What is the best course of treatment for a 40-year-old female patient complaining of bilateral knee pain and difficulty with flexion, with symptoms initially presenting in one knee 3 months prior and recently developing in the other knee?

Bilateral Knee Pain with Flexion Difficulty in a 40-Year-Old Female

Begin with plain radiographs of both knees (AP, lateral, and tangential patellar views) as the initial diagnostic step, followed by targeted treatment based on findings—most likely osteoarthritis or inflammatory arthropathy given the bilateral presentation and age. 1

Initial Diagnostic Approach

Immediate Clinical Assessment

• Rule out urgent conditions first: Check for fever, systemic symptoms, severe swelling, erythema, or inability to bear weight that would suggest septic arthritis or other emergent pathology 2, 3
• Assess pain characteristics: Determine if pain is activity-related with morning stiffness less than 30 minutes (95% sensitive for osteoarthritis in patients >45 years) 4
• Evaluate for referred pain: Hip pathology can present as knee pain—obtain hip radiographs if knee examination is unremarkable but clinical suspicion exists 1
• Consider lumbar spine pathology: If knee radiographs are normal and symptoms persist, referred pain from the lower back must be evaluated 1

Physical Examination Priorities

• Flexion contracture assessment: Measure maximum knee extension with goniometer, as flexion contractures are associated with worse pain, stiffness, and function in a severity-dependent manner 5
• Joint line tenderness: 83% sensitive and 83% specific for meniscal pathology 4
• Effusion detection: Presence of joint effusion may indicate inflammatory process, crystal disease, or infection 1
• Patellofemoral assessment: Anterior knee pain during squat is 91% sensitive for patellofemoral pain syndrome 4

Imaging Strategy

First-Line Imaging

Obtain bilateral knee radiographs including: 1

• Anteroposterior view (standing if possible)
• Lateral view
• Tangential patellar view

Interpretation and Next Steps

If radiographs show osteoarthritis or chondrocalcinosis: 1

• MRI without IV contrast may be appropriate if symptoms are not explained by radiographic findings
• Joint aspiration is appropriate if effusion is present to rule out crystal disease or infection
• CT without IV contrast may be appropriate in specific instances

If radiographs are normal or show only joint effusion: 1

• MRI knee without IV contrast is usually appropriate as the next imaging study
• Consider ultrasound-guided joint aspiration if effusion is present to analyze synovial fluid for crystals or infection 1

Treatment Algorithm Based on Most Likely Diagnoses

For Osteoarthritis (Most Likely Given Age and Bilateral Presentation)

Non-pharmacological interventions (first-line): 1

• Quadriceps strengthening exercises: Statistically significant effect size of 1.05 for pain reduction 1
• Low-impact aerobic exercise: Walking or cycling with effect size of 0.52 for pain relief 1
• Weight loss if BMI ≥25 kg/m²: Results in clinically important functional improvement (WOMAC function subscale 0.69; 95% CI, 0.24-1.14) 1
• Patient education and self-management programs: Reduces pain and increases coping skills 1

Pharmacological interventions: 1

• Oral or topical NSAIDs: Recommended as first-line pharmacologic therapy 1
• Paracetamol (acetaminophen): Can be tried first if NSAIDs are contraindicated, though evidence is limited 1
• Tramadol: Recommended alternative if NSAIDs are not tolerated 1

Interventions NOT recommended: 1

• Acupuncture (strong recommendation against)
• Glucosamine and chondroitin (strong recommendation against)
• Hyaluronic acid injections (not recommended)

Corticosteroid injections: 1

• Evidence is inconclusive for routine use 1
• May provide 1-2 week reduction in synovitis if effusion is present 1
• Can be performed under ultrasound or fluoroscopic guidance 1

For Inflammatory Arthropathy (If Suspected)

If joint aspiration reveals inflammatory or crystal disease: 1

• Synovial fluid analysis is diagnostic
• Power Doppler ultrasound can demonstrate increased synovial blood flow associated with knee pain 1
• Treatment depends on specific diagnosis (crystal disease, inflammatory arthritis)

For Patellofemoral Pain Syndrome (Less Likely but Consider)

If anterior knee pain predominates: 1, 4

• Hip and knee strengthening exercises: Good evidence for pain reduction 1
• Prefabricated foot orthoses: Prescribe if patient responds favorably to treatment direction tests; most beneficial short-term 1
• Patellar taping: Short-term relief of pain with statistically significant effects immediately and 4 days after taping 1
• Education: Challenge inaccurate beliefs, build confidence, explore pain not correlating with damage 1

Critical Pitfalls to Avoid

• Do not order MRI prematurely: Approximately 20% of patients with chronic knee pain have MRI performed without recent radiographs within the prior year 1
• Bilateral structural abnormalities limit diagnostic utility: In patients >70 years, bilateral abnormalities on MRI can be present with primarily unilateral symptoms, limiting ability to discriminate painful from non-painful knees 1
• Do not assume meniscal pathology requires surgery: Conservative management with exercise therapy for 4-6 weeks is appropriate for most meniscal tears, even degenerative ones 4
• Flexion contractures worsen outcomes: Actively measure and address knee extension deficits, as they are independently associated with worse pain, stiffness, and function in severity-dependent manner 5

Referral Considerations

Surgical referral for knee joint replacement: 1

• Consider only for end-stage OA (minimal/no joint space with inability to cope with pain)
• Only after exhausting all appropriate conservative options
• Strong clinical agreement that severely incapacitated patients can have lives transformed by knee replacement 1