Ankle dislocation is a relatively common type of dislocation encountered in the emergency department. It occurs in 2 forms: (1) true dislocation without fracture and (2) fracture-dislocation, which occurs in the vast majority of cases. The ankle joint is composed of 3 main articulations: the talocalcaneal (subtalar), transverse-tarsal (talocalaneonavicular), and tibiotalar (talocrural) joints. The true ankle joint is the tibiotalar joint (between the tibia, fibula, and talus). The combination of these joints gives the foot the ability to compensate for loads placed during walking and other activities.[1]
The human ankle maintains its range of motion under extremely heavy loads and can support several times the human body weight for short periods. Because of stress placed on the ankle as one pushes off in different directions, it is possible to dislocate it by exceeding the ligamentous strength that encloses the ankle.[1]
The stability of the ankle is maintained by 3 groups of ligaments: the tibiofibular syndesmosis, the deltoid ligament, and the lateral collateral ligaments. These ligaments collaboratively limit motion, provide support, and act to resist inversion.[1]
Inspection of the ankle reveals significant edema, with deformity ranging from trace to obvious. Tenting of the skin by the malleoli may be noted. Palpation of the joint reveals tenderness along the joint line, corresponding to areas of capsular or ligamentous disruption. In associated fractures, tenderness, deformity, or tenting proximal to the joint may be seen.
Possible risk factors that may predispose a patient to dislocation include joint hyperlaxity, internal malleolar hypoplasia, peroneal muscle weakness, and a history of prior ankle sprains.[2]
True ankle dislocation without fracture
Dislocation of the upper ankle joint without fracture is described in the literature as very rare. In 33-50%, ankle dislocations are at least first-degree open and are associated with fracture of the tibia, fibula, or talus.[3] Ankle dislocations without fracture occur when significant force applied to the joint results in loss of opposition of the articular surfaces. Because of the large amount of force required and the inherent stability of the tibiotalar joint, dislocation of the ankle joint is rarely seen without an associated fracture. Researchers argue that this is due in part to the strength of the ankle joint ligaments and the relative weakness of the bones that make up the ankle.[2]
A systematic review of English literature identified 154 cases of pure ankle dislocation and demonstrated that sporting accidents (31%) and motor vehicle accidents (30%) are the most common causes. A total of 73% (112/154) of cases occurred in males, and 50% (77/154) were open.[4]
Ankle dislocations are orthopedic emergencies that require immediate treatment to avoid neurovascular impairment. They are usually accompanied by 1 or more comminuted fractures of the ankle mortis. Primary goals of treatment are immediate reduction of the joint and relief of neurovascular stress. External fixation is a prompt, fairly easy treatment that one should keep in mind for pure ankle dislocations.[5]
For ankle dislocations without fracture, imaging via magnetic resonance imaging (MRI) and computed tomography (CT) scan allows a detailed evaluation of injury severity. The decision for further treatment should be based on findings on these scans. Reconstructing the medial and lateral capsular ligaments may be necessary. With a consequent treatment algorithm, a good functional outcome can be achieved.[6]
Fracture-dislocation of the ankle
Fracture-dislocation of the ankle represents substantial injury to the bony and soft tissue structures of the ankle.[7] Bone stabilization, joint immobilization, anatomic reduction, and intervention for soft tissue protection should be performed as early as possible.[8]
Clinical and functional results have been found to be worse in patients with open ankle fractures.[8] Researchers report that with open ankle fractures, the rate of arthrosis increased with age, and use of a syndesmosis screw had a positive but not a statistically significant effect on clinical and functional outcomes.[8]
Open reduction internal fixation (ORIF) is an accepted treatment for displaced tarsometatarsal joint (TMTJ) fracture-dislocations. In general, hardware is routinely removed after 4 months to allow restoration of joint motion and to avoid complications of hardware failure. Little consensus has been reached regarding the optimal time for hardware removal, or whether hardware retention leads to adverse outcomes. Older age has been correlated with lost reduction, and elevated body mass index is correlated with hardware failure.[9]
Distraction arthroplasty is a viable acute and definitive treatment option for ankle fracture in patients with significant medical comorbidities.[10]
A study that aimed to compare functional outcomes after ORIF in ankle fractures with and without dislocation found that ankle fracture-dislocation occurred more frequently in patients who were older, female, and diabetic. At a median follow-up of just over 3 years, functional outcomes after fracture-dislocation were generally poorer than after fracture without dislocation, and patients rated pain on a subscale of the Foot and Ankle Outcome Score (FAOS) assessment as statistically significantly worse.[7]
Some controversy exists regarding the treatment of ankle dislocations. However, outcomes appear to be satisfactory in cases treated with immediate reduction of the joint and relief of neurovascular stress as the primary goals of treatment.[11]
The ankle joint is designed for a balance of stability and flexibility, particularly the former. Joint stability is provided by close articulation of the talus with the tibia and fibula. The mortise design further enhances the stability of the configuration.
