Long-term sequelae of pelvis irradiation: histological and microradiographical study of a femoral head.

Despite the lack of radiological signs, a femoral head showed histological and microradiographical features of osteonecrosis, 54 years after massive irradiation of the right hip. Intertrabecular spaces were invaded by connectivo-vascular tissue with focal accumulation of mast cells, and several resorption foci were filled with mononucleated cells. Moreover, all the microradiographs showed peculiar hypercalcified lines, sometimes containing empty osteocytic lacunae, the origin of which is difficult to precise. This study suggests that massive irradiation of weight-bearing epiphyses may be responsible for particularly long-term hypovascularity, osteonecrosis and disturbed bone remodeling.