ankle anatomy

Welcome to Leg Day #5 of the SplintER Series. The focused history and physical ankle exam of the patient with an acute ankle injury is a crucial tool often overlooked in the Emergency Department (ED). Our hope is that after enough practice, you will be able to complete your ankle exam within 2 minutes! The key is to practice, practice, and practice some more.

Why the Ankle Exam Matters

Acute ankle injuries are frequently encountered in the Emergency Department. The majority of acute ankle pain can be diagnosed with a good history and physical examination. Plain film imaging and, occasionally, a computed tomography (CT) scan can help with diagnosis and management.

Key Questions for Your History

  1. What was the mechanism of injury and what symptoms occurred afterwards? Subsequent symptoms include swelling, inability to bear weight, fevers/chills, and erythema
  2. What is the location of pain?
  3. Was there a previous injury or surgery to the affected ankle?
  4. Has the patient experienced similar pain previously?

Key Points for the Ankle Exam

Develop a structured approach to your ankle exam and you won’t miss an injury. Here’s our suggestion:

  1. Visually inspect the ankle and ask the patient to take at least 4 steps.
  2. Evaluate the medial and lateral malleolus, lateral 5th toe, and 1st dorsal web space for sensation.
  3. Palpate for a posterior tibial (PT) and dorsalis pedis (DP) pulse.
  4. Evaluate for effusion and reduced range of motion.
  5. Evaluate for focal tenderness especially at the proximal tibia/fibula, posterior edge of lateral/medial malleolus, base of 5th metatarsal (MT), navicular.
  6. Test ankle dorsi/plantar-flexion, eversion, and inversion strength.
  7. Test ankle stability by performing the anterior drawer and talar tilt.
  8. Test syndesmotic stability by performing the squeeze test.
  9. Test achilles tendon injury by performing the Thompson test.

We recommend performing these steps in the sequence described as it allows quick triage and prioritizes the neurovascular exam. The 9 step exam can be broken down into 3 critical questions:

  1. Is the patient neurovascularly intact?
  2. Is the ankle stable?
  3. Is there a fracture?

We review these 3 components in more detail.

  1. Neurologic – test sensation
    • Saphenous – medial malleolus
    • Superficial fibular – lateral malleolus
    • Deep fibular – 1st web space
    • Sural – lateral 5th toe
  1. Vascular
    • Palpate for DP and PT pulses
    • If pulses are not palpable, check for them with a Doppler ultrasound

The ankle joint consists of an articulation of the tibia, fibula, and talus bone. These bones are held stable by 3 groups of ligaments (Figure 1):

  1. Tibio-fibular ligament at the syndesmosis
  2. Medial (deltoid) ligament complex
  3. Lateral collateral ligaments:
    • Anterior talofibular ligament (ATFL)
    • Posterior talofibular ligament (PTFL)
    • Calcaneofibular ligament (CFL)

ankle anatomy

Several tendons are also responsible for ankle stability. The most pertinent in the ED is the Achilles tendon, which inserts on the calcaneus.

Pearl: The peroneal tendons, brevis and longus, contribute to lateral ankle stability. Notably, the peroneus brevis inserts at the base of the 5th metatarsal. An inversion injury may result in this tendon pulling and causing an avulsion fracture at the base of the 5th metatarsal.

There are 4 special tests that evaluate stability of these ligaments and tendon: the squeeze, anterior drawer, talar tilt, and Thompson test (Table 1).

SPECIAL TESTHOW TO PERFORM
SqueezeCompression of the fibula against the tibia at the level of the mid-calf. This will elicit pain in the distal syndesmosis just above the ankle joint if there is syndesmotic injury.

ankle anatomy

Image provided by: Julien Jean-Francois

Anterior DrawerExcessive anterior displacement of the talus relative to the tibia. Indicates anterior talofibular lateral ligamentous injury.

ankle anatomy

Image provided by: Julien Jean-Francois

Talar TiltApply gently inversion force to affected ankle to determine the degree of inversion compared to the unaffected side. Inversion >3mm when compared to the unaffected side indicates ankle instability.

ankle anatomy

Image provided by: Julien Jean-Francois

Thompson TestPlace the patient in a prone position on the examining table with their feet hanging off the edge. Squeezes the calf muscle, and appreciate the degree of plantar flexion. If there is a complete Achilles tendon rupture, plantar flexion will be absent. Be aware that a partial rupture may show normal plantar flexion.

ankle anatomy

Image provided by: Julien Jean-Francois

Table 1. Examination techniques to determine ankle stability

Fractures may present with evidence of deformity, edema, and ecchymosis. Rapid progression of pain and swelling along with inability to bear weight potentially reflect a more serious injury.

