Effect of hip position on blood flow to the femur in puppies.

Utilizing radioactive microspheres, blood flow to the femoral head of immature dogs was measured. Blood flow was measured with the leg in the control position, maximal abduction, submaximal abduction, and the human position of hip immobilization. Maximal abduction (to 90 degrees) significantly decreased flow to the capital femoral epiphysis. Submaximal abduction and the human position did not reduce blood flow. Measurement of flow in the control position immediately after forced abduction demonstrated marked reactive hyperemia. These data indicate that ischemia occurs during 90 degrees forced abduction of the hip. This finding supports the use of lesser degrees of abduction for hip immobilization in the treatment of congenital dislocation of the hip. The vascular anatomy of the head of the femur in puppies and children suggests that these data can be extrapolated to man.