A complete radial collateral ligament avulsion of the small finger metacarpophalangeal joint with displacement through the radial sagittal band.

A displaced complete radial collateral ligament avulsion with associated injury to the sagittal band of the metacarpophalangeal joint of the small finger, if left untreated, may result in chronic pain, instability, weakness, and deformity. A case of a displaced radial collateral ligament that ruptured through the radial sagittal band of the small finger, with resultant injury to the extensor mechanism, is described and discussed with a review of the literature. Proper identification of this injury by physical exam and imaging studies along with surgical repair is associated with good outcome.