Background: The purpose of this study is to determine whether a Stener lesion can be created while testing stability of the ulnar collateral ligament (UCL) of the thumb. Testing was performed in a manner that reproduced clinical examination.
Methods: Six fresh frozen hand and forearm specimens underwent sequential sectioning of the accessory UCL, the proper UCL, and the ulnar sagittal band. Measurements of radial deviation of the metacarpophalangeal (MCP) joint were taken with the thumb in neutral rotation, pronation and supination, both with 0 degrees and with 30 degrees of flexion of the MCP joint. Visual examination was performed to assess the presence of a Stener lesion.
Results: No Stener lesion was created in any position as long as the fascial origin of the ulnar sagittal band at the adductor pollicis longus remained intact. After creating a defect in the ulnar sagittal band, a Stener lesion was created in two specimens, but only when the thumb was flexed and supinated. Pronation provided more stability, and supination provided less stability, with one or both components cut, especially when testing at 30° of flexion. Compared to both components cut without flexion or rotation, there was a statistically significant difference in angulation with the 30 degrees of MCP joint flexion in both neutral rotation in supination.
Conclusions: Performing a physical examination to assess the amount of instability of an ulnar collateral ligament injury did not create a Stener lesion if the exam was performed in a controlled, gentle manner with the thumb held without rotation. If the thumb is held in neutral rotation during the exam, an iatrogenic Stener lesion should not be created.
Keywords: Physical examination; Stener lesion; Stress test; Ulnar collateral ligament of the thumb.