Foot Dislocation


Background

Dislocations of the foot are uncommon but potentially incapacitating injuries. 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.

Pathophysiology

Anatomy

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 the 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 helps 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 the calcaneocuboid joints. The articulations between the midfoot and the forefoot are termed the Lisfranc joints and consist of the 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 occurs through the midtarsal joints. Flexion and extension primarily occurs at the metatarsophalangeal (MTP) and interphalangeal (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 fewer 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 the 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 is a common consequence of 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.


History

Both a detailed medical history and a history of the events surrounding the injury or appearance of symptoms are essential in identifying the type of injury and predisposition to complicating factors.

The history should include the following questions:

  • What was the exact mechanism of injury?

  • Has the patient been able to bear weight since the injury?

  • Does the patient have an underlying medical condition, especially a history of diabetes mellitus?

    • People with diabetes mellitus may have denervation of the foot and are prone to develop Charcot joints. Charcot joints are joints that demonstrate a grossly disorganized structure, deformity, edema, extreme hypermotility, and often remarkably little pain. Function is generally good.

    • Early, accurate recognition of foot injury is particularly important in patients with diabetes mellitus because a delayed diagnosis is associated with the development of Charcot joints.

  • Does the patient have a history of foot surgery or prior injury to the affected foot? (This may make interpretations of radiographs difficult.)

In general, patients who experience dislocations of the foot have other injuries related to the mechanism of injury. A full history of the event should be obtained from the patient or prehospital caregivers. Occasionally, these injuries may occur with minimal trauma. This is especially true with athletes. The history in these cases is usually of increasing pain and edema over a few days, resulting in a significant limitation of mobility, decreased performance, or both. Often, the patient gives no definitive history of a single traumatic event. The presumed mechanism of injury responsible for each type of dislocation is discussed with that dislocation.

Physical

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 prior to and after any reduction.

Assess the vascular status. If no pulse is palpable, urgent reduction of the dislocation is required. Confirm the absence of a pulse with Doppler studies in the emergency department (ED) if possible. Mark the position of the pulse on the skin; this simple measure confirms that a pulse was taken and that it was palpable and also indicates the ideal anatomic location for reassessment. Loss of a previously palpable pulse is a sign that urgent reduction is needed.

Perform a thorough neurologic examination of the foot.

Check for any breaks in the skin. Check for any tenting of the skin, which may necessitate urgent reduction.

Findings may be subtle and nonspecific in persons who present with foot pain from a Lisfranc dislocation in which no single major traumatic event has occurred. [1Edema and tenderness over the joint are usually present. Ecchymoses may develop after a few days. Vascular compromise is rare.

Causes

The risk factors for dislocation of the foot are the same as those for any major trauma (ie, youth, alcohol intake, drug intake). However, dislocations of the foot can result from an apparently simple fall (eg, twisting one's foot in a hole in the ground when jogging).

Numerous different types of dislocations of the foot are recognized.

Subtalar or peritalar dislocation

This is a simultaneous dislocation of the talocalcaneal and talonavicular joints. Note that the talus remains in the ankle mortise. It is typically caused by falls from a height, MVCs, and severe twisting injuries (eg, basketball players who land on an inverted and plantar-flexed foot). [2 

Subtalar dislocation is seen with both high- and low-energy trauma. Sporting activities, commonly basketball, are often the cause of low-energy injuries. The majority of subtalar dislocations are accompanied by fractures of the hindfoot, including osteochondral fractures, calcaneus fractures, and fractures of the posterior process and tubercles of the talus. The diagnosis of subtalar dislocation is usually made on AP, lateral, and oblique radiographs of the foot or ankle. The nature of the deformity often limits radiographic positioning. [3]

The dislocation is typically medial or lateral (rarely anterior or posterior), although medial dislocation is more common (80%). Posterior dislocation may result from hyperplantar flexion. [4Inversion injuries result in medial dislocations and eversion injuries result in lateral dislocations. The navicular bone and forefoot are displaced medially with a medial subtalar dislocation and displaced laterally with a lateral dislocation. These dislocations are frequently associated with fractures of the involved bones and a small percentage are open.

