Effect of Achilles tendon on kinematic coupling relationship between tarsal bones: a pilot finite element study

Abstract

Background: The procedure of percutaneous Achilles tenotomy (PAT) is an important component of the Ponseti method. However, few studies reported the influence of Achilles tendon on kinematic coupling relationship between tarsal bones. The purpose of present study was to demonstrate the effect of Achilles tendon on the kinematic coupling relationship between tarsal bones, and to illustrate how kinematic coupling relationship between tarsal bones works in term of finite element analysis. Methods: A three-dimensional finite element model of foot and ankle was constructed based on the Chinese digital human girl No.1 (CDH-G1) image database using the software of mimics, Geomagic studio, HyperMesh, and Abaqus. The last manipulation of the Ponseti method before the procedure of PAT was simulated. The talus head and the proximal tibia and fibula bone were fixed in all six degrees of freedom, and the outward pressure was added on the first metatarsal head to investigate the kinematic coupling relationship between tarsal bones. Results: The least relationship of kinematic coupling between tarsal bones was found in calcaneus. Stress concentration was mainly observed at the navicular, talus and the medial malleolus. The difference in displacement of the navicular was only found with the Achilles tendon stiffness of 0 N/mm and others. No difference in the navicular displacement was found in the stiffness of Achilles tendon between 40, 80, 200, 400, and 1000 N/mm. The maximum displacement of navicular was observed at the ankle position of PF-20°(plantar flexion-20°). The difference in displacement of the navicular was greater at the ankle position of PF-20°with the Achilles tendon stiffness of 0 N/mm than that at the ankle position of PF-40°with the Achilles tendon stiffness of 40 N/mm. Conclusions: Based on the findings from this study, it was demonstrated that the Achilles tendon existence or not and ankle position had great influence, while increased stiffness of Achilles tendon had no influence on kinematic coupling relationship between tarsal bones. For the cases with severe equinus, earlier implementation of PAT procedure (with the purpose of release the Achilles tendon and reduce the degree of ankle plantar flexion) may be beneficial to the deformity correction.

Three-Dimensional Finite Element Analysis and Biomechanical Analysis of Midfoot von Mises Stress Levels in Flatfoot, Clubfoot, and Lisfranc Joint Injury

“…In clubfoot, our results showed that the von Mises stress decreased in the lateral metatarsal and navicular, but talus stress was increased significantly. The maximum stress distribution in individuals with clubfoot was mainly concentrated on the talus and navicular [ 34 ]. This result was consistent with the pathoanatomy of clubfoot with a thick and short of tibionavicular ligament and medially displaced navicular [ 35 ].…”

“…Tendon and ankle plantar flexion played an important role in affecting clubfoot stress distribution. This phenomenon led to the kinematic coupling relationship where the calcaneus had the least movement, the forefoot was turned up and valgus, and the stress was concentrated on the hindfoot [ 34 ].…”

Finite element analysis of the kinematic coupling effect of the joints around talus when Ponseti manipulation

“…The ligaments were modeled as linear springs. A total of 28 ligaments and the Achilles tendon were modeled as linear springs with assigned stiffness values as our previous study reported [ 15 ]. The contact behavior between the articulating surfaces was considered as frictionless [ 21 ].…”

“…The pulling effect of the medial ligaments was investigated by measuring the displacement of navicular bone when Ponseti manipulation. The detailed process of the model building and the validation of the established model could be reproduced in the published paper [ 15 ]. In present study, the database of CDH-G1 was applied for the establishment of foot and ankle model.…”

“…Nowadays, Ponseti method has been gradually accepted as the “gold standard” for the initial treatment of clubfoot, and its safety and efficacy has been demonstrated consistently in the past decades [ 2 – 4 , 9 ]. Ponseti manipulation of deformity correction was to supinate the forefoot in proper alignment with the hindfoot, and outward pressure was exerted on the first metatarsal to realign simultaneously the talonavicular, the calcaneocuboid, and the subtalar joint [ 9 , 14 , 15 ]. Satisfactory clinical and functional results (Fig.…”