Ankle Joint Anatomy PDF

Ankle (Talocrural) Joint • Articulation between the talus and the tibia and fibula • Crura, crus = leg • Also includes: • Inferior transverse ligament Plantarflexion Dorsiflexion • Commonly classified as a modified hinge synovial joint • Major movements: • Dorsiflexion and plantarflexion • Trip...

Ankle (Talocrural) Joint • Articulation between the talus and the tibia and fibula • Crura, crus = leg • Also includes: • Inferior transverse ligament Plantarflexion Dorsiflexion • Commonly classified as a modified hinge synovial joint • Major movements: • Dorsiflexion and plantarflexion • Triplane joint • Small amount motion in the other two planes Most stable Least stable Ankle Joint Lower Extremity Anatomy II Outline • Osteology and articular surfaces • Joint capsule • Ligaments & clinical correlations • Movements • Arteries and nerves What is the ankle joint? • Hinge-type synovial joint • Between distal ends of tibia and fibula and superior part of the talus (compound joint) • Felt between the tendons and anterior surface of the ankle as a slight depression about 1cm proximal to tip of medial malleolus • Cartilage covers the articular facets of the 3 bones • Fibrous capsule encloses the anterior and posterior joint, which itself is lined by a synovial membrane • Parts of the collateral ligaments of the ankle are part of or blend with the capsule No capsule is shown in these images. Dashed lines are the attachments of the joint capsule, which are just outside the margins of the articular surfaces Bones of the ankle • Distal tibia and fibula and dorsal talus participate in the ankle joint • Bones form a malleolar mortise (next slide) into which the pulley-shaped trochlea of the talus (6) fits. • Medial malleolus (2) • Lateral malleolus (5&19) • Dorsal articular surface of talus (6) Fibula Fibula Tibia Tibia MM LM MM Talus Left leg; Anterior view Left leg; Posterior view Ankle mortise • The ankle joint is shaped like a carpenter's mortise and tenon joint • The distal ends of the tibia and fibula (along with the inferior transverse part of the posterior tibiofibular ligament) form a malleolar mortise Carpenter’s mortise joint Fibula Mortise Tibia Lateral malleolus Tenon • Mortise: concave part/recess; formed by tibia, fibula, and malleoli • Tenon: peg like; formed by dorsal talus Clinicians often refer to the “ankle mortise”. Trauma mechanism in ankle fracture. 2014 Medial malleolus Talus 26 Bones in each Foot • Rearfoot (hindfoot) • Talus • Second largest tarsal bone • Articulates with the tibia and fibula at the ankle joint • Also articulates with the calcaneus and navicular • Calcaneus • Largest and most plantar tarsal bone • Projects posteriorly to form the palpable heel • Not part of the ankle joint Superior View of Left Talus Distal/anterior • Head • Entirely articular Head • Neck • Roughened non-articular area Neck medial lateral Body • Body – 3 articular surfaces involved in the ankle joint: • Trochlear surface • superiorly • Triangular facet • laterally • Comma-shaped facet • medially Proximal/posterior Talus, superior/dorsal view Posterior • Head (1) & Neck of talus (2) • Nice that they are angled toward medial foot • 3- articular facet for articulation with tibia. • Aka: trochlear surface/talar dome • Wider anteriorly than posteriorly • Top of the central part of talus called the body of the talus • 4- articular facet for medial malleolus • 8- articular facet for lateral malleolus. • The inferior tip of this facet called lateral process of talus Medial Lateral Anterior Left Talus Lateral view: Superior view: Medial view: Articular Surfaces of the Ankle Joint • Tibia: • Tibial plafond (1) • Comma-shaped facet on the medial malleolus (2) • Fibula • Triangular shaped facet on the lateral malleolus (3) • Talus • Trochlear surface (4) • Includes the beveled triangular facet on the posterolateral aspect • Articulates with the fibrocartilaginous thickening of the inferior transverse ligament • Triangular shaped facet laterally (5) • Comma-shaped facet medially (6) Right Ankle Joint Ankle Mortise • Ankle mortise • Concavity of the ankle joint • Formed by: • Facets of the tibia and fibula • Fibrocartilaginous thickening of ITL • Ankle tenon • Convexity of the ankle joint • 3 articular surfaces of the talus • Woodworking: • Mortise is a notch into which a tenon (projection) fits to form a joint Ankle Joint • Widest anteriorly* • Tibial plafond is widest anteriorly • Trochlear surface of the talus