Bone loss after total hip arthroplasty.

The aim of the present study is to evaluate periprosthetic bone loss and to compare it with the bone loss in other areas of the body. We also aim to shed light on the course of bone mineral density (BMD) in patients with cemented femoral prosthesis in comparison with those with uncemented ones. We analyzed the BMD using dual-energy X-ray absorptiometry (DEXA) in a consecutively recruited convenience sample of 50 patients with cemented and uncemented total hip arthroplasty (THA). BMD was measured within the first month after surgery as well as 1 year later. In ten of the patients (20%) previously undiagnosed osteoporosis was revealed. Osteoporosis was significantly more frequently detected in patients with cemented compared to those with uncemented femoral stem. We found a significant loss in BMD in the periprosthetic femoral region compared with no losses in other body regions (lumbar spine, radius, contralateral hip). The magnitude of this loss was the highest in Gruen-Zone 7 (mean 15.2% per year). We found no BMD loss difference between patients with cemented and uncemented prosthesis in the Gruen-Zone 2-7. In conclusion these periprosthetic losses may be due to local factors such as periprosthetic bone remodeling, as they contrast with the course of BMD in the lumbar spine, radius and not operated hip.