Ankle And Foot Complex 1a

Ankle and Foot Complex Functions: Stability demands: • Provide stable base of support for body in weight bearing activities without undue muscle or energy expenditure • Acts a rigid lever for effective push off phase of gait cycle Mobility demands: • Dampen the rotations imposed by proximal joints • Being flexible enough to absorb the shock of superimposed body weight • Permitting the foot to adapt to changing terrain

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The foot and ankle consists of 28 bones with 25 complex joints It can be divided into Hind Foot:Talus & calcaneum Mid Foot:Navicular,cuboid & 3 cunieform Forefoot:Metatarsals & phalanges

Ankle Joint: • Synovial joint with 1° of freedom,most congruent joint • Articulation between talus and distal tibia and fibula Articular surface: • Proximal segment is composed of concave surface of tibia and tibial and fibular malleoli – mortise

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Distal segment is formed by the body of talus – has 3 articular surfaces lateral , medial and trochlear/superior facets

Ligaments: • Capsule is thin and weak anteriorly and posteriorly • Two major ligaments maintain contact and congruence of the mortise and talus and control medial- lateral joint stability • Medial collateral ligament• Deltoid ligament • Has superficial and deep fibers • Controls medial distraction stress, checks motion at extremes of range

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Lateral collateral ligamentConsists of Anterior & posterior talofibular lig., calcaneofibular ligament Helps control varus stresses and checks extremes range Anterior talofibular ligament is the weakest & most commonly torn followed by calcaneofibular Posterior talofibular ligament is strongest

Function : • Ankle has 1° of freedom – dorsi flexion/ plantar flexion Other motions are • Talar tilt (Inversion/ Eversion) in the frontal plane, A-P axis • Talar rotation (Abduction/adduction) occurs in the transverse plane/vertical axis

ROM: • Dorsiflexion from neutral : 0 - 20° • Plantar flexion from neutral :0-30° to 50°

Sub Talar Joint (Talocalcaneal) • Composite joint formed by three separate articulations between talus superiorly and calcaneum inferiorly • Consists of anterior, middle & posterior articulations • Together, three surfaces provide a triplanar movement around a single joint axis

Function at the weight bearing sub talar joint is to dampen the rotational forces imposed by the body weight while maintaining contact of foot with supporting surface Tarsal tunnel: • Between the posterior articulation and the anterior and middle articulations there is a bony tunnel formed by a sulcus in the inferior talus and superior calcaneum • Contents of the tunnel are Tibialis Posterior, Flexor Digitorum Longus,Posterior Tibial artery,Posterior Tibial Nerve,Flexor Hallucis Longus •

Ligaments: 2. Calcaneofibular ligament 3. Cervical ligament 4. Interosseus talocalcaneal ligament

Non weight bearing subtalar joint motion: • Supination/pronation of subtalar joint can be described by motion of its distal non weight bearing segment –calcaneum • Supination=Adduction+Inversion+Plantar flexion • Pronation=Abduction+Eversion+Dorsi flexion

If the calcaneum is observed posteriorly the component of inversion/eversion can be observed • In eversion the medial angulation between the long axis of the tibia and an axis through the tuberosity of the calcaneum ↑ ∴Eversion=Calcaneovalgus •

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In inversion the medial angulation between the long axis of the tibia and an axis through the tuberosity of the calcaneum ↓. ∴ Inversion=Calcaneovarus

Calcaneal positions Neutral calcaneum

Calcaneal valgus (eversion)

Calcaneal varus (inversion)

Weight bearing subtalar joint motion: • The most critical functions of the foot occur in weight bearing, and when the foot is weight bearing, there is effectively a closed chain formed for the lower extremity • Consequently the kinetics and kinematics of this joint will be affected by proximal and distal joints • Calcaneum is not free to move • It can only evert (valgus) and invert (varus) • These movements cannot occur in isolation, the proximal segment of the joint moves but in the opposite direction

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Motions of supination/pronation are absorbed by the tibiofibular mortise Tibia remains unaffected by supination/pronation In this case the talus carries the super imposed body weight along with it Subtalar supinationleg moves laterally Subtalar pronationleg moves medially

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Sub talar joint acts as a mitered hinge between leg and foot Medial rotation of the leg proximally imposes pronation on the distally located foot Lateral rotation of the leg proximally imposes supination on the distally located foot