Clinical, radiographic, and scintigraphic comparison of the mechanical stability of Mueller and Zweymueller total hip prostheses

Abstract

Twenty-two cemented Mueller and 25 uncemented Zweymueller total hip arthroplasties (THAs) were performed in the same period in 47 consecutive randomly selected patients with unilateral primary osteoarthritis. Patients were evaluated using the same clinical and radiographic protocol preoperatively; 3, 6, and 12 months postoperatively; and annually thereafter as well as with Tc 99m MDP three-phase bone scintigraphy 3, 6, 12, and 24 months postoperatively. At 11 periprosthetic regions of interest (ROIs) around the stem and socket of each prosthesis, several radiographic parameters and bone scintigram uptake grade were recorded and correlated to determine the significance of early scintigraphic uptake for prediction of the stability of cemented and uncemented THA components over time. Around stable Zweymueller and Mueller sockets, the radionuclide uptake was similar during all periods of observation. Radionuclide uptake around stable Zweymueller stems was significantly more than around stable Mueller stems at the medial femoral cortex 3 and 6 months postoperatively, at the lateral femoral cortex 3-24 months postoperatively, and near the tip of the stem 3 months postoperatively. Radionuclide uptake around stable Mueller stems was significantly more than around Zweymueller stems at the greater trochanter 6 and 12 months postoperatively and at the lesser trochanter 12 months postoperatively. Any significant deviation of radionuclide uptake at any ROI, time, and THA component during the first 2 years postoperatively in combination with radiographic findings of loosening should be considered a serious predictive sign for loosening of a Mueller or Zweymueller THA component.