Skip to main content
UploadLanguage (EN)Support
BusinessMobileSocial MediaMarketingTechnologyArt & PhotosCareerDesignEducationPresentations & Public SpeakingGovernment & NonprofitHealthcareInternetLawLeadership & ManagementAutomotiveEngineeringSoftwareRecruiting & HRRetailSalesServicesScienceSmall Business & EntrepreneurshipFoodEnvironmentEconomy & FinanceData & AnalyticsInvestor RelationsSportsSpiritualNews & PoliticsTravelSelf ImprovementReal EstateEntertainment & HumorHealth & MedicineDevices & HardwareLifestyle
Zinat Ashnagar, profile picture
Uploaded byZinat Ashnagar
PPTX, PDF332 views

Ankle & foot Complex.session.3

This document discusses the anatomy and biomechanics of the ankle joint and foot. It describes the key bones and joints that make up the ankle and foot complex, including the talocrural joint, subtalar joint, and joints of the midfoot and forefoot. It explains how the medial longitudinal arch supports the foot during standing and how structures like the plantar fascia and windlass mechanism help maintain the arch during gait. Common foot types like pes planus and pes cavus are also summarized. The document outlines the motions of the ankle and subtalar joints during gait and identifies the most and least stable positions of the talocrural joint. Muscles acting on the ankle and foot are identified along with their

Health & Medicine◦
Download to read offline
Presented by : Zinat Ashnagar, PT, PhD Assistant Professor, Tehran University of Medical Sciences https://orcid.org/0000-0001-5515-2130 Zinatashnagar@gmail.com https://www.researchgate.net/profile/Zinat_Ashnagar Kinesiology of the Ankle Joint
2
Ankle & Foot Complex 3 Deep plantar fascia
• The medial longitudinal arch and associated connective tissues are the primary sources of mechanical support for the foot during relatively low stress or near static conditions (e.g. while standing on ease). Ankle & Foot Complex 4
• Without this arched configuration, the large and rapidly produce forces applied against the foot during running and marching, for examples, would likely exceeds the physiologic weight- bearing capacity of the bones. Ankle & Foot Complex 5
ACCEPTING BODY WEIGHT DURING STANDING Ankle & Foot Complex 6
PES PLANUS – “ABNORMALLY DROPPED” MEDIAL LONGITUDINAL ARCH • Pes planus or “flatfoot” describes a chronically dropped or abnormally low medial longitudinal arch. • Often results from joint laxity and an overstretched or weak plantar fascia. • Flexible pes planus appears normal when unloaded, but drops when loaded. 7 Ankle & Foot Complex
ACCEPTING BODY WEIGHT DURING STANDING Ankle & Foot Complex 8
PES CAVUS – ABNORMALLY RAISED MEDIAL LONGITUDINAL ARCH 9 Ankle & Foot Complex
1/25/2020
Pes Cavus • An abnormally high arch places the metatarsal bones at a greater angle with a ground. • When combined with the reduced area of plantar contact, plantar pressures typically rise and shift anteriorly over the forefoot.
• Furthermore, a foot with a chronically raised (and relatively rigid) arch cannot, in theory, optimally absorb the repeated impacts of walking and running. • A person with significant pes cavus may therefore at high higher risk of developing stress-related injuries within the foot and lower limb.
• While walking, maximal dorsiflex occurs late in stance phase, just before the heel rises off the ground (at about 40% of the gait cycle). • Realize that while in the stance phase of walking, the term dorsiflex describes the position of leg relative to the foot. 14 Functional Considerations: Most- and Least-Stable Positions of the Talocrural Joint
• At this point in the gait cycle, the ankle is most stable because most of the collateral ligaments and all of the plantar flexor muscles are stretched.
ROM TALOCRURAL JOINT DURING GAIT 16 Ankle & Foot Complex
17
18
• The dorsiflexed ankle is further stabilized as the wider, anterior part of the trochlea of the talus become wedged into the mortise. • For this reason the close-packed position of the ankle is full dorsiflex. 19
• Such stability is necessary in late stance to prepare for the action of the strongly activated plantar flexor muscles during jumping or the push-off phase of walking.
• The least stable position of the talocrural joint is full plantar flex. • Full plantar flex- loose-packed position of the joints- slackens most of the collateral ligaments and all of the plantar flexor muscles.
22
23
• The position of full plantar flex also causes the mortise (distal tibia and fibula) to “loosen its grip” on the talus. • This places the narrower width of the talus between the malleoli, thereby releasing tension within the mortise. • Weight bearing over a fully plantar flexed ankle, therefore places the ankle at a relatively unstable position. 24
25
FACTORS THAT INCREASE THE MECHANICAL STABILITY OF DORSIFLEXED TALOCRURAL JOINT Ankle & Foot Complex 26
Subtalar joint: Critical Kinematic Link Between the Leg and Foot • Motion at the subtalar joint is commonly expressed in one of two ways: • When the calcaneus is free, such as during the swing phase, or when it is in firm contact with the ground during the stance phase of walking. 27
• While in the stance phase, the leg and talus moves as one mechanical unit over the fixed calcaneus. • Although the motion at the subtalar is small, it is nevertheless important.
