TC-SCINTIMETRY IN 56 CEMENTLESS HIP ARTHROPLASTIES - A PROSPECTIVE, RANDOMIZED COMPARISON OF 2 FEMORAL COMPONENTS

In a prospective, randomized study of cementless total hip arthroplast ies, radionuclide images as well as radiographs were obtained at 6, 12 , and 36 months postoperatively. The femoral component was porous-coat ed, rigid in 28 patients and smooth, isoelastic in 28. The radionuclid e uptake was quantified in the regions of interest and correlated to t he non-operated side. Among prostheses considered to be stable 3 years after surgery, the activity had normalized in the calcar region. The uptake was also reduced below the tip of the prostheses, but the activ ity was still 50 percent increased compared to the non-operated side. The isoelastic prosthesis showed less reduction of activity below the tip than the rigid prosthesis. Proximally, the isoelastic prosthesis s howed no reduction of activity, whereas the rigid prosthesis had norma lized the uptake at the 3-year control. A high rate of non-stable fixa tion was observed for the flexible prosthesis at the radiographic asse ssment, which may have contributed to the increased radionuclide activ ity. Sequential scintimetry may be used as a complement to the radiogr aphic evaluation of the femoral component of the hip prosthesis.