caput Ulna Syndrome (Wrist)

Pathoanatomy:

Synovitis in the DRUJ → ECU subsheath stretching → ECU subluxation → supination of the carpal bones away from the head of the ulna → volar subluxation of the carpus away from the ulna → increased pressure over the extensor compartments → tendon rupture

Treatment:

1. Early synovectomy
2. Manifest caput ulnae syndrome:
   • Resection of ulnar head with dorsal wrist stabilization
   • Arthrodesis of DRUJ with segmental resection of ulna or arthroplasty (Sauve-Kapandji)

Mannerfelt lesion

Pathoanatomy: Rupture of FPL due to abrasion (attritional rupture) over scaphoid osteophyte

Treatment: Exploration of carpal tunnel + Flexor tenosynovectomy +/- Excision of osteophyte + FPL advancement and pull through/FDS4 to FPL tendon transfer/tendon graft/Arthrodesis of IP joint

Vaughan Jackson Syndrome

Definition: Ulnar to radial progression of extensor tendon rupture

Pathoanatomy: Tenosynovitis (synovial infiltration + diminished vascular supply) and Caput ulnae → Attrition over prominent ulna → Rupture of EDQ and EDC of little finger → sequential rupture of the EDC tendons of the ring, long, and index fingers

EPL is commonly ruptured due to attrition over Lister’s tubercle.

Treatment: Treat caput ulnae + Tendon repair or transfers (EIP to EDC or FDS if multiple ruptures)

Rheumatoid thumb

Nalebuff classification

Rheumatoid arthritis diagnostic criteria have been discussed here with mnemonics: Rheumatoid Arthritis Criteria Mnemonics | Epomedicine