The ankle joint is composed of 3 main articulations: talocalcaneal (subtalar), transverse-tarsal (talocalaneonavicular), and tibiotalar (talocrural) joints. The true ankle joint is the tibiotalar joint (between the tibia, fibula, and talus). The combination of these joints gives the foot the ability to compensate for loads placed during walking and other activities.[1]
The stability of the ankle is maintained by 3 groups of ligaments: the tibiofibular syndesmosis, the deltoid ligament, and the lateral collateral ligaments. These ligaments collaboratively limit motion, provide support, and act to resist inversion.[1]
The human ankle maintains its range of motion under extremely heavy loads and can support several times the human body weight for short periods. This factor is increased several-fold during running and jumping activities. Because of stress placed on the ankle as one pushes off in different directions, it is possible to dislocate it by exceeding the ligamentous strength that encloses the ankle.[1]
(See the image below.)
View Image
Anatomy of the lateral ankle ligamentous complex and related structures.
Associated fractures are the rule rather than the exception with ankle dislocations. Ligamentous disruption varies according to the type of dislocation. Neurovascular injury is the principal concern, as with any dislocation. Vascular compromise may result in avascular compromise of the talus, permanent sensation or nerve damage, and lower extremity tissue necrosis; gangrene may occur if the fracture is not promptly reduced. Tented skin may be subject to ischemic necrosis
Children and adolescents have the most ankle dislocations. Dislocations of the ankle are seen more frequently in young males than in any other group. This presumably is related to their increased risk overall for traumatic injury.
A retrospective study of patients with major intra-articular fracture-dislocations reported that major joint fracture-dislocations were most common in the hip and least common in the knee and occurred more often in men than in women. The hip was the most commonly affected joint in men, and the ankle was most commonly affected in women.[12]
Postmenopausal women are at higher risk for associated fractures with ankle dislocation. Increased fracture risk probably is related to osteoporotic changes in this subset of patients.
Dislocated ankles should not be expected to return to premorbid function.
The amount of force and the level of capsular disruption required to dislocate the inherently stable joint can lead to significant injury with lasting effects. To a limited extent, prompt intervention can reduce the risk of complications.
Most cases of pure ankle dislocation treated with early reduction followed by a short period of immobilization and functional rehabilitation have good clinical outcomes.[4]
A study of ankle dislocation involving posterior ankle comminuted fractures reported that the intraoperative ankle dislocation approach appears to be a promising surgical option, providing better functional outcomes and a lower incidence of posttraumatic arthritis than conventional approaches, while not compromising primary healing and healing time.[13]
When a patient presents with ankle injury, a detailed history regarding the mechanism of injury often helps predict the types of injuries to be expected. Furthermore, an understanding of the injury mechanism aids treatment. Because of the inherent stability of the ankle joint mortise and surrounding tendons and ligaments, dislocation is usually caused by high-energy trauma that causes plantar flexion of the ankle combined with either inversion or eversion stress upon the foot.[2] Four types of dislocations are seen around the ankle joint: posterior, anterior, lateral, and superior.
