Hydroxyapatite-coated total hip arthroplasty in osteoporotic patients.

A prospective review was performed on 22 osteoporotic patients (rated from 1 to 3 on the Singh Index) with hydroxyapatite-coated total hip replacements. These results were compared with a control group (Singh Index 4 to 6) of 45 patients (48 hips) with respect to clinical and radiographic data. Surgery was performed over a six-year period (1991 to 1996) and the time to follow-up evaluation averaged 5 years (range: 2 to 7 years). All patients, in both groups, were over 65 years old with an average age of 71 and 73 years, respectively. The pre-operative diagnoses and Harris hip scores were also similar for both groups. Clinical evaluation was based on the Harris Hip score and radiographic evaluations using Engh's criteria. There was no significant difference between the final average Harris hip score in the osteoporotic bone group, which was 87 points, and that for the control group, which was 91 points (p > 0.05). Radiographic evaluation demonstrated confirmed bone ingrowth in most patients in each group; one patient in each group had suspected bone ingrowth. No stems were revised for aseptic loosening and no endosteal lysis was found. Progressive bone formation was seen around the femoral stem proximally. The acetabular components demonstrated no sign of mechanical loosening or osteolysis. Bone formation was found in most patients in zone I, and in a few patients also in zone III. On the basis of the results of this study, it is believed that osteoporotic bone as a factor by itself should not compromise the early results of hydroxyapatite total hip arthroplasty and should provide good results in the long term.