Background
The ankle joint is composed of 2 joints: the true ankle joint and the subtalar joint. Ankle fractures refer to fractures of the distal tibia, distal fibula, talus, and calcaneus. The true ankle joint contains the tibia (medial wall), fibula (lateral wall), and talus (the floor upon which the tibia and fibula rest). The true ankle joint allows dorsiflexion and plantar flexion or the "up and down" movement of the ankle. The foot can be made to point toward the floor or toward the ceiling via the true ankle joint.
The subtalar joint consists of the talus and the calcaneus. The subtalar joint allows the foot to be inverted or everted, that is, the sole of the foot can be made to face inward (inverted) or face outward (everted) through the subtalar joint.
During evaluation of ankle fractures, the mechanism of injury (eg, eversion, inversion, dorsiflexion, plantar flexion), associated injuries (eg, vascular, ligamentous, capsular), the need for immobilization (eg, application of a splint), and the need for referral to a specialist for further treatment or evaluation (eg, additional immobilization, surgery, or rehabilitation) are all important components of care.
For more information on fractures, see Medscape's Fracture Resource Center.
Pathophysiology
The primary motion of the ankle at the true ankle joint (tibiotalar joint) is plantarflexion and dorsiflexion. Inversion and eversion occur at the subtalar joint.
Excessive inversion stress is the most common cause of ankle injuries for 2 anatomic reasons. First, the medial malleolus is shorter than the lateral malleolus, allowing the talus to invert more than evert. Second, the deltoid ligament stabilizing the medial aspect of the ankle joint offers stronger support than the thinner lateral ligaments. As a result, the ankle is more stable and resistant to eversion injury than inversion injury. However, when eversion injury occurs, there is often substantial damage to bony and ligamentous supporting structures and loss of joint stability.
Posterior malleolar fractures are usually associated with other fractures and/or ligamentous disruption. They are commonly associated with fibular fractures and are often unstable.
Transverse malleolar fractures usually represent an avulsion-type injury. Vertical malleolar fractures result from talar impaction.
Epidemiology
Of all the ankle injuries evaluated in the ED, only 15% are ankle fractures. The frequency of ankle fractures has been increasing for the past 20 years, and the rate is approximately 187 in 100,000 person-years.
Mortality/Morbidity
Patients with unrecognized or undertreated open ankle fractures are at high risk of infection including local infection, osteomyelitis, and sepsis. Gas gangrene is the most serious infectious complication. It can be both limb and life threatening.
Vascular supply to the ankle and foot may become compromised by development of a compartment syndrome or direct injury to blood vessels from bone fragments.
Talus fractures, those commonly occurring in snowboarding trauma, can cause osteoarthritis and subtalar joint degeneration.
A calcaneal fracture may compromise inversion and eversion of the ankle. Surgical complications and prolonged rehabilitation are common with calcaneal fractures.
Older patients with ankle fractures experience more long-term complications than younger patients.
Age and Sex
The male-to-female ratio for ankle fracture is 2:1. Most patients younger than 50 years are male, while most older than 50 years are female.
In children, ankle fractures have an incidence of 1 in 1000 per year. [1] Pediatric ankle bones are susceptible to medial malleolar and transitional fractures of the distal tibia.
As the population ages, ankle fractures are becoming more common. An increase in fall risk and osteoporosis are risk factors.
Prognosis
The prognosis can be improved with prompt, accurate diagnosis and appropriate treatment and referral.
Complex open fractures with substantial soft-tissue damage have a worse prognosis than isolated closed ankle fractures.
Isolated, nondisplaced lateral malleolus fracture, the most common ankle fracture, has a favorable prognosis and heals unremarkably.
Aggressive rehabilitation helps reduce the majority of morbidity associated with ankle fractures.
Patient Education
For excellent patient education resources, visit eMedicineHealth's First Aid and Injuries Center. Also, see eMedicineHealth's patient education article Broken Ankle (Ankle Fracture).
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Maisonneuve injury. Mortise view shows transverse fracture of the medial malleolus and widening of the tibiofibular syndesmosis without a fracture of the fibula. This injury is suggestive of a proximal fibula fracture (Maisonneuve fracture).
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Pilon fracture in a 35-year-old man who fell 20 ft. Anteroposterior radiograph shows at least 2 fracture lines extending to the articular surface (plafond) of the tibia.
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A 13-year-old girl with triplane fracture. Anteroposterior radiograph shows a sagittal component through the distal tibia epiphysis.
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An 11-year-old girl with juvenile Tillaux fracture. Mortise view shows fracture involving the lateral portion of tibial epiphysis.
