Dislocated Ankle (Ankle Dislocation)
A dislocated ankle means the tibia and talus no longer maintain their normal anatomic relationship.
The ankle is a hinge joint that connects the lower leg to the foot. The tibia and fibula come into contact with the talus, forming the ankle mortise. The majority of weight-bearing occurs between the tibia and talus. While the shape of the mortise helps align the ankle joint, ligaments are important for stability.
A dislocated joint occurs when bones that form a joint no longer maintain their normal relationship. In the ankle, it means the tibia and talus no longer maintain their normal anatomic relationship.
A dislocated ankle is commonly associated with fractures of the distal ends of the tibia and fibula (malleolus) along with damage to the ligaments that support the ankle joint. Isolated ligament injuries can also result in dislocation.
Causes and risk factors for a dislocated ankle?
Ankle dislocations result from trauma. Forces cause fractures or ligament tears, resulting in the dislocation injury.
The ankle is a stable joint and dislocation direction depends on foot position and force application. Ankle dislocations are often associated with joint fractures.
Common causes of dislocations include falls, motor-vehicle crashes, and sports injuries.
The most common type of ankle dislocation is posterior dislocation, occurring when the foot is plantarflexed (toes pointing downward) during injury. The ankle is forced inward (inversion) or outward (eversion), tearing the ligaments and destabilizing the ankle.
Anterior dislocations occur when the talus is pushed forward and the foot is dorsiflexed (toes pointed upward). The force from the front pushes the tibia backward.
Lateral dislocations occur when the ankle is twisted, either inverted or everted, with associated fractures of the medial or lateral malleolus.
Superior dislocation refers to the talus being jammed upward into the space between the tibia and fibula, resulting from an axial loading injury. This is known as a pilon injury and can occur from landing on one’s feet or from a car accident where the foot is pressed against the brake pedal.
Symptoms of a dislocated ankle
Dislocations are painful and cause obvious deformity of the ankle joint. Walking or standing may be difficult or impossible.
Nerve damage or inflammation can cause numbness and tingling in the foot.
Immediate swelling and bruising occur in the ankle joint area.
Depending on the injury mechanism, other associated injuries may occur in the foot, knee, or spine.
Diagnosis of a dislocated ankle
A health care professional will take a history to understand injury mechanism and guide treatment. Past medical history and previous ankle injuries are relevant.
Clinical diagnosis of a dislocated ankle is based on the appearance of the ankle. Physical examination determines the abnormal relationship between the tibia, fibula, and talus. Other potential associated injuries in the foot and knee are examined.
Pulses and sensation in the foot are evaluated due to the potential for stretched or damaged blood vessels and nerves during ankle dislocation. Skin complications can occur because stretched skin can lose its blood supply.
X-ray is initially used to evaluate the extent of injury, bone alignment, and fractures. Post-reduction X-ray may be performed to confirm proper realignment of the bones after reduction.
In specific situations, CT or MRI scans may be considered to assess joint surface damage, hidden fractures, and the ligaments and tendons that stabilize the ankle joint.
Treatment for a dislocated ankle
Emergency treatment aims to reduce the ankle dislocation by returning the bones as close as possible to their normal position. Gentle traction usually realigns the bones. Medication may be used for sedation and muscle relaxation.
If the blood and nerve supply to the foot is at risk or if the skin is tented and stretched, reduction of the ankle joint may be necessary even before taking an X-ray to preserve nerve and blood vessel function.
After reducing the ankle pain, the blood and nerve supply to the foot are re-evaluated, and a temporary plaster or fiberglass splint is applied.
An orthopedic or podiatric consultation may be required, especially if unstable fractures, nerve or artery damage, or the inability to reduce the ankle are present and emergency surgery is needed.
Even if the ankle dislocation is reduced, surgery may be needed later to stabilize damaged structures. The decision for surgery and the type of surgery are individualized based on the patient and their situation.
Recovery time for a dislocated ankle
After initial treatment, rehabilitation may take six to 12 weeks before the patient can return to their normal activities.
Prognosis for a dislocated ankle
Returning to pre-injury function is the goal, but it may not always be achievable for patients who have dislocated their ankle.
Ankle dislocation can damage the blood supply to the joint cartilage, leading to arthritis. Improper bone alignment after injury increases the risk of future arthritis.
Arthritis causes pain, stiffness, and loss of range of motion in the ankle. This can affect gait and other parts of the skeleton, including the hips and back.
Preventing a dislocated ankle
A dislocated ankle is mostly accidental and difficult to prevent.
Risk factors include recurrent sprained ankles, weak muscles around the ankle (especially the peroneal muscle), and diseases that cause hypermobile joints (e.g., Ehlers-Danlos syndrome, Marfan syndrome, Down syndrome).
References:
Richards, P.J., et al. "Ankle Fractures and Dislocations: a Pictorial Review." Trauma. 15.3 July 2013.
Sethi, Manish K., et al. Orthopedic Traumatology: An Evidence Based Approach, 2nd Ed. Switzerland: Springer International Publishing, 2018.
Sethi, Manish K., et al. Orthopedic Traumatology: An Evidence Based Approach, 2nd Ed. Switzerland: Springer International Publishing, 2018.
