Evaluation of periprosthetic bone using dual-energy X-ray absorptiometry: Precision of the method and effect of operation on bone mineral density

Abstract

To assess the perioperative bone loss of femur during total hip arthroplasty (THA), periprosthetic bone mineral density (BMD) of the seven regions of interests (Gruen zones) was determined with dual-energy x-ray absorptiometry (DXA) preoperatively in both proximal femurs and postoperatively in the involved side in 53 patients with degenerative hip osteoarthrosis. The mean (standard deviation, SD) precision error (coefficient of variation percent, CV%) in various regions of interest (ROIs) based on two consecutive measurements (n = 16) were 2.3 (0.8)%, 2.5 (1.5)%, and 2.8 (1.6)% for uncemented stems, cemented stems, and control sides, respectively. Furthermore, the mean variability caused by the rotation of femur was 3.5 (1.4)%. The most significant perioperative bone loss (13.5-19.2%) was found in the calcar area (zone 7) after noncemented THA. Zone 4, representing the bone below the prosthesis, also showed BMD decreases. These decreases suggest perioperative bone loss owing to rasping and reaming the calcar and bone canal. However, after cemented THA, highly significant BMD increases were found in all the lateral zones. The calcar area was the only site where significant perioperative bone loss was detected (12.8%). In conclusion, DXA is a precise method for quantifying bone mass and density changes in the follow-up of THA. However, when interpreting the results, the preoperative BMD, differences between the femurs and the effect of operation on bone mass should be taken into account. We suggest that the best reference for BMD follow-up is the periprosthetic BMD of the involved side measured soon after the THA.

Changes in periprosthetic bone remodelling after redesigning an anatomic cementless stem

“…In the early post-operative period, rapid bone loss can be detected as a consequence of post-operative rest, partial weight bearing and surgical technique [10,11]. In order to quantify and reduce the amount of this loss, which ranged between 0.2% to 8.8%, we took the post-operative scan as the baseline value to calculate later changes due to the biomechanical response to the implant.…”

“…In the last 20 years, dual-energy X-ray absorptiometry (DEXA) has been used to quantify the changes of bone mineral density (BMD) attributed to periprosthetic remodelling, and it is thought to be ideal for long-term follow-up studies [1,11,21].…”

Five-year DEXA study of 88 hips with cemented femoral stem

“…The density of the cement mantle will hardly change with time. Therefore, the BMD changes occurring postoperatively should reflect changes of the periprosthetic bone density [14]. The cement itself and especially its content of radiopaque contrast will add a constant to the value of the bone mineral content (BMC), which might imply an underestimation of the recorded changes when evaluated as change in percent.…”

“…To obtain baseline values for comparison, we used the postoperative values, measured within a week after the index surgery [2,14,18]. With this method, the bone loss due to operation, estimated at 13-19% in the calcar area, was excluded [14].…”

“…With these methods, however, only qualitative data on periprosthetic bone can be obtained [11]. The technical improvements in dual-energy X-ray absorptiometry (DEXA) have made it possible to accurately measure the quantity of bone near a metallic implant [11,12,14]. Recently quantitative computed tomography (QCT)-assisted osteodensitometry has also been shown to be useful in assessing the in vivo structural bone changes after total hip arthroplasty (THA) [20,21].…”