Moayedi M, Arshi A R, Salehi M, Akrami M, Javadi Asl N, Naemi R
Department of Mechanical Engineering, Amirkabir University of Technology, Iran.
Biomechanics and Sports Engineering Groups, Biomedical Engineering Department, Amirkabir University of Technology, Iran.
Comput Biol Med. 2023 Jan;152:106381. doi: 10.1016/j.compbiomed.2022.106381. Epub 2022 Dec 10.
Hammer toes are one of the common deformities of the forefoot that can lead to compensatory changes during walking in individuals with this condition. Predicting the adverse effects of tissue damage on the performance of other limbs is very important in the prevention of progressive damage. Finite element (FE) and musculoskeletal modeling can be helpful by allowing such effects to be studied in a way where the internal stresses in the tissue could be investigated. Hence, this study aims to investigate the effects of the hammer toe deformity on the lower extremity, especially on the plantar fascia functions. To compare the joint reactions of the hammer toe foot (HTF) and healthy foot (HF), two musculoskeletal models (MSM) of the feet of a healthy individual and that of a participant with hammer toe foot were developed based on gait analysis. A previously validated 3D finite element model which was constructed using Magnetic Resonance Imaging (MRI) of the diabetic participant with the hammer toe deformity was processed at five different events during the stance phase of gait. It was found that the hammer toe deformity makes dorsiflexion of the toes and the windlass mechanism less effective during walking. Specifically, the FE analysis results showed that plantar fascia (PF) in HTF compared to HF played a less dominant role in load bearing with both medial and lateral parts of PF loaded. Also, the results indicated that the stored elastic energy in PF was less in HTF than the HF, which can indicate a higher metabolic cost during walking. Internal stress distribution shows that the majority of ground reaction forces are transmitted through the lateral metatarsals in hammer toe foot, and the probability of fifth metatarsal fracture and also progressive deformity was subsequently increased. The MSM results showed that the joint reaction forces and moments in the hammer toe foot have deviated from normal, where the metatarsophalangeal joint reactions in the hammer toe were less than the values in the healthy foot. This can indicate a vicious cycle of foot deformity, leading to changes in body weight force transmission line, and deviation of joint reactions and plantar fascia function from normal. These in turn lead to increased internal stress concentration, which in turn lead to further foot deformities. This vicious cycle cause progressive damage and can lead to an increase in the risk of ulceration in the diabetic foot.
槌状趾是前足常见的畸形之一，会导致患有这种病症的个体在行走过程中出现代偿性变化。预测组织损伤对其他肢体功能的不利影响对于预防渐进性损伤非常重要。有限元（FE）和肌肉骨骼建模有助于通过一种能够研究组织内部应力的方式来研究此类影响。因此，本研究旨在探讨槌状趾畸形对下肢的影响，尤其是对足底筋膜功能的影响。为了比较槌状趾足（HTF）和健康足（HF）的关节反应，基于步态分析建立了一名健康个体和一名患有槌状趾足的参与者的足部肌肉骨骼模型（MSM）。使用患有槌状趾畸形的糖尿病参与者的磁共振成像（MRI）构建的一个先前经过验证的三维有限元模型，在步态站立期的五个不同事件中进行了处理。研究发现，槌状趾畸形会使行走过程中脚趾的背屈和绞盘机制效果变差。具体而言，有限元分析结果表明，与健康足相比，槌状趾足中的足底筋膜（PF）在承重方面发挥的主导作用较小，且PF的内侧和外侧部分均承受负荷。此外，结果表明槌状趾足中PF储存的弹性能量比健康足少，这可能表明行走过程中的代谢成本更高。内部应力分布表明，槌状趾足中大部分地面反作用力通过外侧跖骨传递，随后第五跖骨骨折以及渐进性畸形的可能性增加。肌肉骨骼模型结果表明，槌状趾足中的关节反应力和力矩已偏离正常，其中槌状趾中的跖趾关节反应小于健康足中的值。这可能表明足部畸形的恶性循环，导致体重力传递线发生变化，关节反应和足底筋膜功能偏离正常。这些反过来又导致内部应力集中增加，进而导致进一步的足部畸形。这种恶性循环会造成渐进性损伤，并可能导致糖尿病足溃疡风险增加。
