We examined a group of 26 patients (28 hip joints) with postdysplastic osteoarthritis who were operated in 1995 and 1996.

The Zweymüller Bicon prosthesis was used in all cases. Only patients with dysplasia Type B and C according to Eftekhar were included. By the method of Ranawat and Pagnana, the true acetabular region and the approximate femoral head centre were determined on preoperative and postoperative radiographs. The patients were controlled in 1999 with HHS. Antero-posterior radiographs of the pelvis and lateral radiographs of the acetabulum according to Zweymüller were made in all hips.

In most of the operated hip joints the true center of the rotation differed from the ideal centre, with the maximal difference being 18 mm cranially. Cranial placement of the cup occurred more frequently in Type C. No patient was reoperated, and as determined by radiographs, there were no indications of loosening in the acetabular and femoral components.

The Zweymüller Bicon total hip joint endoprosthesis is suitable in most cases of postdysplastic osteoarhritis of the hip. No special or individual implant was necessary in 1995 and 1996. Good primary stability and a good result was achieved in all cases. We consider this type of hip implant as especially useful in CDH osteoarthritis.