is widest anteriorly • Joint is most stable in full dorsiflexion • Wider surfaces come together and there is less movement between bones • “Wedging” of the talus gives stability • Joint is least stable in full plantarflexion Triangular area for ITL Summary: Ankle movements, and talus fit in the ankle mortise • In full dorsiflexion: • wider, anterior part of the trochlear surface (dome) is fully in the mortise. • This pushes against fibula and causes a small amount of lateral rotation of the fibula. • tight packing of the talus in the mortise is the most stable position of the ankle. • During plantar flexion: • Narrower part of the talus occupies most of the mortise. • There is no pressure against the fibula, which returns to its pre-dorsiflexion position by medial rotation. • In full plantar flexion, the ankle is in its least stable position • Wobble possible: small amounts of abduction, adduction, inversion, and eversion Cavazos & Harkless, 2021 Planes & Movements of the Foot* • Sagittal plane • Dorsiflexion • Dorsum (superior aspect) of the foot moves closer to the leg • Extensor muscles cause dorsiflexion • Plantarflexion • Plantar foot (sole) moves further from the leg • Flexor muscles cause plantarflexion Dorsum • Coronal plane • Inversion • Plantar (sole) foot turns medially Plantar • Eversion • Plantar (sole) foot turns laterally • Transverse plane Dorsum Plantar • Abduction • Adduction Distal Tibia • Medial malleolus • Medial surface • Rough, subcutaneous • Attachment site for ligaments Anterior Posterior border of fibular notch • Lateral surface • Articular and smooth • Comma shaped facet Tibial plafond • Tibial plafond • Inferior articular surface of the tibia • “domed ceiling” Medial Malleolus of the Tibia • Distal tip of medial malleolus • Attachment site for the medial collateral ligament (MCL) of the ankle joint • Deltoid ligament Consists of: • Anterior colliculus (1) • Larger, more inferior • Posterior colliculus (2) • Intercollicular groove (3) Lateral view, left Medial view, left Medial Malleolus of the Tibia • Posterior surface • Groove for tibialis posterior tendon Left tibia • Lateral surface Posterior groove • Comma-shaped articular facet for the talus • Anterior colliculus is larger and projects more inferiorly • Posterior colliculus is smaller • “tail of the comma” Right tibia Right tibia Comma-shaped articular facet Posteroinferior and somewhat lateral view Directly posterior Tibial Plafond • Articular surface on the inferior aspect of the tibia • Wider anteriorly • Continuous with the commashaped facet • Angled so the posterior edge projects further inferiorly than does the anterior edge • Posterior malleolus • The distally protruding posterior aspect of the distal tibia (tibial plafond) Posterior malleolus Lateral Malleolus Stabilizing TibFb • Lateral surface • Subcutaneous and palpable • Convex and rough • Most inferior aspect (apex; 7) is located posteriorly • More proximally, ligamentous attachment of • AITFL (2) • Towards the anterior border • PITFL (4) and inferior transverse ligament (6) 7 • Towards the posterior border lateral tubercle posterior facet lateral process of talus Left fibula Lateral Malleolus Medial surface • Triangular shaped facet for articulation with the talus (13) • Base is superior, apex is inferior • Convex surface • Lateral malleolar fossa (14) • Roughened area posterior to and extending more inferior to the facet • Concave • Attachment of two ligaments • Part of the PITFL PITFL • Upper part of fossa • Posterior talofibular ligament • One of 3 ligaments of the lateral collateral ligament (LCL) of the ankle joint • Attaches to inferior portion of the fossa PTFL Lateral Malleolus • Anterior border • Thick, rounded and rough • Attachment of the other 2 ligaments of the LCL of ankle joint A B • A. Anterior talofibular ligament (ATFL) • B. Calcaneofibular ligament (CFL) • Posterior border • Groove for peroneal tendons A • From the lateral compartment of the leg • Lateral malleolus lies more posteriorly and projects further distally than the medial malleolus* B Inferior View of Ankle Mortise • (2) anterior colliculus of the medial malleolus • (5) apex of the lateral malleolus • (10) comma-shaped articulate facet • (13) triangular articular facet for the talus • (14) fibular fossa • (17) posterior malleolus Tibial plafond PTFL Lateral collateral ligaments of the ankle joint Ankle X-ray • Trochlear surface of the talus (red arrow) • Wider anteriorly • narrower posteriorly