Department of Orthopaedic Surgery, Faculty of Medicine, Oita University, Yufu, Japan.
Department of Mechanical Engineering, College of Engineering, Nihon University, Koriyama, Japan.
Clin Orthop Surg. 2024 Oct;16(5):724-732. doi: 10.4055/cios23350. Epub 2024 Aug 12.
In total hip arthroplasty (THA), the ideal stem length remains uncertain; different stem lengths are used in different cases or institutions. We aimed to compare the stress distributions of cementless tapered wedges and short stems in femurs with different femoral marrow geometries and determine the appropriate fit.
Finite element models were created and analyzed using HyperMesh and LS-DYNA R11.1, respectively. The 3-dimensional shape data of the femurs were extracted from computed tomography images using the RETOMO software. Femurs were divided into 3 groups based on the Dorr classification. The computer-aided design data of cementless tapered wedge-type and short stems were used to select the appropriate size. In the finite element analysis, the loading condition of the femur was assumed to be walking. Volumes of interest (VOIs) were placed within the femur model at the internal and external contact points of the stem based on Gruen zones. The average stresses and strain energy density (SED) of the elements included in each VOI were obtained from the preoperative and postoperative models.
The von Mises stress and SED distributions of the cementless tapered wedge and short stems were similar in their respective Dorr classifications. In both stems, the von Mises stress and SED after THA were lower than before THA. The von Mises stress and SED of the cementless tapered wedge stem were higher than those of short stems. Cementless tapered wedge-type stems tended to have lower rates of change than short stems; however, Dorr C exhibited the opposite trend. In the Dorr classification comparison, the von Mises stress and SED were greater for both stems in the order of Dorr C > Dorr B > Dorr A, from Zone 2 to Zone 6.
In Dorr A and B, the short stem exhibited a natural stress distribution closer to the preoperative femur than the tapered wedge stem; however, in Dorr C, the short stem may have a greater effect on stress distribution, suggesting that it may cause greater effects, such as fracture in the early postoperative period, than other Dorr types.
在全髋关节置换术（THA）中，理想的柄长度仍不确定；不同的病例或机构使用不同的柄长度。我们旨在比较不同股骨骨髓几何形状的骨水泥型锥形楔形和短柄的应力分布，并确定合适的匹配。
使用 HyperMesh 和 LS-DYNA R11.1 分别创建和分析有限元模型。使用 RETOMO 软件从计算机断层扫描图像中提取股骨的 3 维形状数据。根据 Dorr 分类，将股骨分为 3 组。使用骨水泥型锥形楔形和短柄的计算机辅助设计数据选择合适的尺寸。在有限元分析中，假设股骨的加载条件为行走。根据 Gruen 区，在股骨模型内部和外部与柄接触点处放置感兴趣体积（VOI）。从术前和术后模型中获得每个 VOI 内元素的平均应力和应变能密度（SED）。
在各自的 Dorr 分类中，骨水泥型锥形楔形和短柄的 von Mises 应力和 SED 分布相似。在这两种柄中，THA 后的 von Mises 应力和 SED 均低于 THA 前。骨水泥型锥形楔形柄的 von Mises 应力和 SED 高于短柄。与短柄相比，骨水泥型锥形楔形柄的变化率较低；然而，Dorr C 表现出相反的趋势。在 Dorr 分类比较中，von Mises 应力和 SED 在 Dorr C > Dorr B > Dorr A 顺序中，从第 2 区到第 6 区，两种柄均较大。
在 Dorr A 和 B 中，短柄比锥形楔形柄表现出更接近术前股骨的自然应力分布；然而，在 Dorr C 中，短柄可能对应力分布有更大的影响，这表明它可能在术后早期引起更大的影响，例如骨折，而不是其他 Dorr 类型。
Zotero 插件
