Irregularity of the apophysis of the ischial tuberosity.

We report five cases of irregularity of the apophysis of the ischial tuberosity (Kremser's disease). In four, plain radiographs showed that the density of the radiolucent area increased within several months of a minor injury. Serial computerised tomography demonstrated new bone formation across the widened apophyseal plate, although there was no change in the shape or density of the apophysis itself. The separation repaired and remodelled spontaneously within a year. In one case, CT showed that the apophyseal ossification centre was smaller than that on the opposite side. Our findings showed that in four cases the irregularity of the apophysis of the ischial tuberosity may have been caused by an avulsion fracture, but the appearance in the fifth case was a normal variant of the ossification centre.