tailieunhanh - báo cáo hóa học:" Hip abductor moment arm - a mathematical analysis for proximal femoral replacement"

Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí sinh học quốc tế đề tài : Hip abductor moment arm - a mathematical analysis for proximal femoral replacement | Henderson et al. Journal of Orthopaedic Surgery and Research 2011 6 6 http content 6 1 6 JOURNAL OF ORTHOPAEDIC SURGERY AND RESEARCH RESEARCH ARTICLE Open Access Hip abductor moment arm - a mathematical analysis for proximal femoral replacement Eric R Henderson1 German A Marulanda1t David Cheong2t H Thomas Temple3t G Douglas Letson2t Abstract Background Patients undergoing proximal femoral replacement for tumor resection often have compromised hip abductor muscles resulting in a Trendelenberg limp and hip instability. Commercially available proximal femoral prostheses offer several designs with varying sites of attachment for the abductor muscles however no analyses of these configurations have been performed to determine which design provides the longest moment arm for the hip abductor muscles during normal function. Methods This study analyzed hip abductor moment arm through hip adduction and abduction with a trigonometric mathematical model to evaluate the effects of alterations in anatomy and proximal femoral prosthesis design. Prosthesis dimensions were taken from technical schematics that were obtained from the prosthesis manufacturers. Manufacturers who contributed schematics for this investigation were Stryker Orthopaedics and Biomet. Results Superior and lateral displacement of the greater trochanter increased the hip abductor mechanical advantage for single-leg stance and adduction and preserved moment arm in the setting of Trendelenberg gait. Hip joint medialization resulted in less variance of the abductor moment arm through coronal motion. The Stryker GMRS endoprosthesis provided the longest moment arm in single-leg stance. Conclusions Hip abductor moment arm varies substantially throughout the hip s range of motion in the coronal plane. Selection of a proximal femur endoprosthesis with an abductor muscle insertion that is located superiorly and laterally will optimize hip abductor moment arm in single-leg stance compared to one .