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This is the clinical evidence summary written for health professionals. It is technical, and it lists the research this page was built from. You do not need to read it to understand your treatment or to make a decision about it.

Anatomy & Pathophysiology¶

Bony Anatomy¶

• The ankle mortise is formed by the tibial plafond, medial malleolus, and lateral malleolus [3].
• The ankle mortise articulates with the dome of the talar body [3].
• The talar dome is wider anteriorly and narrower posteriorly [3].
• The ankle mortise widens 1 to 1.5 mm during motion from plantar flexion to dorsiflexion [3].
• Medial and superior clear spaces appear wider with the foot in plantar flexion [3].
• The distal fibula has a convex medial surface that articulates with the concave incisura fibularis of the distal lateral tibia [3].
• The fibula rotates approximately 2 degrees within the incisura during ankle motion and ambulation [3].
• Ankle dorsiflexion results in external rotation and proximal translation of the fibula [3].
• The primary functions of the foot and ankle are to provide weight-bearing support and forward ambulation [3].

Ligamentous Anatomy¶

• The lateral ankle ligaments function as restraints to varus and inversion forces at the ankle [3].
• The anterior talofibular ligament (ATFL) originates from the anteroinferior aspect of the lateral malleolus, 1 cm proximal to its tip, and extends to the lateral aspect of the talar neck [3].
• The calcaneofibular ligament (CFL) extends from the tip of the lateral malleolus to the lateral aspect of the calcaneus [3].
• The posterior talofibular ligament (PTFL) extends from the posterior lateral malleolus to the posterolateral talus [3].
• The ATFL is the weakest ankle ligament [3].
• The PTFL is the strongest ankle ligament [3].
• The distal tibiofibular joint (ankle syndesmosis) and fibula provide stability against lateral talar translation [3].
• The deltoid ligament complex is the primary ankle stabilizer during stance [3].
• The deep deltoid ligament extends from the apex of the medial malleolus to the medial talar body [3].
• The deep deltoid ligament functions primarily to resist lateral talar translation and external rotation [3].
• The posterior deep deltoid is the most important component of the deep deltoid ligament [3].
• The superficial deltoid ligament extends from the distal medial malleolus to the navicular bone, sustentaculum tali of calcaneus, medial talus, and spring ligament [3].
• The superficial deltoid ligament functions primarily to resist valgus and eversion ankle forces [3].
• The deltoid ligament consists of superficial and deep layers, with at most six bands, of which only the tibionavicular ligament, tibiospring ligament, and deep posterior tibiotalar ligament are constant [8].
• The tibiocalcaneal portion of the superficial deltoid ligament is the strongest component and resists eversion of the calcaneus [8].
• The deep portion of the deltoid ligament is organized into two short, thick, discrete bands: the anterior and posterior deep tibiotalar ligaments [8].
• The anterior and posterior deep tibiotalar ligaments are intra-articular but extrasynovial [8].
• The deep posterior band comprises the largest band of the deltoid complex [8].
• The deep deltoid ligament has the highest load to failure at 713.8 N ± 69.3 compared with the lateral collateral ligaments [8].
• The dominant mode of failure for the deep deltoid ligament is an intrasubstance rupture near its talar insertion [8].
• The dominant mode of failure for the superficial deltoid ligament is at its insertion on the anterior malleolus [8].
• Valgus tilting of the talus within the mortise requires complete rupture of both the superficial and deep deltoid ligaments [8].

Biomechanics & Motion¶

• The ankle joint is responsible for most sagittal plane motion of the foot and ankle [3].
• The range of motion for plantar flexion is 23 to 48 degrees [3].
• The range of motion for dorsiflexion is 10 to 23 degrees [3].
• The ankle joint also contributes to inversion, eversion, and rotation [3].
• A simplified model of the ankle joint has a horizontal axis from anteromedial to posterolateral [3].
• A simplified model of the ankle joint has a coronal axis from superomedial directed distally and laterally to the tip of the fibula [3].

Pathophysiology & Injury Patterns¶

• More than 75% of ankle ligament injuries involve the lateral ligament complex, particularly the ATFL and CFL [9].
• Medial ligament injuries are usually seen in association with a fracture or joint injury [9].
• Isolated rupture of the deltoid ligament without lateral ligamentous or fibular injury is rare [8].
• Syndesmotic injury, lateral ligamentous injury, and fibular fractures are common associated injuries with deltoid ligament injury [8].
• The Danis–Weber Type A classification describes a transverse fracture of the fibula below the tibiofibular syndesmosis, sometimes associated with an oblique or vertical fracture of the medial malleolus [7].
• The Danis–Weber Type B classification describes an oblique fracture of the fibula at the level of the syndesmosis, often accompanied by an avulsion injury on the medial side [7].
• The Danis–Weber Type C classification describes a fracture above the level of the syndesmosis, meaning the tibiofibular ligament and part of the interosseous membrane must have been torn [7].
• To achieve a reduced ankle, the fibula must be restored to its full length [7].
• To achieve a reduced ankle, the talus must sit squarely in the mortise with no tilt [7].
• To achieve a reduced ankle, the medial joint space must be restored to its normal width [7].
• To achieve a reduced ankle, there must be no tibiofibular diastasis [7].
• Syndesmotic malreduction risk is associated with incisura anatomy, where deep incisuras with the fibula not engaged are at risk of overcompression [11].
• Anteverted incisuras are at risk of anterior fibular translation in syndesmotic malreduction [11].
• Retroverted incisuras are at risk of posterior fibular translation in syndesmotic malreduction [11].
• Fixation of a syndesmotic injury with a single suture-button construct did not restore physiological fibular motion [11].

