Thumb Collateral Ligament Injury



Thumb Collateral Ligament Injury


James Paul Hovis

Ngozi Mogekwu Akabudike



INTRODUCTION



  • Pathoanatomy



    • Primary arc of thumb metacarpophalangeal (MCP) joint motion is flexion/extension with minor arcs of abduction/adduction and pronation/supination.


    • The thumb MCP joint has minimal intrinsic stability because of the large radius of curvature of proximal phalanx base.


    • Thumb MCP joint has radial and ulnar collateral ligaments, with each collateral ligament being composed of proper and accessory collateral ligament components.


    • Proper collateral ligaments originate from the condyles of the metacarpal head and travel obliquely to insert on the volar third of the proximal phalanx.


    • Proper collateral ligaments are tight in flexion and loose in extension.


    • Proper ulnar collateral ligament resists radial deviation of thumb in flexion.


    • Proper radial collateral ligament resists ulnar deviation of thumb in flexion.


    • Accessory collateral ligaments originate from an area on the metacarpal head volar to the proper collateral ligament origin and insert on the volar plate and sesamoids.


    • Accessory collateral ligaments are tight in extension and loose in flexion.


    • Accessory ulnar collateral ligament resists radial deviation of thumb in extension.


    • Accessory radial collateral ligament resists ulnar deviation of thumb in extension.


    • Floor of the joint is formed by the volar plate.


    • Dynamic stability is provided to the joint through tendinous attachments of the adductor pollicis, flexor pollicis brevis, and extensor pollicis brevis.



  • Mechanism of injury



    • Acute injury because of sudden forced radial deviation (abduction) of the thumb.


    • Acute injury because of sudden forced ulnar deviation (adduction) of the thumb.


    • Chronic instability of the thumb MCP joint from inadequate treatment of an acute ligament tear or progressive attenuation of the ligament.


    • Ligament is commonly torn from the proximal phalanx and still attached to metacarpal. Rarely the ligament can tear proximally from the metacarpal.


    • The most common fracture pattern is an avulsion fracture from the base of the proximal phalanx where the ligament inserts.


    • Associated injuries can include tears of the dorsal capsule and ulnar aspect of the volar plate.


  • Epidemiology



    • Acute injury is particularly common in skiers and ball-handling athletes. Falling while gripping the ski pole causes the handle to rapidly abduct the thumb.


    • Chronic injury is also called “gamekeeper’s thumb” because of attenuation of the collateral ligament from repetitive breaking of rabbit’s necks using the index finger and thumb.


    • Ulnar collateral ligament injury is more common than radial collateral ligament injury.


EVALUATION



  • History



    • Fall onto an outstretched hand with the thumb abducted


    • Repetitive abduction activities at the thumb MCP joint


    • Difficulty with pinch or gripping with thumb and index finger


    • Pain worsened by forceful pinch or torsional motions of the hand such as unscrewing jar tops


    • Pain, tenderness, and ecchymosis at the ulnar or radial aspect of the thumb MCP joint


  • Physical examination



    • Physical examination is usually sufficient to make the diagnosis.


    • Inspect the resting posture of the thumb for volar subluxation or radial deviation of the MCP joint.


    • Pain with palpation of the ulnar or radial aspect of thumb MCP joint



    • Ecchymosis and swelling of the ulnar or radial aspect of thumb MCP joint


    • Weakness or pain with power pinch


    • Mass at ulnar aspect of thumb MCP joint may represent a Stener lesion.


    • Stener lesion—avulsed ligament with or without bony attachment displaced proximal and above the adductor aponeurosis such as that the aponeurosis prevents contact of the injured ligament with the avulsion site.


    • There is no potential mass from interposition on the radial side of the MCP joint comparable with the Stener lesion seen on the ulnar side.


    • With radial collateral ligament rupture, a dorsoradial prominence of the metacarpal head can be commonly seen.


    • Thumb MCP joint range of motion can be limited by pain.


    • Similar criteria to assess ulnar collateral ligament stability can be applied to the radial collateral ligament.


    • Must stress joint in extension and 30 degrees of flexion



      • Greater than 35 degrees of joint laxity with stress suggests complete ligament tear.


      • Fifteen degrees more joint laxity when compared to contralateral thumb suggests complete ligament tear.


      • Joint opening without resistance or clear endpoint suggests complete tear.


      • Partial torn ligaments usually have a discrete endpoint despite some laxity.


      • Radial deviation of extended thumb tests ulnar accessory collateral ligament.


      • Radial deviation of flexed thumb tests ulnar proper collateral ligament.


      • Ulnar deviation of extended thumb tests radial accessory collateral ligament.


      • Ulnar deviation of flexed thumb tests radial proper collateral ligament.


    • Representative image(s)


  • Imaging

May 7, 2019 | Posted by in ORTHOPEDIC | Comments Off on Thumb Collateral Ligament Injury
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