Watanabe Ryunosuke, Mishima Hajime, Totsuka Sho, Nishino Tomofumi, Yamazaki Masashi
Department of Orthopaedic Surgery, Institute of Medicine, University of Tsukuba, Tsukuba, Japan.
Arthroplast Today. 2023 Apr 21;21:101140. doi: 10.1016/j.artd.2023.101140. eCollection 2023 Jun.
Primary stability of the femoral stem is important for the long-term results of cementless total hip arthroplasty. Cementless collared stems have been known to have higher stability than collarless stems when there is a contact between the collar and the calcar. The purpose of this study was to compare the stabilities of collared stem and collarless stem in 2 loading conditions: 1) flat walking and 2) stair climbing.
We constructed 3 finite element models. In the first model, the collar had contact with the calcar. The second model had a 1 mm gap between the calcar and the collar. The third model was constructed with a collarless stem. The proximal femur around the stem was divided into 3 zones: the upper zone (Gruen zones 1 and 7), the middle zone (Gruen zones 2 and 6), and the lower zone (Gruen zones 3 and 5). The micromotion at the stem/bone interface was measured at each zone of the 3 models under the 2 loading conditions.
The results showed that collared stems were more stable when the collar was in contact with the calcar than when a gap was left between the collar and the calcar. In particular, collar contact was highly effective in suppressing the micromotion proximal to the stem.
Compared to the collarless stem, the collared stem had comparable stability when there was a gap at the collar and calcar interface and higher stability when there was contact between the collar and the calcar.
股骨柄的初始稳定性对于非骨水泥型全髋关节置换术的长期效果至关重要。当柄颈与股骨距接触时，已知有颈柄比无颈柄具有更高的稳定性。本研究的目的是比较有颈柄和无颈柄在两种加载条件下的稳定性：1）平地行走和2）爬楼梯。
我们构建了3个有限元模型。在第一个模型中，柄颈与股骨距接触。第二个模型在股骨距和柄颈之间有1毫米的间隙。第三个模型采用无颈柄构建。柄周围的近端股骨分为3个区域：上部区域（Gruen区域1和7）、中部区域（Gruen区域2和6）和下部区域（Gruen区域3和5）。在两种加载条件下，测量3个模型每个区域在柄/骨界面处的微动。
结果表明，当柄颈与股骨距接触时，有颈柄比柄颈与股骨距之间留有间隙时更稳定。特别是，柄颈接触在抑制柄近端的微动方面非常有效。
与无颈柄相比，当柄颈与股骨距界面存在间隙时，有颈柄具有相当的稳定性；当柄颈与股骨距接触时，有颈柄具有更高的稳定性。
