Watanabe Ryunosuke, Nishino Tomofumi, Yoshizawa Tomohiro, Hirose Fumi, Yasunaga Shota, Shimasaki Koshiro, Mishima Hajime
Department of Orthopaedic Surgery, Institute of Medicine, University of Tsukuba, Tsukuba, Japan.
Arch Orthop Trauma Surg. 2025 Jul 12;145(1):370. doi: 10.1007/s00402-025-05987-6.
Intraoperative periprosthetic femoral fractures (IPFF) are serious complications of total hip arthroplasty (THA) that occur more frequently with cementless stems than with cemented stems. Although cerclage wiring is commonly used to stabilize IPFFs, the biomechanical effects of subsequent stem fixation methods remain unclear. This study aimed to compare the biomechanical stability of cemented and cementless stems following cerclage wire fixation in an experimental IPFF model.
Six fourth-generation composite femurs with simulated Vancouver A2-type fractures were stabilized using a single 1.8 mm cerclage wire. Identical stem designs of polished cemented stems and fully hydroxyapatite-coated cementless stems were implanted in three specimens of each group. After applying a vertical axial load of 2000 N, an additional 40° of internal rotation was imposed. The primary outcome was the maximum torque at the time of fracture. Secondary outcomes included the maximum internal rotation angle, construct stiffness (calculated from force-displacement curves above 1500 N), and peak strain at three positions on the cerclage wire, measured using strain gauges.
The maximum torque was significantly higher in the cemented group compared to the cementless group (160.8 ± 24.9 vs. 89.1 ± 18.0 N·m, p = 0.016). Although the differences in stiffness and internal rotation angle were not statistically significant, both trended higher in the cemented group. The peak strain was consistently lower in the cemented group, with a significant difference at the medial side of the fracture line (p = 0.011, Cohen's d = - 3.64).
Cemented stems demonstrated superior biomechanical stability following cerclage wire fixation in the IPFF model, likely because of improved stress distribution via the cement mantle. Therefore, cemented fixation may be a favorable option for managing IPFF during THA.
术中假体周围股骨骨折（IPFF）是全髋关节置换术（THA）的严重并发症，非骨水泥型股骨柄比骨水泥型股骨柄更常发生。虽然环扎钢丝常用于稳定IPFF，但后续股骨柄固定方法的生物力学效应仍不清楚。本研究旨在比较在实验性IPFF模型中环扎钢丝固定后骨水泥型和非骨水泥型股骨柄的生物力学稳定性。
使用一根1.8毫米的环扎钢丝稳定六个具有模拟温哥华A2型骨折的第四代复合股骨。每组三个标本中植入相同设计的抛光骨水泥型股骨柄和全羟基磷灰石涂层非骨水泥型股骨柄。在施加2000N的垂直轴向载荷后，再施加40°的内旋。主要结果是骨折时的最大扭矩。次要结果包括最大内旋角度、结构刚度（根据1500N以上的力-位移曲线计算）以及使用应变片测量的环扎钢丝三个位置的峰值应变。
骨水泥型组的最大扭矩显著高于非骨水泥型组（160.8±24.9对89.1±18.0N·m，p = 0.016）。虽然刚度和内旋角度的差异无统计学意义，但在骨水泥型组中两者均呈上升趋势。骨水泥型组的峰值应变始终较低，在骨折线内侧有显著差异（p = 0.011，Cohen's d = -3.64）。
在IPFF模型中环扎钢丝固定后，骨水泥型股骨柄表现出更好的生物力学稳定性，可能是因为通过骨水泥套改善了应力分布。因此，骨水泥固定可能是THA期间处理IPFF的有利选择。
