Spratley E M, Matheis E A, Hayes C W, Adelaar R S, Wayne J S
Orthopaedic Research Laboratory, Departments of Biomedical Engineering and Orthopaedic Surgery, Virginia Commonwealth University, Richmond, VA, USA.
Ann Biomed Eng. 2014 Sep;42(9):1913-22. doi: 10.1007/s10439-014-1048-y. Epub 2014 Jun 12.
Following IRB approval, a cohort of 3-D rigid-body computational models was created from submillimeter MRIs of clinically diagnosed Adult Acquired Flatfoot Deformity patients and employed to investigate postoperative foot/ankle function and surgical effect during single-leg stance. Models were constrained through physiologic joint contact, passive soft-tissue tension, active muscle force, full body weight, and without idealized joints. Models were validated against patient-matched controls using clinically utilized radiographic angle and distance measures and plantar force distributions in the medial forefoot, lateral forefoot, and hindfoot. Each model further predicted changes in strain for the spring ligament, deltoid ligament, and plantar fascia, as well as joint contact loads for three midfoot joints, the talonavicular, navicular-1st cuneiform, and calcaneocuboid. Radiographic agreement ranged across measures, with average absolute deviations of <5° and <4 mm indicating generally good agreement. Postoperative plantar force loading in patients and models was reduced for the medial forefoot and hindfoot concomitant with increases in the lateral forefoot. Model predicted reductions in medial soft-tissue strain and increases in lateral joint contact load were consistent with in vitro observations and elucidate the biomechanical mechanisms of repair. Thus, validated rigid-body models offer promise for the investigation of foot/ankle kinematics and biomechanical behaviors that are difficult to measure in vivo.
经机构审查委员会（IRB）批准，从临床诊断为成人获得性平足畸形患者的亚毫米级磁共振成像（MRI）中创建了一组三维刚体计算模型，并用于研究单腿站立时术后足/踝关节功能和手术效果。模型通过生理关节接触、被动软组织张力、主动肌肉力量、全身重量进行约束，且不采用理想化关节。使用临床常用的放射学角度和距离测量以及前足内侧、前足外侧和后足的足底力分布，针对匹配的患者对照对模型进行了验证。每个模型还预测了弹簧韧带、三角韧带和足底筋膜的应变变化，以及三个中足关节（距舟关节、舟状骨-第一楔骨关节和跟骰关节）的关节接触负荷。放射学一致性在各项测量中有所不同，平均绝对偏差<5°和<4毫米表明总体一致性良好。患者和模型中的术后足底力负荷在前足内侧和后足处降低，同时前足外侧增加。模型预测内侧软组织应变降低和外侧关节接触负荷增加与体外观察结果一致，并阐明了修复的生物力学机制。因此，经过验证的刚体模型为研究体内难以测量的足/踝关节运动学和生物力学行为提供了前景。
