Bone mineral density of the femur in autopsy retrieved total knee arthroplasties

Abstract

Bone mineral density (BMD), as measured by DEXA, can vary depending on bone rotation and fat content of soft tissues. We performed DEXA measurements, under controlled positioning, on 24 autopsy-retrieved femora from patients who had fully functional and asymptomatic successful TKA to determine periprosthetic BMD changes and compared results to 24 normal cadaveric femora. In TKA specimens, BMD was affected by gender, preoperative diagnosis, and zone under analysis. The lowest mean BMD was in the anterior femoral condylar zone. Males had higher mean BMD at all zones while patients with preoperative diagnosis of osteoarthritis had higher BMD in the posterior condylar zone. The mean BMD in the anterior femoral condylar zone in TKA specimens was significantly lower than in normal specimens without arthroplasties, most likely due to stress shielding.

Keywords: DEXA; bone mineral density; distal femur; knee arthroplasty; stress shielding; total knee arthroplasty.