Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate (DISC), Università Degli Studi di Genova, Viale Benedetto XV N°6, 16132, Genoa, Italy.
IRCCS Ospedale Policlinico San Martino, UO Clinica Ortopedica, Largo Rosanna Benzi N° 10, 16132, Genoa, Italy.
Arch Orthop Trauma Surg. 2024 Feb;144(2):917-926. doi: 10.1007/s00402-023-05080-w. Epub 2023 Oct 5.
The influence of THA stem design on periprosthetic femoral fractures (PFFs) risk is subject of debate. This study aims to compare the effects of different cementless stem designs on stress-strain distributions in both physiological and osteoporotic femur under various loading conditions.
A biomechanical study using finite-element analysis was conducted. Four models were developed: three with implanted femurs and a native one chosen as control. Each model was analyzed for both healthy and osteoporotic bone. The following stem designs were examined: short anatomical stem with femoral neck preservation, double-wedge stem, and anatomical standard stem. Three loading conditions were assessed: gait, sideways falling, and four-point bending.
During gait in physiological bone, the anatomical stem and the short anatomical stem with femoral neck preservation showed stress distribution similar to the native model. The double-wedge stem reduced stress in the proximal area but concentrated it in the meta-diaphysis. In osteoporotic bone, the double-wedge stem design increased average stress by up to 10%. During sideways falling, the double-wedge stem exhibited higher stresses in osteoporotic bone. No significant differences in average stress were found in any of the studied models during four-point bending.
In physiological bone, anatomical stems demonstrated stress distribution comparable to the native model. The double-wedge stem showed uneven stress distribution, which may contribute to long-term stress shielding. In the case of osteoporotic bone, the double-wedge stem design resulted in a significant increase in average stress during both gait and sideways falling, potentially indicating a higher theoretical risk of PFF.
THA 柄设计对假体周围股骨骨折（PFF）风险的影响存在争议。本研究旨在比较不同非骨水泥柄设计在不同载荷条件下对生理和骨质疏松股骨的应力-应变分布的影响。
采用有限元分析进行生物力学研究。共建立了 4 个模型：3 个植入股骨模型和 1 个正常股骨模型作为对照。每个模型均进行了健康和骨质疏松骨的分析。研究了以下三种柄设计：保留股骨颈的短解剖柄、双楔形柄和解剖标准柄。评估了三种载荷条件：步态、侧方跌倒和四点弯曲。
在生理骨的步态中，解剖柄和保留股骨颈的短解剖柄的应力分布与正常模型相似。双楔形柄减少了近端区域的应力，但将其集中在骨干中段。在骨质疏松骨中，双楔形柄设计使平均应力增加了 10%。在侧方跌倒时，双楔形柄在骨质疏松骨中表现出更高的应力。在四点弯曲时，研究的模型中没有任何一个表现出平均应力的显著差异。
在生理骨中，解剖柄表现出与正常模型相似的应力分布。双楔形柄表现出不均匀的应力分布，这可能导致长期的应力屏蔽。在骨质疏松骨中，双楔形柄设计导致步态和侧方跌倒时平均应力显著增加，这可能表明 PFF 的理论风险更高。
