EM@3AM – Ankle Sprains

Authors: Jared Cohen, MD, MHA (EM Resident Physician, SAUSHEC, USA) and Erica Simon, DO, MHA (@E_M_Simon, EM Chief Resident, SAUSHEC, USAF) // Edited by: Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UT Southwestern Medical Center / Parkland Memorial Hospital) and Brit Long, MD (@long_brit, EM Attending Physician, SAUSHEC, USAF)

Welcome to EM@3AM, an emdocs series designed to foster your working knowledge by providing an expedited review of clinical basics. We’ll keep it short, while you keep that EM brain sharp.

An 18-year-old male, without significant past medical history, presents to the ED for a lower extremity injury. The young man reports “twisting his ankle” during basketball practice one hour prior to arrival.  He describes his lower extremity pain as constant (8/10), localized to the lateral aspect of his right ankle, and limiting his ambulation. He denies alterations in extremity sensation and previous ankle injury/trauma.

Pertinent physical examination findings:
MSK (Right lower extremity):
Hip: Full, painless ROM. No obvious trauma. No erythema/induration.
Knee: No evidence of joint effusion (patellar ballottement test negative). No joint ecchymosis, erythema, or induration. No TTP of the fibular head. Negative anterior and posterior drawer. Negative Apley Compression.
Ankle: Significant ecchymosis localized to the lateral malleolus extending to the lateral midfoot. Significant Edema. TTP anterior to the lateral malleolus. Positive anterior drawer test. Negative talar tilt test. Negative squeeze test.

Meets Ottawa Ankle criteria.

What do you suspect as a diagnosis? What’s the next step in your evaluation and treatment?

Answer: Ankle Sprain^1-7

• Epidemology: Greater than 5 million ankle injuries occur annually in the U.S.¹ Ankle sprains account for 40% of all sports-related injuries.²
• Classification of Sprains:
  • Anatomic Location:
    • Lateral ankle sprain: most common ankle injury; results from inversion mechanism.³ The lateral ligament complex consists of the anterior talofibular ligament (ATFL; most frequently injured), calcaneofibular ligament (CFL), and the posterior talofibular ligament.³
      • Maffulli classification for lateral ankle sprains => performed only after rest, ice, compression, and elevation (RICE) therapy for 48 hours + early ROM exercises:²
        • Grade I: Partial tear
        • Grade II: ATFL tear
        • Grade III: ATFL + CFL tear
    • Medial ankle sprain: given the tensile strength of the deltoid ligament, this is a rare ankle eversion injury that may result in avulsion of the medial malleolus.³
    • High ankle sprain: injury to the anterior tibiofibular ligament, posterior tibiofibular ligament, transverse tibiofibular ligaments, or interosseous membrane (syndesmosis) due to forces which rotate the talus within the mortise (separating the tibia and fibula, and injuring the syndesmotic fibers).³
      • Note: Both medial and high ankle sprains are classified according to the following:²
        • Grade I: Strain
        • Grade II: Partial tear
        • Grade III: Complete tear
        • Note: Grade II and III deltoid and syndesmotic injuries assigned following MRI.²

