Periprosthetic bony changes after cementless total hip arthroplasty

15 hips of 15 patients with collarless, straight stem, cementless total hip prostheses made up of titanium alloy have been evaluated. The mean age was 54 years (range, 37-67 years), the mean follow up was 30 months (range, 12-54). Patients were evaluated clinically with the Harris hip score, radiologically with anteroposterior and lateral radiographs and osteodensitometrically with anteroposterior DEXA (Dual Energy X-Ray Absorbtiometry) measurements in the Lunar and Gruen zones. As a result of stress shielding there were resorption of calcar femorale in all patients. On the other hand, there was hypertrophy of cortical and/or cancellous bone around the distal end of the femoral stem in 11 patients (%73) and hypertrophy of cancellous bone around the superolateral corner of the proximal part of the stem in 13 patients (%87). This biologic remodeling which presents itself as atrophy and/or hypertrophy around the femoral stem, begins within the first six months following the operation. In follow up for up to 4.5 years, no harmfull eftects of this resorptive bone remodeling has been observed cJinically. To understand if it is harmful or not, we need long term follow up of patients. if an osteodensitometric study is planned, immediate postoperative DEXA measurements must be done and later measurements should be compared to the first ones.