PREDICTION OF FEMORAL FRACTURE LOAD USING AUTOMATED FINITE-ELEMENT MODELING

Hip fracture is an important cause of morbidity and mortality among th e elderly. Current methods of assessing a patient's risk of hip fractu re involve local estimates of bone density (densitometry), and are lim ited by their inability to account for the complex structural features of the femur. In an effort to improve clinical and research tools for assessing hip fracture risk, this study investigated whether automati cally generated, computed tomographic (CT) scan-based finite element ( FE) models can be used to estimate femoral fracture load in vitro. Eig hteen pairs of femora were examined under two loading conditions - one similar to loading during the stance phase of gait, and one simulatin g impact from a fall. The femora were then mechanically tested to fail ure and regression analyses between measured fracture load and FE-pred icted fracture load were performed. For comparison, densitometry measu res were also examined. Significant relationships were found between m easured fracture load and FE-predicted fracture load (r = 0.87, stance ; r = 0.95, fall; r = 0.97, stance and fall data pooled) and between m easured fracture load and densitometry data (r = 0.78, stance; r = 0.9 1, fall). These results indicate that this sophisticated technique, wh ich is still early in its development, can achieve precision comparabl e to that of densitometry and can predict femoral fracture load to wit hin -40% to + 60% with 95% confidence. Therefore, clinical use of this approach, which would require additional X-ray exposure and expenditu re for a CT scan, is not justified at this point. Even so, the potenti al advantages of this CT/FE technique support further research in this area. (C) 1998 Elsevier Science Ltd. All rights reserved.