ACL重建后胫股关节软骨早期退变的定量研究：生物力学与纵向MRI综合分析
简介
该研究结合3年纵向MRI与机器人步态模拟，发现ACLR术后3年胫骨平台后部软骨显著变薄（内侧中央区减少10%，外侧后区减少14%），同时步态周期中胫股关节接触压力中心持续后移（内侧5.29mm、外侧4.73mm）。这种压力中心位移与局灶性软骨变薄在时空上吻合，提示动态负荷生物标志物可用于术后早期骨关节炎风险分层。
英文摘要
BACKGROUND: Anterior cruciate ligament reconstruction (ACLR) restores stability but is often followed by early cartilage degeneration. The contribution of altered dynamic contact pressure during gait to this degeneration remains poorly understood. PURPOSE: To investigate the biomechanical mechanisms underlying early cartilage degeneration after ACLR, with a focus on dynamic contact pressure distribution during gait. STUDY DESIGN: Controlled laboratory study. METHODS: In a 3-year longitudinal magnetic resonance imaging (MRI) study of patients with ACLR (n = 30), cartilage thickness of the tibial plateau was quantitatively assessed using deep-learning-based 3-dimensional segmentation techniques. In parallel, cadaveric knees (n = 8) were tested under intact, ACL-deficient, and ACL-reconstructed conditions using a 6 degree-of-freedom robotic simulator replicating gait cycles. Tibiofemoral contact pressure and pressure center trajectories were recorded using pressure-sensitive film. RESULTS: Quantitative MRI analyses revealed significant cartilage thinning in the posterior tibial subregion 3 years after ACLR. On the medial plateau, the central medial tibia, internal medial tibia, and posterior medial tibia subregions exhibited mean reductions of 10% (P = .027), 21% (P = .019), and 13% (P = .041), respectively. On the lateral plateau, significant decreases were observed in central lateral tibia (9%; P = .031), posterior lateral tibia (14%; P = .029), and external lateral tibia (15%; P = .035). In robotic gait simulations, the reconstructed knees exhibited persistent posterior displacement of the whole-gait-cycle contact center of stress on both tibial plateaus (residual shifts: medial, 5.29 mm; lateral, 4.73 mm; both P < .05). Additionally, the contact area was significantly enlarged in early stance (2%-12% gait cycle) and terminal swing (75%-100%), especially in the medial compartment. CONCLUSION: ACLR-induced pressure center displacement coincides with focal posterior cartilage degeneration, forming a spatiotemporal mechanical-pathological chain. This work highlights the potential of dynamic loading biomarkers for early osteoarthritis risk stratification and targeted mechanical intervention. CLINICAL RELEVANCE: Persistent shifts in tibiofemoral pressure centers after ACLR coincide with focal cartilage thinning, suggesting a mechanical pathway to post-ACLR osteoarthritis. Identifying such dynamic loading biomarkers may guide early risk stratification and targeted interventions in sports medicine.