改良MacIntosh前交叉韧带重建术后胫股接触应力与移植物负荷的体外评估
简介
该研究采用8具尸体膝关节（平均年龄56岁），在机器人操作平台上比较了完整状态、ACL切断状态和改良MacIntosh ACL重建术后的生物力学表现。关键发现：与完整膝关节相比，改良MacIntosh ACLR使外侧间室峰值接触应力增加0.31–0.35 MPa（P<0.03），接触应力中心前移1.3–3.3 mm（P<0.05）；同时内旋和内翻松弛度分别降低…
英文摘要
BACKGROUND: The modified MacIntosh anterior cruciate ligament reconstruction (ACLR) consists of a combined intra- and extra-articular construct using iliotibial band autograft. It is used in skeletally immature patients to avoid physeal injury. However, its effect on articular cartilage contact mechanics, rotational laxity, and graft loading is poorly understood. HYPOTHESIS: Relative to the intact knee, a modified MacIntosh ACLR would (1) increase and anteriorize lateral tibiofemoral contact stress, (2) decrease internal rotation (IR) and varus laxity, and (3) offload the intra-articular graft relative to the native ACL in response to simulated pivot-shift loads. STUDY DESIGN: Controlled laboratory study. METHODS: Eight cadaveric knees (mean age 56 ± 7 years; 50% male) were tested on a robotic manipulator in 3 states: intact, ACL-sectioned, and modified MacIntosh ACLR. Peak contact stress and the anterior-posterior position of the center of contact stress (CCS) in the lateral compartment were calculated during simulated pivot shifts. Laxity was assessed for 3 uniplanar loading conditions (134 N anterior, 8 N·m varus, and 5 N·m IR) at knee flexion angles from 0° to 90°. Tissue forces were determined via the principle of superposition. RESULTS: After modified MacIntosh ACLR, peak stress increased by 0.31 to 0.35 MPa (P < .03) and the CCS shifted anteriorly by 1.3 to 3.3 mm (P < .05) relative to the intact knee. ACLR decreased IR and varus laxity by 18% to 24% (P≤ .01) and 13% to 24% (P < .02), respectively, compared with the intact state. During simulated pivot shift, in situ force in the intra-articular graft component (27 to 36 N) was 51% to 65% less than native ACL force, whereas the extra-articular component carried 25 to 30 N. CONCLUSION: In a cadaveric model of a simulated pivot shift, a modified MacIntosh ACLR anteriorized and mildly increased lateral compartment contact stress compared to the native knee, while decreasing lateral compartment contact stress relative to the ACL-deficient knee. The extraarticular limb also increased constraint to rotational loads, partially offloading the intra-articular graft. CLINICAL RELEVANCE: Partial intraarticular graft offloading with clinical pivoting maneuvers provides a biomechanical rationale for the low number of graft failures after modified MacIntosh ACLR. The ability of a modified MacIntosh ACLR to decrease and anteriorize contact stress in the posterior aspect of the lateral compartment offloads the region most affected by ACL injury and the pivot shift contact. Long-term clinical studies are needed to determine whether altered contact mechanics after modified MacIntosh ACLR influence long-term cartilage health.