This is an overview of South African iliac crest bone histomorphometric findings. The examination Bone in health: a study of 346 healthy black and white South African subjects revealed thicker trabeculae and greater osteoid and erosion values in blacks. If this finding reflects greater bone turnover, then bone in blacks would be renewed more frequently and be less prone to fatigue failure. The finding of higher bone marrow cellularity in blacks is in keeping with greater bone turnover. Greater bone turnover and sturdier micro architecture may contribute to the lower fragility fracture rates in blacks.

Bone disease in black teenagers is discussed. Rickets, due to dietary calcium deficiency, is associated with grotesque limb deformities and severe osteomalacia (OM). Dietary calcium deficiency was found to aggravate Rickets in endemic fluorosis. Genu valgum and varum deformities were also found to be attributable to dietary calcium deficiency. Some patients developed nutritional secondary hypoparathyroidism before going on to OM. The most severe OM was seen in boys aged 16 to 19 years. Teenagers with slipped upper femoral epiphysis were found to be osteopoenic. This may explain why the slip in blacks is more severe and more frequently bilateral than in whites.

In black adults, African haemosiderosis (from traditional beer brewed in iron pots) was found to be associated with increased erosion depth and disconnection of the trabecular network. Bone formation was not impaired. Alcohol bone disease, on the other hand, showed predominantly osteoblast impairment. Patients with femoral neck fractures (FNF) had both haemosiderosis and alcohol bone disease. FNFs were found in younger black patients than white and were predominantly in males. The osteoporosis was also more severe and OM was not seen.

We studied the histomorphometry of the trabecular bone of 19 black men and 15 black women over the age of 60 years who had sustained fractured neck of femur (FNF) as a result of minor trauma. The findings were correlated with indicators of iron overload (ferritin and vitamin C).

A striking feature was the presence of iron granules in the bone marrow of 16 of the men and nine of the women, together with fibrosis. Present in large numbers, the granules were quantitated. There were significantly more iron granules in the men than in the women (p =0.05). Ferritin levels were higher in those patients with large numbers of granules than in those with few or no granules. There was no clear correlation with the indicators, bone formation or resorption.

We concluded that iron overload is a strong aetiological factor in black male FNF patients. In postmenopausal female FNF patients, the possible aetiological role of iron overload is complicated by hormone deficiency.