File Name: biomechanics of foot and ankle .zip
Sports Injuries pp Cite as.
- Functional Anatomy of the Ankle
- 3rd Congress of the International Foot and Ankle Biomechanics (i-FAB) Community
- Current trends in the biokinetic analysis of the foot and ankle
- Welcome to Thieme E-Books & E-Journals
Although the importance of studying the anatomy of structures of the ankle and foot joints is fundamental, evidence points to a low correlation between static and dynamic measurements; this could represent a problem in the study of the functioning of the ankle and foot during daily activities. For this, we performed a literature review and divided the article into 6 sections: 1 functional biomechanics of the ankle and foot; 2 dynamic joint stability; 3 functional stability mechanisms of the foot; 4 functional stability mechanisms of the ankle; 5 gait and running biokinetics; 6 the role of proximal joints in ankle and foot movement. At the end of this article, the reader should be able to understand how the 3-dimensional biokinetic analysis of the ankle and foot can contribute along with imaging examinations to the clinical setting, thus allowing the construction of a more complete profile of the patient.
Functional Anatomy of the Ankle
This paper provides an introduction to the biomechanics of the ankle, introducing the bony anatomy involved in motion of the foot and ankle. The complexity of the ankle anatomy has a significant influence on the biomechanical performance of the joint, and this paper discusses the motions of the ankle joint complex, and the joints at which it is proposed they occur.
It provides insight into the ligaments that are critical to the stability and function of the ankle joint. It describes the movements involved in a normal gait cycle, and also highlights how these may change as a result of surgical intervention such as total joint replacement or fusion. The ankle joint complex is comprised of the lower leg and the foot and forms the kinetic linkage allowing the lower limb to interact with the ground, a key requirement for gait and other activities of daily living.
Despite bearing high compressive and shear forces during gait, the ankle's bony and ligamentous structure enables it to function with a high degree of stability, and compared with other joints such as the hip or knee, it appears far less susceptible to degenerative processes such as osteoarthritis, unless associated with prior trauma.
This paper will highlight key anatomical bony structures and soft tissues that form the ankle joint complex and will further highlight how the ankle joint complex functions during walking and how pathology changes these movements. The foot and ankle is made up of the twenty-six individual bones of the foot, together with the long-bones of the lower limb to form a total of thirty-three joints.
The ankle joint complex is made up of the talocalcaneal subtalar , tibiotalar talocrural and transverse-tarsal talocalcaneonavicular joint. The calcaneus is the largest, strongest and most posterior bone of the foot, providing attachment for the Achilles tendon. It is located inferiorly to the talus, and forms a triplanar, uniaxial joint with the talus.
The two similarly articulated facets of the anterior talocalcaneal joint on the inferior aspect of the talus are convex, and on the superior aspect of the calcaneus are concave, while the facets for articulation of the posterior talocalcaneal joint on the inferior aspect of the talus are concave, and on the superior aspect of the calcaneus are convex.
This geometry allows inversion and eversion of the ankle, and whilst other motion is permitted at this joint, most of eversion and inversion of the foot is provided here. The key linkage between the two is the interosseous talocalcaneal ligament, a strong, thick ligament that extends from the articular facets of the inferior talus to the superior surface of the calcaneus.
Two further ligaments, the lateral talocalcaneal ligament and the anterior talocalcaneal ligament also contribute to the connection of this joint, 1 however these are relatively weak. The talocalcaneal joint is also supported by the calcaneofibular part of the lateral collateral ligament and the tibiocalcaneal ligament of the deltoid. Furthermore, the long tendons of peroneus longus, peroneus brevis, flexor hallucis longus, tibialis posterior, and flexor digitorum longus provide additional support.
The tibiotalar joint forms the junction between the distal tibia and fibula of the lower leg and the talus. The load-bearing aspect of this joint is the tibial-talar interface. The talus bone includes the head, neck and body, and has no direct muscle connection. The trochlea of the talus fits into the mortise formed from the distal ends of the long bones of the shin. The malleoli of the tibia and fibula act to constrain the talus, such that the joint functions as a hinge joint, and primarily contributes to the plantar- and dorsiflexion motion of the foot.
However, the geometry of the joint, such as the cone-shaped trochlea surface and the oblique rotation axis do indicate it may not function simply as a hinge. In stance phase, the geometry of the joint alone is sufficient to provide resistance to eversion; otherwise stability is derived from the soft tissue structures. The tibiotalar joint is a diarthrosis and is covered by a thin capsule attaching superiorly to the tibia, and the malleoli, and inferiorly to the talus.
Stability is given to the joint through three groups of ligaments. The tibiofibular syndesmosis limits motion between the tibia and fibula during activities of daily living, maintaining stability between the bone ends. The syndesmosis consists of three parts — the anterior tibiofibular ligament, the posterior tibiofibular ligament and the interosseous tibiofibular joint.
