Thumb Base Arthritis

Epidemiology

  • 80% of postmenopausal women have XR changes
  • XR doesn’t always correlate with symptoms

Anatomy of CMCJ

  • Saddle shaped
    • Allows polyaxial motion
  • 3 Ligaments
    1. Dorsal
    2. Lateral
    3. Volar Ulnar - Beak (most important)

Aetiology

  • Beak ligament attenuation and rupture leads to instability of CMCJ
  • Instability leads to arthritis

Presenting Features

  • Activity-related pain
  • Weak grip
  • Pain and weakness opening jars
  • Night pain
  • Superimposed carpal tunnel syndrome common (40%)

Examination

  • Wasted thenar eminence – disuse
  • Squaring of thumb base
  • Adducted 1st metacarpal
  • Compensatory MCPJ hyperextension – increases hand span

Grind Test

  • Axial compression and grind
  • Less pain on distraction and grinding

Crank Test

  • Axial compression and flexion, extension pain

Investigations

  • AP hand
  • Roberts view (true AP of thumb)
    • Thumb maximally abducted & forearm maximally pronated

Classification (Eaton & Littler)

Stage 1

  • Joint space widening
  • Synovitis and effusion
  • No OA changes

Stage 2

  • Osteophytes <2mm in size
  • Mild subluxation
  • Joint space narrowing

Stage 3

  • Osteophytes >2mm in size
  • Significant subluxation
  • Joint more significantly narrowed

Stage 4

  • Widespread arthritis – especially of STT joint

Management

  • Treat symptoms and functional impairment – not XR

Non-Operative

  • Splinting
  • Physio (thenar muscle strengthening)
  • Activity modification
  • Analgesia
  • Corticosteroid injection – in clinic or theatre

Operative Management

  • Decision making based on:
    • Pain
    • Functional expectations
    • Degree of arthritis

Trapezium Preservation

  • No arthritis
  • Instability-related pain
Thumb Metacarpal Stabilisation with Split FCR
  • Reconstructs the Beak ligament
Extension Osteotomy
  • Unload CMCJ

Trapezium Sacrificing Procedures

  • Much more common
Trapeziectomy
  • Gold standard for patients overall
  • 80-90% good results
  • Problems:
    • Thumb will be weaker
    • Instability of Metacarpal
Trapeziectomy plus Ligament Reconstruction and Interposition
  • Postulated to have better results
  • Not proven in any study
Arthrodesis
  • For young manual workers only
  • Preserves power
  • Clenched fist position:
    • 30° abduction
    • 20° flexion
  • Technically difficult and prone to complications
Osteotomy – Abduction, Extension
  • Good results described for Stage 1-3
Arthroplasty
  • Ball and socket constrained design
  • Previous failures
  • Still some good series
  • Lacks follow-up > 3 years
  • Higher complication rate

Outcomes

  • In general, all procedures have an 80-90% success with good selection
  • Warn regarding long rehab time and time to see full benefit – 3-6 months
  • Need for splinting for 3-6 months
Back to top