What is the recommended full workup for knee pain?

Comprehensive Workup for Knee Pain

The optimal workup for knee pain requires a systematic approach including detailed history, physical examination, appropriate imaging, and laboratory tests when indicated, tailored to the patient's specific risk factors, pain characteristics, and clinical presentation. 1

Initial Assessment

History

• Obtain detailed information about:
  • Age (OA more common in patients ≥45 years) 2
  • Location of pain (anterior, posterior, medial, lateral) 3
  • Onset (acute vs. gradual), duration, and quality of pain 3
  • Presence of mechanical symptoms (locking, catching, instability) 2
  • Associated swelling, erythema, or warmth 3
  • History of trauma or injury 3
  • Activity-related pain patterns and morning stiffness (OA typically <30 minutes) 2
  • Previous treatments and their effectiveness 1
  • Impact on daily activities and quality of life 1

Physical Examination

• Conduct a systematic examination including:
  • Inspection for deformity, swelling, muscle atrophy, and skin changes 3
  • Palpation of joint line, patella, and surrounding structures 3
  • Range of motion assessment (active and passive) 3
  • Strength testing of quadriceps and hamstrings 1
  • Neurovascular assessment 3
  • Special tests:
    • McMurray test for meniscal tears (61% sensitivity, 84% specificity) 2
    • Joint line tenderness assessment (83% sensitivity, 83% specificity for meniscal tears) 2
    • Anterior/posterior drawer tests for cruciate ligament integrity 3
    • Valgus/varus stress tests for collateral ligament integrity 3
    • Patellofemoral assessment (squat test - 91% sensitive for patellofemoral pain) 2

Diagnostic Testing

Imaging

• Plain radiographs:

  • First-line imaging for chronic knee pain (>6 weeks) or acute trauma meeting specific criteria 3, 4
  • Standard views: weight-bearing anteroposterior, lateral, and sunrise/merchant views 4
  • Evaluate for fractures, degenerative changes, osteochondral defects, and joint effusions 4

• Advanced imaging (when indicated):

  • Computed Tomography (CT): Best for detailed fracture evaluation in trauma cases 4
  • Magnetic Resonance Imaging (MRI):
    • Reserved for cases when surgery is being considered or when pain persists despite conservative treatment 3
    • Excellent for evaluating soft tissue structures (menisci, ligaments, cartilage) 4
  • Musculoskeletal ultrasound:
    • Useful for evaluating effusions, Baker's cysts, and superficial structures 3
    • Can be used for dynamic assessment and guided interventions 3

Laboratory Tests

• Consider in specific clinical scenarios:
  • Complete blood count, erythrocyte sedimentation rate, C-reactive protein: When infection or inflammatory arthritis is suspected 3
  • Synovial fluid analysis: For suspected infection, crystal arthropathy, or inflammatory conditions 3
  • Rheumatoid factor, anti-CCP antibodies: When rheumatoid arthritis is suspected 5
  • Uric acid: When gout is suspected 5

Special Considerations

Urgent Referral Indications

• Severe pain, swelling, and instability or inability to bear weight after acute trauma 3
• Signs of joint infection (fever, erythema, severe pain, limited range of motion) 3
• Suspected fracture or dislocation 4

Common Pitfalls to Avoid

• Ordering MRI before appropriate clinical evaluation and plain radiographs 4
• Failing to consider referred pain from hip or spine pathology 3
• Attributing all knee pain in older adults to osteoarthritis without ruling out other causes 2
• Recommending surgery for degenerative meniscal tears without an adequate trial of conservative management 2

Management Approach Based on Diagnosis

Osteoarthritis

• First-line: Exercise therapy, weight loss (if overweight), education, and self-management programs 2, 1
• Pharmacological: Start with paracetamol; if ineffective, consider NSAIDs (oral or topical) 1
• Consider intra-articular corticosteroid injections for flares, especially with effusion 1, 5

Patellofemoral Pain

• Hip and knee strengthening exercises, foot orthoses, patellar taping 2
• Avoid unnecessary surgery 2

Meniscal Tears

• Conservative management with exercise therapy for 4-6 weeks for most tears 2
• Consider surgical referral only for severe traumatic tears (e.g., bucket-handle) with mechanical symptoms 2

By following this comprehensive approach to knee pain evaluation, clinicians can make accurate diagnoses and develop appropriate treatment plans that prioritize patient function, quality of life, and long-term outcomes.