Hou Ziwei, Zheng Kai, Xu Ming, Yu Xiuchun
Department of Orthopedics, The 960th Hospital of the People's Liberation Army, Jinan, China.
Front Bioeng Biotechnol. 2024 Oct 14;12:1493738. doi: 10.3389/fbioe.2024.1493738. eCollection 2024.
Tumor resection near the proximal end of the femur and revision surgery of the distal femoral prosthesis may result in a very short bone segment remaining at the proximal end of the femur, known as ultrashort residual proximal femur (URPF). In this study, we propose a triangular fixation stem (TFS) prosthesis to improve the fixation of URPF. The aim of this research is to investigate the biomechanical properties of the TFS prosthesis and compare it with the conventional stem (CS) prosthesis through biomechanical experiments, providing preliminary biomechanical evidence for prosthetic fixation of URPF.
A biomechanical study was conducted using Sawbones to explore initial stability. Twelve Sawbones were used to create a bone defect model, and prostheses were designed and fabricated to emulate TFS fixation and CS fixation structures. Axial compression and horizontal torsion experiments were performed on the fixed models using a mechanical testing machine, recording maximum displacement, maximum torque, and femoral strain conditions.
Under an axial compressive load of 2800 N, the overall displacement of the TFS group was 3.33 ± 0.58 mm, which was significantly smaller than that of the CS group (4.03 ± 0.32 mm, P = 0.029). The femoral samples of the TFS group demonstrated that the strain value alterations at the medial points 2, 3, 5, 6 and the lateral point 10 were conspicuously smaller than those of the conventional stem group (P < 0.05). Under torsional loads at levels of 1°, 3°, and 5°, the torques of the TFS group were 3.86 ± 0.69 Nm, 3.90 ± 1.26 Nm, and 4.39 ± 1.67 Nm respectively, all of which were significantly greater than those of the CS group (1.82 ± 0.82 Nm, P < 0.001; 2.05 ± 0.89 Nm, P = 0.016; 1.96 ± 0.50 Nm, P = 0.015 respectively).
The TFS prosthesis improves fixation strength and reduces strain on the femur's proximal surface. Compared to CS fixation, it offers better resistance to compression and rotation, as well as improved initial stability.
股骨近端附近的肿瘤切除以及股骨远端假体的翻修手术可能会导致股骨近端残留非常短的骨段，即超短股骨近端残留（URPF）。在本研究中，我们提出一种三角形固定柄（TFS）假体以改善URPF的固定。本研究的目的是通过生物力学实验研究TFS假体的生物力学性能，并将其与传统柄（CS）假体进行比较，为URPF的假体固定提供初步的生物力学证据。
使用Sawbones进行生物力学研究以探索初始稳定性。使用12个Sawbones创建骨缺损模型，并设计和制造假体以模拟TFS固定和CS固定结构。使用机械测试机对固定模型进行轴向压缩和水平扭转实验，记录最大位移、最大扭矩和股骨应变情况。
在2800N的轴向压缩载荷下，TFS组的总体位移为3.33±0.58mm，明显小于CS组（4.03±0.32mm，P = 0.029）。TFS组的股骨样本表明，内侧点2、3、5、6和外侧点10处的应变值变化明显小于传统柄组（P < 0.05）。在1°、3°和5°的扭转载荷下，TFS组的扭矩分别为3.86±0.69 Nm、3.90±1.26 Nm和4.39±1.67 Nm，均明显大于CS组（分别为1.82±0.82 Nm，P < 0.001；2.05±0.89 Nm，P = 0.016；1.96±0.50 Nm，P = 0.015）。
TFS假体提高了固定强度并减少了股骨近端表面的应变。与CS固定相比，它具有更好的抗压和抗旋转能力，以及更高的初始稳定性。
