ABSTRACT
When adult developmental dysplasia of hip (DDH) patients have developed secondary os- teoarthritis of hip (OAH) with serious clinical symptoms,total hip replacement (THR) is their first choice of treatment.The anatomic structures of the acetabulum and femur in these patients are ahnormal and special,such as small and shallow cup,small femoral head,and narrow medullary cavity at proximal femoral shaft.As a result,the THR for DDH patients is quite different from the conventional ones and is thus highly difficult.We review in this paper the clinical classification of DDH,which is important for its treatment,the difficulties we will have in THR, especially in acetabular reconstruction and femoral prosthesis placement,and also strategies to resolve them.