Patellar dislocation in army conscripts

Between 1990 and 1996, 119 Finnish male conscripts underwent operative treatment for patellar dislocation. There were 68 conscripts (58%) with primary and 51 conscripts (42%) with recurrent patellar dislocation. Sixty-five (55%) dislocations occurred during military service, 40 (34%) occurred during sports activities, and 14 (11%) occurred during leisure time. The most common cause of injury was military training at battle exercises (n = 30). The typical injury mechanism was knee valgus rotation on fixed foot and tibia (97 conscripts, 82%). Surgical procedures performed were open in 75 conscripts (63%) and arthroscopically assisted in 44 conscripts (37%). Twenty-three (19%) redislocations occurred during follow-up (mean, 6 years; range, 3-9 years). The subjective outcome of treatment was excellent in 23 (19%), good in 42 (35%), moderate in 44 (37%), and poor in 10 (9%) conscripts. The most common residual complaint was patellofemoral pain (25 conscripts, 21%). Only 42 (35%) conscripts were able to finish their military service normally; fitness classification was decreased in 16 conscripts (13%), and 61 (52%) were temporarily exempted from military service (class E). The results of operative treatment did not differ significantly in conscripts with primary and recurrent dislocation, except for the time of first recurrence, which was significantly longer in conscripts with primary than with recurrent dislocation (27 versus 9 months). Patellar dislocation is the most common form of severe knee injury among conscripts and significantly hampers military service. Operative treatment yields only satisfactory results. Preventive measurements should be considered. A suggested algorithm for the treatment and classification of acute and recurrent patellar dislocation among military conscripts is presented.