Rotational Deformity of Long Finger Caused by Isolated Metacarpophalangeal Joint Capsular Injury: A Case Report.

CASE: A 49-year-old woman presented after a leash-pulling injury with ring and small finger proximal phalanx fractures. Pain and supination of the long finger metacarpophalangeal (MCP) joint were noted without collateral ligament injury on examination or imaging. Surgical exploration noted isolated capsular avulsion, which was repaired with restoration of alignment and full range of motion with relief of pain and instability at 1-year follow-up. CONCLUSION: This is a unique case of isolated finger MCP capsular injury causing rotatory instability. Surgeons should consider exploration and repair in cases of rotatory instability without other cause and failing nonoperative treatment.