Finger Deformity

Mallet Finger

• Finger deformity caused by disruption of the terminal extensor tendon distal to DIP joint

• may be bony or tendinous: Xrays are needed

• Treatment

  • extension splinting of DIP joint for 6-8 weeks for 24 hours daily

    • for soft tissue injury or for non displaced bony avulsion

    • avoid hyper-extension

    • PIP joint must be FREE

  • Surgery

    • ORIF or percutaneous

      • Indications

        • volar subluxation of distal phalanx 

        • >50% of articular surface involved ( relative indication)

        • >2mm articular gap ( relative indication)

    • Surgical reconstruction for chronic cases ( if normal joint, but results not so good)

    • DIP arthrodesis ( if painful joint)

Swan Neck Deformity

• Characterized by

  • hyperextension of PIP

  • flexion of DIP

• Caused by

  • Primary lesion: lax volar plate

  • Secondary lesion: imbalance of muscle forces on PIP (extension force > flexion force)

    • MCP joint volar subluxation (rheumatoid arthritis)

    • Mallet finger

    • FDS laceration

    • Intrinsic contracture (Seen in rheumatoid arthritis)

Treatment

• Conservative : double ring splint (to prevent hyper extension of PIP)

• Surgical: volar plate advancement and correct PIP joint muscles imbalances with either

  • Central slip tenotomy (Fowler) : most used

  • FDS tenodesis indicated with FDS rupture

  • Spiral oblique retinacular ligament reconstruction

Boutonniere Deformity

• Deformity characterized by

  • PIP flexion

  • DIP extension

• Caused by rupture of the central slip over PIP joint from (laceration, traumatic avulsion (jammed finger),

  capsular distension in rheumatoid arthritis

• pathoanatomic sequence includes

  • rupture of central slip 

  • attenuation of triangular ligament and palmar migration of collateral bands and lateral bands

    • causes intrinsic muscles of the hand (lumbricals) to act as flexors at the PIP joint

    • lumbricals also extend the DIP joint without an opposing or balancing force

Associated conditions

• rheumatoid arthritis

• pseudo-boutonniere: refers to PIP joint flexion contracture in the absence of DIP extension

Physical exam

• Deformity

• Elson test is the most reliable way to diagnose a central slip injury before the deformity is evident