• Evaluation:
  • Perform a thorough H&P. The mechanism of injury should direct a focused examination.
  • Examination:
    • Assess for signs of neurovascular compromise. (More often encountered in the setting of posterior ankle dislocation. Dislocation + neurovascular compromise or skin tenting = immediate reduction and orthopedic consultation).²
    • Assess gait
    • Examine the ipsilateral knee: palpate the fibular head => Maisonneuve fracture.²
    • Evaluate the syndesmosis:
      • Most reliable test = external rotation:⁴
        • Patient seated with hip and knee flexed, and the foot and ankle in the neutral position. With the knee facing forward, external rotation is applied to the foot. The test is positive if the pain is reproduced at the anterior syndesmosis.
    •  Evaluate for Achilles tendon injury = Thompson’s test:
      • Patient in the prone position with the feet hanging off the table, or with the knees flexed and the feet hanging over the end of a chair. As the examiner squeezes the patient’s calf muscle, plantar flexion of the ankle should occur if the Achilles tendon is intact. The test is positive if the foot remains in the neutral position or if there is minimal plantar flexion of the ankle compared with the unaffected side.
    •  Evaluate the for lateral ankle sprain as applicable:
      • ATFL injury assessment = anterior drawer test:²
        • Patient seated and the distal tibia stabilized with one hand of the examiner while the other hand grasps the heel and the foot is anteriorly translated (repeat on contralateral limb for comparison). Complete ATFL tear => the talus subluxates anteriorly and a dimple forms on the anterolateral joint area.
      • CFL injury assessment = talar tilt test:²
        • Patient seated and the leg secured with the examiner’s hand while the heel is grasped with the opposite hand and an inversion force is administered to cause talar tilt (repeat on contralateral limb for comparison).
    •  Evaluate for medial ankle injury by assessing for deltoid insufficiency:²
      • Patient should be asked to lower himself or herself to a squatting position with the feet flat on the floor => if insufficiency: medial malleolus becomes overtly prominent as compared with the other ankle (a positive medial malleolar pointing sign).
    •  Clinical Decision Tool: Ottawa Ankle Rules:
      • Systematic review of 27 studies (n =15,581) => highly sensitive for the exclusion of ankle fracture (96.4-99.6%).⁵
  •  Imaging:
    • Ottawa ankle positive:
      • AP, lateral, and mortise views recommended for lateral, medial, and high ankle sprains:
        • Lateral radiograph: allows assessment of medial joint space.
        • Mortise view: allows for measurement of the lateral displacement of the lateral malleolus and the width of the syndesmosis.
      • Suspicion for Grade II or III lateral ankle sprain => bilateral stress views (talar tilt): allows calculation of the difference in the angle between the distal tibial articular surface and dome of the talus.
      • Assessment of medial ankle sprains and high ankle sprains => weight-bearing films recommended.²
      • High ankle sprain: imaging should include the entire tibia and fibula (Maisonneuve).²
      • Non-emergent MRI indicated if concern for Grade II or III deltoid ligament or syndesmotic injury.²
•  Treatment:²
  • Lateral ankle sprains => aircast, RICE, early ROM, progressive weight bearing.
  • Medial ankle sprains =>
    • Grade I: aircast, RICE, rehab/ROM exercises, return to activity within 3 weeks.
    • Grade II and Grade III: Orthopedic consult: complete deltoid insufficiency may require surgical repair vs. boot/orthotic immobilizer, physical therapy, and orthopedic follow-up for graduated return to activity.
  • Syndesmotic injuries =>
    • Grade I: aircast, RICE, rehab/ROM exercises, return to activity within 3-6 weeks under ortho supervision.
    • Grade II and Grade II: Orthopedic consult for surgical repair.

• Pearls:
  • As many as 30% of patients with ankle sprains develop chronic ankle instability.⁶
  • False negative Thompson’s tests may occur following delayed patient presentation: hematoma may cause reconstitution of the tendon.⁷

References:

1. Daly PJ, Fitzgerald RH, Jr., Melton LJ, Ilstrup DM. Epidemiology of ankle fractures in Rochester, Minnesota. Acta Orthop Scand 1987;58:539-44.
2. Molloy A, Selvan D. Ligamentous Injuries of the Foot and Ankle. In DeLee & Drez’s Orthopaedic Sports Medicine. 4^th ed. Philadelphia, Saunders. 2015; 116:1392-1407.e2.
3. Williams GN, Jones MH, Amendola A. Syndesmotic ankle sprains in athletes. Am J Sports Med 2007;35:1197-207.
4. Alonso A, Khoury L, Adams R. Clinical tests for ankle syndesmosis injury: reliability and prediction of return to function. J orthop Sports Phys Ther. 1998; 27:276-284.
5. Jenkins M, Sitler M, Kelly J. Clinical usefulness of the Ottawa Ankle Rules for detecting fracutres of the ankle and midfoot. J Athl Train. 2010; 45(5):480-482.
6. Konradsen L, Bech L, Ehrenbjerg M, Nickelsen T. Seven years follow-up after ankle inversion trauma. Scand J Med Sci Sports 2002;12:129-35.
7. Gravlee J, Hatch R, Galea A. Achilles tendon rupture: a challenging diagnosis. J Am Board Fam Pract. 2000; 13(5):371-373.

For Additional Reading:

Diagnostic accuracy of ankle x-rays: How often do we miss fractures?

How can we improve?

Diagnostic accuracy of ankle x-rays: How often do we miss fractures? How can we improve?