Namba R S, Keyak J H, Kim A S, Vu L P, Skinner H B
University of California, San Francisco, USA.
Clin Orthop Relat Res. 1998 Feb(347):261-7.
Proximal atrophy and thigh pain are recognized problems with some cementless femoral stems in total hip arthroplasty. It is thought that reduced femoral stress from alterations in load transfer caused by an intramedullary stem contributes to proximal femoral atrophy. An increase in flexural rigidity and bone stress near the stem tip is thought to contribute to thigh pain. A three-dimensional finite element analysis study was performed to calculate stresses in the proximal femur and bone near the stem tip before and after implantation of a collared, proximally coated, cementless femoral prosthesis. The influence of prosthetic material was examined by changing implant composition from cobalt chrome to titanium alloy and leaving all other parameters constant. Femoral stress was increased twofold immediately below the collar with the titanium implant compared with the cobalt chrome. However, the proximal femoral stress in the titanium implanted model was still 1/10 that in the corresponding region of the unimplanted femur model. At the stem tip, as much as a 30% reduction in femoral stress was seen with the titanium stem compared with the cobalt chrome. These findings suggest biomechanical evidence of an advantage for titanium as an implant material compared with cobalt chrome for cementless femoral stems.
在全髋关节置换术中，近端萎缩和大腿疼痛是一些非骨水泥型股骨柄存在的公认问题。据认为，髓内柄导致的负荷转移改变使股骨应力降低，这是造成股骨近端萎缩的原因。柄尖附近的抗弯刚度和骨应力增加被认为是导致大腿疼痛的原因。进行了一项三维有限元分析研究，以计算在植入带颈、近端涂层的非骨水泥型股骨假体之前和之后近端股骨及柄尖附近骨骼中的应力。通过将植入物成分从钴铬合金改为钛合金并保持所有其他参数不变，研究了假体材料的影响。与钴铬合金相比，钛植入物使柄下方紧挨着的部位股骨应力增加了两倍。然而，钛植入模型中的股骨近端应力仍为未植入股骨模型相应区域应力的1/10。在柄尖处，与钴铬合金相比，钛柄使股骨应力降低了多达30%。这些发现表明，与钴铬合金相比，钛作为非骨水泥型股骨柄的植入材料具有生物力学优势的证据。
