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Running
Published in Paul Grimshaw, Michael Cole, Adrian Burden, Neil Fowler, Instant Notes in Sport and Exercise Biomechanics, 2019
So far, only the major movements of the lower limb in the sagittal plane (side view) have been considered. While these are clearly the largest movements that occur, there are other, smaller movements that are of equal or greater importance to potential injury risk. The movements of the subtalar joint have been the focus of much attention in the research literature due to their suspected role in the aetiology of injury. The subtalar joint lies just below the ankle joint and is formed by the talus above and calcaneus (heel bone) below. It is at this joint that the movements of inversion (turning the sole of the foot inwards) and eversion (turning the sole of the foot outward) mainly occur. During any form of gait, the motions of the subtalar joint and the other plane joints in the foot and ankle serve a shock-absorbing function. Just prior to impact, the foot is positioned in a supinated position (inverted, adducted and plantar flexed) such that the outside portion of the heel makes first contact with the ground. Immediately following impact, the foot flattens as the whole of the foot is placed onto the floor and the subtalar joint moves from inversion to eversion. This movement is known as pronation. As this happens the plantar fascia (ligaments and tendons of the sole of the foot) becomes stretched and the supporting musculature works eccentrically to resist this flattening. These actions help to reduce the impact force by effectively softening the impact and slowing the descent of the body more gradually.
Designing for Foot and Ankle Anatomy
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
The tarsal bones form the rear of the foot and can be subdivided into proximal bones and distal bones. The proximal bones include the calcaneus and the talus. The calcaneus is the largest tarsal bone. You can feel its solid structure at the back and bottom of your foot. The calcaneal (Achilles) tendon attaches to the calcaneus and extends to the strong muscles on the posterior of the leg. The talus, as the uppermost foot bone, interfaces with the bones of the leg above it, the tibia and the fibula, to form the ankle (talocrural joint). Find the joint by locating the intersection of the leg and the foot. Refer to the illustration of the lower limb in Chapter 5 if needed. Run your hands down the inside and outside length of your leg from about mid-calf until you feel two protrusions. On the medial side of your leg you will feel the medial malleolus which is the distal end of the tibia. Along the outside feel the lateral malleolus which is the most distal portion of the fibula. The medial malleolus is slightly higher. Because these protrusions of the ankle do not lie on the same transverse plane (parallel to the ground), the total circumference for footwear, like high-top, pull-on boots, should be designed to comfortably encircle both malleoli. The tibia transmits the weight of the body to the talus. The fibula, with the ankle ligaments, acts as a strut to stabilize the talus beneath the tibia. The talus is unusual, as no muscles attach to it (Hamill & Knutzen, 2003). The talus rests on the calcaneus below, forming the subtalarjoint. The ankle structure, while amazingly sturdy, is very flexible and also susceptible to sprains as described later in this chapter.
A review of the role of lower-leg strength measurements in ankle sprain and chronic ankle instability populations
Published in Sports Biomechanics, 2022
Kathy Liu, Amanda N. Delaney, Thomas W. Kaminski
From a biomechanical perspective, the ankle is a complex joint because while the ankle moves in all three cardinal planes of the body, researchers have argued that the axis of rotation of the ankle joint changes with motion of the ankle (Brockett & Chapman, 2016; Leardini et al., 2014; Leitch et al., 2010) (Figure 1). The numerous bony articulations contribute to the static stability of the ankle joint complex. The talocrural joint, the articulation between the distal tibia and fibula to the talus, is a hinge joint that allows for plantar flexion and dorsiflexion. The subtalar joint, the articulation between the talus and calcaneus, is a condyloid joint that allows for plantar flexion and dorsiflexion, as well as, inversion and eversion. Beyond the motions of plantar flexion/dorsiflexion and inversion/eversion, the ankle will also pronate and supinate. During pronation, the ankle will dorsiflex, evert, and abduct, creating motion in all three cardinal planes of the body (Brockett & Chapman, 2016). Likewise, during supination, the ankle will plantar flex, invert, and adduct (Brockett & Chapman, 2016). Researchers have reported that individuals with CAI have limited range-of-motion (ROM) and altered kinematics of the ankle joint during activity as a result of alterations to the bony and ligamentous restraints (Bonnel et al., 2010; Herb et al., 2018; Hubbard & Hertel, 2006; Kipp & Palmieri-Smith, 2013; Koshino et al., 2016; Medina Mckeon & Hoch, 2019).
Foot pronation
Published in Footwear Science, 2019
Benno Nigg, Anja-Verena Behling, Joseph Hamill
In the past 40 years, biomechanical research has primarily concentrated on the rear foot. The rear foot has two major functional joints: the subtalar joint (i.e. the joint between the calcaneus and the talus), and the talocrural or ankle joint (i.e. the joint between the talus and the tibia). The ankle joint axis is close to a mediolateral axis through the ankle joint complex. The subtalar joint axis (Figure 1) is a line pointing from the ground surface on the posterior and lateral side of the foot toward the medial anterior side of the foot and inclined by about 42 degrees (Inman, 1976). The rotations about the subtalar joint axis are defined as pronation and supination: