Poor fixation of the Mittelmeier hip prosthesis

We have evaluated 30 Mittelmeier hips on an average 3.3 years after the operation. Seven hips had been revised because of severe pain and mechanical loosening and one because of fracture of the threaded ceramic cup. Only five of the remaining 22 hips were asymptomatic. There was radiographic migration of the acetabular and femoral components in more than one third of the hips and increased scintimetric values around the femoral component in all but two hips. Unfavorable design of the Mittelmeier prosthesis may be an important etiologic factor contributing to poor component fixation and inferior clinical results. (author)