The effect of direction of the dislocation on long-term prognosis is still controversial. [56]

Total talar dislocation

A rare dislocation, this injury typically results from very high-energy trauma. The talus is completely out of the ankle mortise and is rotated such that the inferior articulation points posteriorly and the talar head points medially.

These dislocations are commonly open and result in avascular necrosis of the talus, loss of ankle motion due to traumatic arthritis, and ischemic skin loss from underlying skin pressure.

Talar dislocation with associated distal fibular fracture (Weber C) has been reported. [7 

When total talar dislocation injuries occur with an open wound, the talus often has associated fractures with remaining soft-tissue attachments.  Initial radiographs are often obtained with nonconventional positioning. After initial reduction, CT is performed to further characterize associated injuries. [3]

Lisfranc dislocation

Dislocation fractures of the tarsometatarsal joints are referred to as Lisfranc injuries. This type of dislocation is caused by several mechanisms, including rotational forces about a fixed forefoot, axial loading in a plantar flexed foot, and crush injuries. These injuries may also be a manifestation of a developing neuropathic or Charcot joint arthropathy.

Tremendous energy is usually required to subluxate or dislocate the Lisfranc joint complex. This energy frequently results in extensive soft-tissue injury. Occasionally, minor rotational injuries may cause this problem. This is particularly well described in athletes and in older patients. [8]

The clinician must be careful not miss these injuries. Evaluate the alignment of the metatarsal bones with their corresponding tarsal bones on radiographs. The first, second, and third metatarsals should line up with the medial, middle, and lateral cuneiforms respectively. The fourth and fifth metatarsals should line up with the cuboid.

A good starting point for evaluation is to inspect the medial aspect of the middle cuneiform to be directly in line with the medial aspect of the second metatarsal. Any disruption is indicative of a dislocation, which may have spontaneously reduced.

Lisfranc dislocations are classified according to the direction of injury in the horizontal plane and include the following:

  • Homolateral, in which all 5 metatarsals move in the same direction

  • Partial, or isolated, in which 1 or 2 metatarsals are displaced from the others

  • Divergent, in which the first metatarsal displaces medially, with one or more of the other metatarsals are displaced laterally

  • Some studies estimated that 20% of Lisfranc injuries are missed upon initial presentation to the ED. Subtle injuries to the Lisfranc joint do occur and may be difficult to diagnose. Slight widening (2-5 mm) of the space between the first and second metatarsals may be seen, as well as a widening of the space between the middle and medial cuneiforms.

Metatarsophalangeal (MTP) and interphalangeal (IP) dislocation

First MTP dislocations, although rare given the inherent stability of the joints, typically result from large forces. [9These dislocations are typically dorsal and are often open.

Dislocations of the other metatarsophalangeal joints are not unusual and typically are caused by trauma. The dislocation is most frequently a lateral or dorsal displacement of the digit on the metatarsal head.

IP dislocations are less common than MTP dislocations. Most occur in the first toe as a direct result of axial loading.

Other dislocations

Although very rare, other dislocations in the foot have also been described.

Isolated fracture dislocation of the navicular on the talus has been described. It occurs following a fall from a height and is usually treated with open reduction and internal fixation.

Cuboid and cuneiform fractures are sometimes associated with tarsometatarsal dislocations, but they may present as isolated fracture-dislocation. They are unstable frequently and require open reduction and internal fixation.

Differential Diagnoses



Laboratory Studies

Laboratory studies are generally not indicated for diagnosing foot dislocations. However, if an intravenous line is placed for conscious sedation purposes, routine preoperative laboratory samples may be drawn to facilitate definitive management of foot dislocations.

Imaging Studies

Routine radiography of the foot should include 3 views: anteroposterior, lateral, and 45 º internal oblique.

  • The hindfoot is assessed via the lateral projection and the midfoot and forefoot via the anteroposterior and oblique projections.

  • Any identified hindfoot injury should prompt standard imaging of the ankle.

  • Additional views, such as the Harris (axial) view to evaluate the subtalar joint and calcaneus, can be obtained to improve imaging of certain areas of the foot.

  • Weightbearing views may reveal subtle Lisfranc abnormalities.

Increasingly, CT scanning is being used to help evaluate fractures and dislocations in the foot and in particular to help evaluate calcaneal and talar fractures.

MRI is often used to diagnose stress fractures and to evaluate the various tendons and ligaments of the foot.

