Amstutz H C, Nasser S, More R C, Kabo J M
Division of Orthopaedic Surgery, University of California, School of Medicine, Los Angeles 90024-6902.
Clin Orthop Relat Res. 1989 May(242):104-19.
Total hip arthroplasty in the young patient remains a considerable challenge. Cemented arthroplasty has an unacceptably high failure rate. Porous ingrowth designs are one alternative, but bone ingrowth is unpredictable, thigh pain is a frequent clinical finding, stress shielding is often observed, revision is more complicated, and microporous components are mechanically weaker. A new anthropometric femoral component has been designed with a goal of long-term stability through osseointegration. The prosthesis is optimized for canal fill in the distal metaphysis and proximal diaphysis. The components are manufactured in 16 sizes, with cutting broaches precisely machined to the same dimensions to provide an exact fit to the femur. The high-strength TiAl6V4 alloy stem is combined with heads of either CoCr alloy or alumina (Al2O3) for reduced polyethylene wear. The 135 degrees neck-shaft angle and modular design allow for restoration of the abductor lever arm. Because the prosthesis is not porous coated, it is also suitable for use with cement. In cemented application, the prosthesis shape provides an optimal cement mantle. Seventy-one total hip arthroplasties have been performed using the Anthropometric Total Hip (ATH) prosthesis: 31 with exact-fit cementless fixation and 40 with cement. Of those using cementless fixation, 21 have been followed for more than one year (mean, 20 months; range, 12-48 months). The early clinical findings are as good as, or superior to, other cementless designs used at the authors' institution. Stress remodeling of the proximal femur occurs early and stabilizes by one year. The observed changes appear to improve the stability of the prosthesis. Clinical and roentgenographic findings suggest the osseointegration of the ATH femoral component.
年轻患者的全髋关节置换术仍然是一项颇具挑战的任务。骨水泥型关节置换术的失败率高得令人难以接受。多孔长入型设计是一种选择，但骨长入情况难以预测，大腿疼痛是常见的临床症状，应力遮挡现象也经常出现，翻修手术更为复杂，而且微孔部件的机械强度较弱。一种新的人体测量学股骨部件被设计出来，其目标是通过骨整合实现长期稳定性。该假体针对干骺端远端和骨干近端的髓腔填充进行了优化。部件有16种尺寸可供选择，切割拉刀经过精确加工，尺寸相同，以确保与股骨精确匹配。高强度TiAl6V4合金柄与钴铬合金或氧化铝（Al2O3）股骨头相结合，以减少聚乙烯磨损。135度的颈干角和模块化设计有助于恢复外展肌杠杆臂。由于该假体没有多孔涂层，因此也适用于骨水泥固定。在骨水泥固定应用中，假体形状可提供最佳的骨水泥套。使用人体测量学全髋关节（ATH）假体进行了71例全髋关节置换术：31例采用精确匹配的非骨水泥固定，40例采用骨水泥固定。在采用非骨水泥固定的患者中，21例随访时间超过一年（平均20个月；范围12 - 48个月）。早期临床结果与作者所在机构使用的其他非骨水泥设计相当，甚至更优。股骨近端的应力重塑在早期就会发生，并在一年时趋于稳定。观察到的变化似乎提高了假体的稳定性。临床和影像学检查结果表明ATH股骨部件实现了骨整合。