Investigations¶

Osteochondral Lesions¶

• Osteochondral lesions are seen in up to 70% of ankle sprains and 75% of ankle fractures [12, 13].
• The most common location for osteochondral lesions is the medial talar dome [12, 13].
• Modern data indicate that the most common location for medial talar dome lesions is central, contradicting historical beliefs that posterior locations were more common [12, 13].
• Medial talar dome lesions are larger and deeper than lateral lesions [12, 13].
• Lateral talar dome lesions are less common than medial lesions [12, 13].
• Lateral talar dome lesions are more often unstable, displaced, or symptomatic than medial lesions [12, 13].
• Lateral talar dome lesions are often refractory to conservative measures [12, 13].
• AP, mortise, and lateral weight-bearing ankle x-rays may not demonstrate subtle osteochondral lesions [12, 13].
• CT scans are helpful for determining the integrity of subchondral bone and identifying cysts in osteochondral lesions [12, 13].
• MRI is sensitive for all osteochondral lesions but the edema pattern frequently overestimates the severity of the injury [12, 13].
• Linear fluid signal deep to subchondral bone on MRI indicates an unstable osteochondral injury [12, 13].
• MRI has a sensitivity of 92% for predicting stable versus unstable osteochondral lesions [12, 13].

Ankle Fractures and Syndesmosis¶

• MRI lacks additional diagnostic value for stability assessment of the ankle mortise in supination-external rotation-type ankle fractures [16].
• Preoperative computed tomography scans play a role in operative planning for malleolar ankle fractures [16].
• Malreduction of the posterior malleolus is significantly more likely to lead to malreduction of the syndesmosis [16].
• Ultrasonographic examination can be used to evaluate the deltoid ligament in bimalleolar equivalent fractures [16].

General Imaging Principles¶

• Advanced imaging is often helpful in diagnosis when combined with a thorough clinical examination for foot and ankle injuries [15].
• MRI is used for the evaluation of anterolateral soft tissue impingement of the ankle [1, 17].
• MRI is used for the evaluation of osteochondral lesions of the talus [1].
• MRI is used for the pre-operative evaluation of the anterior talofibular ligament in chronic ankle instability [1].
• MRI is used for the diagnosis of plantar plate injury with reference to intraoperative findings [1].
• MRI is used for the evaluation of traumatic ligamentous injuries of the ankle and foot [1].
• CT and MR imaging are used for the evaluation of the postoperative ankle and foot [1].
• MRI is used for the evaluation of peroneal tendon abnormalities in routine foot and ankle imaging [14].
• MR imaging is used for the evaluation of entrapment neuropathies of the lower extremity, including the ankle and foot [18].

References¶

[1] Campbell S Operative Orthopaedics 4 Volume Set. REFERENCES > FOOT AND ANKLE.

[3] Miller S Review Of Orthopaedics. SECTION 16 PATELLAR TRACKING IN TOTAL KNEE ARTHROPLASTY > BIOMECHANICS OF THE FOOT AND ANKLE.

[7] Apley And Solomon S Concise System Of Orthopaedics And Trauma. Treatment.

[8] Orthopaedic Knowledge Update Sports Medicine 6. Ankle and Foot Injuries and Other Disorders > Ankle Sprains > Medial Ankle Injury.

[9] Apley And Solomon S Concise System Of Orthopaedics And Trauma. INJURIES OF THE ANKLE.

[11] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Foot and Ankle Anatomy and Biomechanics > Annotated References.

[12] Miller S Review Of Orthopaedics. SECTION 16 PATELLAR TRACKING IN TOTAL KNEE ARTHROPLASTY > OSTEOCHONDRAL LESIONS.

[13] Miller S Review Of Orthopaedics. OSTEOCHONDRAL LESIONS.

[14] Campbell S Operative Orthopaedics 4 Volume Set. MULTIPLE Z-PLASTY RELEASE OF A CONGENITAL RING > PERONEAL TENDONS.

[15] Orthopaedic Knowledge Update Sports Medicine 6. Ankle and Foot Injuries and Other Disorders > Summary.

[16] Orthopaedic Knowledge Update Trauma. Ankle Fractures > Annotated References.

[17] Campbell S Operative Orthopaedics 4 Volume Set. ARTHROSCOPIC EXAMINATION AND DEBRIDEMENT OF THE ANKLE JOINT > IMPINGEMENT.

[18] Campbell S Operative Orthopaedics 4 Volume Set. COMBINED HAMMER TOE AND MALLET TOE DEFORMITY WITH ASSOCIATED DOUBLE CORNS > REFERENCES > TARSAL TUNNEL SYNDROME.