System for description of congenital hip abnormalities. Type A, shortened femur and absent femoral neck (hip joint appears formed on radiograph); type B, severe proximal femoral shaft deformity with rudimentary femoral head and pseudoarthrosis; type C, small tufted proximal femur, absent femoral head, and shallow acetabulum; type D, absence of proximal femoral shaft, femoral head, and acetabular hypoplasia.