The deltoid ligament is fan shaped and comprises the anterior and posterior tibiotalar ligaments, the tibionavicular ligament and the tibiocalcaneal ligament. The lateral collateral ligaments reduce inversion of the joint, limiting varus stresses and reduce rotation.
The anterior and posterior ligaments withstand high tensile forces under plantar and dorsiflexion respectively. These ligaments provide stability to the lateral tibiotalar joint, 4 , 5 , 6 and are frequently damaged during inversion injuries such as ankle sprain.
The calcaneofibular ligament is the only direct connective tissue between the tibiotalar and subtalar joints. This joint has already been referred to in the explanation of the tibiotalar joint. In some literature it is considered as a core aspect of the tibiotalar joint, but may also be considered as a distinct joint. As previously detailed, the anterior and posterior tibiofibular ligaments and interosseous ligament maintain the joint between the tibia and fibula.
The ligamentous constraint of the joint makes it highly susceptible to injury, and is often involved in ankle fracture and eversion injuries. The transverse tarsal joint Chopart's joint combines the junction between the talus and navicular, where anteriorly, the talar head articulates with the posterior aspect of the navicular, and the calcaneocuboid joint, the joint between the calcaneus and the cuboid.
The transverse tarsal joint is considered as part of the same functional unit as the subtalar joint as they share a common axis of motion, 3 , 4 also contributing to eversion-inversion motion of the foot.
The majority of motion within the foot and ankle is produced by the twelve extrinsic muscles, which originate within the leg and insert within the foot. These muscles are contained within four compartments. The anterior compartment consists of four muscles: the tibialis anterior, the extensor digitorum longus, the extensor hallucis longus, and the peroneus tertius. The tibialis anterior and the extensor hallucis longus produce dorsiflexion and inversion of the foot. The peroneus tertius produces dorsiflexion and eversion of the foot.
The extensor digitorum longus only produces dorsiflexion of the foot. The lateral compartment is composed of two muscles: the peroneus longus and the peroneus brevis, which produce plantarflexion and eversion of the foot. The posterior compartment consists of three muscles: the gastrocnemius, the soleus, and the plantaris, which contribute to plantarflexion of the foot. The deep posterior compartment is composed of three muscles: the tibialis posterior, the flexor digitorum longus, and the flexor hallucis longus, which produce plantarflexion and inversion of the foot.
Combinations of these motions across both the subtalar and tibiotalar joints create three-dimensional motions called supination and pronation. During supination, a combination of plantarflexion, inversion and adduction causes the sole to face medially.
In pronation, dorsiflexion, eversion and abduction act to position the sole facing laterally. Diagram illustrating relative motions of the ankle joint complex. Whilst many authors consider the tibiotalar joint to be a simple hinge joint, there has been some suggestion that it is multi-axial, due to the internal rotation that occurs during dorsiflexion, and the external rotation that occurs in plantarflexion.
However, there is evidence to suggest the tibiotalar joint is indeed uniaxial, but the simultaneous motion observed occur as a result of its oblique axis.
Diagram illustrating the sagittal and frontal plane axis of rotation for the ankle joint complex. Dashed line represents the axis of rotation for the dorsiflexion and plantarflexion.
The intersecting point between the bold and dashed line represents the point of rotation for inversion and eversion. Diagram illustrating the ankle joint complex axis of rotation in the transverse plane. The intersecting point represents the point of rotation for internal and external foot progression toe in or toe out gait. Studies of the talar anatomy have highlighted the difference in radial curvature in the medial and lateral aspects, indicating the axis of rotation of the ankle joint will vary as motion changes.
Motion about these axes cannot occur simultaneously, and the transition between axes during motion is estimated to occur close to the neutral position of the joint. In a similar way to the tibiotalar joint, the subtalar joint creates multiple motion during plantar and dorsiflexion, resulting in pronation and supination. The ankle range of motion ROM has been shown to vary significantly between individuals due to geographical and cultural differences based on their activities of daily living, 12 in addition to the method used for assessing ROM.
Motion of the ankle occurs primarily in the sagittal plane, with plantar- and dorsiflexion occurring predominantly at the tibiotalar joint. However, despite this limitation, gait analysis is still a commonly used tool for the quantification of ankle joint complex kinematics and kinetics. During a normal gait cycle, the stance phase can be split into three sub-phases based on the sagittal motion of the ankle; i the heel rocker; ii the ankle rocker and iii the forefoot rocker.
The heel rocker phase begins at heel strike, where the ankle is in a slight plantarflexed position pivoting around the calcaneus the continuation of plantarflexion until the end of the heel rocker phase when the foot is flat on the ground.
