What are the initial management steps for pain and swelling above one knee?

Initial Management of Pain and Swelling Above One Knee

Begin with plain radiographs (anteroposterior, lateral, tunnel, and tangential patellar views) to exclude fracture, effusion, and structural pathology, followed by clinical assessment for deep vein thrombosis risk and consideration of joint aspiration if effusion is present. 1, 2

Immediate Diagnostic Workup

Imaging Protocol

• Obtain plain radiographs first (AP, lateral, tunnel, and tangential patellar views) as the initial imaging modality for any patient presenting with knee pain and swelling 3, 1
• Radiographs identify fractures, joint effusion, osteochondritis dissecans, osteoarthritis, and other structural abnormalities that guide subsequent management 3, 2
• Do not order MRI without obtaining radiographs first, as approximately 20% of patients with chronic knee pain inappropriately receive MRI without prior radiographs 1

Critical Red Flag Assessment

• Rule out deep vein thrombosis (DVT) in patients with unilateral leg swelling, as DVT above the knee carries significant risk for pulmonary embolism (50-60% of untreated cases, with 25-30% mortality) 3
• Calculate Wells score and obtain D-dimer if DVT is suspected; if clinical prediction score is low and D-dimer is normal, DVT is unlikely 3
• Perform ultrasound of lower extremity veins if DVT cannot be excluded clinically, as this is the preferred initial imaging for suspected DVT 3

Joint Aspiration Considerations

• Aspirate the joint if significant effusion is present to aid diagnosis and relieve pain 4
• Send aspirate for cell count, Gram stain, culture, and crystal analysis to exclude septic arthritis (which requires urgent surgical consultation) or crystalline arthropathy 4
• Use ultrasound guidance if needed, justified by ICD-10 code M25.46x (effusion) 1

Physical Examination Priorities

Localization of Pathology

• Assess for focal tenderness to localize structural pathology: joint line tenderness suggests meniscal tear (83% sensitivity, 83% specificity), while anterior knee pain with squatting suggests patellofemoral pathology (91% sensitivity) 5
• Examine for mechanical symptoms including locking, catching, or giving way, which distinguish symptomatic meniscal tears from asymptomatic degenerative changes (present in most patients over 70 years) 2, 5
• Evaluate range of motion, effusion, warmth, and erythema to differentiate inflammatory from mechanical causes 3

Inflammatory Markers

• Obtain ESR and CRP if inflammatory arthritis is suspected, particularly if symptoms persist beyond 4 weeks or if joint swelling (synovitis) is present 3
• Consider autoimmune panel (ANA, RF, anti-CCP) if inflammatory arthritis remains in the differential after initial workup 3

Initial Symptomatic Management

First-Line Analgesia

• Start with acetaminophen (paracetamol) as the preferred initial oral analgesic, dosed up to 4 grams daily, which has demonstrated efficacy comparable to NSAIDs for knee pain with superior safety profile 3, 6
• Acetaminophen can be used safely long-term (up to 2 years in studies) with minimal adverse events (1.5%) 3

Second-Line Options

• Escalate to NSAIDs (ibuprofen or naproxen) if acetaminophen is insufficient, using the lowest effective dose for the shortest duration 3, 7
• NSAIDs should be used with caution in patients with cardiovascular risk factors, gastrointestinal history, or renal impairment due to increased risk of adverse events 7
• Consider topical NSAIDs as an alternative with lower systemic side effects and demonstrated efficacy for localized knee pain 3

Adjunctive Measures

• Intra-articular corticosteroid injection is indicated for acute flares of knee pain, especially when accompanied by effusion, providing rapid symptom relief 3
• This can be performed at initial presentation if significant effusion and inflammatory signs are present 3

Advanced Imaging Indications

When to Proceed to MRI

• Order MRI without contrast if radiographs are normal or non-diagnostic and symptoms persist, as MRI has 88% sensitivity and 90% specificity for meniscal tears and accurately depicts cartilage damage and bone marrow lesions 1, 2
• MRI is particularly useful for characterizing osteochondritis dissecans lesions or when concomitant pathology (meniscal tear, ligament injury, cartilage damage) is suspected 3

Common Pitfalls to Avoid

• Do not assume all swelling is intra-articular: consider suprapatellar bursitis, Baker's cyst, cellulitis, or referred pain from hip or lumbar spine pathology 1, 8
• Do not overlook DVT in the differential, particularly in patients with risk factors (immobility, recent surgery, malignancy) presenting with unilateral leg swelling 3
• Document laterality specifically using ICD-10 codes M25.461/M25.462 (right/left knee effusion) and M25.561/M25.562 (right/left knee pain) rather than unspecified codes to improve reimbursement and clinical clarity 1
• Do not order MRI for degenerative meniscal tears in patients over 40 years without first attempting conservative management, as surgery is not indicated even with mechanical symptoms in this population 5