H • Convex anterior to posterior N • Concave medial to lateral (more subtle) PP • Lateral malleolus of the fibula (F) • More posterior than the medial malleolus of the tibia (T) Talus; head, neck and posterior process Fibula Tibia Lateral Ankle X-ray • The fibula, tibia and talus are superimposed on each other in this x-ray view • The whitest area (most radiopaque) is where all three bones overlap Posterior malleolus • Distal aspect of medial malleolus • The lateral malleolus • More inferior and posterior than the medial malleolus Medial malleolus, anterior colliculus Apex of lateral malleolus Lateral Ankle X-ray • Talus • • • • • Head (1) Neck (2) Lateral process (3) Posterior process (4) Trochlear surface (5) • Talar dome 5 1 2 4 3 Clinical sidelight: ankle arthritis Normal ankle joint Osteoarthritis Prosthetic joint placement • Osteoarthritis: degenerative joint disease • Loss of articular hyaline cartilage narrowed the space between the tibial plafond and the talus • In severe cases, if prosthetic joint isn’t an option, arthrodesis can be done • Immobilization of joint relieves pain Ankle Joint Fibrous Capsule • Fibrous ankle joint capsule • Attaches to the margins of all of the articular surfaces except • Anterior trochlear surface, capsule extends onto the dorsal neck of talus • Quite thin anteriorly • Also thin posteriorly and blends with the inferior transverse ligament • Lined with synovial membrane A. Coronal section thru the ankle joint Synovial Cavity • Extends superiorly between the tibia and the fibula a short distance • Creating a small recess (A) • In image B, the synovial cavity was injected with fluid under pressure B. • It balloons out anteriorly because the fibrous capsule is so thin anteriorly • The advantage of a thin capsule anteriorly is that it allows flexibility in dorsiflexion and plantarflexion External surface of the fibrous Joint capsule just inferior to the anterior tibiofibular ligament Synovial Cavity • Extends superiorly between the tibia and the fibula a short distance • Creating a small recess (A) • In image B, the synovial cavity was injected with fluid under pressure • It balloons out anteriorly because the fibrous capsule is so thin anteriorly • The advantage of a thin capsule anteriorly is that it allows flexibility in dorsiflexion and plantarflexion Right foot, lateral view Recall: Lateral and medial sides of the ankle • Recall that the lateral compartment of the leg muscles cross the lateral side of the ankle joint, posterior to the lateral malleolus Lateral malleolus PB/PL PL/FL • Recall that the deep posterior compartment of the leg muscles and neurovasculature cross the medial side of the ankle joint, posterior to the medial malleolus Collateral Ligaments of the Ankle Joint • Major stabilizing structures • Deltoid ligament • MCL of ankle • Strongest and most extensive • LCL of the ankle O • Weaker • Distinctly divided into 3 collaterals separate bands Lateral Collateral Ligament of the Ankle Joint • Anterior talofibular ligament (ATFL) • Distinct, short ligament, blends with the capsule • Attaches to talar neck • Calcaneal fibular ligament (CFL) • Long, cord-like • Attaches to lateral calcaneus • Superior to peroneal tubercle • Posterior talofibular ligament (PTFL) • Somewhat triangular in shape • Attaches to lateral tubercle of posterior process of the talus • May have a tibial band Lateral Collateral Ligament of the Ankle Joint • Anterior talofibular ligament (ATFL) • Travels horizontal • Calcaneal fibular ligament (CFL) • Travels somewhat vertically • From anterosuperior to posteroinferior • Peroneal tendons are superficial to it • Posterior talofibular ligament (PTFL) • Nearly horizontal Inversion • The plantar (sole) foot moves medially • Increases the stress on the LCL of the ankle joint • Eversion is when the plantar foot moves laterally • Both occur in the coronal plane • A small amount of inversion occurs at the ankle joint • More inversion occurs at the subtalar joint Inversion Ankle Sprain A. Plantarflexed ankle • (A) When the ankle is plantarflexed • ATF ligament is near vertical B. Neutral • Prone to injury, stretch or tear • (B) When the ankle is neutral • CFL is near vertical and prone to injury • (C) When ankle is dorsiflexed • PTFL becomes more vertical and prone to injury • Overall, the PTFL is the least likely to be torn C. Dorsiflexed ankle Deltoid Ligament • Superficial layer consists of 3 bands that all blend together • Proximal attachment: anterior