骰骨截骨外侧柱延长术改善II期可复性平足生物力学环境的应用基础研究

Lateral column lengthening is a main surgical method to correct stage II flexible flatfoot forefoot abduction deformity, traditional treatment methods often make the foot in a non-physiological state with a high incidence of various complications. Based on the anatomical features of the cuboid, we propose the possibility of lateral column lengthening with cuboid osteotomy to correct the flexible flat foot. In our early study, we used the cuboid osteotomy to lengthen the lateral column to correct stage II flatfoot, the results showed that the pressure of the medial column was significantly reduced, and the talonavicular coverage angle was obviously corrected, which meant cuboid osteotomy lateral column lengthening was an effective method to correct the abduction deformity. However, the exact mechanism is not clear. In this project, we would establish intact foot model, flexible flatfoot model and cuboid osteotomy model, intending to complete radiographic and biomechanical experiments with double-plane X-ray dynamic imaging and loading test technique. We hope to clarify the effect on different distraction width and implant shape for stage II flexible flatfoot. The ultimate aim of this project is to reveal the biomechanical mechanism of cuboid osteotomy lateral column lengthening for stage II flexible flatfoot in order to provide the theoretical basis for the effective treatment of flatfoot deformity.

外侧柱延长术是纠正II期可复性平足前足外展畸形的主要手术方式，传统治疗方法多会使足部处于非生理状态，各种并发症发生率高。基于骰骨的解剖学特点，我们提出存在通过骰骨截骨延长外侧柱纠正可复性平足的可能性。我们在前期利用骰骨截骨撑开外侧柱模拟纠正II期可复性平足，内侧柱应力显著降低，距舟覆盖角得到明显纠正。提示骰骨截骨延长外侧柱可以纠正前足外展畸形，但具体机制尚不清楚。在本项目中，我们拟基于正常尸体标本、可复性平足模型和骰骨截骨模型，利用双平面X线动态成像和加载测试技术行影像学和生物力学实验，进一步明确骰骨不同撑开宽度对II期可复性平足生物力学环境的纠正作用，探索骰骨截骨不同植入物形状对II期可复性平足生物力学环境的影响，从而揭示骰骨截骨外侧柱延长术对II期可复性平足生物力学环境改善的机制，为临床合理治疗可复性平足症提供理论基础。

可复性平足是临床上常见的足部畸形，以足弓降低或消失为主要特点，发展到一定阶段可并发足部骨、关节及软组织病变，导致下肢疼痛、无力，行走受限等症状出现。传统的手术方式过于重视足部外形纠正，往往忽视了力学环境的改善，使足部在非生理状态出现疼痛症状。本研究旨在通过骰骨截骨延长外侧柱纠正II期可复性平足，从生物力学和影像学两个方面展开研究，明确骰骨不同撑开宽度对II期可复性平足生物力学环境的纠正作用，探索骰骨截骨不同植入物形状对II期可复性平足生物力学环境的影响，进而揭示骰骨截骨外侧柱延长术对II期可复性平足生物力学环境改善的机制，探索出科学合理的治疗策略和手术方法。生物力学研究结果发现，骰骨截骨分级撑开2-5mm，随着撑开宽度的增加，前足外展得到纠正，且内侧柱压强逐渐下降,外侧柱压强随之上升，当撑开宽度为3mm时，足底压强分布最接近正常足底压强分布特点，继续增大撑开宽度，外侧柱压强过高，第4、5跖骨下压强显著增大。影像学结果发现，骰骨截骨延长外侧柱后，平足模型前足外展情况得到显著纠正，且随着外侧撑开宽度的逐渐增大，第一跖骨距骨角、距舟覆盖角均明显减小。当撑开宽度大于3mm时，正侧位第一跖骨距骨角和距舟覆盖角均小于正常足，存在过度矫形的风险。改变植入物形状，发现楔形内植物跟骰关节内峰值压强最接近于正常足，对跗横关节锁定和解锁机制影响最小，纠正畸形的同时可以有效避免关节面负荷过大。因此，综合生物力学和影像学分析，我们最终提出骰骨截骨外侧柱延长手术可以有效纠正II期可复性平足畸形，改善足部生物力学环境，避免距下关节损伤及邻近关节退变，为治疗方案的选择及预后评估提供基础理论依据，同时为可复性平足症的预防和矫形支具的研发提供思路，在降低并发症发生率、改善患者生活质量，节省医疗开支等方面具有重要的社会和经济价值。