Biomechanical factors in loosening of the Stanmore hip.

A series of 33 Stanmore total hip replacements with aseptic loosening was compared to a matched control series without loosening. Risk factors were previous hip surgery and osteopenia of the proximal femur. Biomechanical factors, notably varus position of the femoral stem and insufficient cementation, were of significance for the implant loosening. Alteration of the operative technique is recommended, emphasizing a correct valgus or neutral position of the femoral component and improved cementation.