Locked lateral patellar dislocation: a rare case of irreducible patellar dislocation requiring open reduction

Irreducible patellar dislocations are rare injuries, but those that do occu r are mainly directed intra-articularly. In this case, a 53-year-old woman sustained a locked lateral patellar dislocation when falling from a chair. A preoperative CT-scan revealed bony avulsions at the insertion of the vast us medialis muscle, the medial retinaculum, and partial disruption of the l igamentum patellae from the apex patellae. Open reduction was necessary and the torn structures were reattached with anchor systems and satures. Posto perative management included intensive physiotherapy. At 1 year after surge ry, the patient was without swelling or pain and had a normal gait, but fle xion was restricted to 120 degrees. All postoperative radiographs showed th e patella correctly placed in the femoral groove.