Two cases of osteochondritis dissecans affecting several joints.

Osteochondritis dissecans affecting a single joint has been widely studied since the term was first introduced by Konig in 1887. Multiple lesions are comparatively uncommon ; those most often reported are lesions of both medial femoral condyles (Hermanson 1946, King 1932). Other combinations reported are : the medial femoral condyle and opposite patella (Archer and Peterson 1930) ; both patellae (ibid.) ; both knees and both elbows (Watson-Jones 1943); and both knees and one elbow (King 1935, quoting \Valter). It is here proposed to describe two cases of multiple lesions, and to examine in the light of these cases some of the hypotheses of etiology. CASE REPORTS Case 1-(Figs. 1 to 6.) A gardener, aged eighteen years, gave a history of seven months’ pain in the left buttock, experienced on walking. The left knee was sometimes swollen. For four years he had been unable to extend either of his elbows fully, and the left one ached at times. He could remember no severe injury, but was a keen player of football and cricket and had been one of the best athletes at his school. There was no record of any joint trouble in other members of his family. Examination-The patient was short and wiry, and showed no evidence of endocrine disorder. In each elbow there were ten degrees of limitation of flexion, extension and supination; rotation caused crepitus over the radial head. In the left hip there was slight limitation of abduction and medial rotation. An effusion was present in the left knee with pain on full flexion. The other joints were clinically normal. Radiograp/is revealed osteochondritis dissecans of each patella. In each elbow the capitellum showed an area of osteoporosis and the radial heads showed some irregularity suggesting osteochondritis dissecans, but much less than was disclosed at operation. Control radiographs of the hands revealed no osteoporosis. Biochemistry and /zaematology-Blood count, normal ; serum calcium, 109 milligrammes per cent ; inorganic phosphorus, 46 milligrammes per cent ; serum alkaline phosphatase, 1 1 4 King-Armstrong units ; serum acid phosphatase, 24 King-Armstrong units ; blood urea, 21 milligrammes per cent ; urinary calcium, 250 milligrammes in twenty-four hours ; urea clearance, 96’S per cent of average function ; faecal fat, normal ; Wassermann reaction, negative. Operations-Left elbow : A loose body was removed from between the humerus and the radius; it corresponded closely with the shape of an eroded area on the outer side of the radial head, which was excised. Right elbow: Two loose bodies were removed from in front of the lower end of the humerus. The cartilage of the capitellum was softened centrally and that of the radial head showed similar but more pronounced changes. It seemed likely that the loose bodies had originated from these lesions. Right knee: The medial articular surface of the patella was grossly degenerated, the cartilage being heaped up and softened in parts, and eroded elsewhere. The patella was excised. The femorai surfaces were intact and no loose body was found. Left knee: An eroded area on the postero-medial aspect of the patella extending centrally into the bone was curetted and the edges were bevelled. The femoral surfaces were intact and no loose body was found. Follow-up-Six months after the last operation the knees had fully recovered but both