Stress examination of the thumb metacarpophalangeal ulnar collateral ligament

1. Isolated division of the proper ulnar collateral ligament produces more valgus laxity when the joint is tested in 30° of flexion than in full extension.

True

In Heyman's anatomic study, dividing the proper collateral ligament significantly increased valgus instability of the flexed joint, with significantly less laxity in extension. Only after the accessory collateral ligament and palmar plate were also divided did laxity in extension no longer differ significantly from that in 30° of flexion, which is why both positions are tested.

• Heyman P, Gelberman 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 Relat Res. 1993;(292):165-71. PMID 8519106

2. Because normal thumbs show little side-to-side variation, comparison with the uninjured thumb is a reliable criterion for complete rupture.

False

Malik and colleagues tested 200 normal thumbs: 34% of people had a side-to-side difference of 10° or more in extension and 12% a difference of at least 15°. They judged contralateral comparison unreliable in many individuals and recommended the lack of a definite end point on stress testing as the sign of complete rupture.

• Malik AK, Morris T, Chou D, Sorene E, Taylor E. Clinical testing of ulnar collateral ligament injuries of the thumb. J Hand Surg Eur Vol. 2009;34(3):363-6. PMID 19349298

3. In Heyman's prospective series, valgus laxity greater than 35° with the joint in extension indicated tears of both the proper and accessory ligaments, and most such thumbs had a Stener lesion.

True

In the clinical arm of the study, instability greater than 35° in extension consistently indicated disruption of both ligament components, and a Stener lesion was found in 15 of 17 such thumbs. Stress testing in extension and in 30° of flexion was highly predictive of both disruption and displacement of the ligament.

• Heyman P, Gelberman 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 Relat Res. 1993;(292):165-71. PMID 8519106

4. Supinating the thumb during stress testing improves accuracy by stabilising the joint.

False

In Mayer's cadaver study, supination decreased and pronation increased valgus stability compared with neutral rotation. Testing in supination could make a partial tear look complete, and testing in pronation could make a complete tear look partial, so the authors recommend standardised testing in neutral rotation.

• Mayer SW, Ruch DS, Leversedge FJ. The influence of thumb metacarpophalangeal joint rotation on the evaluation of ulnar collateral ligament injuries: a biomechanical study in a cadaver model. J Hand Surg Am. 2014;39(3):474-9. PMID 24495627

5. In a cadaver model, gentle stress testing could not produce a Stener lesion while the fascial origin of the ulnar sagittal band remained intact.

True

Lankachandra and colleagues reproduced clinical stress testing in six specimens after sequential ligament sectioning. No Stener lesion was produced in any position while the fascial origin of the ulnar sagittal band remained intact; after that structure was divided, a Stener lesion occurred in two specimens, and only with the thumb flexed and supinated. The authors conclude that a controlled, gentle examination with the thumb held in neutral rotation should not create an iatrogenic Stener lesion.

• Lankachandra M, Eggers JP, Bogener JW, Hutchison RL. Can Physical Examination Create a Stener Lesion?. J Hand Surg Asian Pac Vol. 2017;22(3):350-354. PMID 28774254