Practice Essentials
Dislocation of the foot is an uncommon but potentially incapacitating injury. The mechanism of injury may vary from a simple fall to a major motor vehicle collision (MVC). The foot is a complex structure, and injuries often occur in patients who sustain multiple trauma. The clinician must understand common patterns of injury and maintain a high index of suspicion in examining the appropriate radiographs to avoid missing foot dislocations.
Dislocations of the foot are commonly associated with other significant injuries sustained during falls or MVCs. Delay in recognition of dislocations is common because of the distracting effect of associated injuries, or because of the subtle nature of these injuries. Early reduction and immobilization may reduce morbidity. Injury may occur at any age, although the more severe forms of dislocation associated with MVCs are more common in young adult males.
Risk factors for dislocation of the foot are the same as those for any major trauma (ie, youth, alcohol intake, drug intake). However, dislocation of the foot can result from an apparently simple fall (eg, twisting one's foot in a hole in the ground when jogging).
Diagnosis
Both a detailed medical history and a history of events surrounding the injury or appearance of symptoms are essential in identifying the type of injury and predisposition to complicating factors. Examination of the foot usually reveals an obvious deformity; however, some dislocations are accompanied by substantial soft tissue edema. The exact nature of the injury may be unclear until radiography is performed.
Neurovascular examination is critical both before and after any reduction.
Laboratory studies generally are not indicated for diagnosing foot dislocation. Routine radiography of the foot should include 3 views: anteroposterior (AP), lateral, and 45º internal oblique.
Radiologists must have a thorough understanding of anatomy, mechanisms, and patterns of these injuries to diagnose and help clinicians assess treatment options and prognosis. [1]
Treatment
Reduction of some foot dislocations, especially isolated dislocations of the talus or some of the more complex dislocations of the Lisfranc joint complex, can be very difficult and is inadvisable in the ED. In these cases, consulting an orthopedic specialist is always wise.
Urgent reduction of a dislocation in the ED is often necessary to prevent further vascular or neurologic compromise. Whenever possible, adequate analgesia should be ensured; conscious sedation may be required. The joint should be reduced via gentle traction, and the limb should then be immobilized. Further therapy or operative intervention may be required after this initial reduction.
If the dislocation is open, antibiotics are essential.
Urgent ED orthopedic consultation is indicated for subtalar, total talar, and Lisfranc dislocations.
Additionally, first metatarsophalangeal (MTP) and interphalangeal (IP) joint dislocations that are open or are not reducible require orthopedic consultation. Most other MTP and IP dislocations are easily managed by the ED physician.
Many complications, including avascular necrosis, compartment syndrome, and degenerative arthritis, have been reported. Residual pain and loss of function are common consequences due to the complex biomechanics of the foot.
The effect of the direction of dislocation on long-term prognosis remains controversial. [2] When treating midfoot trauma, it is important for the clinician to fully understand the injury pattern, as this dictates the principles and techniques of fixation. Identification and knowledge of injury patterns will aid surgeons in future management of these injuries and may improve treatment outcomes. [3]
Pathophysiology
The foot consists of 26 bones and 57 articulations. The foot is composed of 3 functional and anatomic regions. The hindfoot consists of the talus and the calcaneus. The midfoot consists of the navicular, the cuboid, and the 3 cuneiforms. The forefoot contains 5 metatarsals and 14 phalanges.
The foot also contains numerous accessory centers of ossification that are occasionally mistaken for avulsion injuries. The presence of a smooth cortical surface and lack of associated soft tissue edema help to differentiate these normal variants from fractures.
The articulations between the hindfoot and the midfoot are the midtarsal or Chopart joints. These joints are the talonavicular and calcaneocuboid joints. The articulations between the midfoot and the forefoot are termed the Lisfranc joints and consist of 5 tarsometatarsal joints.
The subtalar joint, between the talus and the calcaneus, accounts for most inversion and eversion injuries to the hindfoot. Adduction and abduction of the forefoot primarily occur through the midtarsal joints. Flexion and extension primarily occur at the MTP and IP joints.
Epidemiology
All dislocations in the foot (with the exception of simple dislocations of the toes) are uncommon injuries. The most common of these injuries is a dislocation that involves the Lisfranc joint complex. The rarity of these injuries makes diagnosis difficult. A significant proportion of the more subtle dislocations are not diagnosed upon initial presentation. Dislocations through the Lisfranc joint complex are thought to have an incidence of about 1 in 50,000 persons with orthopedic trauma per year, representing less than 1% of all dislocations.
Dislocations of the foot are commonly associated with other significant injuries sustained during falls or MVCs. Delay in recognition of dislocations is common because of the distracting effect of associated injuries or because of the subtle nature of these injuries. Early reduction and immobilization may reduce morbidity.
Many complications, including avascular necrosis, compartment syndrome, and degenerative arthritis, have been reported. Additionally, residual pain and loss of function are common consequences resulting from the complex biomechanics of the foot.
The male-to-female ratio is 6:1. This differential is largely due to the higher number of young males who sustain significant trauma.
Injury may occur at any age, although the more severe forms of dislocation associated with MVCs are more common in young adult males.