29
• The normal subtalar joint is well utilized during walking and running, especially on unlevel terrain. • For example, when standing on level ground, the leg and talus are in relative alignment with the calcaneus (A). 30
• Consider what happens when the foot encounters uneven ground (B). • In this scenario, the calcaneus rotates, resulting in inversion of the subtalar joint. • This “righting” mechanism of the foot allows the leg to remain vertical, even while standing or walking on uneven surfaces. • If this motion is excessive, however, it may result in a sprain of the lateral ligaments. 31
• In other circumstances, it may be necessary that the calcaneus remains firmly planted on the ground, while the leg and body cut in medial or lateral directions (C). • With the calcaneus well fixed, a medially directed movement of the talus and leg can occur as subtalar joint inversion. 32
• Realize that, although different bones are moving, in B and C, the final position of the subtalar joint in both scenarios is the same: “INVERSION”. • Without the available motion provided by the subtalar joint, walking on uneven surfaces would be extremely difficult and would likely result in loss of balance or injury to the ankle and foot.
CHANGE IN HEIGHT IN THE MEDIAL LONGITUDINAL ARCH 34 Ankle & Foot Complex
CHANGE IN HEIGHT IN THE MEDIAL LONGITUDINAL ARCH
• In the healthy foot, MLA (Medial Longitudinal Arch) rises and lowers cyclically throughout the gait cycle. • During most of the stance phase, the arch lowers slightly in response to the progressive loading of body weight. 36
• Structures that resists the lowering of the arch absorb local stress as the foot is progressively compressed by body weight. • This load attenuation mechanism offers essential protection to the foot and lower limb against stress-related, overuse injury.
• During the first 30 to 35% of gait cycle, the subtalar joint pronates (everts), adding an element of flexibility to the midfoot. • By late stance, the arch rises sharply as the now supinating subtalar joint adds rigidity to the midfoot. 39
The rigidity prepares the foot to support the large loads produced at the peak of the push off phase.
• The ability of the foot to repeatedly transform from a flexible and shock-absorbent structure to a more rigid lever during each gait cycle is one of the most important and clinically relevant actions of the foot.
• Immediately after the heel contact phase of gait, the dorsiflexed talocrural joint and slightly supinated subtalar joint rapidly plantar flex and pronate. • The amount and the speed of the pronation nevertheless influence the kinematics of the more proximal joints of the lower extremity. 42
• These effects can be readily appreciated by exaggerating and dramatically slowing the pronation action of the rearfoot during the initial loading phase of gait.
• While standing over a loaded and fixed foot, forcefully but slowly internally rotate the lower limb and observe the associated pronation at the rearfoot and lowering of the MLA. • If sufficiently forceful, this action also tends to internally rotate, slightly flex and adduct the hip and create a valgus stress on the knee. 44
45
ACTIONS ASSOCIATED WITH EXAGERRATED PRONATION OF THE SUBTALAR JOINT DURING WEIGHT BEARING Joint of Region Action Hip Internal rotation, flexion, and adduction Knee Increased valgus stress Rearfoot Pronation (eversion) with a lowering of medial longitudinal arch Midfoot and Forefoot Supination (inversion) 46 Ankle & Foot Complex
47
1/25/2020
Basic Functions of Distal Intertarsal Joints • As a group, the distal intertarsal joints: 1) Assist the transverse tarsal joint in pronating and supinating the midfoot 2) Provide stability across the midfoot by forming the transverse arch of the foot.
Cuneonavicular Joint • The major function of Cuneonavicular joint is to help transfer components of pronation and supination distally from the talonavicular toward the forefoot.
1/25/2020
Cuboideonavicular Joint • Synarthrodial (fibrous) or sometimes synovial • Provides a relatively smooth contact point between the lateral and medial longitudinal columns of the foot. • Articular surfaces slide slightly against each other during movement of the midfoot, most notably during inversion and eversion.
Intercuneiform and Cuneocuboid joint Complex • Consists of three articulation: • Two between the set of three cuneiforms, and • one between the lateral cuneiform and medial surface of the cuboid.
1/25/2020
• Forms the transverse arch of the foot. • This arch provides transverse stability to the midfoot. • Under the load of body weight, the transverse arch depresses slightly, allowing body weight to be shared across all five metatarsal heads. Intercuneiform and Cuneocuboid joint Complex
• The transverse arch receives support from intrinsic muscles; extrinsic muscles, such as the tibialis posterior and fibularis lungus; connective tissues;and the keystone of the transverse arch: the intermediate cuneiform
1/25/2020
1/25/2020 Tarsometatarsal joints
1/25/2020
Tarsometatarsal Joints • The tarsometatarsal joints are the basilar joints of the forefoot. • Mobility is least at the second and third tarsometatarsal joints, in part because of strong ligaments and the wedged position of the base of the second ray between the medial and lateral cuneiforms.
