ENDOPROSTHESES FOR OSTEONECROSIS OF THE FEMORAL-HEAD - A COMPARISON OF 4 MODELS IN YOUNG-PATIENTS

Eighty-eight hip arthroplasties were carried out in 75 patients, all a ged 50 years or less, with osteonecrosis. All the operations were carr ied out by one surgeon. Four different methods were used: a standard c emented arthroplasty; a cemented THARIES surface replacement; an uncem ented surface replacement; a cemented titanium femoral surface hemiart hroplasty. Comparable clinical improvement occurred in all 4 groups in itially. Aseptic loosening, with intersurface degradation and osteolyt ic lesions, was the most common cause of failure in the 3 types which had a polythene bearing. Polyethylene is the major contributor to bone boss around the endoprosthesis and loosening. Fixation of the surface hemiarthroplasty remained intact in every patient and failure was sec ondary to wear of the acetabular cartilage. We recommend surface hemia rthroplasty as an interim solution for young patients with stage III o r early stage IV osteonecrosis because this procedure conserves bone s tock, there is Little osteolysis and it can easily be revised.