Surgery in acute patellar dislocation--evaluation of the effect of injury mechanism and family occurrence on the outcome of treatment.

A retrospective study was made of 270 patients and 284 knees with acute patellar dislocation treated operatively. The mean follow up time was 4.1 years. Medical history revealed 21.1% of cases with previous dislocations and 15.6% of cases with family occurrence of patellar dislocation. The dislocation resulted from an athletic performance in 41.5% of cases. The sport events most often associated with patellar dislocation were soccer, gymnastics, and ice hockey. All cases were treated with reefing of medial capsule. Release of lateral patellar retinacula was performed in 243 cases. Two cases were treated primarily with the Elmslie-Roux-Trillat procedure. The subjective result of operative treatment was better and the redislocation rate was lower if the injury mechanism was traumatic rather than non-traumatic and if there was no history for family occurrence of patellar dislocation.