[Progressive fragmentation of a bipartite patella: apropos of a case].

Purpose Of The Study: Progressive dissolution of the supero-lateral fragment of a bipartite patella is reported.

Material And Methods: The patient, a 44 year old professor of gymnastics, was examined for long standing anterior knee pain. For many years, his daily activities included forceful knee flexion exercises. Serial radiographs, between 1986 and 1990, revealed a progressive fragmentation of the accessory ossification center and accompanying calcific deposits in the lateral patellar retinaculum.

Results: Surgical excision of the calcific mass and accessory ossification center relieved the painful symptomatology completely, allowing the patient full normal function at one year's follow-up.

Discussion: The pathological findings were compatible with a dystrophic calcinosis associated with detritic synovitis. A pathogenic mechanism is hypothesized for this unusual and progressive course of a common condition: Repetitive trauma, in this case forceful knee flexion exercises, shear microscopic bony fragments of the poorly vascularized accessory ossification center. These microscopic fragments act as deposits of an apatite crystal which go on to induce the secondary soft tissue calcifications seen in our patient.