What is the diagnosis and management for a patient with unilateral lower leg pain that worsens after prolonged sitting and improves with walking, considering potential vascular causes such as intermittent claudication and peripheral arterial disease (PAD)?

Diagnosis: This is NOT Intermittent Claudication from Peripheral Arterial Disease

The clinical presentation described—unilateral leg pain worsening after prolonged sitting and improving with walking—is inconsistent with vascular claudication and instead suggests neurogenic claudication from lumbar spinal stenosis or venous pathology. 1, 2

Why This is NOT Vascular Claudication

The symptom pattern violates cardinal features of intermittent claudication:

• Pain triggered by sitting (not walking): Vascular claudication must be consistently triggered by walking a reproducible distance, not by static positioning 1, 2
• Improvement with ambulation: Classic claudication worsens with walking and resolves within 10 minutes of rest—the exact opposite of this presentation 1, 2, 3
• Pain pattern contradicts vascular physiology: Ischemic muscle pain requires increased metabolic demand (exercise), not decreased demand (sitting) 2

Most Likely Alternative Diagnoses

Lumbar Spinal Stenosis (Neurogenic Claudication)

• Pain worsens with standing or walking (especially downhill), improves with sitting or forward flexion 1, 4
• Can present unilaterally depending on nerve root compression 3
• Patients often describe relief when leaning forward (shopping cart sign) 1

Chronic Venous Insufficiency

• Heaviness and aching that worsens with prolonged sitting or standing 1
• Improves with walking due to calf muscle pump activation 1
• Look for edema, skin changes, or varicosities on examination 1

Diagnostic Algorithm

Step 1: Measure Ankle-Brachial Index (ABI)

• Obtain resting ABI with or without segmental pressures to objectively exclude PAD 1, 4, 2
• Interpretation: ≤0.90 = PAD confirmed; 0.91-0.99 = borderline; 1.00-1.40 = normal; >1.40 = noncompressible arteries requiring toe-brachial index 1, 4

Step 2: If ABI is Normal (Expected in This Case)

• For suspected neurogenic claudication: Order MRI lumbar spine to evaluate for spinal stenosis 1
• For suspected venous disease: Perform venous duplex ultrasound to assess for chronic venous obstruction 1

Step 3: If ABI is Abnormal (Unlikely Given Symptom Pattern)

• Perform exercise treadmill ABI testing if exertional symptoms persist despite normal resting ABI 1, 4
• This would demonstrate post-exercise ABI drop >20% in true vascular claudication 4

Management Based on Diagnosis

If Neurogenic Claudication Confirmed

• Physical therapy focusing on lumbar flexion exercises 1
• NSAIDs for symptom control 1
• Epidural steroid injections if conservative therapy fails 1
• Surgical decompression for severe, refractory cases 1

If Venous Disease Confirmed

• Compression therapy (20-30 mmHg graduated compression stockings) 1
• Leg elevation when possible 1
• Regular walking to activate calf muscle pump 1

If PAD Unexpectedly Confirmed (ABI ≤0.90)

• Initiate supervised exercise training as first-line therapy 3
• Start statin therapy to improve walking distance 3
• Prescribe antiplatelet therapy (aspirin or clopidogrel) 5
• Consider cilostazol 100 mg twice daily if symptoms persist despite exercise therapy, which improves maximal walking distance by 28-100% 6, 7
• Revascularization only if daily activities severely compromised despite conservative therapy 3

Critical Clinical Pitfall

Do not assume all leg pain is vascular. The ACC/AHA guidelines emphasize that pain not improving with rest violates the cardinal definition of claudication, which must consistently resolve within 10 minutes of stopping activity 1, 2. Pain that improves with continued walking is a red flag for non-vascular etiology 1.