Ankle and foot Joints

Sustentaculum tali

"Shelf " of bone protruding from the medial, superior surface of the calcaneus. The middle facet of the subtalar joint is located on the upper surface of this feature.

Travserse Tarsal joint: bones

2 joints: -Independent -Synovial -Aligned transversely Talo-calcaneal-navicular joint: -Continuation of the anterior part of the subtalar joint -Ball and socket type Calacaneo-cuboid joint: -Planar type

Talus

2nd largest tarsal bone; only bone in the foot that articulates with the tibia and fibula. Has a head, neck and body Articular dome at top withstands the whole body weight. Posterior part can separate (os trigonum) Body wider anteriorly: -In flexion the thinnest part of the talus is in the mortise during plantar flexion which is unstable -In extension the widest part gets rammed into mortise pushing the fibular to the side making it rock side during dorsiflexion. Vulnerable blood supply. Fractures of the neck or dislocation an cause avascular necrosis of the proximal talus - similar to the scaphoid. It is surrounded by things it has to move against which decreases the space for blood vessels.

Cuneiforms

3 medial tarsal bones between navicular, metatarsals and cuboid

Tarsals

7 bones that make up the ankle: Calcaneus, Talus bone, Cuboid bone, Navicular bone, Cuneiform bones (Medial, Intermediate, Lateral)

Hallux Valgus

A bunion. The swelling and deformity of the metatarsophalangeal joint, usually at the base of the big toe. Deformity in which the great toe is angled laterally toward the other toes.

Ankle

A gliding joint between the distal ends of the tibia and fibula and the proximal end of the talus. Synovial joint - hinge

Subtalar

A joint in the ankle found between the talus and calcaneus.

Supination and pronation

Action of long tendons depends on position to axis Ankle axis: • Posterior: Plantar flex • Anterior: Dorsi flex Subtalar axis: • Medial: inversion & adduction of the forefoot • Lateral: eversion & abduction of the forefoot Longitudinal axis: • Medial: inversion & adduction of the forefoot • Lateral: eversion & abduction of the forefoot

Mortise

Anatomical term indicating a wedge shape. Often used to describe the boney arch formed by the tibial plafond and the two malleoli in the ankle.

Anterior Tibiofibular ligament

Anterior ankle, inferior portion of tibia and fibula attaches fibula to tibia lateral aspect Obliquely from anterior distal tibia to anterior surface of lateral malleolus

Transverse Tarsal

Anterior surfaces of talus and calcaneus articulate with posterior surfaces of navicular and cuboid.

Intertarsal movements

Axis: -Longitudinal axis -Mid and forefoot rotate as a unit on hind foot Function: -Start of the inversion and eversion cascade

Subtalar joint movement

Axis: Runs upwards and anterior From the lateral calcaneal tubercle to the medial talar neck Direction: Inversion and eversion of the forefoot Movement at slightly abnormal angle. Combined axis allows inversion/eversion

Talo-calcaneal-navicular joint

Ball - talar head Socket - navicular (anteriorly), sustentaculum tali and anterior calcaneous (inferiorly) and spring bifrucate ligaments between them. Stability dependent upon strong interosseous ligaments All foot bones proximal to MT/P joint are united by longitudinal ligaments If calcaneous moves it moves subtalar joint which moves talus which moves fibular - all linked together.

Tarsometatarsal Joint

Between the tarsals and metatarsals

Combined Movements

Both are triplanar movements Pronation: - talus (plantarflexion, addution) -Calcaneous (eversion) Supination: - talus (dorsiflexion and abduction) -Calcaneous (inversion)

Cervical ligament

Calcaneus to talus (at the neck of the talus), Stabilizes subtalor joint, assists with resupination

Injury Cascade

Collateral Structural Damage -strain -tear -avulsion fracture Talus rotation: -impact fracture -rotation fracture

Subtalar Joint

Components: -2 separate synovial joints between talus and calcaneous -Functionally one as they act together ("clinical subtalar joint") -At the anterior talocalcaneal articulation, a concave area of the talus fits on a convex surface of the calcaneus. -The posterior talocalcaneal articulation is formed by a concave surface of the talus and a convex surface of the calcaneus. Posteriorly: -Talus body articulates with posterior calcaneous Anteriorly: -Part of the T-N-C joint -Talus head articulates with the anterior calcaneous, navicular, sustentaculum tali and spring ligament.

