What is the diagnosis and treatment for a 41-year-old female with left leg muscle pain radiating posteriorly from the knee up the back of the leg?

Diagnosis: Lumbar Radiculopathy (Sciatica)

This 41-year-old woman has lumbar radiculopathy, most likely from L5 or S1 nerve root compression, given the posterior leg pain radiating from knee upward along the sciatic nerve distribution. 1, 2

Clinical Presentation and Differential

The posterior leg pain radiating from the knee upward is the classic distribution of sciatica, representing nerve root compromise from mechanical pressure or inflammation. 1 This pattern differs from:

• Piriformis syndrome - which causes buttock pain radiating down the posterior thigh, typically worsened by sitting, with pain on hip flexion/adduction/internal rotation and negative straight leg raise 3
• Spinal stenosis - which presents with bilateral leg symptoms relieved by sitting/spine flexion, more common in patients >65 years 4
• Hip pathology - which would cause lateral hip/thigh pain without radiation below the knee 1
• Peripheral artery disease - which causes claudication with walking that resolves with rest, associated with diminished pulses 1

The posterior distribution from knee upward suggests L5 or S1 radiculopathy rather than L4, which would cause anterior/lateral thigh and lower leg pain. 2

Initial Diagnostic Approach

Do not obtain immediate imaging unless severe or progressive neurological deficits develop. 2 The straight-leg raise test (positive between 30-70 degrees) has 91% sensitivity for herniated disc and should be performed. 4

Critical Red Flags Requiring Urgent Evaluation:

• Progressive motor weakness (foot drop for L5, plantarflexion weakness for S1) 2
• Bladder or bowel dysfunction 2
• Saddle anesthesia suggesting cauda equina syndrome 4
• Severe or progressive bilateral leg weakness 4

Physical Examination Priorities:

• Straight leg raise test (30-70 degrees) 4
• L5 assessment: great toe and foot dorsiflexion strength 4
• S1 assessment: plantarflexion strength and ankle reflexes 4
• Sensory testing in dermatomal distribution 1

Treatment Algorithm

First 4-6 Weeks (Conservative Management)

The natural history shows improvement within the first 4 weeks with noninvasive management in most patients. 2

Pharmacologic treatment:

• NSAIDs as first-line: optimize dosing to 600-800mg ibuprofen three times daily (not just twice daily) 2, 4
• Acetaminophen as alternative first-line option 4
• Skeletal muscle relaxants as second-line 4
• Consider gabapentin early - it has potential to prevent central sensitization and has shown efficacy in sciatica case reports, starting 300mg once daily and titrating to 900mg three times daily as tolerated 5

Non-pharmacologic treatment:

• Continue activity as tolerated - remaining active is more effective than bed rest 2, 4
• Superficial heat application 4
• Spinal manipulation 4

Imaging Indications

MRI is indicated only if:

• Symptoms persist beyond 4-6 weeks despite conservative management AND patient is a candidate for epidural steroid injection or surgery 2
• Red flags are present 2

MRI is superior to CT for visualizing nerve roots and soft tissues without radiation exposure. 4 Over 90% of symptomatic lumbar disc herniations occur at L4/L5 and L5/S1 levels. 2

If Conservative Treatment Fails After 6 Weeks

For subacute radiculopathy with contained herniation:

• Transforaminal corticosteroid administration (evidence level 2B+) 6

For chronic radiculopathy:

• Pulsed radiofrequency treatment adjacent to the dorsal root ganglion (evidence level 2C+) 6
• Adhesiolysis and epiduroscopy for refractory cases (evidence level 2B+/-) 6

Reassessment Timeline

Reevaluate at 1 month if symptoms persist without improvement. 2, 4 Earlier reassessment is warranted if:

• Neurological deficits develop 2
• Pain becomes severe and refractory 2
• Any red flag symptoms emerge 2

Common Pitfalls to Avoid

• Do not prescribe prolonged bed rest - maintaining activity reduces disability 4
• Do not obtain routine imaging without red flags - it exposes patients to unnecessary radiation without clinical benefit 4
• Do not assume negative straight leg raise excludes radiculopathy - it has 91% sensitivity, missing 9% of true cases 2
• Do not ignore psychosocial factors (depression, job dissatisfaction, passive coping) - they predict worse outcomes and delayed recovery 4
• Do not delay urgent evaluation if cauda equina syndrome is suspected - this is a medical emergency requiring immediate MRI and surgical consultation 4