Up to 20% of Lisfranc fracture-dislocations are misdiagnosed or missed during the initial evaluation. [10Lisfranc injuries typically present to EDs with pain particularly with weight bearing, with swelling, and after a characteristic mechanism of injury. Diagnosis is via clinical examination and radiologic investigation, typically plain radiographs and CT scans. [11Sensitivity and specificity of MRI identification of Lisfranc injuries have been reported to be as high as 94% and 75%, respectively. [12 Ultrasound is now also being used to evaluate Lisfranc injuries. [13]

Other Tests

Doppler may be performed to detect pulses.



Approach Considerations

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 inadvisable in the ED. In these cases, consulting an orthopedic specialist is always wise. Closed reduction is frequently insufficient and open reduction and internal fixation are required.

Urgent reduction of a dislocation in the ED is often necessary to prevent further vascular or neurological compromise. Whenever possible, ensure adequate analgesia; conscious sedation may be required. The joint should be reduced using 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.

Prehospital Care

When the dislocated foot is seen as one of numerous injuries in a patient with major trauma, management of the other potentially life-threatening injuries takes priority.

When the dislocation is an isolated injury, immobilize the limb to make the patient as comfortable as possible and promptly transport the patient.

Control bleeding with direct pressure and cover any open dislocation with a sterile dressing.

Emergency Department Care

Immediate management may be dictated by concomitant injuries. Assess the neurovascular status of the foot as part of the secondary survey. Consider an urgent reduction of any dislocation that causes significant neurovascular compromise.

In cases of isolated injury, assess and record neurovascular status. Urgent radiographs should be obtained. Make arrangements for referral to an orthopedic specialist for reduction of the dislocation and further management as appropriate.

Remember the possibility of compartment syndrome developing after severe injuries to the foot. Often the signs of compartment syndrome may be initially masked by the severe pain related to the injury. Failure to diagnose this problem can result in serious long-term sequelae for the patient including contractures, deformities, and chronic pain. A high index of suspicion for this complication is required, and measurement of compartment pressures in the foot should be instituted if any findings suggest that this complication is present.

Any open dislocation associated with or without a fracture should typically not be reduced in the ED. Appropriate prophylactic antibiotics should be administered, and the tetanus status of the patient should be updated. Sterile dressings should be applied.

Treatment of subtalar and total talar dislocations include the following:

  • Most subtalar dislocations can be treated with closed reduction under appropriate analgesia and sedation. [14The interposition of soft tissues may prevent reduction, necessitating open reduction. Consider an urgent reduction if significant neurovascular compromise is evident. [15]

  • Total talar dislocations are often open and, as such, should not be reduced in the ED. If a closed injury is present or if urgent reduction is necessary secondary to neurovascular compromise, reduction may be attempted ideally with appropriate consultation available.

  • With the knee flexed, apply longitudinal traction at the foot. Initial accentuation of the injury followed by reversal of the deformity with pressure over the talus may result in reduction. For example, after distraction, apply an abduction force for a medical dislocation.

Lisfranc dislocations frequently require operative reduction. An orthopedic surgeon should be involved in the care of these injuries. ED care typically involves appropriate analgesia, ice, and elevation. [16]

In a study of 31 patients with dislocations and fracture-dislocations of the Lisfranc joint over a 10-year period, outcomes were evaluated based on the Baltimore Painful Foot score (PFS) and American Orthopaedic Foot and Ankle Society (AOFAS) mid-foot scoring scale. Of the surgical treatments, internal fixation with screws had the highest scores. Eight patients (25.8%) developed posttraumatic arthritis of the tarsometatarsal joints. [17]

Dislocations of the toes often can be reduced under local anesthesia (digital block) in the ED with simple longitudinal traction. Dislocations of the first toe may be difficult to reduce.

Consultations

Urgent ED orthopaedic consultation is indicated for subtalar, total talar, and Lisfranc dislocations.

Additionally, first metatarsophalangeal (MTP) and interphalangeal (IP) dislocations that are open or not reducible require orthopedic consultation. Most other MTP and IP dislocations are easily managed by the ED physician.

Complications

One of the major complications of dislocations of the foot involves a failure to make the diagnosis. Some of these dislocations can be subtle, especially those around the Lisfranc joint complex. These dislocations often are missed, resulting in significant morbidity.

