Pelvis #9 - Answers

1. Osteonecrosis of left hip, secondary to old left intertrochanteric fracture
2. Multiple hereditary exostosis syndrome involving right proximal femur

Findings

1. Subchondral collapse of left femoral head, with sclerosis in weight-bearing portion of femoral head
2. Old, healed intertrochanteric fracture of left femoral neck with heterotopic bone medial to lesser trochanter
3. Lucent channel in left femoral neck from previous dynamic hip screw
4. Widened, dysplastic right femoral neck with sessile osteochondromas along medial margin

Brief Discussion

The findings in the weight-bearing portion of the left femoral head are fairly typical of osteonecrosis. Often the femoral blood supply through the intertrochanteric area is sufficient that osteonecrosis does not usually complicate a fracture there. Alas, it was not sufficient in this case.

The widened right femoral neck is classic for multiple hereditary exostosis syndrome. Usually both hips are involved in that syndrome, but occasionally the involvement is unilateral. The humeral head and necks may look similarly short and thickened. When one first discovers an osteochondroma elsewhere in the body, the primary question to answer is whether the patient simply has a single sporadic lesion or the syndrome of multiple hereditary exostoses. This is important because of the markedly increased likelihood of malignant degeneration in the hereditary form.

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