Irreducible lateral dislocation of patella due to an intact retinaculum

Lateral dislocation of the patella is a common injury that can be treated s uccessfully nonoperatively. The authors present a patient with lateral disl ocation of the patella in which the patella rotated 90 degrees about its ve rtical axis. The retinaculum had been avulsed from the anterior aspect of t he patella but was otherwise intact. Because the intact retinaculum prohibi ted closed reduction, open reduction was performed. The patient has returne d to full, unrestricted activities.