Measurement of bone density around total knee arthroplasty using fan-beam dual energy X-ray absorptiometry

The clinical survival of joint arthroplasties is clearly associated with th e quality of surrounding bone environment. Bone mineral density (BMD) is an important measure of bone strength and quality. Periprosthetic BMD can be measured by using dual-energy X-ray absorptiometry (DXA) with special softw are algorithms. We studied short-term reproducibility of the periprosthetic BMD measurements after total knee arthroplasty (TKA) in 30 patients with p rimary osteoarthrosis. The operated knees and the contralateral control kne es were measured twice and the results were expressed as a coefficient of v ariation (CV%). The average precision error was 3.1% in femoral regions of interest (ROI) and 2.9% in tibial ROIs after TKA. In the prosthesis-free co ntrol knees, CV% were similar; 3.2% and 2.5%, respectively. The best precis ion was found in the femoral diaphyses above the implant (1.3%), whereas th e least reproducible BMD was determined in the patellar region of the TKA k nees (6.9%). Our results confirm that DXA measures precisely small bone min eral changes around TKA and makes it possible to follow bone remodeling DXA and may provide a feasible method for monitoring TKA in the future.