WHLLE osteochondritis dissecans of the knee is comparatively common, the occurrence of the condition in the ankle appears to be sufficiently unusual to warrant the recording of a single case.
CASE REPORT
HISToRY.-Miss Z . M., a European schoolteacher, aged 26, was first seen on July 16, 1948, when she stated that she had " put out " her left ankle a few hours previously. She had been sitting on the floor in a cross-leg position, and on rising to her feet she had felt a sudden sharp pain in the left ankle, and immediately had the sensation that the joint was locked. The pain had rapidly subsided to a dull ache, but the sensation of locking persisted.
She gave a previous history of a severe sprain of the left ankle in 1940, since when there had been occasional brief, sharp pains in the joint, and on one occasion twelve months ago momentary locking had occurred. Those subsequent incidents were not provoked by any further particular trauma to the ankle.
ON EXAMINATION.-The left ankle-joint was held in a position of mid-plantar flexion. The only active movement possible was a slight increase in the amount of plantar flexion. On passive movement a greater degree of plantar flexion was obtained, lateral movements at the subtaloid joint were present, but dorsiflexion of the foot appeared to be solidly blocked and the attempt to produce ir: caused considerable pain within the ankle. There was no obvious swelling of the joint. A localized area of tenderness was present on the anterolateral aspect at the level of the joint line.
Radiological examination (Fig. 484) revealed a loose body, apparently completely separated and lying in the