Calcaneofibular ligament injuries typically occur in conjunction with an anterior talofibular ligament injury within the scope of a lateral ankle sprain and are rarely found isolated. These injuries can comprise either ligament tears, avulsion fractures, or both.
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Epidemiology
The calcaneofibular ligament is the second most common ligament injured (after the anterior talofibular ligament) in a very high percentage of lateral ankle sprains. Isolated calcaneofibular ligament injury is rare 1,2.
Associations
posterior talofibular ligament injury (uncommon) 8
subtalar joint injury
Clinical presentation
Clinical signs and symptoms are that of an acute lateral ankle sprain, but in case of a calcaneofibular injury they will be typically more severe and also depending on the grade of injury will result in talocrural joint instability and talar tilt. Conversely, an unstable ankle joint after sustaining a lateral ankle sprain will more likely coincide with a calcaneofibular ligament injury. The calcaneofibular ligament can additionally be assessed with the inversion stress test in a dorsiflexed position 1,2.
Complications
If left untreated calcaneofibular injury can lead to the following conditions:
Pathology
Mechanism
Calcaneofibular ligament injuries typically occur along with an anterior talofibular ligament injury within the scope of a lateral ankle sprain. The typical mechanism is excessive supination of the rearfoot on an externally rotated lower leg, leading to an inversion-internal-rotation type injury 1,2. Isolated injury is rare but can occur on supination or inversion on a dorsiflexed ankle where the anterior talofibular ligament is relaxed 1.
Radiographic features
Plain radiograph
Plain radiographs may show a lateral malleolar tip or avulsion fracture other findings include lateral malleolar soft tissue swelling.
Ultrasound
The calcaneofibular ligament will be hypoechoic and thickened or swollen in case of a sprain. Partial tears might show anechoic defects and undulated or irregular ligament fibers. Complete tears might show anechoic defects, ligament stumps displaced superficial to the usually overlying peroneal tendons.
MRI
The usual appearances of calcaneofibular ligament injury are thickening in case of a sprain or chronic injury, ligament contour irregularities, partial discontinuity, and signal intensity changes in case of partial tear and complete discontinuity and fiber retraction in case of a complete tear 3-5.
Similar to other ligament injuries inhomogeneity of the ligament with intraligamentous signal intensity on fat-suppressed T2-weighted or intermediate weighted sequences indicate intrasubstance tearing 6.
In addition to the ligamentous alterations, there might be bone-marrow signal alterations at the distal fibular and calcaneal insertion sites or signs of tenosynovitis of the peroneal tendons.
Radiology report
In case of a calcaneofibular injury the report should look similar to that of a lateral ankle sprain and should include the description of the following:
calcaneofibular ligament injury (sprain, partial tear, complete tear)
anterior (and/or posterior) talofibular ligament injury (sprain, partial tear, complete tear)
concomitant subtalar joint injury
avulsion injuries of the lateral malleolus
signs of tenosynovitis or injury to the peroneal tendons
possible concomitant syndesmotic injury
fractures or fracture-dislocations
chondral or osteochondral injury
Treatment and prognosis
Calcaneofibular ligament injuries are the result of a more serious form or higher grade lateral ankle sprain and the calcaneofibular ligament provides a significant contribution to lateral ankle stability 6,7.
Management is nevertheless most often conservative and includes initial treatment with rest, ice, compression and elevation (RICE) and semi-rigid ankle brace and/or a short-term period of immobilization in more severe cases6.
Subsequent therapy includes a comprehensive rehabilitation with emphasizing proprioception, neuromuscular and postural control with motion or movement exercises, strengthening exercises, balance training, and endurance and agility exercise 6.
Surgical treatment is decided on an individual basis and includes ligament repair or reconstruction either arthroscopically or with an open approach. Surgery can reduce recurrence rate, but has similar overall outcomes as conservative management 6.
Differential diagnosis
peroneal tendon dislocation/retinaculum injury
Practical points
Calcaneofibular ligament injuries usually go along with anterior talofibular ligament injuries, which should be looked out for on MRI or ultrasound in the assessment of an ankle injury.
In the case of combined anterior talofibular and calcaneofibular ligament injury, the deltoid ligament should also be assessed for possible deltoid ligament injury.
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