Posterior
A posterior dislocation is the most common type of ankle dislocation.[14] The talus moves in a posterior direction in relation to the distal tibia as force drives the foot backward.[15] The wider anterior talus wedges back, resulting in forced widening of the joint. This must be accompanied by disruption if the tibiofibular syndesmosis is involved, or fracture if the lateral malleolus is affected, which occurs most commonly when the ankle is plantar flexed.
Anterior
Anterior dislocations result from the foot being forced anteriorly at the ankle joint.
Typically, anterior dislocation occurs when the foot is fixed and a posterior force is applied to the tibia, or it can occur with forced dorsiflexion.
Lateral
Lateral dislocations result from forced inversion, eversion, or external or internal rotation of the ankle. They are associated uniformly with fractures of the malleoli or the distal fibula or both.
Superior
Diastasis occurs when a force drives the talus upward into the mortise. These dislocations usually are the result of a fall from a height. In such cases, the patient should be evaluated carefully for concomitant spine injury and fracture of the calcaneus.
The amount of force and the level of capsular disruption required to dislocate the inherently stable joint can lead to significant injury with lasting effects. To a limited extent, prompt intervention can reduce the risk of complications.
Complications of ankle dislocation may include the following:
Nonunion or malunion
Synostosis
Entrapment of the tibialis posterior tendon or of a fracture fragment
Cartilaginous injury
Osteochondral fractures of the talar dome
Joint stiffness and decreased range of motion (eg, osteoarthritis[16] )
Arterial injury (anterior and posterior tibial, peroneal)
Compartment syndrome (rare)
With open reduction internal fixation (ORIF), hardware is generally routinely removed after 4 months to allow restoration of joint motion and to avoid complications of hardware failure. Little consensus has been reached regarding the optimal time for hardware removal, or whether hardware retention leads to adverse outcomes.[9]
Routine radiographic examination of the ankle includes the following views:
Anteroposterior
Lateral
Mortise or oblique views: These are taken with an internal rotation of 10-20 degrees. This places the medial and lateral malleoli in the same horizontal plane, which provides optimal viewing of the tibial plafond and the talar dome.
Obtain prereduction and postreduction films.
Computed tomography (CT) may be indicated for evaluation of osseous structures, occult fractures, and alignment.
Ultrasound may be used for guiding injection of pain medicine into the ankle.[17]
For patients with obvious or complete neurovascular compromise, perform reduction prior to radiographic studies. Prompt reduction is important in reducing the risk of complications related to neurovascular compromise.
Reduction is accomplished with the knee in flexion to reduce tension on the Achilles tendon. With one hand on the heel and the other on the dorsum of the foot, apply traction while maintaining countertraction at the knee. Entrapment of the tibialis posterior tendon (or of a fracture fragment within the joint space) may result in an irreducible dislocation.
Anesthesia includes Bier block, spinal block, conscious sedation with narcotics and/or benzodiazepines, or general anesthesia. Bier block is the preferred method because of its efficacy and risk profile, although time may not permit in cases of vascular compromise. Another technique is the hematoma block (injection of intra-articular local anesthetic into the ankle joint and associated fracture hematoma). Ross et al suggest this as an alternative to conscious sedation, avoiding the risks of seizure and/or respiratory arrest.[18]
Prehospital personnel should immobilize the joint in keeping with standard procedure for any extremity injury.
If neurovascular compromise is identified in the field when examination reveals a cold, discolored, and pulseless or insensate foot, the joint should be realigned unless transport time is brief. This is accomplished by providing in-line traction with countertraction. Traction or splinting should be maintained en route to the hospital.
Intravenous opioids should be administered to keep the patient comfortable, especially if traction is applied to reduce the dislocation en route. If intravenous opioids are unavailable, intravenous benzodiazepine medications can be used as an alternative.
Early reduction is essential because delay may increase the risk of neurovascular compromise or damage to the articular cartilage. For patients with vascular compromise, perform reduction prior to radiologic examination.
