Calcaneofibular Ligament Injury

Updated: Jul 28, 2023
  • Author: Bryan L Reuss, MD; Chief Editor: Sherwin SW Ho, MD  more...
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Practice Essentials

Ankle injuries are among the most common injuries seen in physician offices and emergency departments (EDs) because the ankle is the most frequently injured joint in the body. [1, 2, 3, 4] Ankle injuries are a major cause of time loss from work or other daily activities and constitute up to 25% of all time-loss injuries from running and jumping sports. [5]  Sprains account for 85% of ankle injuries and, of these sprains, 85% are caused by inversion injuries. An inversion sprain results in an injury to the lateral ligaments, one of which is the calcaneofibular ligament (CFL). Most ankle sprains can be managed with a short period of immobilization (see image below) followed by rehabilitation therapy, but chronic instability is best treated surgically. [6]

Aircast providing rigid lateral ankle support. Aircast providing rigid lateral ankle support.

Signs and symptoms

The injury history can include the following signs and/or symptoms:

  • Pain is primarily located on the lateral side of the ankle joint

  • Presence of edema (increases with the severity of a sprain)

  • Presence of ecchymosis (increases with the severity of a sprain)

  • Presence of joint instability (increases with the severity of a sprain)

  • Audible pop or crack heard at the time of the injury

  • Possible inability to bear weight on the affected ankle

See Presentation for more detail.


Obtain plain films of the injured ankle to detect any bony lesions. The talar tilt film is the stress film that is most beneficial for the diagnosis of a CFL injury/tear.

See Workup for more detail.


Generally, grade I and grade II sprains are treated conservatively, whereas the decision to treat grade III lateral ankle sprains (often associated with a complete tear of the anterior talofibular ligament [ATFL] and CFL) is approached on an individual basis.

See Treatment and Medication for more detail.



Causes of injury to the lateral ankle include the following:

  • Walking, running, or jumping on uneven surfaces increases the risk of an inversion sprain and subsequent injuries to the CFL.

  • Proprioceptive deficit, peroneal muscle weakness, and subtalar instability increase the risk of an inversion injury.

  • Previous injury to the ankle is a risk factor: athletes have a 2.3-fold greater risk of recurrence after a previous ankle injury.



United States statistics

An estimated 1 ankle inversion injury occurs per 10,000 people per day, or 23,000 ankle inversion injuries per day. Of these ankle inversion injuries, the CFL is the second most common ligament injured after the anterior talofibular ligament (ATFL). [4]


Functional Anatomy

The CFL courses from the distal fibula to the calcaneus by extending from the distal anterior margin of the lateral malleolus to insert onto the posterior lateral tubercle of the lateral wall of the calcaneus. [7, 8, 9, 10] The CFL lies deep to the peroneal tendons, is cylindrical in shape, and, because it crosses 2 joints, it acts as a subtalar joint stabilizer.

A study by Larkins et al confirmed the role of the CFL as a primary ligamentous stabilizer for talar tilt. [11]  Similarly, a study by Hunt et al found that the CFL makes a considerable contribution to lateral ankle stability. [12]


Sport-Specific Biomechanics

The CFL is 20-30 mm long, 3-5 mm thick, and 4-8 mm wide, and the angle of the CFL from the fibula to the calcaneus is 10 º -45 º posterior to the axis of the fibula. Except in the extremes of inversion, the CFL is in a lax position. With an inverted ankle, strain on the CFL is highest in dorsiflexion; thus, when the ankle is dorsiflexed or in a neutral position, the CFL is the lateral ligament that is most often injured in inversion sprains. Although isolated CFL tears are uncommon, CFL tears in combination with ATFL tears are the second most common injury pattern (20% of injuries). Midsubstance rupture of the CFL remains the most common injury pattern, although a number of fibula or calcaneus avulsion-type injury patterns exist. [13]



The prognosis of CFL injuries is usually good with proper treatment, and 75-100% of patients achieve good or excellent outcomes.


Important complications of ankle injuries include continued pain and chronic instability, which should be addressed. The first treatment option should be a course of conservative management, including increasing the strength and flexibility around the ankle and the use of an orthosis with ankle and subtalar support (see image below). If conservative treatment is unsuccessful or unsatisfactory, surgical repair of the ligament is the preferred treatment. In addition, if the patient continues to have pain over the long term, other causes of the patient's pain should be explored (ie, talar dome osteochondral lesions).

Aircast providing rigid lateral ankle support. Aircast providing rigid lateral ankle support.

Patient Education

Patient education should occur through an injury awareness program that highlights the importance of proper footwear, strengthening techniques, bracing support, and proprioceptive training.

For patient education resources, visit eMedicineHealth's First Aid and Injuries Center.