99mTc-SN-pyrophosphate scintigraphy following traumatic posterior dislocation of the hip.

Avascular necrosis of the head of the femur is a serious complication of traumatic dislocation of the hip joint; therefore 99mTc-SN-pyrophosphate scintigraphy was carried out 10 to 14 weeks (average 12 weeks) after the injury on 12 patients to determine whether it was possible to demonstrate reduced or no activity of the head of the femur before development of radiological avascular necrosis of the head of the femur. Increased activity was observed in 9 of 11 hips with fracture-dislocation of the head of the femur, acetabulum or both, and normal activity was demonstrated in the contralateral hip of all patients. During the follow-up period avascular necrosis of the head of the femur developed in four hips from 6 to 20 months after the accident. It is concluded that 99mTc-SN-pyrophosphate scintigraphy 12 weeks after traumatic dislocation of the hip was unable to identify hips at risk of later development of avascular necrosis of the head of the femur.