Pure Ankle Dislocation: A Rare but Important Orthopedic Injury
Pure Ankle Dislocation is an extremely rare orthopedic injury in which the talus (the bone that forms the lower part of the ankle joint) is displaced from its articulation with the tibia and fibula without any associated fractures. Unlike typical ankle dislocations, which are usually accompanied by fractures, pure ankle dislocation involves only ligamentous disruption. These injuries are rare but significant, often requiring prompt reduction and careful management.
How Common It Is and Who Gets It? (Epidemiology)
Pure ankle dislocations account for:
- 0.065% of all ankle injuries.
- 0.46% of all ankle dislocations.
These injuries are exceedingly rare, with only three confirmed cases documented over a 12-year period at a tertiary hospital with a catchment population of over 1.3 million. The incidence is extremely low, making it difficult to diagnose promptly and challenging to treat due to its rarity.
Why It Happens – Causes (Etiology and Pathophysiology)
Pure ankle dislocations typically result from high-energy trauma such as:
- Motor vehicle accidents.
- Falls from heights.
- Sports injuries, especially from high-impact landings (e.g., football, basketball).
The mechanism generally involves a combination of: - Axial loading (a downward force through the leg).
- Plantarflexion (foot pointing downward).
- Inversion or eversion (twisting inward or outward), which can rupture key ligaments around the ankle.
How the Body Part Normally Works? (Relevant Anatomy)
The tibiotalar joint (where the tibia and talus meet) is integral to the movement of the foot and ankle. This joint allows for dorsiflexion (lifting the foot upward) and plantarflexion (pointing the foot downward). The ligaments surrounding the joint, particularly the lateral collateral ligaments and posterior tibial tendon, provide stability. In a dislocation, the talus is forcibly displaced from the tibia and fibula, which severely compromises the joint’s stability and function.
What You Might Feel – Symptoms (Clinical Presentation)
The symptoms of pure ankle dislocation include:
- Severe pain at the site of the injury.
- Visible deformity or abnormal positioning of the foot.
- Swelling and bruising.
- Inability to bear weight on the injured leg.
- The foot may be rigid and difficult to move, with the talus displaced away from its normal position.
How Doctors Find the Problem? (Diagnosis and Imaging)
Diagnosis is based on:
- Physical examination to assess the deformity and tenderness.
- X-rays to confirm the dislocation and rule out fractures.
- CT scans to detect hidden fractures, particularly in the talus or surrounding bones.
- MRI can be used to assess soft tissue damage, such as ligament tears or osteochondral lesions.
- Neurovascular assessment is crucial, as vascular compromise occurs in 19% of cases.
Classification
Fernandes proposed a classification system for ankle dislocations based on direction and mechanism:
- Type I: Posteromedial/Medial (axial loading, plantarflexion, internal rotation).
- Type II: Lateral (axial loading, plantarflexion, external rotation).
- Type III: Superior (axial loading, dorsiflexion, external rotation).
- Type IV: Anterior (axial loading, plantarflexion, anterior force).
Other Problems That Can Feel Similar (Differential Diagnosis)
Conditions that may mimic pure ankle dislocation include:
- Fractures of the talus or distal fibula.
- Sprains or strains of the ankle ligaments.
- Posterior ankle impingement or subtalar joint dislocation.
Treatment Options
Non-Surgical Care
- Immediate reduction of the dislocated joint under sedation or anesthesia.
- Short leg cast immobilization for 2–6 weeks to allow healing and prevent further injury.
- Physical therapy to restore range of motion and strength after immobilization.
Surgical Care
- Open reduction and possible ligament repair in cases of open dislocations or significant soft tissue damage.
- Neurovascular assessment and surgical debridement if vascular compromise is detected.
- Ligament reconstruction may be necessary in cases of severe instability or chronic dislocation.
Recovery and What to Expect After Treatment
- Non-weight bearing for 2 to 6 weeks depending on the severity of the injury.
- Physical therapy to improve mobility and strengthen the ankle.
- Return to normal activities typically occurs within 3 to 6 months, but full recovery may take longer.
Possible Risks or Side Effects (Complications)
- Infection at the surgical or dislocation site.
- Nerve injury or vascular compromise leading to numbness or weakness.
- Chronic pain, instability, or post-traumatic arthritis.
- Nonunion or delayed healing in rare cases.
Long-Term Outlook (Prognosis)
The prognosis is generally good for closed pure ankle dislocations, with 59% of patients reporting no symptoms after treatment. However, 18% experience ankle stiffness, and 10% develop arthritis. Chronic instability occurs in only 2.7% of cases, especially in those with open injuries or insufficient rehabilitation.
Out-of-Pocket Costs
Medicare
CPT Code 27840 – Ankle Dislocation Treatment (Reduction): $94.15
Medicare Part B typically covers 80% of the approved cost for this procedure once your annual deductible has been met, leaving you responsible for the remaining 20%. Supplemental Insurance plans such as Medigap, AARP, or Blue Cross Blue Shield generally cover the remaining 20%, minimizing or eliminating out-of-pocket expenses for Medicare-approved procedures. These plans work in coordination with Medicare to fill the coverage gap.