Spring ligament

Connects sustanaculum tali with the inferior surface of navicular Calcaneonavicular ligament. strengthens and supports medial longitudinal arch.

Lisfranc ligament

Connects the base of the medial cuneiform to the base of the 2nd metatarsal

Deltoid ligament

Fans out from the inferior surface of the medial malleoulus to the talus and proximal tarsal bones, protecting against stress from eversion.

Medial Stabilising Structures

Helps resist inversion and eversion with strong collateral structures. Medial (deltoid) ligament: -Superficial and deep -Stronger than sustentaculum tali -strong and continuous, forms a fan and doesnt allow talus any movement. Long tendons: -3 posterior long tendons of deep posterior leg compartment - flexor digitorum longus, flexor hallacis longus and tibialis posterior.

Foot joints and parts

Hind foot, Transverse Tarsal Joint, Mid foot, Tarsometatarsal Joint, Fore foot

Malleoli fractures

If from inversion/eversion injuries are caused by avulsion or by direct force applied through the talus. Examination of an ankle starts at the knee and finishes at the forefoot.

2nd Tarsometatarsal Joint

Immobility: Metatarsal base fixed between the medial and lateral cuneiforms Ligaments: -2nd MT base - medial cuneiform (lisfranc ligament) -2nd MT base - lateral cuneiform Clinical: -2nd MT stress fracture (too much walking - army recruits - or dancers) -Marker of high energy transfer -Dorsalis pedis artery at risk. Ischeamic fore-foot

Extrapyramidal control

In walking over uneven ground, the foot remains pointing straight forward due to reciprocal rotation at the knee, hip or pelvis mediated by extrapyramidal control.

Superior Stabilising structures

Interosseous membrane Anterior Tibiofibular ligament The mortise and tenon shape of bones Posterior tibiofibular ligament

Transverse tarsal joint

Inversion and eversion dependent on this Anterior surfaces of talus and calcaneus articulate with posterior surfaces of navicular and cuboid. Gliding. Inversion and eversion. Works with subtalar joint for inversion/eversion.

Tarsometatarsal

Joint between metatarsals with corresponding tarsals

Interphalangeal

Joints between the phalanges

Lateral stabilising structures

Lateral and medial ligaments become a lot tighter in dorsiflexion. Lateral ligament: 3 parts - posterior tibiofibular ligament, calcaneofibular ligament, anterior tibiofibular ligament. Tightest in dorsiflexion Lot weaker, not continuous, allows talus to move, Essential to allow foot and ankle to move together - add a little bit more stability. An inversion sprain can involve any of the three lateral ligaments

Plantarflexion

Leg muscles which run behind the medial malleolus: -Flexor Hallucis Longus -Flexor Digitorum longus -Tibialis posterior -Fibularis longus and brevis Achilles muscles are the most important

Tibiofibular Diastasis

Limited by anterior and posterior tibiofibular ligaments and interosseous ligament

Subtalar Joint ligaments

Location: -Tarsal canal and sinus Most important: -Interosseous ligament -Cervical -Stability dependent upon strong interosseous ligaments

Dorsiflexion

Movement brought about by leg muscles which run over the anterior surface of the ankle: -Tibialis anterior -Extensor Hallucis longus -Fibularis tertius

Transverse Tarsal Joint

Name the joint where the Calcaneus, talus, navicular and cuboid articulate.

Intertarsal joints

Numerous: -Intercuneiform -Navicularcuneiform -Cubocuneiform Type: -Synovial Joints -Planar Stability: -Strong ligaments Movement: -Little gliding movements

Posterior Tibiofibular ligament

Posterior ankle; inferior portion of tibia and fibula; attaches fibular to tibia, lateral aspect Runs obliquely, distal tibia to posterior surface of lateral malleolus.

