What are the best approaches to diagnose and treat chronic ankle pain?

Chronic Ankle Pain: Diagnostic and Treatment Approach

Start with plain radiographs of the ankle (anteroposterior, lateral, and mortise views) as your initial imaging study, then proceed to MRI without IV contrast if radiographs are normal or if you need to evaluate soft tissues, ligaments, tendons, or osteochondral lesions. 1

Initial Diagnostic Workup

First-Line Imaging

• Obtain standard ankle radiographs immediately including anteroposterior, lateral, and mortise views (mortise obtained by internally rotating the foot 15-20 degrees) 1
• Radiographs can identify osteoarthritis, osteochondral abnormalities, stress fractures, prior trauma, calcified intra-articular bodies, ankle effusions (53-74% accuracy), ossific fragments indicating ligamentous injury, and erosions from chronic synovitis 1
• Weight-bearing radiographs provide additional information about stability if the patient can tolerate them 2

Critical Red Flags to Assess Immediately

Before proceeding with standard musculoskeletal evaluation, you must exclude vascular emergencies:

• Check for critical limb ischemia by palpating dorsalis pedis and posterior tibial pulses bilaterally, looking for absent/diminished pulses, elevation pallor, dependent rubor, skin discoloration, ulceration, or tissue loss 3
• Obtain urgent vascular evaluation if pain worsens at rest and improves with leg dependency, especially with diabetes, smoking, renal failure, or known atherosclerotic disease 3
• Perform ankle-brachial index testing if vascular compromise is suspected 3

Advanced Imaging Algorithm

When Radiographs Are Normal

MRI without IV contrast is the next appropriate study for most scenarios with normal radiographs 1:

• For suspected osteochondral lesions: MRI should be ordered next, as radiography misses 41% of osteochondral abnormalities and fails to show cartilage-only injuries 1
• For suspected tendon abnormalities: Either MRI or ultrasound is appropriate, though MRI provides more comprehensive evaluation of deep structures and bone marrow 1, 4
• For suspected ankle instability: Either MRI or MR arthrography should be ordered 1
• For suspected impingement syndrome: MRI without contrast is the study of choice 1
• For pain of uncertain etiology: MRI without contrast should be ordered after normal radiographs 1

When Radiographs Show Degenerative Changes

If multiple sites of osteoarthritis are present on radiographs, determining the pain source becomes critical:

• Image-guided anesthetic injection (fluoroscopy-, CT-, or US-guided) with or without corticosteroid is effective for identifying the specific pain source and aids surgical planning 1
• MRI without contrast is appropriate to evaluate cartilage integrity, bone marrow, and associated soft tissues (ligaments, tendons) if these injuries are clinically suspected 1
• CT without contrast may be helpful specifically to visualize subchondral cysts 1

Modalities NOT Routinely Used First-Line

• CT: Not routinely first-line but more sensitive than bone scintigraphy for impingement syndromes; reserve for osseous detail when fracture or complex bony anatomy requires evaluation 1, 4
• Ultrasound: Not routinely first-line due to operator-dependent nature and limited assessment of bone marrow and deep structures 1, 4
• Bone scan/SPECT-CT: Not routinely used first-line; SPECT/CT can detect osteochondral lesions, occult fractures, or painful accessory bones but lacks specificity 1, 4
• Arthrography, CT arthrography, MR arthrography: Not routinely used for initial evaluation 1

Common Clinical Scenarios

Chronic Achilles Tendinopathy

• After 3 months of failed conservative treatment, MRI of the ankle without IV contrast is the most appropriate next study 4
• MRI evaluates bone marrow edema patterns indicating insertional pathology or stress injury 4
• Avoid corticosteroid injections near the Achilles tendon due to rupture risk 3

Post-Sprain Chronic Pain

• Sequelae from lateral ankle sprains are the most common cause of chronic ankle pain, affecting 20-40% of patients after ankle sprain 5, 6
• Common causes include incomplete rehabilitation, intra-articular lesions (osteochondral and meniscoid lesions), chronic instability, undetected syndesmotic or deltoid sprains, chronic tendon degeneration, and stress fractures 6
• Patients complain of vague lateral/anterolateral pain, giving-way sensation, swelling, stiffness, locking, and crepitation 6

Ankle Instability Assessment

• Gravity stress views are more reliable than manual stress views for evaluating supination-external rotation injuries 2
• A difference >2 mm between standard mortise and gravity stress views indicates instability 2
• Increased instability risk with medial tenderness, bruising, swelling, fibular fracture above syndesmosis, bi/trimalleolar fractures, open fracture, or high-energy injury 2

Treatment Principles

Conservative Management (First-Line)

• Early functional bracing, physical therapy for strengthening, and proprioceptive exercises are preferred for most patients 5
• Neuromuscular rehabilitation, balance training, NSAIDs, manual mobilization, ice therapy, and compression 7
• Control pain and swelling acutely with NSAIDs and RICE (rest, ice, compression, elevation), then restore normal range of motion, strengthen muscle groups, and retrain proprioception 8
• Daily pain medications or full immobilization devices are rarely necessary 5

When Conservative Management Fails

• Consider minimally invasive options including arthroscopic surgery, steroid injections, plasma-rich plasma injections, hyaluronic acid injections, radiofrequency therapies, and shockwave therapies 7
• Image-guided nerve blocks can be helpful for diagnostic purposes and surgical planning 1

Key Clinical Pitfalls

• Missing vascular emergencies: Always check pulses and assess for critical limb ischemia before attributing pain to musculoskeletal causes 3
• Underutilizing MRI: Radiography misses significant pathology including 41% of osteochondral abnormalities and most soft-tissue injuries 1
• Ordering advanced imaging too early: Always start with plain radiographs—they're diagnostic in many cases and guide subsequent imaging 1
• Incomplete rehabilitation: This is the most common cause of chronic pain after ankle injury 6
• Missing reflex sympathetic dystrophy: Look for discoloration, glossy skin, and temperature changes, which can occur even after minor trauma 6