Utilize the Ottawa Ankle Rules (OAR) to guide your examination [1]. For more information on the OAR, please click here. We have created a suggested physical exam which includes elements of the OAR to utilize in the ED.

Where Do I Palpate?What am I looking for?
Malleoli: Medial and lateral, posterior and inferior aspectsMalleolar fracture
Navicular bone: Dorsal aspectNavicular fracture
Base of the 1st /2nd Metatarsal: plantar aspectLisfranc injury or fracture-dislocation
5th metatarsal: At the baseJones/pseudo-Jones fracture
Entire length of the tibia and fibula: remember to perform a squeeze testSyndesmotic injury and Maisonneuve fracture
Other
If the patient is unable to take 4 steps or moreAnkle instability or pain from a fracture
Table 2. Focused ED physical examination to evaluate for ankle or foot fracture

Pearl: Evaluate for proximal tibia and fibula tenderness. Higher energy ankle trauma can translate up the syndesmosis and result in injuries such as a spiral fracture of the proximal third of the fibula (Maisonneuve). 

If injury is suspected, a standard 3 view ankle series with anteroposterior, mortis, and lateral view is indicated (Figure 2).

ankle anatomy

Figure 2. Standard ankle radiographs. Anteroposterior (A), mortise (B), and lateral views (C). Case courtesy of Dr Craig Hacking, Radiopaedia.org.

An Example Case

An 18-year-old high school basketball player presents to the emergency department complaining of ankle pain. He was in practice last night when he came down from a rebound and landed on another players foot, inverting the ankle.

Utilizing our 3 critical questions an ankle exam is performed:

  1. Neurovascular status: Sensation and pulses are intact.
  2. Ankle stability: The anterior drawer, talar tilt, and Thompson are normal. The squeeze test is positive; there is concern for tibio-fibular sprain/rupture.
  3. Fracture: There is no significant deformity, but there is significant swelling of the lateral ankle. The patient reports tenderness over the posterior aspect of the distal fibula. He is not able to bear weight; there is concern for a fracture.

Per the OAR, ankle radiographs are warranted given his inability to bear weight and tenderness over the lateral malleolus. There is no acute fracture noted on a 3-view ankle radiograph.

The athlete likely has a syndesmotic injury or a “high ankle sprain”.  A splint or walking boot may be used to immobilize the joint and the athlete should be advised to use crutches and be non-weight bearing until follow up. 

Expert Commentary: Dr. Kori Hudson

Associate Professor of EM, Georgetown University
Team Physician for Georgetown University
Consulting Physician for the Washington Capitals

Foot and ankle injuries are among the most common musculoskeletal injuries that we see in urgent care centers and emergency departments. The most common pitfall may be the failure to perform a complete ankle exam. Forgetting to examine the proximal tibia and fibula or mid-foot in a patient with distracting ankle pain may lead the practitioner to order only ankle films. Foot or tibia/fibula films may reveal additional injuries. Proximal fibula fractures in the Maisonneuve pattern and fractures of the base of the 5th metatarsal in the Jones and pseudo-Jones patterns are both common in the inversion mechanism described in our case. 

Furthermore, when the patient describes pain or tenderness at the Lisfranc joint, weight bearing views of the foot may be required in order to identify the injury.  Comparison views may also be helpful. See figures 3 and 4 below.

Figure 3. Lisfranc Ligament—Normal Alignment. Courtesy of Dr Wael Nemattalla, Radiopaedia.org

ankle anatomy

Figure 4. Homolateral Lisfranc fracture-dislocation. Courtesy of Dr Alexandra Stanislavsky, Radiopaedia.org

Looking for more orthopedic information? Check out the SplintER archives

References:

  1. Stiell IG, Greenberg GH, McKnight RD, Nair RC, McDowell I, Worthington JR. A study to develop clinical decision rules for the use of radiography in acute
    ankle injuries. Ann Emerg Med. 1992 Apr;21(4):384-90. PubMed PMID: 1554175.
Julien Jean Francois, MD

Julien Jean Francois, MD

Georgetown University Emergency Medicine
Julien Jean Francois, MD

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William Denq, MD CAQ-SM

William Denq, MD CAQ-SM

Clinical Assistant Professor
Department of Emergency Medicine
University of Arizona
William Denq, MD CAQ-SM

@willdenq

Clinical Assistant Professor Emergency Medicine and Sports Medicine University of Arizona George Washington University '18 University of Pittsburgh '14 and '10
William Denq, MD CAQ-SM

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