Abstract
1. Regional osteoporosis is a common finding in osteoid osteoma. It may in fact be a constant feature because it was present in all the patients reported in this paper and was suspected in others who have not been included in this report because of insufficient information.
2. Five of our six cases showed osteoporosis about the hip. Osteoporosis is more likely to be noticed in this region than in other parts of the extremities because both hips are usually radiographed on one film. We have seen several instances in which we suspected generalised osteoporosis of an extremity but Case 5 was the only one in which comparable radiographs had been taken of both feet.
3. When there is osteoporosis in the region of a joint with symptoms referred to that joint an osteoid osteoma may be the cause. The nidus may lie at some distance from the joint surfaces and may not be seen in standard radiographs of the joint (Case 4). Additional radiographs including a wider area than usual may be necessary to show the lesion, and tomography is sometimes required.
