Ankle Joint Osteology Ankle Joint consists of tibial plafond medial malleolus lateral malleolus talus motion main motion plantar flexion dorsiflexion secondary motions inversion/eversion rotation Distal tibiofibular joint consists of distal fibula incisura fibularis concave surface of distal lateral tibia motion fibular rotates within incisura during gait mortise widens when ankle goes from plantar to dorsiflexion syndesmosis screws limit external rotation Joint reaction force ankle joint 5 times body weight with walking on level surfaces Ankle Ligament Introduction Primary ligaments of ankle include (see below for details) medial Deltoid ligament Calcaneonavicular ligament (Spring Ligament) lateral Syndesmosis (includes AITFL, PITFL, TTFL, IOL, ITL) Anterior talofibular ligament (ATFL) Posterior talofibular ligament (PTFL) Calcaneal fibular ligament (CFL) Lateral talocalcaneal ligament (LTCL) Syndesmosis Function responsible for integrity of ankle mortise Anatomy Syndesmosis components Anterior-inferior tibiofibular ligament (AITFL) Posterior-inferior tibiofibular ligament (PITFL) deep portion of this ligament sometimes reffered to as the inferior transverse ligament Transverse tibiofibular ligament(TTFL) Interosseous ligament (IOL) Physical Exam test to identify a syndesmosis injury include external rotation test squeeze test Imaging AP and mortise ankle radiographs used to evaluate the tibiofibular clear space and tibiofibular overlap tibiofibular clear space should be < 5 mm tibiofibular overlap for AP view > 10 mm weight bearing mortise view is most accurate radiograph for diagnosis CT scan is most accurate for assessment but true normals have not been validated and comparison to the uninjured side are helpful Clinical conditions high ankle sprain & syndesmosis injury ankle fracture Anterior Talofibular Ligament (ATFL) Function primary restraint to inversion in plantar flexion resists anterolateral translation of talus in the mortise weakest of the lateral ligaments Anatomy extends from the anteroinferior border of the fibula to the neck of the talus origin is 10mm proximal to tip of fibula inserts directly distal to articular cartilage of the talus (18mm distal to joint line) runs 45°-90° to longitudinal axis of the tibia Physical exam anterior drawer in 20° of plantar flexion test competency by anterior drawer in 20° of plantar flexion and compare to uninjured side forward shift of more than 8 mm on a lateral radiograph is considered diagnostic for an ATFL tear Imaging stress radiographs more accurate in chronic injuries MRI can diagnose injury arthroscopic findings can confirm MRI imaging ultrasound more accurate than radiographs Clinical Conditions low ankle sprains Posterior Talofibular Ligament (PTFL) Function strongest of the lateral ligaments plays only a supplementary role in ankle stability when the lateral ligament complex is intact under greatest strain in ankle dorsiflexion and acts to limit posterior talar displacementwithin the mortise as well as talar external rotation if ATFL and CFL are incompetent, then short fibers of PTFL restrict internal and external rotation, talar tilt, and dorsiflexion; long fibres inhibit only external rotation, talar tilt, and dorsiflexion Anatomy origin is posterior border of fibula inserts on posterolateral tubercle of the talus runs perpendicular to longitudinal axis of the tibia Physical exam no specific clinical test for isolated PTFL injury Imaging MRI can indicate structural injury, rarely indicated Clinical Conditions rarely injured, except in association with a complete dislocation of the talus Calcaneal Fibular Ligament (CFL) Function primary restrain to inversion in neutral or dorsiflexed position restrains subtalar inversion, thereby limiting talar tilt within mortise Anatomy origin is anterior border of fibula, 9mm proximal to distal tip inserts on calcaneus 13mm distal to subtalar joint and deep to peroneal tendon sheaths Physical exam inversion (supination) test perform with ankle in slight dorsiflexion talar tilt test angle formed by tibial plafond & talar dome is measured as inversion force is applied to hindfoot (<5 deg is normal for most ankles) useful for evaluation of combined injury of both ATFL and CFL ligament Imaging talar tilt radiographs ankle arthrograms CFL rupture can lead to extra-articular dye leakage into the peroneal tendon sheath MRI Clinical Conditions injury occurs with ankle inversion with the foot in the neutral position low ankle sprain Lateral Talocalcaneal Ligament (LTCL) Function thought to stabilize the talocalcaneal joint Anatomy short narrow ligamentous band that connects the lateral process of the talus to the lateral surface of the calcaneus located anterior and medial to calcaneofibular ligament Physical Exam no specific test for this ligament Imaging LTCL ligament (red arrows) identified distinctly from the calcaneofibular ligament relationship of the calcaneofibular ligament (green arrow) and the LTCL (red arrow) Clinical conditions often injured in conjunction with ATFL injuries low ankle sprain Deltoid Ligament Function primary restraint to valgus tilting of the talus both the superficial and deep layers individually resist eversion of the hindfoot stabilizes ankle against plantar flexion, external rotation and pronation Anatomy superficial layer crosses both ankle and subtalar joints originates from anterior colliculus and fans out to insert into the navicular neck of the talus, sustenaculum tali, and posteromedial talar tubercle the tibiocalcaneal (sustenaculum tali) portion is the strongest component in the superficial layer and resists calcaneal eversion deep layer crosses only ankle joint functions as the primary stabilizer of the medial ankle prevents lateral displacement and external rotation of the talus originates from inferior & posterior aspects of medial malleolus and inserts on medial and posteromedial aspects of the talus Physical exam eversion test with ankle in neutral, evaluates superficial layer external rotation stress test evaluates syndesmosis and deep layer Imaging radiographs mortise radiograph with medial clear space widening can suggest injury gravity stress view can identify medial clear space widening MRI normal deltoid ligament ruptured deltoid ligament Clinical conditions ankle fracture injury occurs with pronation (eversion) trauma leading to forced external rotation and abduction of ankle may occur with fracture of the medial malleolus high ankle sprain & syndesmosis injury Calcaneonavicular Ligament (Spring Ligament) Function static stabilizer of the medial longitudinal arch and head of the talus Anatomy attaches from the sustentaculum tali to the inferior aspect of the navicular consists of the superomedial and inferior calcaneonavicular ligaments superomedial ligament is larger and the most important stabilizer to medial longitudinal arch Physical Exam flattening of medial longitudinal arch suspect injury in associated posterior tibial tendon pathology Imaging MRI can diagnose tear (green arrow, intact ligament; red arrow, disrupted ligament) Clinical conditions posterior tibial tendon dysfunction calcaneonavicular ligament (spring ligament) most likely to be attenuated in type II flatfoot deformity secondary to posterior tibial tendon dysfuction acute spring ligament tear acute trauma can occur with forceful landing on flat foot the tibialis posterior tendon is usually normal