Treating Posterior Medial Ankle Pain In A Juvenile Patient After An Ankle ‘Sprain’

These authors detail the diagnosis and treatment of a 10-year-old, who presented with posterior ankle pain that urgent care clinicians originally diagnosed as an ankle sprain.

Each day, approximately 20,000 patients in the United States present with an acute ankle sprain, which is also the most common musculoskeletal injury.¹ The most common mechanisms of ankle injuries are plantarflexion, inversion and external rotation of the tibia. The lateral ligament complex is involved in up to 75 to 90 percent of all sprains.^1-4 Isolated rupture of the deltoid ligament is less common but can coexist with lateral ankle injuries.^4,5

Successful treatment generally occurs with conservative management. However, a subset of patients experience persistent symptoms that are attributable to impingement lesions, ligamentous laxity, osteochondral defects and/or tendinous pathology.^1,4,6,7

When evaluating for posterior medial ankle pain, one should consider the following differential diagnoses: tarsal tunnel syndrome; posterior medial ankle impingement; and tendinopathies of the posterior tibialis, flexor hallucis longus and Achilles tendons. Other differential diagnoses are retrocalcaneal bursitis; Haglund’s deformity; osteochondral defects; fracture of the medial malleolus, talus and/or calcaneus; medial tibial stress syndrome; distal tibial epiphysitis; tumor; and subtalar joint pathology.

A thorough history, exam and diagnostic testing/imaging can help determine the appropriate diagnosis. The purpose of this case study is to evaluate posterior medial ankle pain following a common ankle sprain.

A Closer Look At The Patient Presentation

A 10-year-old healthy female presented to the clinic with a chief complaint of posterior medial ankle pain that started three months prior to the appointment after she suffered an ankle sprain. The patient did not remember the mechanism of injury but recalled “feeling a pop.” She presented to urgent care at that time and radiographs revealed no fracture. The patient received a diagnosis of a sprain and went home with no treatment.

Since then, she had been ambulating but unable to participate in athletic activities. The patient consistently developed moderate swelling by the end of the day, causing her to limp. Home treatments included intermittent icing and children’s Motrin with minimal relief. She denied any prior ankle injuries, functional instability, weakness or neurologic symptoms. The patient denied any recent constitutional symptoms, weight changes or other joint pains. Her mother has a history of psoriatic arthritis.

The patient’s physical exam revealed mild tenderness and edema along the posterior tibialis, flexor hallucis longus and flexor digitorium longus tendons at the retromalleolar level. She had mild tenderness along the medial gutter. There was no tenderness at the deltoid ligament, medial malleolus or distal tibial epiphysis. She had minimal tenderness at the lateral gutter and anterior talofibular ligament. Her ankle range of motion was guarded and she was unable to perform a single heel raise. She had no gross deformities. Her neurovascular status was intact and she had a negative Tinel’s sign.

Weightbearing plain films revealed mild medial soft tissue edema, an open distal tibial physis and no signs of fracture or neoplasm. A magnetic resonance image (MRI) showed a large ankle joint effusion with mild scarring, fibrosis and synovitis along the posterior medial aspect of the joint. There was no tear of the posterior tibialis, flexor hallucis longus or flexor digitorum longus tendons, no tear of the deltoid or spring ligaments, and no osteochondral defect. There was mild irregularity of the anterior talofibular ligament, suggesting a remote injury. She had no pathology of the calcaneofibular ligament or peroneal tendons.

We performed an ankle arthrocentesis, aspirating 5 cc of blood-tinged, clear fluid. Lab results showed no crystals or culture growth. The white blood cell count was 12,000/mm³ with 62 percent polymorphonuclear leukocytes.

We did not provide a diagnostic injection, given our concern for chondrotoxicity. The patient had minimal improvement with a period of immobilization in a controlled ankle motion (CAM) boot. We then decided to proceed with diagnostic ankle arthroscopy and synovial biopsy.

The biopsy report indicated moderate, non-specific chronic synovitis. She had no villiform synovial projections, lymphoid aggregates, rheumatoid nodules or crystal deposition disease. There was no malignancy.

She had immediate relief following arthroscopic debridement, which supports the diagnosis of ankle impingement syndrome. Given her family history, young age and significant development of hypertrophic tissue, we referred her to pediatric rheumatology to rule out any rheumatic diseases.

What You Should Know About Ankle Impingement Syndromes

Ankle impingement syndromes refer to painful restricted ankle joint motion caused by soft tissue or osseous overgrowth, or as a result of nerve entrapment.⁵ Posterior medial impingement syndromes are less common and typically occur after a severe inversion ankle injury in which axial compression and supination of the talus crushes the posterior medial structures between the medial malleolus and the medial wall of the talus.^4-5,7-9 These structures can include the joint capsule, the posterior tibiotalar band of the deltoid ligament, the transverse tibiofibular ligament and the posterior tibialis and flexor hallucis longus tendons.^5-8

After an injury, the inflammatory response begins. This is followed by the formation of thickened, disorganized, fibrous scar tissue that becomes entrapped within the medial gutter and posterior aspect of the medial malleolus. Given the mechanism of injury, these symptoms can coexist with lateral ankle pain and instability. The lateral ligamentous complex also often predominates the initial clinical presentation, obscuring posterior medial symptoms in the early stages of recovery.^4,7,9

One should consider posterior medial impingement syndrome in patients with persistent posterior medial ankle pain following an inversion injury. Perform a thorough history, clinical exam, diagnostic injection and obtain appropriate imaging. When one suspects impingement, diagnostic arthroscopy and synovial biopsy can help further define pathology. Debridement of the impinging soft tissues has demonstrated successful outcomes with improvement of symptoms and functional recovery.^5-7,9-12

Dr. Nguyentat is a Fellow at the Silicon Valley Foot and Ankle Fellowship at the Palo Alto Medical Foundation in Mountain View, Calif.

Dr. Jennings is affiliated with the Department of Orthopedics and Podiatry at the Palo Alto Medical Foundation in Mountain View, Calif. She is a Fellow of the American College of Foot and Ankle Surgeons.

References

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