Recurrent atraumatic superior dislocation of the patella: case report and review of the literature.

Recurrent atraumatic superior dislocation of the patella with spontaneous reduction prevented by interlocking osteophytes has not been previously reported. Eight previous case reports were noted in the literature with single episodes of interlocking by osteophytes in a superior dislocation, none with recurrence, and all treated by closed reduction. The presentation of a 60-year-old woman with recurrent atraumatic superior dislocation of the patella on three separate occasions required closed reduction due to interlocking patella and trochlear osteophytes that were preventing spontaneous reduction. Arthroscopic debridement of these osteophytes resulted in no functional limitation or recurrence of dislocation at 28-month follow-up. This case demonstrates successful arthroscopic treatment of this previously unreported condition. In light of the increasingly active aging population with coexistent patellofemoral joint osteoarthritis, this presentation may become more frequent.