Postreduction radiographs should confirm proper joint alignment. Appropriate pain management is the greatest contribution an emergency physician can make to the patient's care.
Dislocations of the ankle are, by definition, unstable due to accompanying disruption of the lateral or medial ligaments or the tibiofibular syndesmosis. These injuries require an immediate orthopedic or podiatric consultation for surgical intervention that may involve internal or external fixation of any associated fractures and repair of capsular or ligamentous tears.[2, 19]
The Ottawa Ankle Rules, originally developed by Stiell and colleagues, provide a clinical decision approach to guide assessment of ankle injuries, particularly to determine the need for radiography in the emergency department.[20, 21]
The American College of Radiology (ACR) Appropriateness Criteria for acute trauma to the ankle in adults and children older than 5 years note that the Ottawa Ankle Rules recommend ankle radiographs if any of the following is present: (1) inability to bear weight immediately after the injury, OR (2) point tenderness over the medial malleolus, or the posterior edge or the inferior tip of the lateral malleolus or talus or calcaneus, OR (3) inability to ambulate 4 steps in the ED.[22]
Clinical Context:
Narcotic analgesic with greater potency and a much shorter half-life than morphine sulfate. This is the drug of choice (DOC) for conscious sedation analgesia. With short duration (30-60 min) and ease of titration, this is an excellent choice for pain management and sedation. It is easily and quickly reversed by naloxone. After the initial dose, subsequent doses should not be titrated more frequently than q3h or q6h.
Clinical Context:
Drug combination indicated for relief of moderately severe to severe pain. DOC for aspirin-hypersensitive patients. Different strengths available.
Clinical Context:
DOC for analgesia due to reliable and predictable effects, safety profile, and ease of reversibility with naloxone. Various IV doses are used; commonly titrated until desired effects are obtained.
Pain control is essential for quality patient care. It ensures patient comfort, promotes pulmonary toilet, and aids physical therapy regimens. Many analgesics have sedating properties that benefit patients who have sustained injuries.
Clinical Context:
Depresses all levels of the CNS, including the limbic and reticular formation, possibly by increasing the activity of GABA, a major inhibitory neurotransmitter. Individualize dosage and increase cautiously to avoid adverse effects.
Clinical Context:
Sedative-hypnotic in benzodiazepine class that has a short onset of effect and a relatively long half-life. By increasing GABA, a major inhibitory neurotransmitter, it may depress all levels of the CNS, including the limbic and reticular formation. When a patient needs to be sedated for longer than 1 day, this medication is excellent. Monitor the patient's blood pressure after administering the dose, and adjust as necessary.
Patients with painful injuries usually experience significant anxiety. Anxiolytics allow the clinician to administer a smaller analgesic dose to achieve the same effect.
James E Keany, MD, FACEP, Associate Medical Director, Emergency Services, Mission Hospital Regional Medical Center, Children's Hospital of Orange County at Mission
Disclosure: Nothing to disclose.
Coauthor(s)
Dekker McKeever, DPM, Chief Podiatric Surgery Resident Physician, Trauma and Reconstruction Specialist, Mission Hospital Regional Medical Center
Disclosure: Nothing to disclose.
Specialty Editors
Francisco Talavera, PharmD, PhD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference
Disclosure: Received salary from Medscape for employment. for: Medscape.
David B Levy, DO, FAAEM, Senior Consultant in Emergency Medicine, Waikato District Health Board, New Zealand; Associate Professor of Emergency Medicine, Northeastern Ohio Universities College of Medicine
Disclosure: Nothing to disclose.
Chief Editor
Trevor John Mills, MD, MPH, Chief of Emergency Medicine, Veterans Affairs Northern California Health Care System; Professor of Emergency Medicine, Department of Emergency Medicine, University of California, Davis, School of Medicine
Disclosure: Nothing to disclose.
Additional Contributors
Joseph J Sachter, MD, FACEP, Consulting Staff, Department of Emergency Medicine, Muhlenberg Regional Medical Center
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