Factors Associated with Calcar Resorption in Cemented Total Hip Prostheses

Abstract

Patient data and radiograms from a series of 237 total hip replacements were evaluated by means of a computer program. Middle-aged patients and those without other dysfunctions of the lower extremities than the primary hip disease were prone to develop calcar resorption. Patients who did not use supportive aids preoperatively and subjects doing well without aids postoperatively were more frequently represented in the group with calcar resorption. The CAD-prosthesis (Computer Assisted Design, Howmedica), was positively correlated to resorption at calcar at 6 months postoperatively compared to the Charnley-Muller prosthesis. A negative correlation to valgus oriented femoral components was noted. Vertical placement of the acetabular cup, large cups and a long distance between the femur and the pelvis was noted to occur more often in the group with calcar resorption. Mechanical factors are concluded to be predominant in early calcar resorption and are suggested to be of clinical importance for the long term results.