Other complications include the following:

  • Infection as a result of compound dislocations or, occasionally, as a postoperative complication

  • Long-term stiffness of the foot

  • Foot pain not specifically localized to one area

  • Secondary osteoarthritis

  • Avascular necrosis, especially of the talus, after a total talar dislocation

  • Damage to the medial plantar nerve with associated wasting of the intrinsic muscles of the foot (rare)

Compartment syndrome injuries are associated with long-term morbidity in a significant proportion of patients.

In one study, 48% of patients with midfoot dislocations (Chopart and Lisfranc joints) had a fair or poor result at follow-up 20-56 months after the injury. Fair or poor in this classification indicated substantial limitation of activities. [18The authors found that the quality of the initial reduction was the major determinant for obtaining an excellent long-term result.



Medication Summary

Administer analgesia as appropriate. Ensure adequate coverage against tetanus. If dislocation is compound, broad-spectrum intravenous antibiotics are required. Generally, a cephalosporin is the drug of choice. Dirty wounds may need the addition of an aminoglycoside to target gram-negative organisms. Injuries heavily contaminated with soil or farmyard waste require penicillin to protect against Clostridium perfringens.

Analgesics

Class Summary

Pain control is essential to 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.

Fentanyl citrate (Duragesic, Sublimaze)

More potent narcotic analgesic with much shorter half-life than morphine sulfate. DOC for conscious sedation analgesia.

With short duration (30-60 min) and easy titration, excellent choice for pain management and sedation. Easily and quickly reversed by naloxone.

After initial dose, subsequent doses should not be titrated more frequently than q3h or q6h.

Oxycodone and acetaminophen (Percocet)

Drug combination indicated for relief of moderately severe to severe pain. DOC for aspirin-hypersensitive patients.

Oxycodone and aspirin (Percodan)

Drug combination indicated for relief of moderately severe to severe pain.

Hydrocodone bitartrate and acetaminophen (Vicodin ES)

Drug combination indicated for relief of moderately severe to severe pain.

Anxiolytics

Class Summary

Patients with painful injuries usually experience significant anxiety. Anxiolytics allow the clinician to administer a smaller analgesic dose to achieve the same effect.

Midazolam (Versed)

DOC for procedural sedation to aid in reduction of anxiety associated with fractures or dislocations. Provides antegrade amnesia. Dose q1-2h.

Sedative hypnotics

Class Summary

Procedural sedation for reductions may require a sedative hypnotic.

Propofol (Diprivan)

Phenolic compound. Sedative hypnotic agent used for induction and maintenance of sedation or anesthesia.

Antibiotics

Class Summary

Prophylaxis is given to patients with compound dislocations.

Cefazolin (Ancef, Kefzol, Zolicef)

First-generation semisynthetic cephalosporin that binds to one or more penicillin-binding proteins, arrests bacterial cell wall synthesis, and inhibits bacterial replication. Primarily active against skin flora, including Staphylococcus aureus. Total daily dosages are same for IV and IM routes.

Gentamicin (Gentacidin, Garamycin)

Aminoglycoside antibiotic used for gram-negative bacterial coverage. Commonly used in combination with both an agent against gram-positive organisms and one that covers anaerobes.

Used in conjunction with ampicillin or vancomycin for prophylaxis in patients with compound dislocations. Dosing regimens numerous and adjusted based on CrCl and changes in volume of distribution. May be given IV or IM.

Vancomycin (Vancocin)

Potent antibiotic directed against gram-positive organisms and active against enterococcal species. Used to treat septicemia and skin-structure infections. Used in conjunction with gentamicin for prophylaxis in patients with penicillin allergy with compound dislocations. May need to adjust dose in patients with renal impairment.

Ampicillin (Omnipen, Marcillin)

Used along with gentamicin for prophylaxis in patients with compound dislocations. Interferes with bacterial cell wall synthesis during active replication, causing bactericidal activity against susceptible organisms. Given in place of amoxicillin in patients unable to take PO medication.

Penicillin G (Pfizerpen)

Interferes with synthesis of cell wall mucopeptide during active replication, resulting in bactericidal activity against susceptible microorganisms.


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