colliculus only • Distal attachment: navicular, calcaneus and talus • Deep layer consists of 2 distinct bands • Proximal attachment: both colliculi and the groove • Distal attachment: talus only • Anterior ligament may be absent Deep anterior Talotibial ligament T N C T Superficial Deltoid Ligament • Distal attachments: • Naviculotibial ligament • Dorsal medial surface of the navicular • Plantar calcaneonavicular ligament (spring ligament) • Weakest ligament • Calcaneotibial ligament (deep) (deep) • Sustentaculum tali (ledge of bone) of the calcaneus • Strongest of superficial bands • Superficial talotibial ligament • Medial tubercle of the posterior process of the talus • May be absent (spring ligament) Deep Deltoid Ligament • Anterior talotibial ligament • Attaches to neck of talus • Variable in size, may be absent • Posterior talotibial ligament • Proximal attachment: • Posterior colliculus • Distal attachment: • Medial tubercle of the posterior process of the talus • Strong and thick (deep) (deep) Deltoid Ligament Posterior talotibial ligament Tibiocalcaneal ligament Tibionavicular ligament Anterior tibiotalar ligament 4 ligaments of the deltoid ligament Ankle Ligaments 1 2 Groove for tibialis posterior tendon 3 Groove for Peroneal tendons 7 MT, LT = medial and lateral tubercles of posterior process of talus 8 4 MT LT 5 ST ST = sustentaculum tali of calcaneus 6 9 calcaneus • 1. tibia • 2. interosseous membrane • 3. Posterior inferior tibiofibular ligament (PITFL) • 4. posterior talofibular ligament (PTFL) • 5. calcaneofibular ligament (CFL) • 6. peroneal tendons (cut) • More superiorly, they travel in the groove posterior to the lateral malleolus • 7. trochlear surface of the talus • 8. deltoid ligament • Posterior talotibial ligament • Calcaneotibial ligament • 9. posterior talocalcaneal ligament • Ligament of the subtalar joint Posterior view right ankle Inversion Injury ankle sprain Ligamentous Injury of the Ankle Eversion Injury ankle sprain High ankle sprain Tri-malleolar Ankle Fracture Eversion sprains • Forceful eversion, deltoid ligament is stretched and can cause partial or complete tear (sprain) • Deltoid ligament may often not tear and medial malleolus will break (avulsion fracture) Physical Exam Tests for Torn Ligaments or Ligamentous Laxity Anterior Drawer Test Torn ATFL Inversion Stress Test / Talar Tilt Torn ATFL and CFL Clinical sidelight: anterior drawer test • Anterior drawer test checks for collateral ankle ligament tears • A hand stabilizes the leg, and another holds the heel and pulls anteromedially or anterolaterally to test excessive movement • If anterior talofibular ligament is ruptured, lateral side of talus will move anteriorly and talus will pivot medially • Foot will swing medially (passive adduction) more than normal • If deltoid ligament is ruptured, the entire foot will not move straight anteriorly • Drawer test attempts to make foot veer laterally (passive abduction) Interested in ankle injuries? Evaluation and management of ankle syndesmosis injuries, 2011. Testing anterior talofibular ligament Movements at the Ankle Joint • Modified hinge joint • Major movements are: • Dorsiflexion • 10-20o • Extensor muscles of the anterior compartment • Plantar flexion • 20-45o • Flexor muscles of posterior compartment Movements and range of motion of the foot at the ankle joint • Range of motion of the ankle joint is measured from the neutral position, with the axis of the foot at 90 degrees to the leg. Dorsiflexion: muscles of the anterior compartment of the leg Plantarflexion: muscles of the posterior and lateral compartments of the leg Maximum dorsiflexion: usually about 20 degrees. Maximum plantarflexion: usually about 50 degree Lots of variability of you search the literature. Movements at the Ankle Joint • Actually the ankle joint has a triplane axis • There is a small amount of motion in the other two planes: • Transverse (external/internal rotation) • Coronal (abduction/adduction) • During dorsiflexion the fibula moves slightly: • Externally rotates • Abducts • Moves proximally • Widens the ankle mortise for the trochlear surface of talus Ankle Joint Axis of Motion • It is easier to think of it as one slightly oblique transverse axis between the two malleoli (dashed line) AP axis (long. axis of foot) Movement on coronal plane (inversion/eversion) • Dorsiflexion and plantarflexion occur around this axis • With dorsiflexion of the ankle joint • Some eversion and abduction of the rearfoot • With plantar flexion of the ankle joint, there is • Some inversion and adduction of the rearfoot Transverse axis Dorsiflexion/ plantar flexion Vertical axis (long. axis of tibia) Movement on transverse plane. (abduct/adduct) Ligaments and ankle movements Strain (stretched lig . ) vs Sprain (town • In Dorsiflexion: • Calcaneofibular ligament is close to vertical • More vulnerable to stretch in inversion Calcaneofibular ligament lig s) - • In Plantarflexion: • Anterior talofibular ligament • more vulnerable to stretch and tear in inversion • AITFL is generally thinner and weaker than CFL; more easily torn Anterior talofibular ligament Sciatic nerve: 1. Tibial n. Left leg Common peroneal n. Popliteal artery 2. Review Compartments of the Leg • Posterior compartment • Posterior tibial artery • Tibial nerve • Anterior compartment • Anterior tibial artery • Thru proximal interosseous membrane • Deep peroneal nerve • Lateral compartment • Peroneal artery • Sends branches to lateral compartment • Gives off perforating peroneal artery • Thru distal interosseous membrane into anterior compartment • Superficial peroneal nerve Posterior Anterior Anterior Tibial Artery Anterior tibial artery • Travels in anterior compartment • Located deep to muscles • Proximal branches: Medial malleolar artery • Anterior/posterior tibial recurrent arteries • Genicular anastomosis (knee jt) • Distal branches: • Anterior medial/ lateral malleolar arteries • Malleolar arteries (ankle jt) • Becomes dorsalis pedis artery distal to the ankle Dorsalis pedis artery Posterior Tibial Artery PT artery • Travels in the posterior compartment of the leg • And then posterior to the medial malleolus • Gives off several branches before bifurcating into two terminal branches Posterior medial Malleolar arteries • Communicating branch to the peroneal artery • Forms an anastomosis • Posterior medial malleolar arteries • Anastomoses with anterior medial malleolar a. • Medial calcaneal branches • Artery to the tarsal canal • 1 cm proximal to the bifurcation • Gives off deltoid arteries Dorsalis pedis artery Artery to the tarsal canal MEDIAL VIEW Peroneal Artery • Also travels in deep posterior compartment • Branches: • Perforating peroneal artery • Thru interosseous membrane distally into the anterior compartment of the leg Artery of sinus tarsi Artery of tarsal canal Posterior right ankle • Communicating branch • Posterior lateral malleolar arteries • Malleolar anastomosis (ankle joint) • Terminates into lateral calcaneal branches • Does not typically continue further into the foot Coronal plane thru right ankle joint Blood Supply to the Ankle Joint • Malleolar anastomosis: • Malleolar arterial network • Branches from all 3 arteries of the leg • Anterior tibial artery • Anterior lateral malleolar artery • Anterior medial malleolar artery • Posterior tibial artery • Posterior medial malleolar artery • Communicating artery • Peroneal artery • Perforating branch • Posterior lateral malleolar artery Blood supply and innervation of ankle joint • Arterial supply: malleolar branches of anterior tibial, posterior tibial, and peroneal/fibular arteries. • Innervation: common peroneal/fibular nerve and tibial nerve • Review the cutaneous innervation surrounding the ankle joint Helpful images and slides Talus Articulates with the Tibia and Fibula at the Ankle Joint Posterior Left Ankle Anterior Left Ankle tibia tibia 2. Medial malleolus 5. Lateral malleolus 14. fossa fibula fibula 8 LP 20 LP Articular 6. Trochlear surface of the body of talus Surfaces: 7. Head of the talus Nonarticular: 17. Posterior process of the talus LP = lateral process of the talus Lateral ligament of ankle Unlike deltoid, the 3 lateral collateral ligaments of the ankle are all separated • Anterior talofibular ligament (7) • Posterior talofibular ligament • Not in view in the image because of it’s more posterior position • Calcaneofibular ligament (22) Ligaments of the ankle: posterior view Lateral ankle: • Posterior talofibular ligament (28) can be seen running from lateral malleolar fossa to the lateral tubercle of posterior talus • Cacaneofibular ligament (22) can be seen running from the side of the calcaneus to the lateral malleolus • Medial ankle: • Posterior tibiotalar/talotibial ligament(3) connects the posterior colliculus of medial malleolus to medial tubercle of posterior talus • Tibiocalcaneal/calcaneotibial ligament (31) runs from anterior colliculus of medial malleolus to sustentaculum tali