Base of Thumb Injuries

Background

  • Thumb provides up to 40% of hand function
    • Total disability = loss of 22% of bodily function
  • CMC is biconcave-convex saddle-shaped joint
  • Axis of MC is pronated and flexed 80o relative to other MC

Imaging

  • True AP – Robert’s view
  • True lateral – Bett’s view
  • Oblique view
  • Kapandji PA view

Fractures

  • Most common in young (0-16) and elderly (65+)
  • Classification:
    • Extra-articular
    • Partial intra-articular (Bennett)
    • Complete intra-articular (Rolando)
    • Severely comminuted fracture

Extra-articular

  • Metadiaphyseal junction fractures most common (epibasal fracture)
  • Apex dorsal angulation due to AddP, FPL & APB on distal fragment
  • Accept up to 30o angulation
    • Anything more = compensatory MCP hyperextension
  • Management:
    • Closed reduction – axial traction, extension & pronation with direct pressure over fracture
    • ORIF – k-wires, lag screw, plate, ex-fix

B>Bennett

  • Described by E.H. Bennett in 1882
  • Intra-articular 2 part fracture – volar ulnar fragment
  • Fragment held by anterior oblique ligament attachment to trapezium (beak ligament)
  • MC shaft subluxes dorsal/proximal/radial
  • Mechanism:
    • Axial load on partially flexed MC
  • Look for trapezium fractures and UCL injuries

Gedda classification

  • Type 1 = large single ulnar fragment with subluxation of MC base
  • Type 2 = impaction fracture without subluxation of MC base
  • Type 3 = small ulnar avulsion fragment with CMC dislocation

Management

  • Closed reduction – axial traction, abduction and pronation with pressure over MC base
  • Tensions dorsal ligament complex to reduce (Edmunds, 2006)
  • Poorer outcomes with casting alone (Kjaer-Peterson et al. 1990)
  • Closed reduction + intermetacarpal fixation to 2nd MC and/or trapezium
    • Can add k-wire through volar ulnar fragment
  • Open reduction if >1-2mm displacement/intra-articular step (controversial in literature)
    • Wagner approach
  • Consider distraction + ex-fix for fragments too small to fix

Rolan>Rolando

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  • Described by Silvio Rolando in 1910
  • Y or T shaped 3 part intra-articular fracture
    • Volar ulnar fragment + dorsal radial fragment
  • Worse prognosis – over 50% CMC OA (Langhoff et al. 1991)
  • Management:
    • CRIF for simple 3 part fractures if <1mm displacement
    • ORIF if >1mm displacement
    • Distraction + fixation/ligamentous reduction for highly comminuted fractures
      • Traction pinning, external fixation

    • 1st CMC>1st CMC Dislocation

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  • Rare (<1% of thumb injuries)
  • Mostly dorsal
  • Mechanism:
    • Axial force on flexed thumb
    • Dorsal force through 1st web space (e.g. handlebar into thumb)
  • Presentation:
    • Pain, swelling and bruising over thenar eminence
    • Unable to form fist

    • Anatomy>Anatomy

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  • 16 ligaments stabilise CMC joint — 4 important ones:
    • Dorsoradial ligament check rein to radial subluxation (most important)
    • Anterior oblique ligament (superficial/deep)
    • Posterior oblique ligament
    • Intermetacarpal ligament

    • Investi>Investigations

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  • Standard radiographs
  • MRI
    • Persistent/recurrent instability post reduction
    • Guides ligament reconstruction

    • Managem>Management

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  • Closed reduction + immobilisation in extension/pronation
    • Only if stable on reduction
  • Closed reduction + percutaneous pinning
    • Recommended treatment
    • For more unstable injuries
  • Adding dorsal capsuloligamentous reconstruction with FCR autograft + pinning  leads to better strength & ROM and lower pain (Simonian & Trumble 1996)
  • Low incidence of recurrent dislocation

    • Ulnar C>Ulnar Collateral Ligament Injuries

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  • Thumb MCP joint stable throughout flexion/extension arc
  • Range of motion is extremely variable – even between sides in same pt
  • Consists of two parts:
    • Proper collateral ligament – taut in flexion
    • Accessory collateral ligament – taut in extension
  • Dynamic stability from adductor pollicis, FPB and EPB
  • Mechanism of injury
    • Excessive radial deviation at MCP joint
  • Acute injury = skier’s thumb
    • Usually distal avulsion
    • 50% have P1 fractures
  • Chronic injury = gamekeeper’s thumb

    • Physical exam>Physical exam

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  • Can differentiate complete from partial tears
  • Difficult in acute injuries due to pain/spasm
  • Unstable injury:
    • >35o joint angulation on valgus stress of flexed MCP = complete proper collateral lig tear
    • >35o joint angulation on valgus stress of extended MCP = complete accessory collateral lig tear
    • Greater than 20o variation in side to side valgus laxity
    • Lack of firm end point on stress testing

    • Stener lesion>Stener lesion

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  • UCL torn and displaced proximal/superficial to adductor pollicis aponeurosis
  • Aponeurosis interposed between ligament and attachment point = unable to heal
  • Diagnosis:
    • Palpable mass proximal to MCPJ
    • XR – may seen bony Stener lesion
    • MRI – specificity 95%, sensitivity 96%
  • Indication for surgical repair

    • Treatment

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  • Acute:
    • Stable injuries/partial tears – 4 weeks immobilisation spica splint/cast
    • Unstable injuries/complete tears – surgical repair
      • Suture repair of ends vs suture anchor repair of avulsions
    • Avulsion fractures with no bony Stener lesion = controversial
      • Generally non-op for undisplaced fractures that are stable on stress testing
        • Be careful with stress testing – may turn undisplaced into displaced lesion
        • Consider leaving for 1-2 weeks then stress testing once pain settled and lesion not as mobile
      • Variable outcomes, painless non-unions, ongoing instability
    • Chronic (gamekeeper’s thumb)
      • Reconstruct only in absence of significant MCPJ arthritis
      • Up to 2yrs can consider mobilisation of UCL from scar and repair to bone with anchors
      • Dynamic procedures – utilising adductor pollicis or EPB
      • Static procedures – free tendon grafts to reconstruct ligaments

    Complications

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  • General:
    • Reduced grip/pinch strength and reduced function
    • Post-traumatic OA and pain/stiffness
    • Fractures
      • Malunion/non-union
      • Deformity
    • CMC dislocation + UCL injury
      • Recurrent instability
    • Surgical
      • Injury to dorsal branches of SRN
      • Pin site infection
      • Failed repair/reconstruction

    References

    >Referencesock-list">
  • Carlsen BT & Moran SL. Thumb trauma: Bennett fractures, Rolando fractures, and ulnar collateral ligament injuries. J Hand Surg Am. 2009 May-Jun;34(5):945-52.
  • Edmunds JO. Traumatic dislocations and instability of the trapeziometacarpal joint of the thumb. Hand Clin. 2006 Aug;22(3):365-92.
  • Kjaer-Peterson K, Langhoff O, Andersen K. Bennett’s fracture. J Hand Surg Br. 1990 Feb;15(1):58-61.
  • Langhoff O, Andersen K, Kjaer-Peterson K. Rolando’s fracture. J Hand Surg Br. 1991 Nov;16(4):454-9.
  • Simonian PT & Trumble TE. Traumatic dislocation of the thumb carpometacarpal joint: early ligamentous reconstruction versus closed reduction and pinning. J Hand Surg Am. 1996 Sep;21(5):802-6.

    • Contributions

    >Contributionsby Dr James Drummond (orthopaedic registrar) 2020