In an elderly patient with intense knee pain and suspected osteoarthritis or gout, with limited resources, is a knee X-ray (X-ray) a reasonable initial diagnostic step?

Knee X-ray as Initial Diagnostic Step in Resource-Limited Settings

Yes, knee X-ray is an appropriate and recommended initial diagnostic step for an elderly patient with intense knee pain and suspected osteoarthritis or gout, even in resource-limited settings. 1, 2

Primary Recommendation

Plain radiographs (minimum anteroposterior and lateral views) are the mandatory first imaging study for chronic knee pain and should always be obtained before considering any advanced imaging. 1, 2 This approach is cost-effective and prevents the inappropriate use of MRI, which occurs in approximately 20% of patients who receive advanced imaging without recent radiographs. 1, 2

Age-Based Justification

For your elderly patient, X-rays are particularly justified because:

• Patients ≥55 years old automatically meet Ottawa Knee Rule criteria for radiographic imaging, even without other clinical findings. 3, 2
• The American College of Radiology specifically recommends radiographs for patients in this age group as the initial diagnostic approach. 1, 2

Diagnostic Utility for Suspected Conditions

For Osteoarthritis

• Radiographs effectively detect joint space narrowing, osteophytes, and other structural changes characteristic of osteoarthritis, which are the most commonly reported findings (joint space narrowing appears in 38% of reports). 4
• X-rays provide sufficient information to guide initial conservative management in most cases. 5, 6

For Gout

• While X-rays cannot directly visualize uric acid crystals, they can show joint effusion (coded as M25.461/M25.462/M25.469) and help rule out other pathology. 1
• If radiographs show effusion and gout remains suspected, the effusion code justifies ultrasound-guided aspiration for crystal analysis, which is the definitive diagnostic test for gout. 1

Resource-Appropriate Algorithm

Step 1: Obtain knee X-rays (anteroposterior and lateral views minimum, add tangential patellar view if resources permit). 1, 2

Step 2: If X-rays show:

• Osteoarthritic changes: Proceed with conservative management (pain control, physiotherapy). 6
• Joint effusion only: Consider aspiration for crystal analysis if gout suspected. 1
• Normal findings with persistent pain: Consider referred pain from hip or lumbar spine before ordering MRI. 1, 7

Step 3: Reserve MRI for cases where radiographs are normal or show only effusion but pain persists after 5-7 days, or when mechanical symptoms suggest meniscal/ligamentous injury. 2

Critical Pitfalls to Avoid

• Do not skip radiographs and proceed directly to MRI, as this wastes limited resources and violates evidence-based imaging guidelines. 1, 2
• Do not overlook referred pain sources—if knee X-rays are unremarkable, evaluate hip and lumbar spine clinically before attributing all symptoms to the knee. 1, 7
• Document specific laterality (right/left knee) using codes M25.461/M25.462 rather than unspecified codes to improve diagnostic clarity. 1

Important Caveat About X-ray Limitations

While X-rays are the appropriate first step, be aware that radiographic findings may influence patient beliefs about treatment in potentially undesirable ways—patients shown X-ray images believe surgery is more necessary (mean difference 1.1 points on 0-10 scale) compared to clinical diagnosis alone. 8 When explaining X-ray findings, emphasize conservative management options regardless of radiographic severity.