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Designing for Foot and Ankle Anatomy
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
Ligaments are essential components of the foot and ankle, stabilizing the bones at the joints while also allowing motion and flexibility. They are frequently named for the bones where they attach. The ligaments at the ankle are the largest and strongest in the region, but they are also most often injured (Figure 8.5). Acute ligamentous ankle sprains (stretching or tearing of fibers in a ligament) occur in many sports as well as in everyday life (Hootman, Dick, & Agel, 2007). Normal motion at the ankle includes inversion and eversion (Figure 8.6-A and Figure 8.6-B). Inversion ankle sprains tend to happen when the planted foot quickly inverts relative to the leg, although they can also occur when the foot is “searching for ground,” such as when unexpectedly stepping off a curb. The tibia shifts on the talus while the foot turns onto the lateral side (Hamill & Knutzen, 2003). Refer to Figure 8.6-C. The injury most often involves the anterior talofibular ligament, and possibly also the calcaneofibular ligament, and/or the posterior talofibular ligament. The medial, deltoid, ligament is stronger and less likely damaged unless the foot everts very forcefully with the tibia shifting laterally on the talus while the foot turns to the medial side (Figure 8.6-D). The lateral malleolus, the distal end of the fibula, tends to limit the extent of eversion motions. Torn ligaments may heal with scarring, but are never the same after a sprain, so some athletic footwear is designed to try to prevent injury.
The Anatomy of Joints Related to Function
Published in Verna Wright, Eric L. Radin, Mechanics of Human Joints, 2020
A number of morphological features are directed toward resisting posterior shear forces. One is the shape of the trochlear surface of the talus, which is wider anteriorly than it is behind (Fig. 9A). This helps to prevent the mortise riding forward upon the talus during the stance phase, and this mechanism clearly also depends upon the integrity of the inferior tibiofibular syndesmosis and the posterior fibers of the collateral ligaments (including the posteriorly directed calcaneofibular ligament). Additionally, the socket of the mortise is deepened posteriorly by the downward extension of the tibial shaft (the “posterior malleolus”) and the inferior transverse tibiofibular ligament (Fig. 23A).
Lower extremity injuries
Published in Youlian Hong, Roger Bartlett, Routledge Handbook of Biomechanics and Human Movement Science, 2008
William C. Whiting, Ronald F. Zernicke
Lateral ankle sprains exhibit sequential ligament failure. The anterior talofibular ligament (ATFL) fails first because of its orientation at the instant of loading and its inherent weakness (Siegler et al., 1988). When the ankle is plantar flexed (as in ankle-foot supination), the ATFL aligns with the fibula and acts as a collateral ligament (Carr, 2003). This alignment and the ATFL’s structural weakness predispose the ATFL to injury. The calcaneofibular ligament (CFL) typically tears next, followed rarely by failure of the posterior talofibular ligament (PTFL).
Differences in the locomotion biomechanics and dynamic postural control between individuals with chronic ankle instability and copers: a systematic review
Published in Sports Biomechanics, 2022
Peimin Yu, Qichang Mei, Liangliang Xiang, Justin Fernandez, Yaodong Gu
Several studies conducted various types of jump-landings to investigate the differences between individuals with CAI and copers (De Ridder et al., 2015; C. Brown et al., 2008; Brown et al., 2009; Doherty et al., 2016, 2016dd; Brown et al., 2011; Lin et al., 2019). It was found that CAI individuals had more ankle frontal displacement (C. Brown et al., 2008), greater variances of ankle inversion/eversion angles (Brown et al., 2009), greater hip flexion (Doherty et al., 2016d, 2016), external rotation and hip flexion displacement (Brown et al., 2011; De Ridder et al., 2015) during the landing phase. Repetitive ankle sprains in CAI individuals might cause the impairment of the calcaneofibular ligament, which functions to facilitate the ankle movement in the frontal plane (Stormont et al., 1985). CAI individuals, therefore, had greater ankle motion in the frontal plane (C. Brown et al., 2008; Brown et al., 2009). Greater hip flexion and flexion displacement indicated that individuals with CAI may rely on the hip joint to keep balance during the landing phase compared to copers (Hertel et al., 2002). Doherty et al. (2016d) found CAI individuals had increased hip joint stiffness, which might indicate involvement of hip joint to counteract downward velocity while landing. As for the muscle activity, the medial gastrocnemius, functioning as ankle plantar flexor and knee flexor, was related to ankle and knee stability (Nashner, 1977). During the initial landing phase, individuals with CAI had more muscle activation in the medial gastrocnemius and soleus (Lin et al., 2019). The increased muscle activation of the medial gastrocnemius (MG) in CAI individuals may facilitate ankle stability during landing. Further, the activity of tibialis anterior in CAI individuals reduced compared to copers (Dundas et al., 2014). Tibialis anterior (TA) as a dorsiflexor and invertor of the ankle joint played a crucial role in ankle stability. Reduced TA activation might lead to instability of the talonavicular joint, which could cause the pronating posture of the foot as well as lateral ankle stress in the CAI group (Rosen et al., 2013). In the progression of the movement tasks with rapid decelerations (jump/drop-landing), CAI individuals relied on the hip strategies and greater muscle co-activation to maintain balance. Further, the variability of ankle frontal plane motion in CAI individuals increased compared to copers, which might indicate the worse ability to overcome the injury risk. Bilaterally completed landing exercises and variability analysis might be beneficial and be included in the rehabilitation programme for the acute lateral ankle sprain.