The study describes the topography, morphology and growth of osteophytes in forty femoral heads removed from patients presenting with advanced osteoarthritis of the hip. In addition to standard histological techniques, radiography of serial bone slices and in vivo bone labelling with tetracycline and ³²P were used. The pattern of major osteophyte formation appeared to be influenced by the direction, degree and rate of displacement of the femoral head in relation to the acetabulum; four principal patterns of growth were noted. Osteophytes form part of extensive osteogenic processes that involve bone structure in the osteoarthritic joint.

1. Osteogenesis in the osteoarthritic femoral head has been examined with radioactive ³²P and tetracycline bone markers.

2. In advanced osteoarthritis considerable osteogenic activity was observed, particularly in osteophytes, around cysts and in some areas of bone sclerosis.

3. Two forms of osteogenesis were seen: a form of enchondral ossification, and apposition of new bone to existing bone trabeculae.

4. The findings support previous studies suggesting that rapid turnover of bone tissues occurs in advanced osteoarthritis.

1. A case of compression of the deep palmar branch of the ulnar nerve by an accessory abductor minimi digiti muscle is described.

2. The morphology of abnormal muscles in the hypothenar region is discussed.

3. Five previously reported cases of ulnar nerve compression at the wrist by an anomalous muscle are reviewed.

4. When symptoms are produced by an anomalous hypothenar muscle, they seem to be related to the anatomical site of the muscle and the presence of muscle hypertrophy. Occupational factors may be important in producing this hypertrophy.