Changes in bone mineral density following total knee arthroplasty: a 1-year follow-up study by dual energy X-ray absorptiometry

Abstract

The assessment of bone density by means of dual energy Xray absorptiometry is a valid option for monitoring bone changes. In this study, time-related bone changes after total knee arthroplasty implantation were assessed in eight postmenopausal women (aged 62–72 years) up to one year from surgery. The pattern of bone changes followed a well-known design: an initial phase of accelerated bone loss and a subsequent phase of partial bone recovery. The greatest bone loss was observed at 2 months after surgery: 5.0% for the whole periprosthetic bone in the AP projection and 11.5% for the bone in the LL projection. In the following ten months the bone loss in the AP projection was completely recovered while the periprosthetic bone evaluated in the LL projection showed a residual bone loss of 9.0%. At 12 months from surgery, the distal femur in LL projection showed the greatest bone loss: 20.0% for the anterior region of interest and 17.0% for the posterior one. A significant correlation was found between the maximum postoperative bone loss and the residual bone loss at 12 months. These results suggest that pharmacological and rehabilitative strategies may be useful for the conservation of bone stock.