• The second and third rays produce an element of longitudinal stability throughout the foot, similar to the second and third rays in the hand. • This stability is useful in late stance as the forefoot prepares for the dynamics of push off.
The functional stability of the first tarsometatarsal joint is considered an important mechanism that assists the MLA in safely accepting and sharing the loads incurred during walking.
• Most literature describes a natural mechanical coupling of the kinematics at the first tarsometarsal joint: • Specifically, plantar flex occurs with slight eversion, and dorsiflex with slight inversion.
OSTEOKINEMATICS OF FIRST TARSOMETATARSAL JOINT Ankle & Foot Complex 66
Combining plantar flex and eversion, for example, allows the medial side of the foot to better conform around irregular surfaces on the ground.
1/25/2020
• A pair of collateral ligaments spans each metatarsophalangeal joint, blending with and reinforcing the capsule. • As in the hand, each collateral ligament courses obliquely from a dorsal-proximal to a plantar-distal direction, forming a thick cord portion and a fan-like accessory portion.
METATARSOPHALANGEAL JOINT 71 Ankle & Foot Complex
• The accessory portion attaches to the thick, dense plantar plate, located on the plantar side of the joint. • Fibers from deep plantar fascia attach to the plantar plates and sheaths of the flexor tendons.
• Movements at the MP joints occur in two degrees of freedom: • Extension (DF) and Flexion (PF) (Sagittal plane about ML axis) • Abduction and Adduction (horizontal plane about a vertical axis)
Foot Flat (8% Point of the Gait Cycle) • Foot flat is defined as the point at which the entire plantar surface of the foot is in contact with the ground. • This event is often described as the loading response phase.
Mid Stance (30% Point of the Gait Cycle) • Mid stance occurs as the lower leg approaches the vertical Position. • The leg is in single-limb support, as the other limb is freely swinging forward. • The hip and the knee are in near extension, as the ankle continues to move into greater dorsiflexion.
HALLUX VALGUS Ankle & Foot Complex 77
1/25/2020 (1) adduction of the first metatarsal (toward the midline of the body), evidenced by the increased angle between the first and second metatarsal bones; (2) lateral deviation of the proximal phalanx with dislocation or subluxation of the first metatarsophalangeal joint;
(3) displacement of the lateral sesamoid; (4) rotation (eversion) of the phalanges of the great toe; and (5) exposed first metatarsal head, forming the so- called “bunion.”
Windlass effect 1/25/2020
windlass effect • The “windlass effect” of the plantar fascia is demonstrated while a subject stands on tiptoes. • A windlass is a lifting device consisting of a rope wound around a cylinder that is turned by a crank. • The rope is analogous to the plantar fascia, and the cylinder is analogous to the metatarsophalangeal joint.
• In the normal foot, contraction of the extrinsic plantar flexor muscles lifts the calcaneus, thereby transferring body weight forward over the metatarsal heads. • The resulting extension of the metatarsophalangeal joints (shown collectively as white disk) stretches (winds up) the plantar fascia within the medial longitudinal arch (red spring).
Windlass effects 1/25/2020
• The increased tension from the stretch raises the arch and strengthens the midfoot and forefoot. • Contraction of the intrinsic muscles provides additional reinforcement to the arch.
• The foot with pes planus (flatfoot) typically has a poorly supported medial longitudinal arch. • During an attempt to stand up on tiptoes, the forefoot sags under the load of body weight. • The reduced extension of the metatarsophalangeal joints limits the usefulness of the windlass effect. • Even with strong activation of the intrinsic muscles, the arch remains flattened and the midfoot and forefoot unstable.
COMMON FIBULAR (PERONEAL) NERVE 88 Ankle & Foot Complex
TIBIAL NERVE 89 Ankle & Foot Complex
ACTIONS ACROSS TALOCRURAL AND SUBTALAR JOINTS 90 Ankle & Foot Complex
MUSCLES OF THE ANTERIOR COMPARTMENT OF THE LEG (PRETIBIAL “DORSIFLEXORS”) • Muscles – Tibialis anterior – Externsor digitorum longus – Extensor hallucis longus – Fibularis tertius • Innervation – Deep branch of the fibular nerve 91 Ankle & Foot Complex
PRETIBIAL MUSCLES 92 Ankle & Foot Complex
1/25/2020
LATERAL COMPARTMENT MUSCLES 94 Ankle & Foot Complex
1/25/2020
1/25/2020
LATERAL COMPARTMENT OF THE LEG (“EVERTORS”) • Muscles – Fibularis longus – Fibularis brevis • Innervation – Superficial branch of the fibular nerve 97 Ankle & Foot Complex
• The line of force of several plantar flexor muscles while the subject rises on the tip toes. • Note that the fibularis longus and tibialis posterior form a sling that supports the transverse and medial longitudinal arches. 1/25/2020
1/25/2020 the pull of the gastrocnemius and tibialis posterior muscles causes a slight supination of the rear foot, which adds further stability to the foot.