[Plication of the hip synovium above the femur neck].

A 23 year old man, expert in karate, complained of sudden movements of right hip during "circular kicks", followed by persistent pain. Arthrography showed synovial plication in joint at upper border femoral neck, with a tongue-like projection from upper recess extending to head/neck junction and provoking bone erosion visible on standard images. Recovery followed resection of the fold. This is probably the first case of this type to be published. The lesion recalls the internal synovial plica of knee but differs from "frenula capsulae" and does not appear to have been described by anatomists. As in the knee it is probably an embryonic relic.