Results of Bipolar Endoprosthetic Arthroplasty in Avascular Necrosis of Femoral Head

In this study, we investigated the results of bipolar endoprosthesis of the acetabular side in the avascular necrosis of the head.We selected 31 joints of 23 cases who had been operated on for more than 3 years ago. The motive was, idiopathic 16 joints, alcohol 6 joints, steroid 5 joints and after fracture of the femoral neck 5 joints. Acetabular reaming was done in 6 cases, 7 joints. We investigated (1)proximal migration of the outer head, (2) existence of the roof osteophyte and (3) existence of osteolysis with the passing year's X ray.(1) Proximal migration was seen in 4 joints (12.9%), in the 3 joints, acetabular reaming was done.(2) Roof osteophyte was seen in the 6 joints that was not seen in the proximal migration.Bipolar endoprosthesis is elective for the avascular necrosis of the femoral head.We concluded that acetabular migration is the factor the bad results and that roof osteophyte contributes to the stability of the outer head.