What is the most appropriate next step regarding imaging for a patient with persistent posterior ankle pain and mild swelling, who has improved with physical therapy, has full plantar flexion strength, and a negative Achilles squeeze test, and has a history of insidious onset posterior ankle pain with mild fusiform swelling in the mid-Achilles tendon?

Imaging Recommendation for Persistent Achilles Tendinopathy

MRI of the ankle without IV contrast is the most appropriate next imaging study for this patient with persistent mid-Achilles tendinopathy after 3 months of conservative treatment. 1

Clinical Context

This patient presents with classic Achilles tendinopathy (not rupture), evidenced by:

• Insidious onset posterior ankle pain with fusiform mid-tendon swelling 2, 3
• Full plantar flexion strength (intact tendon continuity) 3
• Negative Achilles squeeze test (excludes complete rupture) 2
• Symptoms persisting beyond 6 weeks, meeting criteria for chronic ankle pain 1

Why MRI is the Appropriate Next Step

MRI without IV contrast is the reference standard for comprehensive evaluation of tendon pathology when conservative management has not fully resolved symptoms after 3 months. 1

MRI Provides Critical Diagnostic Information:

• Characterizes the extent and chronicity of tendinopathy, including intratendinous degeneration, partial tears, and peritendinous inflammation 4, 3, 5
• Evaluates bone marrow edema patterns that may indicate insertional pathology or stress injury 1
• Identifies associated pathology such as retrocalcaneal bursitis, paratenonitis, or occult calcaneal stress fractures 3, 5
• Guides surgical planning if debridement or tendon transfer becomes necessary for refractory cases 3, 5

Why Initial Radiographs Are Not Sufficient:

While radiography is appropriate as the initial imaging study for chronic ankle pain 1, this patient has already undergone 3 months of physical therapy with incomplete resolution. Radiographs have limited sensitivity for soft tissue pathology and would likely miss:

• Intratendinous degeneration and partial tears 4, 3
• Peritendinous inflammation and adhesions 5
• Early insertional calcification or bone marrow edema 1, 3

Alternative Imaging Modalities (Less Appropriate)

Ultrasound:

• Not routinely the next study for chronic Achilles tendinopathy evaluation 1
• While US can visualize tendon abnormalities, it is operator-dependent and provides limited assessment of bone marrow and deep structures 1

CT Without Contrast:

• Not routinely used for chronic ankle pain or tendon pathology 1
• CT is reserved for osseous detail when fracture or complex bony anatomy requires evaluation 1

Bone Scan:

• Not routinely used for chronic ankle pain evaluation 1
• Lacks specificity for tendon pathology 1

Clinical Pitfalls to Avoid

• Do not delay imaging beyond 3 months of failed conservative therapy, as this may miss progressive tendon degeneration requiring surgical intervention 3
• Do not assume normal strength excludes significant pathology—partial tears and chronic tendinopathy can present with preserved strength initially 2, 3
• Do not confuse this with acute trauma—the insidious onset and 3-month duration place this firmly in the chronic pain category requiring different imaging algorithms 1