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Basics ⬇

Author: Christopher A.Gee, MD, MPH, FACEP, CAQSM

Description

  • Lateral ankle sprains are the most common injury sustained by athletes (1) and comprise approximately 14% of all sports-related injuries (2).
  • Over 80% of sprains are due to an inversion type of mechanism that injures the lateral ankle ligaments.
  • Whereas the medial side of the ankle has the broad, strong deltoid ligament as a restraint, the lateral side of the ankle has three smaller ligaments that act as the static restraint system.
  • Primary static restraints to ankle inversion:
    • Anterior talofibular ligament (ATFL): passes from the tip of the fibula to the lateral talar neck; taut in plantar flexion; injured most commonly
    • Calcaneofibular ligament (CFL): passes inferior and posterior from the tip of the fibula to the lateral calcaneus; usually injured with the ATFL
    • Posterior talofibular ligament (PTFL): passes posteriorly from the fibula to the talus; injured less often
  • These ligaments are injured in a sequential pattern as extreme inversion and plantarflexion forces are placed on the ankle. The ATFL is injured first (isolated ATFL injuries occur in approximately 2/3 of injuries). After the small ATFL is injured, the CFL then is stressed and injured, followed by the PTFL. The ankle joint capsule is also sprained during an inversion injury. Given this pattern, isolated CFL injuries are uncommon.
  • Increasing inversion force leads to more damage to lateral ligaments and capsule.
  • Bony support of the distal fibula assists the deltoid ligament in restricting eversion stress to the ankle.
  • The smaller medial malleolus provides less protection and allows inversion stress to injure the lateral ankle ligaments more easily.
  • Ankle sprain grading:
    • Grade 1: stretch or partial tearing of ligaments but no gross laxity
    • Grade 2: partial tear of ligaments with increased laxity of ankle but still firm end point
    • Grade 3: complete rupture of ligaments; gross laxity of ankle with no end point

Epidemiology

Incidence

Very common injury in athletes and the general population, with around 23,000 cases every day (3)

Etiology and Pathophysiology

Lateral ankle sprains occur when the ankle is stressed with extreme inversion and plantarflexion forces that overcome the static restraints (ligaments, capsule). Spraining and tearing of the ligaments leads to pain, swelling, and varying degrees of disability.

Risk-Factors

  • Athletes (especially those involved in sports with jumping near other players and quick “cutting” motions, i.e., basketball, soccer, football) (4)
  • Dancers
  • Congenital tarsal coalition (allows less “give” in the foot and results in more stress to ankle)
  • Prior ankle injury (Previously injured or stretched ligaments provide less overall stability.) (5)

Diagnosis ⬆ ⬇

History

Patients report history of inversion-type injury often with an audible pop. This is followed by rapid swelling, pain, and an inability to walk.

Physical Exam

  • Physical examination reveals ecchymosis and diffuse swelling about the ankle joint.
  • Tenderness to palpation is noted along the course of injured ligaments and can be diagnostic of which ligaments are injured.
  • Palpation of the anterior ankle joint and the talar dome with the foot in full plantarflexion can help to diagnose other forms of pathology (i.e., osteochondral defects).
  • It is important to palpate both the medial and lateral malleoli and the base of the 5th metatarsal to examine for possible fracture (i.e., Ottawa Ankle Rules) (6).
  • Occasionally, the ankle ligaments can be disrupted, and the stress passed up the tibiofibular syndesmosis. This leads to syndesmotic injuries or the so-called high ankle sprain.
  • Assess neurovascular status by feeling distal pulses and manually testing appropriate muscle groups.
  • Grading of ankle injury can be accomplished by testing the integrity of various ligaments. Examiner also should take into account the fact that prior ankle sprains may have left residual laxity on either side.
  • Anterior drawer:
    • Tests stability of ATFL; performed by holding the distal tibia and pulling the heel forward. Increased laxity relative to the opposite side indicates a tear of the ATFL. The anterior drawer test in the ankle has poor sensitivity and specificity.
    • Inversion tilt: tests stability of CFL; performed by holding the distal tibia and moving the foot from a neutral position to an inversion position. Increased laxity compared with opposite side indicates a tear of the CFL.

Differential Diagnosis

  • Tibia fracture (shaft, malleolus, etc.)
  • Pilon fracture
  • Fibula fracture (malleolus, Maisonneuve)
  • Avulsion fracture
  • Osteochondral defect in talar dome/tibial plafond
  • Anterior ankle impingement
  • Os trigonum syndrome
  • Talus fracture
  • Calcaneal fracture
  • Peroneal subluxation
  • Bimalleolar/trimalleolar fracture

Diagnostic Tests & Interpretation

  • Plain radiographs of affected ankle (including anteroposterior, lateral, and mortise views) to rule out fracture (weight-bearing if able)
  • May not need to perform x-rays if patient doesn’t have tenderness along posterior 6-cm edge of lateral and medial malleoli and can bear weight initially after injury (Ottawa Ankle Rules) (6)
  • Computed tomography (CT) scans may be performed to evaluate for occult fracture.
  • Magnetic resonance imaging (MRI) is rarely useful in ankle sprains but may be useful in assessing integrity of various ligaments in patients with chronic ankle instability or in evaluation of osteochondral defects that are not apparent on radiographs.

