Author
Lars Grimm, MD, MHS
House Staff
Department of Internal Medicine
Duke University Medical Center
Durham, North Carolina
Disclosure: Lars Grimm, MD, MHS, has disclosed no relevant financial relationships.
Editor
Felix Chew, MD
Professor, Department of Radiology, Vice Chairman for Radiology Informatics,
Section Head of Musculoskeletal Radiology
University of Washington
Seattle, Washington
Disclosure: Felix Chew, MD, has disclosed no relevant financial relationships.
Ankle injuries are the most common injuries to occur during sports and recreational activities. The vast majority of ankle injuries are sprains, accounting for 20% of all sports injuries. Given the incidence, physicians must be able to rapidly differentiate between sprains and fractures while maintaining a high index of suspicion for injuries that may require urgent surgery. The radiograph shown demonstrates a pronation-external rotation type ankle fracture in a 27-year-old woman with a medial malleolus fracture, high fibula fracture, and ligamentous tear widening the tibiofibular syndesmosis.
The ankle joint consists of the true ankle joint and the subtalar joint. The true ankle joint is formed from the tibia, fibula, and talus, while the subtalar joint is formed from the talus and calcaneus. The true ankle joint allows dorsiflexion and plantar flexion, while the subtalar joint allows eversion and inversion. The ankle mortise is formed by the medial malleolus medially, the tibial plafond superiorly, and the lateral malleolus laterally.
Multiple ligaments are responsible for maintaining normal ankle alignment and function. Medial and lateral views of the ankle are shown with the bones and ligaments of the ankle identified. Not shown is the interosseus membrane, which connects the tibia and fibula along their lengths. Disruption in any of the bones or ligaments can be responsible for patient ankle complaints. Given the complex interrelation between the bones and ligaments of the ankle, multiple concomitant disruptions typically form after injuries.
Ankle sprains are a clinical diagnosis that begins with a detailed description of the mechanism of injury and ankle positioning. Excessive inversion stress is the most common mechanism of injury because the medial ankle ligaments are stronger than the lateral and the medial malleolus is shorter than the lateral. Prior injury, improper shoe wear, lack of stretching, ability to bear weight, swelling, and popping sensations are clues to the mechanism of injury. Physical examination begins with comparison of the bilateral ankles for symmetry, edema, ecchymosis (shown), tenderness, crepitus, or deformity. Assess active and passive range of motion as well as the ability to bear weight. Image courtesy of Wikimedia Commons.
Multiple focused ankle maneuvers may help localize a ligamentous injury. The anterior drawer test (shown) assesses the integrity of the anterior talofibular ligament and is performed by applying forward traction to the heel of a foot in 10-15 degrees of plantar flexion, as shown. Forward movement of 1 cm is significant for injury. The talar tilt test (shown) assesses the integrity of the calcaneofibular ligament by applying adduction and inversion to the midfoot with the foot in 20-30 degrees of plantar flexion, as shown. A shifting of the talus in the mortise indicates injury. The crossed-leg test evaluates for a syndesmotic sprain by having the patient cross the injured leg over the other knee while seated. Pressure on the medial knee will cause ankle pain in a positive test result.
Routine radiographic imaging of ankle injuries is not cost effective because less than 15% will show fractures. The Ottawa ankle rules have been devised to provide guidelines for adults about when to order imaging studies. Ankle pain plus any of these findings are indications for ankle radiographs. Standard views of the ankle are anteroposterior, lateral, and mortise views. In the mortise views, the ankle is rotated 15 degrees internally to provide a better view of the ankle mortise. Computed tomography and magnetic resonance imaging may be indicated on a case-by-case basis to better define fractures or ligamentous injury and aid in surgical planning.
Ankle sprains can be graded by the West Point Sprain Grading System. All sprains should be treated with rest, ice, compression, and elevation (ie, RICE). First-degree or mild second-degree sprains can be treated conservatively with compression dressing and referral to physical therapy for range of motion and strength training. Severe second- and third-degree sprains should be treated with a plaster or fiberglass posterior splint in the emergency department. There is some evidence that a short, 10-day period of immobilization may help ligament healing. Orthopaedist or sports medicine referral is indicated because most patients will require physical therapy to prevent functional loss. Surgical intervention is reserved for high-level athletes with severe third-degree sprains on a case-by-case basis.
Numerous strategies have been promoted to help prevent initial and recurrent ankle injuries. Physical therapy exercises with tilt boards (shown) and bracing or taping have been shown to be the most effective ways to prevent first-time and recurrent ankle sprains. Tilt boards improve ankle balance and coordination by strengthening the small muscles of the ankle. Ankle taping is equally as effective as a brace, but deteriorates in effectiveness rapidly with use and becomes completely ineffective after 40 minutes. Orthotics, specialized footwear, stretching, and eversion exercises have also been recommended for ankle injuries but have shown less consistent results.
