A, Infant with severe proximal femoral focal deficiency. In addition to absent femur, tibia is short and lateral ray is absent. B, At 5 years of age, after Boyd amputation. Distal femoral epiphysis is seen, but there is no femoral shaft or head. Acetabulum shows no sign of development. Cartilaginous anlage of distal femoral epiphysis was present at birth but not yet radiographically evident.