Talar shape

Pressure on the lateral malleolus in dorsiflexion Less stability in plantar flexion Fashion problems - high heels puts ankle in dorsiflexion. More unstable as the thinnest part of talus is in the mortise.

Tenon

Projecting part of joint for inserting into mortise. In the case of the ankle is the talus.

venostasis

Reduced or stopped blood flow to a vein

Talus role and location

Role: Linking leg and foot Location: Surrounded by a circle of bones and ligaments - -Tibia mortise and malleoli -Superiorly tibio-fibular ligaments -Collateral ligamental complexes -Inferiorly 2 ligaments Clinical significance: -The circle is stronger medially so inversion injury is more likely to result in ligamentous or bony damage -Stability is lost if the circle is broken in 2 or more places -Often one of the breaks will occur in the soft tissue and so will not be visible on plain radiology.

MT/P and IP joints

Same as hand General differences: -Less movement Specific difference: -risk of hallus valgus becuase long tendons only held in position by fibrous bands Have collateral ligaments.

Key Ligaments

Spring Ligament: -Sustentaculum tali and posterior navicular -Supports tala head -Maintains medial longitudinal arch Short Plantar: -Overlies spring ligament -Anterior calcaneous and cuboid -Maintains longitudinal arches Long Plantar: -Overlies short plantar -Posterior calcaneous to 2-4 MT heads -Bridges fibularis longus -Maintains the longitudinal arches

Ankle ligament Injury

Stability: -Maximal in dorsiflexion Injury most likely: -Plantar flexion -Inversion injuries -Lateral ligaments If severe: -Many fibres are partly or completely torn -Blood tracks under deep fascia -Instability of the ankle joint -Associated fractures

Inversion and Eversion cascade

Start: -Initially movements around longitudinal axis occur at the transverse tarsal joint (limited range of movement) Transfer: -Force is transferred passively to the subtalar joint which is much more mobile Limits: -When this too reaches its limit the talus rotates which in turn causes movement of the fibula.

Ankle: joint and bones

Synovial joint, hinge Mortise and tenon arrangement important for stability Bones: -Malleoli and inferior tibia -Talus

Avulsion fracture

Tearing away of a part; fragmentation of bone where the pull of a strong ligamentous or tendinous attachment tends to forcibly pull the fragment away from the rest of the bone.

Os Trigonum

Term used when the lateral tubercle does not unite with the body of the talus. Talus - posterior aspect to the lateral tubercle Can look like fracture on xrays

Foot bones

The foot or pes, consists of 26 bones: grouped as tarsus, metatarsus, and phalanges. - 7 Tarsal bones - Metatarsals - Phalanges

Summary

The joints of the knee, ankle and foot work together to facilitate movement on uneven terrain and changes in direction. Supination and pronation of the foot involves all these joints. The ankles is almost a pure hinge joint. Hence it has strong collateral ligaments and is the site where flexion of the foot occurs. The subtalar joint is the main site for inversion and eversion. The talus is key to understanding how the ankle and subtalar joint work. The foot is divided into 3 parts by a combination of joints. Compared with the hand there tends to be little movement due to the surrounding tough ligaments The insertion of the long tendons from the leg means the inversion/eversion rotatory motion starts at the forefoot. This is transmitted proximally to the subtalar joint by ligaments connecting the MT/P and transverse intertarsal joints.

Virchow's triad

The name for the three conditions that predispose a person to clot formation: venostasis, disruption of the vessel lining (endothelial damage), and hypercoagulability. Common in IV drug users, prone to DVT because of it.

Movement

True Hinge joint Transverse Axis: -Through the talus -Back and Lateral -Down and Lateral -not a straight line, slightly to lateral side. -Slightly off plane so that in flexion get slight talus rotation. Movement: -Slight talar rotation -50 degree plantar flexion -25 degree flexion

Tarsometatarsal Joint Bones

Types: Cuneiform: 1, 2, 3rd MT Cuboid: 4th and 5th MT Differences from carpometacarpal: -little movement -medial cuneiform: 1st MT -2nd MT base

Metatarsophalangeal

the joints between the metatarsal bones of the foot and the proximal bones (proximal phalanges) of the toes.