Roytman Gregory R, Lahik Sophia, Tommasini Steven M, Wiznia Daniel H, Fram Brianna R
Orthopaedics and Rehabilitation, Yale University, New Haven, Connecticut, USA.
Biomedical Engineering, Yale University, New Haven, Connecticut, USA.
J Orthop Res. 2025 Sep;43(9):1599-1605. doi: 10.1002/jor.26113. Epub 2025 May 30.
Surgeons often use long antegrade intramedullary nails (aIMNs) when fixing fractures of the proximal femur in geriatric patients. However, risk of peri-implant fracture in relation to aIMN termination level has not yet been studied. We therefore studied the correlation between aIMN nail tip termination level and extent of distal femur fracture in three different loading scenarios using finite element models of seven different length aIMNs. These were loaded into 3D models of synthetic osteoporotic femurs, which were loaded in single-leg stance (SLS) with body weight load at the femoral head, torsion (TOR) counterclockwise to failure with 120 Nm of torque, and distal impact/fall (DIF) simulating direct fall on the knees at 1000 mm/sec. The maximum stress in SLS and percentage of failed elements for TOR and DIF were recorded. For SLS, aIMN tip termination and maximum stress were not correlated (ρ = 0.1429, p = 0.7599) and there was no apparent trend in the data. For TOR, more proximal aIMN tip termination demonstrated a significant correlation with greater percentage of failed area (ρ = 0.9286, p = 0.0025). For DIF, aIMN tip termination was not correlated with the percentage of failed elements (ρ = -0.6071, p = 0.1482), but demonstrated a statistically significant Gaussian relationship (coeffs: = 2.22 (p = 1.13 × 10), = 58.61 (p = 1.89 × 10), = 17.46 (p = 1.79 × 10)) where 60 mm aIMN tip termination demonstrated the greatest percentage of failed area. Therefore, we found a strong linear relationship between more proximal aIMN termination in the femur and extent of failure in TOR. There was a statistically significant Gaussian relationship between metaphyseal termination and extent of failure in DIF.
在老年患者股骨近端骨折固定时，外科医生常使用长顺行髓内钉（aIMN）。然而，与aIMN终止水平相关的植入物周围骨折风险尚未得到研究。因此，我们使用七种不同长度aIMN的有限元模型，研究了在三种不同加载情况下aIMN钉尖终止水平与股骨远端骨折范围之间的相关性。将这些模型加载到合成骨质疏松股骨的3D模型中，在单腿站立（SLS）状态下，股骨头承受体重负荷，以120 Nm的扭矩逆时针扭转（TOR）直至破坏，以及模拟膝盖直接着地的远端冲击/跌倒（DIF），速度为1000 mm/sec。记录SLS中的最大应力以及TOR和DIF情况下的失效单元百分比。对于SLS，aIMN钉尖终止与最大应力不相关（ρ = 0.1429，p = 0.7599），数据中也没有明显趋势。对于TOR，aIMN钉尖终止越靠近近端，与更大的失效面积百分比呈显著相关（ρ = 0.9286，p = 0.0025）。对于DIF，aIMN钉尖终止与失效单元百分比不相关（ρ = -0.6071，p = 0.1482），但呈现出统计学上显著的高斯关系（系数： = 2.22（p = 1.13×10）， = 58.61（p = 1.89×10）， = 17.46（p = 1.79×10）），其中aIMN钉尖终止60 mm时失效面积百分比最大。因此，我们发现股骨中aIMN终止越靠近近端与TOR中的失效程度之间存在很强的线性关系。在DIF中，干骺端终止与失效程度之间存在统计学上显著的高斯关系。
