Ankle And Foot Complex 2ia

Talocalcaneonavicular Joint (TCN) • TCN joint name ties together talonavicular and talocalcaneal (subtalar) joints that are anatomically and functionally related • Talonavicular articulation is formed proximally by the anterior portion of the head of the talus and distally by concave posterior navicular

Ligaments: b. Spring ligament (plantar calcaneo navicular ligament) (11) c. Deltoid ligament d. Bifurcate ligament (lateral calcaneo navicular ligament) (15)

Joint function: • Talus acts as a ball bearing placed between the tibiofibular mortise superiorly, calcaneum inferiorly and navicle anteriorly • Motion of the weight bearing talus at one end will produce motion at other end • Forces transmitted through the leg to the talus are shared by each of the articular surfaces that make up the TCN • TCN joint is key to foot function

Transverse Tarsal Joint / mid tarsal joint: • Compound joint formed by talonavicular and calcaneocuboid joint • Because the talonavicular joint is classically considered to be a part of transverse tarsal joint, it belongs to two joint complexes- TCN joint and the transverse tarsal joint • Other component of transverse tarsal joint is calcaneocuboid joint • Two joints together present an S shaped joint line that transects the foot horizontally dividing the hind foot from midfoot and forefoot

Navicular and cuboid are essentially immobile in the weight bearing foot • Transverse tarsal joint motion therefore, is considered to be the motion of the talus and of the calcaneum on a relatively fixed naviculocuboid unit Joint Structure: • Talonavicular articulation is formed proximally by the anterior portion of the head of the talus and distally by concave posterior navicular • Calcaneocuboid joint is formed proximally by the anterior calcaneus and distally by posterior cuboid •

Action : • Transverse joint is transitional link between the hind foot and the fore foot serving iii. To add supination and pronation range to the TCN joint iv. To compensate the fore foot and hindfoot position • Compensation refers to the ability of the forefoot to remain flat on the ground while the hindfoot is in varus or valgus

Tarsometatarsal joints : • Plane synovial joints formed by cuboid and three cuneiform bones and the bases of five metatarsals • Ist TMT: Base of Ist metatarsal & medial cuneiform • IInd TMT : Base of IInd metatarsal & middle cuneiform with sides of medial and lateral cuneiform

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IIIrd TMT: Base of IIIrd metatarsal & lateral cuneiform IVth & Vth TMT : Base of IVth, Vth metatarsal & cuboid There are also articulations between bases of metatarsals so that motion at one permits motion of another

Joint Function: • These joints attempt to regulate the position of the metatarsals and phalanges relative to the weight-bearing surface • When the position of hindfoot is extreme and the transverse tarsal joint is inadequate to provide compensation the TMT joints rotate to provide further adjustment of fore foot

Metatarsophalangeal Joint: • Condyloid synovial joint with 2° freedom – Flexion/Extension, Abduction/Adduction • ‘Index Minus Foot’- 56% people have 2nd metatarsal the longest followed by the 1st, through the 3rd to 5th • ‘Index plus minus foot’ - 28% people have 1st-2nd are of equal length • ‘Index plus foot’- 16% people have 2nd metatarsal smaller than the 1st

The Ist MTP has two sesamoid bones which help to increase the lever arm of FHB, protects the FHL against the weight bearing trauma • The heads of the metatarsal bear weight in stance phase Joint Function: • The MTP joints serve primarily to allow the foot to “hinge” at the toes so that the heel may rise off the ground while still maintaining the small but dynamic base of support afforded by the toes and the toe musculature •

Metatarsal Break: • Refers to single oblique axis that lies through the second to the fifth metatarsal heads • Metatarsal break may range from 54° to 73° compared to the long axis of the foot • From weight bearing heel to rise there will be an active contraction of plantar flexors • The musculature cannot normally lift the body weight unless the joints of the hindfoot and mid foot are fully supinated and locked • That is the heel will rise when the foot has become a rigid lever from the calcaneus through the metatarsals

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The rigid lever will rotate around the metatarsal break –MTP axis LOG moves forward but lies within the BOS to maintain stability The obliquity of the axis helps in evenly distributing the weight across the toes. With a coronal axis excessive pressure would be laid on the 1st and 2nd metatarsals

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‘Hallux Valgus’- first toe is normally adducted on the first metatarsal about 15°, an increase in this angle

Inter phalengeal Joints (IP) • Synovial Hinge Joints • 1° of freedom – flexion/extension • Function to smooth the weight shift to the opposite foot in gait and help maintain the stability by pressing against the ground both in static posture and in gait

Plantar Arches: • The bony and ligamentous configuration of the TCN joint, the transverse tarsal joint, and the TMT joints combine to produce a structural vault with in the foot • Shape and arrangement of bones are particularly responsible for stability of plantar arches • 2 different arches 5. Longitutional arch: • Based posteriorly at the calcaneum and anteriorly at the metatarsal heads • Medial and lateral • The medial side is the side for reference

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Transverse arch: Visualized at the level of the anterior tarsals and at the bases of metatarsals Middle cuneiform is the keystone of the arch

Function: • The arches are adapted exclusively to serve weight bearing functions of the foot Stability functions: • The following stability functions could be performed by a foot with a fixed arch structure. e. Distribution of weight through the foot for proper weight bearing f. Conversion of foot to a rigid lever • Distribution of body weight depends on the shape of the arch and location of LOG • It begins at the talus

In bilateral stance the talus receives 50% of body weight and in unilateral stance it is 100% • 50% of the weight received by the talus is divided into subtalar and TCN and calcaneocuboid articulations • Because of the medial location of the talus the medial side bears more weight than the lateral • Similarly in bilateral stance distribution of weight across the MT heads occurs in a 2:1:1:1:1 ratio from 1st-5th ray Mobility functions: f. Dampening the shock of weight bearing g. Adapting to changes in supporting surface h. Dampening super imposed rotations •

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Pes Planus – flat foot Pes cavus – high arch