In-Depth Notes on Finger Injuries

Overview of Finger Injuries and Anatomy

  • Understanding the anatomy and biomechanics behind finger injuries is crucial for diagnosis and treatment.

Pulley System in Fingers

  • Pulley System:

    • Tethers finger flexors to the bone.

    • Two types of pulleys:

    • A (Annular): Hold tendons close to the bone in rings.

    • C (Cruciform): Cross-shaped, supporting tendons.

  • Function: Prevents bowstringing of tendons during finger flexion.

Common Injuries Related to the Pulley System

  • Bowstring Injury:

    • Caused by rupture of pulleys, particularly A3 between proximal and middle phalanx.

    • Results in the flexor digitorum popping into the palm (visualized in provided images).

  • Trigger Finger:

    • A form of tenosynovitis affecting flexor tendons.

    • Symptoms: Swollen tendon which gets caught on the pulley, causing a triggering sensation.

    • Treatment:

    • Conservative: Splinting to immobilize tendons; allows inflammation to decrease.

    • Cortisone Injections: Effective in reducing inflammation.

    • Surgical Intervention: If conservative treatment fails, surgery to cut the tendon sheath may be necessary.

Mallet Finger

  • Also known as Baseball Finger.

    • Injury from hyperflexion or impact (common in sports).

    • Affects the distal extensor tendon, causing distal interphalangeal (DIP) joint flexion.

    • May lead to long-term deformities like swan neck if untreated.

  • Swan Neck Deformity:

    • Characterized by distal interphalangeal flexion and proximal interphalangeal extension.

    • Often results from intact central band of the extensor mechanism with lax volar plate.

    • More prevalent in individuals with rheumatoid arthritis.

Finger Deformities

  • Boutonniere Deformity:

    • Damage to the central slip while retaining lateral bands.

    • Results in the proximal phalanx appearing to protrude through lateral bands (like a boutonniere).

    • Can occur from acute injuries or conditions like rheumatoid arthritis.

Jersey Finger

  • Commonly associated with athletes who hyperextend their fingers, particularly grabbing a jersey.

    • Involves tearing of the flexor digitorum profundus.

    • Clinical Presentation: Inability to flex the DIP joint when making a fist.

Ulnar Collateral Ligament Injury (Skier's Thumb)

  • Injured through hyperabduction of the thumb (originally while skiing).

    • Leads to instability and weak pincer grasp.

    • Diagnosis: Valgus stress test for thumb indicating laxity.

    • Treatment:

    • Thumb Spica Splint: Commonly used for immobilization.

    • Surgery: May be needed for severe cases.

Osteoarthritis vs. Rheumatoid Arthritis

  • Osteoarthritis:

    • Presents with Heberden's and Bouchard's nodes.

    • Characterized by bony enlargement, especially at DIP and PIP joints but not at MCP.

    • Associated with bony spurs and bone growth.

  • Rheumatoid Arthritis:

    • Displays ulnar drift and deformities like boutonniere and swan neck.

    • Destructive changes in bone structure present, leading to joint erosion rather than bony spurs.

Conclusion

  • Understanding these injuries and their anatomical implications helps in effective treatment and rehabilitation strategies. Review and seek clarification on any complex topics as needed.