Olsen Michael, Al Saied Mohamed, Morison Zachary, Sellan Michael, Waddell James P, Schemitsch Emil H
Martin Orthopaedic Biomechanics Laboratory, Li Ka Shing Institute, St. Michael's Hospital, University of Toronto, Toronto, ON, Canada
Division of Orthopaedic Surgery, Department of Surgery, St. Michael's Hospital, Toronto, ON, Canada.
Proc Inst Mech Eng H. 2014 Dec;228(12):1275-80. doi: 10.1177/0954411914562872.
Mid-head resection short-stem hip arthroplasty is a conservative alternative to conventional total hip replacement and addresses proximal fixation challenges in patients not suitable for hip resurfacing. It is unclear whether proximal femoral morphology impacts the ultimate failure load of mid-head resection implanted femurs, thus the aim of this study was to investigate the effect of native neck-shaft angle (NSA) and coronal implant alignment on proximal femoral strength. In total, 36 synthetic femurs with two different proximal femoral morphologies were utilized in this study. Of them, 18 femurs with a varus NSA of 120° and 18 femurs with a valgus NSA of 135° were each implanted with a mid-head resection prosthesis. Femurs within the two different femoral morphology groups were divided into three equal coronal implant alignment groups: 10° valgus, 10° varus or neutral alignment. Prepared femurs were tested for stiffness and to failure in axial compression. There was no significant difference in stiffness nor failure load between femurs implanted with valgus-, varus- or neutrally aligned implants in femurs with a NSA of 120° (p = 0.396, p = 0.111, respectively). Femurs implanted in valgus orientation were significantly stiffer and failed at significantly higher loads than those implanted in varus alignment in femurs with a NSA of 135° (p = 0.001, p = 0.007, respectively). A mid-head resection short-stem hip arthroplasty seems less sensitive to clinically relevant variations of coronal implant alignment and may be more forgiving upon implantation in some femoral morphologies, however, a relative valgus component alignment is recommended.
股骨头中部截骨短柄髋关节置换术是传统全髋关节置换术的一种保守替代方案，可解决不适合髋关节表面置换患者的近端固定难题。目前尚不清楚股骨近端形态是否会影响股骨头中部截骨植入股骨的最终失效负荷，因此本研究的目的是探讨自然颈干角（NSA）和冠状面假体对线对股骨近端强度的影响。本研究共使用了36根具有两种不同股骨近端形态的合成股骨。其中，18根NSA为120°的内翻股骨和18根NSA为135°的外翻股骨分别植入了股骨头中部截骨假体。将两种不同股骨形态组内的股骨分为三个相等的冠状面假体对线组：外翻10°、内翻10°或中立对线。对制备好的股骨进行轴向压缩刚度测试直至失效。在NSA为120°的股骨中，植入外翻、内翻或中立对线假体的股骨在刚度和失效负荷方面均无显著差异（分别为p = 0.396，p = 0.111）。在NSA为135°的股骨中，外翻方向植入的股骨比内翻对线植入的股骨刚度显著更高，失效负荷也显著更高（分别为p = 0.001，p = 0.007）。股骨头中部截骨短柄髋关节置换术似乎对冠状面假体对线的临床相关变化不太敏感，在某些股骨形态植入时可能更宽容，然而，建议采用相对外翻的假体组件对线。
