|
Year |
2002 |
|---|---|
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Question Number |
168. |
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Category |
Hand |
Question
A 24 year old man reports pain in the thumb at the metacarpophalangeal joint following a fall while skiing. Examination reveals significant swelling, ecchymosis, and a palpable mass on the ulnar side of the joint. Valgus stress testing of the joint reveals a 45 degree laxity in extension. Radiographs show no fractures. What is the next most appropriate step in management?
1- Ultrasound the joint
2- MRI
3- Surgical repair of the ulnar collateral ligament
4- Primary fusion of the thumb metacarpophalangeal joint
5- Thumb spica cast for 6 weeks
Figures
Answer (click for answer)
Preferred response: (3) surgical repair of the ulnar collateral ligament.
Forceful radial deviation of the thumb results in injuries to the ulnar collateral ligament complex resulting in gamekeeper’s or skier’s thumb. These are painful and debilitating in the acute phase and can lead to chronic instability if not recognized and appropriately treated. Examination reveals tenderness over the ulnar collateral ligament and often over the volar plate. Static radiographs are initially obtained to rule out avulsion fracture off the proximal phalanx. Dynamic radiographs are often useful to rule out subluxation with stress. Partial tears will not open up greater than 35 to 45 degrees on stress testing and can advance with thumb spica casting for 4 to 6 weeks, followed by progressive protected range of motion exercises. Complete rupture, opened up greater than 30 to 45 degrees, can be associated with a Stener lesion. This is an interposition of the adductor hood between the ruptured ligament and its insertion on the proximal phalanx. These injuries will not heal without open reduction and repair of the ligament to its bed. Postoperatively, a thumb spica cast is maintained for 4 to 6 weeks, followed by progressive protective range of motion exercises.
In an effort to determine whether valgus stress testing of the thumb metacarpophalangeal joint is predictive of a torn and displaced ulnar collateral ligament, anatomic and prospective clinical studies were performed by Heyman et al and the results correlated. In the anatomic study on autopsy specimens, dividing the proper collateral ligament resulted in a significant increase in valgus instability of the flexed metacarpophalangeal joint. Significantly less laxity was noted when the joint was tested in extension. When the accessory collateral ligament/palmar plate complex was also divided, valgus instability in extension increased to the extent that it no longer differed significantly from the values obtained when the joint was tested in 30 degrees flexion. In the clinical study, valgus instability of greater than 35 degrees when the joint was positioned in extension and then stressed consistently indicated the presence of tears of the proper and accessory collateral ligaments: A Stener’s lesion was present in 15 of 17 such cases (87%). Values on valgus stress testing of the metacarpophalangeal joint in extension and 30 degrees flexion are highly predictive of both disruption and displacement of the ulnar collateral ligament of the thumb.
Reference: Heyman P, Gelverman RH, Duncan K, Hipp JA: Injuries of the ulnar collateral ligament of the thumb metacarpophalangeal joint: biomechanical and prospective clinical studies on the usefulness of valgus stress testing. Clin Orthop 1993; 292:165-71.
Motley GS et al. Adult trauma. In Miller review of orthopedics, 3rd ed. 2000; 510-11.