ACUTE PATELLAR DISLOCATION IN CHILDREN - INCIDENCE AND ASSOCIATED OSTEOCHONDRAL FRACTURES

In a prospective two-year study on urban (city of Helsinki) Finnish ch ildren, 72 acute patellar dislocations were observed. The calculated a nnual incidence rate was 43/100,000 in children under 16 years. A tota l of 28 knees (39%) had associated osteochondral fractures. These frac tures comprised 15 capsular avulsions of the medial patellar margin an d 15 loose intra-articular fragments detached from the patella and/or lateral femoral condyle. The intra-articular fragments were found only after spontaneous relocation of the patella. The femoral fracture con stantly involved the edge of the articular surface in the middle third of the condylar arc.