Treatment ⬆ ⬇

General Measures

  • Initial therapy focuses on PRICE (protection [bracing], rest, ice, compression, elevation) protocol to decrease pain and swelling.
  • Crutches can be used until patient is able to bear weight as tolerated.
  • Various kinds of braces, compression devices, stirrup splints, and walking boots can be used to provide protection and support and to encourage walking.
  • Should advise patients to begin gentle range of motion as soon as pain allows and to keep limb elevated to decrease swelling
  • Severe sprains may be best treated with more motion restriction in devices such as casts or walking boots (7).
  • Progressive therapy through a three-phase approach may best promote rapid recovery:
    • Phase 1 consists of RICE protocols to improve pain and swelling (often weeks 1 to 2).
    • Phase 2 consists of progressive range of motion exercises to improve motion and decrease swelling. Patients should continue to use a protective brace when walking to prevent further injury. Patients should be working toward full weight-bearing during this stage (weeks 2 to 4).
    • Phase 3 begins more aggressive strengthening and rehabilitation exercises. Specifically, patients should work on proprioception and endurance. This can be a formalized physical therapy program as needed (weeks 4 to 6).

Medication

Acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs) can be used after initial injury for pain. NSAIDs should be avoided in patients at risk for gastrointestinal (GI) bleeding.

Additional Therapies

  • Physical therapy can be used to assist patients in strengthening and generally rehabilitating the injured ankle.
  • Electrical stimulation and iontophoresis may have a role in pain and swelling control.

Surgery/Other Procedures

  • In general, most patients recover spontaneously and are able to go back to activities as pain allows. More unstable joints, recurrent injuries, and higher level athletes may need formal physical therapy.
  • Often, general rehabilitation principles and conservative therapy are adequate to return athletes to their sport without more aggressive interventions. Patients rarely need primary repair of ligaments after an acute lateral ankle sprain.
  • Occasionally, severe laxity of lateral ankle restraints may lead to recurrent ankle injuries and chronic ankle instability. These patients may benefit from ligament repair or ankle reconstruction to improve stability.

Ongoing Care ⬆ ⬇

Follow-up Recommendations

Patient Monitoring

  • Patients may return to play once they have achieved a full range of motion and strength as well as being able to perform their sport-specific activities without limitations. Some may be able to return to play with a supportive device to protect from further injury depending on the sport and the patient’s position.
  • Depending on the sport, certain patients may need to go through a progression of sport-specific activities to return to play.

Prognosis

  • Prognosis depends on the extent of injury and any concurrent injuries, but for most patients, prognosis is excellent. More severe injuries may require more extensive rehabilitation for a patient to return to full function and prevent recurrence.
  • Patients with recurrent instability and those in high-risk sports (e.g., volleyball, basketball) may benefit from functional bracing or taping.
  • Patients who fail to undergo proper rehabilitation are often left with chronic instability and recurrent ankle injuries.

Complications

  • Stiffness from prolonged immobilization
  • Recurrent instability
  • Osteochondral defects
  • Chronic regional pain syndromes

References ⬆ ⬇

  1. Roos KG, Kerr ZY, Mauntel TC, et al. The epidemiology of lateral ligament complex ankle sprains in National Collegiate Athletic Association sports. Am J Sports Med. 2017;45(1):201–209.
  2. Fong DT, Chan YY, Mok KM, et al. Understanding acute ankle ligamentous sprain injury in sports. Sports Med Arthrosc Rehabil Ther Technol. 2009;1:14.
  3. Kannus P, Renström P. Treatment for acute tears of the lateral ligaments of the ankle. Operation, cast, or early controlled mobilization. J Bone Joint Surg Am. 1991;73(2):305–312.
  4. Nelson AJ, Collins CL, Yard EE, et al. Ankle injuries among United States high school sports athletes, 2005–2006. J Athl Train. 2007;42(3):381–387.
  5. Malliaropoulos N, Ntessalen M, Papacostas E, et al. Reinjury after acute lateral ankle sprains in elite track and field athletes. Am J Sports Med. 2009;37(9):1755–1761.
  6. Stiell IG, Greenberg GH, McKnight RD, et al. A study to develop clinical decision rules for the use of radiography in acute ankle injuries. Ann Emerg Med. 1992;21(4):384–390.
  7. Lamb SE, Marsh JL, Hutton JL, et al. Mechanical supports for acute, severe ankle sprain: a pragmatic, multicentre, randomised controlled trial. Lancet. 2009;373(9663):575–581.

Clinical Pearls ⬆

  • Extremely common injury that can present with swelling, ecchymosis, and inability to walk
  • Thorough exam and proper imaging (when indicated) can help to avoid missing associated fractures.
  • Treatment involves progression from RICE protocol to progressive weight-bearing and range of motion and finally to strengthening and proprioceptive exercises.