If you have Secondary Insurance such as TRICARE, an Employer-Based Plan, or Veterans Health Administration coverage, it acts as a secondary payer. These plans typically cover any remaining balance, including coinsurance or small deductibles, which generally range from $100 to $300 depending on your plan and provider network.
Workers’ Compensation
If your ankle dislocation is work-related, Workers’ Compensation will cover all medical expenses, including the treatment and rehabilitation of your injury. You will not have any out-of-pocket costs, as the employer’s insurance carrier pays for all covered services directly.
No-Fault Insurance
If your ankle dislocation occurred due to an automobile accident, No-Fault Insurance will typically cover the full cost of treatment, including the reduction procedure and follow-up care. The only potential out-of-pocket expense may be a small deductible or co-payment based on your policy.
Example
John Peterson suffered an ankle dislocation during a fall and required treatment (CPT 27840) to reduce the dislocation. His estimated Medicare out-of-pocket cost was $94.15. Since John had supplemental insurance through Blue Cross Blue Shield, his remaining balance was fully covered, leaving him with no out-of-pocket expenses for the procedure.
Frequently Asked Questions (FAQ)
Q. What is an ankle dislocation?
A. An ankle dislocation occurs when the bones that form the ankle joint are forced out of their normal alignment.
Q. What usually causes an ankle dislocation?
A. An ankle dislocation is typically caused by a high-energy trauma, such as a car accident, fall, or sports injury.
Q. Can an ankle dislocation occur without a fracture?
A. Most ankle dislocations are associated with fractures, but they can rarely occur without one.
Q. What are the symptoms of an ankle dislocation?
A. Symptoms include severe pain, visible deformity, swelling, inability to bear weight, and bruising.
Q. How is an ankle dislocation diagnosed?
A. Diagnosis is confirmed through a physical exam and imaging studies, typically X-rays or CT scans.
Q. What is the immediate treatment for an ankle dislocation?
A. The immediate treatment involves realigning the bones, a procedure called reduction, followed by immobilization.
Q. Is surgery required for ankle dislocations?
A. Surgery is often required, especially if the dislocation is associated with fractures or if the joint is unstable.
Q. How long does it take to recover from an ankle dislocation?
A. Recovery time can vary but typically takes several months and may include physical therapy.
Q. Can ankle dislocations lead to long-term complications?
A. Yes, complications such as chronic pain, joint stiffness, instability, and arthritis can occur.
Q. What kind of rehabilitation is needed after an ankle dislocation?
A. Rehabilitation may involve physical therapy to restore strength, flexibility, and range of motion.
Q. Are there any risks associated with untreated ankle dislocations?
A. Yes, untreated dislocations can lead to poor healing, permanent deformity, and loss of joint function.
Summary and Takeaway
Pure Ankle Dislocation is an extremely rare injury that can cause significant pain and functional impairment. Immediate reduction and careful management are key to ensuring the best outcomes.
Early recognition, appropriate imaging, and structured rehabilitation are crucial for successful recovery.
Clinical Insight & Recent Findings
A 2025 case report published in JACEP Open describes a rare instance of pure posterior ankle dislocation without any associated fracture following a trampoline park injury. The patient—a healthy 21-year-old—presented with severe ankle deformity but intact circulation.
Imaging confirmed a posterior dislocation of the tibiotalar joint without bone fracture. After prompt reduction and splinting, the patient transitioned to a walking boot within two weeks and began physical therapy. The case highlights that, although exceedingly uncommon (occurring in just 0.065% of ankle injuries), such dislocations can occur from high-energy or awkward landings even in young, healthy individuals.
Early diagnosis, reduction, and functional rehabilitation typically lead to excellent recovery, underscoring the importance of careful assessment even when fractures are not seen on X-ray. (“Case of trampoline-related ankle dislocation without fracture – see PubMed.”)
Who Performs This Treatment? (Specialists and Team Involved)
Orthopedic surgeons specializing in foot and ankle injuries perform the reduction and manage the treatment of pure ankle dislocations.
The team may include podiatrists and physical therapists for rehabilitation.
When to See a Specialist?
If you experience severe ankle pain, visible deformity, or an inability to bear weight after an injury, seek immediate medical attention. Early reduction is critical.
When to Go to the Emergency Room?
Seek emergency care if:
- Severe deformity or immobility of the ankle joint.
- Signs of infection or vascular compromise, such as coldness, pallor, or absence of pulses.
What Recovery Really Looks Like?
Recovery involves immobilization, followed by physical therapy to regain strength and mobility in the ankle.
Full recovery takes approximately 3 to 6 months, depending on the severity of the injury and rehabilitation progress.
What Happens If You Ignore It?
Ignoring a pure ankle dislocation can lead to permanent instability, chronic pain, and the potential for post-traumatic arthritis.
How to Prevent It?
Preventing pure ankle dislocations focuses on avoiding high-energy trauma and using protective gear in sports and high-risk activities.
Nutrition and Bone or Joint Health
Ensure adequate calcium, vitamin D, and protein intake to support healing after injury and surgery.
Activity and Lifestyle Modifications
Post-surgery, avoid high-impact activities until the ankle has fully healed, and follow a rehabilitation program to restore strength and flexibility.
Dr. Mo Athar