During this sub-phase the dorsiflexors are eccentrically contracting to lower the foot to the ground. The ankle rocker phase is where the ankle moves from plantarflexion to dorsiflexion during which the shank tibia and fibula rotate forward around the ankle allowing forward progression of the body. For the majority of individuals, inversion occurs at heel-strike, and progresses to eversion during mid-stance phase, allowing the heel to rise and push off into swing. Diagram illustrating typical outputs from gait analysis of five walking trials.
The ankle joint complex bears a force of approximately five times body weight during stance in normal walking, and up to thirteen times body weight during activities such as running. During the second phase, there is a plantarflexor moment as the ankle dorsiflexors contract eccentrically to allow forward progression of the shank over the foot. During the third phase, the plantar flexion moment continues with the plantar flexors contracting concentrically towards toe-off. As walking speed increases, ankle kinetic patterns remain similar in profile but with greater magnitudes.
Ankle joint moments acquired from gait analysis do not commonly report ankle moments in the coronal or transverse planes due to the complex nature of movement of the ankle joint complex and the high variability between individuals.
The negative values correspond with power absorption from the plantar flexors eccentrically contracting during the heel and ankle rocker phases. The ankle has a relatively high level of congruency, meaning that despite experiencing high loads during normal activities, the load-bearing area of the ankle is large 11—13 cm 2 , and it has been proposed that this should result in lower stress than at the hip or knee.
A statically applied load of 1. Age and gender are both influential factors that may change ankle ROM. A study compared gender differences within different age groups, between 20 and 80 year of age. Additionally, there was a reduction in ROM for both genders in the oldest age groups. Degenerative processes of the foot and ankle, such as post-traumatic osteoarthritis may have a significant impact on the biomechanical function of the ankle.
Compared to the hip and knee, post-traumatic osteoarthritis is more prevalent. There have been a number of studies undertaken to explore the impact of ankle surgery on ankle biomechanics.
Common surgical interventions for end-stage ankle OA include total ankle replacement or ankle arthrodesis, both, aimed at improving pain and function of the patient. Joint replacement has been transformative for hip and knee osteoarthritis but for total ankle replacement, problems remain.
Gait analysis can be used as a useful objective tool for measuring functional performance of patients following a surgical intervention. Patients with end-stage ankle osteoarthritis typically walk more slowly, have a reduced ankle ROM and have altered ankle moments compared to healthy controls. For example, ankle joint moments and power remain significantly reduced.
Ankle arthrodesis represents a functionally more conservative alternative with less risk of future requirement for revision. Fusion of the joint, by its nature, limits the function of the tibio-talar joint, and in some cases subtalar fusion can be undertaken simultaneously, effectively locking the ankle in a fixed position.
Gait analysis performed pre- and post-arthrodesis surgery has also demonstrated improvements in walking speeds and spatio-temporal measures. The reduced motion often results in hypermobility of the midfoot causing adjacent joint OA. The anatomy of the ankle joint complex determines that the biomechanics is not just that of a simple hinge joint but that of multi-axial motions occurring simultaneously to facilitate human gait.
Simple factors such as gender and age can impact on the biomechanics of the ankle, and diseases such as arthritis can influence the range of motion and ankle power. Surgical treatment for end stage degeneration significantly influences the biomechanical function of the ankle, and has a notable impact on the surrounding joints. The views expressed in this publication are those of the author s and not necessarily those of the NHS, the National Institute for Health Research or the Department of Health.
The funding source had no role in writing of the manuscript; or in the decision to submit the manuscript for publication.
3rd Congress of the International Foot and Ankle Biomechanics (i-FAB) Community
This paper provides an introduction to the biomechanics of the ankle, introducing the bony anatomy involved in motion of the foot and ankle. The complexity of the ankle anatomy has a significant influence on the biomechanical performance of the joint, and this paper discusses the motions of the ankle joint complex, and the joints at which it is proposed they occur. It provides insight into the ligaments that are critical to the stability and function of the ankle joint. It describes the movements involved in a normal gait cycle, and also highlights how these may change as a result of surgical intervention such as total joint replacement or fusion. The ankle joint complex is comprised of the lower leg and the foot and forms the kinetic linkage allowing the lower limb to interact with the ground, a key requirement for gait and other activities of daily living. Despite bearing high compressive and shear forces during gait, the ankle's bony and ligamentous structure enables it to function with a high degree of stability, and compared with other joints such as the hip or knee, it appears far less susceptible to degenerative processes such as osteoarthritis, unless associated with prior trauma. This paper will highlight key anatomical bony structures and soft tissues that form the ankle joint complex and will further highlight how the ankle joint complex functions during walking and how pathology changes these movements.
Current trends in the biokinetic analysis of the foot and ankle
Yoganandan, N. November 1, J Biomech Eng.
Welcome to Thieme E-Books & E-Journals
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Normal biomechanics of the foot and ankle can be divided into static and dynamic components. The static structures include the bones, joint sur- face congruity.
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