Biomechanical stress analysis of the main soft tissues associated with the development of adult acquired flatfoot deformity

Abstract

Background: Adult acquired flatfoot deformity (AAFD) is traditionally related to a tibialis posterior tendon deficiency. In the intermediate stages, treatments are commonly focused on reinforcing this tissue, but sometimes the deformation appears again over time, necessitating the use of more aggressive options. Tissue stress cannot be consistently evaluated through traditional experimental trials. Computational foot modeling extends knowledge of the disease and could help guide the clinical decisions. This study analyzes the biomechanical stress of the main tissues related to AAFD and their capacity to support the plantar arch. Methods: A FE foot model was reconstructed. All the bones, cartilages and tissues related to AAFD were included, respecting their biomechanical characteristics. The biomechanical tissue stress was quantified. The capacity of each soft tissue to support the plantar arch was measured, following clinical criteria. Findings: Biomechanical stress of the tibialis posterior tendon is considerably superior to both the plantar fascia and spring ligament stress. However, it cannot maintain the plantar arch by itself. Both the tibialis posterior tendon and spring ligament act in reducing the hindfoot pronation, while the plantar fascia is the main tissue that prevents arch elongation. The Achilles tendon action increases the plantar tissue stress. Interpretation: The tibialis posterior tendon stress increases when the spring ligament or the fascia plantar fails. These findings are consistent with the theory that regards the tibialis posterior tendon as a secondary actor because it cannot support the plantar arch and claudicates when the hindfoot has rotated around the talonavicular joint.

Adult Acquired Flatfoot Deformity: Anatomy, Biomechanics, Staging, and Imaging Findings

“…The most important static stabilizers are the spring ligament, talocalcaneal ligaments, deltoid ligaments, plantar fascia, and tarsometatarsal joint complex (6,8) ( Table 2). The abnormal anatomy of AAFD typically starts at the PTT, but dysfunction in this tendon by itself is not enough to lead to substantial deformity (17,(24)(25)(26)(27). Instead, PTT failure leads to overload and predictable abnormalities in the remaining supporting structures, most importantly at the spring ligament and the talocalcaneal ligaments at the sinus tarsi.…”

“…It consists of a thick central cord superficial to the flexor digitorum, a lessprominent lateral cord overlying the abductor digiti minimi, and a small medial cord below the abductor hallucis (70). The plantar fascia is an important support structure that prevents plantar foot elongation and assists in maintaining arch alignment (1,26). Although it is often described as a static stabilizer, it also has a dynamic role during gait through the axis it forms with the Achilles tendon proximally and the plantar plates distally (26,71).…”

“…The plantar fascia is an important support structure that prevents plantar foot elongation and assists in maintaining arch alignment (1,26). Although it is often described as a static stabilizer, it also has a dynamic role during gait through the axis it forms with the Achilles tendon proximally and the plantar plates distally (26,71). Its mechanism of function has been described in several ways.…”

Osteotomies combined with soft tissue procedures for symptomatic flexible flatfoot deformity in children

“…Most children have relatively healthy PTT compared to adults [4]. A previous biomechanical research had revealed that spring ligament appeared to have similar importance to PTT for supporting the medial arch [21]. Thus, we evaluated the quality of the spring ligament and repaired it with imbrication suture.…”

Abnormal Biomechanical Conditions of the Foot in Child with Down Syndrome During Standing: A Finite Element Study

“…A finite element (FE) analysis [14] illustrated that posterior tibial tendinopathy, a common reason of adult acquired flatfoot, weakened the load transmission of the joints at the proximal medial column and overstretched midfoot plantar ligaments, which jeopardize the foot arch and make the foot unstable during gait. However, Christian and his fellows [15] identified the tibialis posterior tendon as a secondary actor in the arch maintenance, compared with the plantar facia and the spring ligament by FE method. Some cadaveric researches found the alterations of mechanical loading such as joint reactive force [16], joints contact pressure [17] to show the implication of foot ligaments by ligament resection.…”