Should a patient with persistent knee pain and negative X-ray be referred to orthopedics or managed conservatively?

Management of Persistent Knee Pain with Negative X-ray

Patients with persistent knee pain and negative X-rays should initially undergo a trial of conservative management with physical therapy for 6-8 weeks before orthopedic referral, unless specific red flags are present. 1

Initial Assessment After Negative X-ray

When X-rays are negative but knee pain persists, the following approach is recommended:

• Consider MRI without IV contrast as the next appropriate imaging study 2
• Evaluate for:
  • Joint effusion
  • Synovitis
  • Popliteal cyst
  • Subchondral cysts
  • Articular cartilage damage
  • Meniscal abnormalities

Red Flags Requiring Immediate Orthopedic Referral

• Mechanical symptoms (true locking or catching)
• Significant joint instability
• Progressive worsening despite conservative treatment
• Inability to bear weight
• Signs of infection (fever, erythema, warmth)

Conservative Management Protocol

1. Exercise Therapy (First-Line)

• Quadriceps strengthening exercises (priority)
• Hamstring strengthening exercises
• Low-impact aerobic activities (swimming, stationary cycling)
• Hip strengthening exercises 1

2. Pain Management

• Acetaminophen as first-line medication
• NSAIDs (oral or topical) as second-line if acetaminophen insufficient
• Consider topical NSAIDs for patients ≥75 years or with GI concerns 1

3. Supportive Measures

• Simple hinged knee brace for comfort during early rehabilitation
• Consider walking aids if needed
• Prefabricated foot orthoses if indicated 1

4. Lifestyle Modifications

• Weight management for patients with BMI ≥25 kg/m² 1
• Activity modification to reduce knee loading

When to Consider MRI

MRI without IV contrast is indicated when:

• Pain persists despite 4-6 weeks of conservative management
• Clinical suspicion for internal derangement exists
• Mechanical symptoms develop during treatment 2

MRI can accurately detect:

• Bone marrow lesions (associated with increased knee pain)
• Subchondral insufficiency fractures (often missed on initial X-rays)
• Meniscal tears (note: these are often incidental findings in older adults) 2

Referral to Orthopedics

Consider orthopedic referral when:

• Conservative management fails after 6-8 weeks of optimized treatment
• Persistent mechanical symptoms (locking, catching)
• Progressive instability despite rehabilitation
• MRI reveals pathology requiring surgical intervention 1

Important Considerations

• Meniscal tears are often incidental findings in older patients, with the majority of people over 70 having asymptomatic tears 2
• In patients aged 45-55, the likelihood of a meniscal tear being present is similar in both painful and asymptomatic knees 2
• For patients with negative knee X-rays, consider referred pain from hip or lumbar spine pathology 2

Follow-up Protocol

• Re-evaluate after 6-8 weeks of conservative management
• If symptoms improve, continue with physical therapy program
• If symptoms persist or worsen, consider MRI and/or orthopedic referral based on clinical presentation 1

Physical therapy with appropriate pain management should be the initial approach for most patients with persistent knee pain and negative X-rays, reserving orthopedic referral for those who fail conservative management or have specific indications for surgical intervention.