Ankle fractures are present in the minority of ankle injuries. Physical examination findings suggestive of ankle fracture are gross deformity, perimalleolar swelling, bony tenderness, discoloration, ecchymosis, blisters, pressure necrosis, and inability to bear weight, as shown in this patient who presented 48 hours after an ankle fracture. Skin continuity needs to be evaluated to ensure it is not an open fracture. Neurovascular status should be assessed and can best be compared to the opposite limb. The pulses in the posterior tibial artery and dorsalis pedis artery can be manually palpated or evaluated with bedside ultrasound. Ankle dislocations are more commonly seen in fractures due to the relative weakness of the bones compared with the ligaments.
The Lauge-Hansen system (shown) and the Danis-Weber system are the most commonly used fracture classification systems. The 4 major injury patterns in the Lauge-Hansen system are supination-adduction, supination-external rotation, pronation-adduction, and pronation-external rotation. The system refers to the initial position of the foot and hindfoot (supination, pronation) and the direction of the injuring force acting through the talus (adduction, abduction, external rotation). In the Danis-Weber system, type A fractures are horizontal avulsion fractures below the mortise, type B fractures are spiral fibular factures at the level of the mortise, and type C fractures are at the level of the mortise and disrupt the fibula and tibia ligamentous attachment.
Supination-adduction (SA), or Weber A, fractures occur when the foot is supinated and an adducting force is applied to the talus. This leads to tension on the lateral ligaments, predominately calcaneofibular, and a transverse fracture to the lateral malleolus (white arrow). The subsequent adduction of the talus causes an oblique medial malleolar fracture (yellow arrow).
Supination-external rotation (SE), or Weber B, fractures occur when the foot is supinated and an external rotational force is applied to the talus. This is the most common mechanism of injury for a twisted ankle. There may be a tear of the anteroinferior tibiofibular ligament, short oblique fracture of the fibula (white arrow), fracture of the posterior malleolus, and transverse fracture of the medial malleolus or tear of the deltoid ligament.
Pronation-external rotation (PE), or Weber C2, fractures occur when the foot is pronated and an external rotation force acts on the talus. This may lead to a medial malleolar fracture, tear of the anteroinferior tibiofibular ligament, oblique or spiral fracture of the midshaft of the fibula (white arrow), and fracture of the posterior malleolus. The midshaft fibula and posterior malleolus fractures distinguish this fracture pattern from the pronation-abduction mechanism.
A Maisonneuve, or Weber C3, fracture is caused by abduction of the talus. It may lead to a tear of the anteroinferior tibiofibular ligament (yellow arrow) and interosseus membrane, fracture of the posterior malleolus or posterior ligament tear, anteromedial capsular injury, fracture of the proximal fibula, and fracture of the medial malleolus (white arrow) or deltoid ligament tear.
Fracture treatment depends on the location and extent of injury. All injuries should be initially stabilized in a neutral position with a pillow, splint, or dressing while awaiting further evaluation. Simple, lateral malleolar fractures (Weber A or supination-adduction) can usually be splinted and then followed as an outpatient. Premade splints can be readily applied with adjustable straps to allow for subsequent readjustments from swelling, as shown. A posterior splint can be applied to maintain the ankle in 90 degrees of flexion. A sugar tong or short leg stirrup splint wraps under the posterior aspect of the foot between the calcaneous and metatarsal heads and is secured in place with an elastic wrap. Splinting with bulky pudding will allow room for subsequent swelling.
More serious fractures may require urgent orthopaedic intervention. Open fractures should be covered with wet sterile gauze to prevent further contamination. Empiric antibiotics and tetanus prophylaxis should be considered. Ankle dislocations are more common with serious fractures and will need to be relocated. Bimalleolar, trimalleolar, pilon, unstable, or open fractures typically require open reduction internal fixation, as shown in this radiograph of a patient with a bimalleolar fracture. Long-term recovery depends on the severity of the injury, ability to realign the fracture fragments, and compliance with rehabilitation efforts. Posttraumatic arthritis is a frequent subsequent complication.
Author
Lars Grimm, MD, MHS
House Staff
Department of Internal Medicine
Duke University Medical Center
Durham, North Carolina
Disclosure: Lars Grimm, MD, MHS, has disclosed no relevant financial relationships.
Editor
Felix Chew, MD
Professor, Department of Radiology, Vice Chairman for Radiology Informatics,
Section Head of Musculoskeletal Radiology
University of Washington
Seattle, Washington
Disclosure: Felix Chew, MD, has disclosed no relevant financial relationships.
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