Reimeringer M, Nuño N, Desmarais-Trépanier C, Lavigne M, Vendittoli P A
a Laboratoire de Recherche en Imagerie et Orthopédie, Génie de la Production Automatisée, École de Technologie Supérieure , 1100 Rue Notre-Dame Ouest Montréal Québec Canada H3C 1K3 .
Comput Methods Biomech Biomed Engin. 2013;16(11):1221-31. doi: 10.1080/10255842.2012.662677. Epub 2012 Mar 28.
One of the crucial factors for short- and long-term clinical success of total hip arthroplasty cementless implants is primary stability. Indeed, motion at the bone-implant interface above 40 μm leads to partial bone ingrowth, while motion exceeding 150 μm completely inhibits bone ingrowth. The aim of this study was to investigate the effect of two cementless femoral stem designs with different lengths on the primary stability. A finite element model of a composite Sawbones(®) fourth generation, implanted with five lengths of the straight prosthesis design and four lengths of the curved prosthesis design, was loaded with hip joint and abductor forces representing two physiological activities: fast walking and stair climbing. We found that reducing the straight stem length from 146 to 54 mm increased the average micromotion from 17 to 52 μm during fast walking, while the peak value increased from 42 to 104 μm. With the curved stem, reducing length from 105 to 54 mm increased the average micromotion from 10 to 29 μm, while the peak value increased from 37 to 101 μm. Similar findings are obtained for stair climbing for both stems. Although the present study showed that femoral stem length as well as stem design directly influences its primary stability, for the two femoral stems tested, length could be reduced substantially without compromising the primary stability. With the aim of minimising surgical invasiveness, newer femoral stem design and currently well performing stems might be used with a reduced length without compromising primary stability and hence, long-term survivorship.
全髋关节置换非骨水泥型植入物短期和长期临床成功的关键因素之一是初始稳定性。事实上，骨 - 植入物界面处超过40μm的运动导致部分骨长入，而超过150μm的运动则完全抑制骨长入。本研究的目的是调查两种不同长度的非骨水泥型股骨柄设计对初始稳定性的影响。一个植入了五种长度直柄假体设计和四种长度弯柄假体设计的第四代复合Sawbones（®）有限元模型，承受代表两种生理活动（快走和爬楼梯）的髋关节和外展肌力。我们发现，在快走过程中，将直柄长度从146mm减少到54mm，平均微动从17μm增加到52μm，而峰值从42μm增加到104μm。对于弯柄，将长度从105mm减少到54mm，平均微动从10μm增加到29μm，而峰值从37μm增加到101μm。两种柄在爬楼梯时也得到了类似的结果。虽然本研究表明股骨柄长度以及柄的设计直接影响其初始稳定性，但对于所测试的两种股骨柄，在不影响初始稳定性的情况下可以大幅缩短长度。为了将手术创伤降至最低，新型股骨柄设计以及目前性能良好的柄可以在缩短长度的情况下使用，而不会影响初始稳定性，从而也不会影响长期生存率。
