What is the appropriate management for a 17-year-old female presenting with sudden joint pain?

Sudden Joint Pain in a 17-Year-Old Girl

In a 17-year-old female with sudden joint pain, immediately determine whether this is monoarticular or polyarticular, assess for signs of infection (fever, inability to bear weight, severe swelling), and obtain plain radiographs as the mandatory first imaging step before any other intervention. 1, 2

Immediate Assessment Priorities

Rule Out Emergent Conditions First

Septic arthritis is an orthopedic emergency and must be excluded immediately in any adolescent with acute joint pain, fever, or inability to bear weight. 1, 3

• If the hip is involved with fever or severe pain, perform ultrasound-guided aspiration urgently, as septic arthritis requires rapid diagnosis to prevent permanent joint damage 1
• Never inject corticosteroids until infection is definitively excluded—this can cause catastrophic outcomes including tendon rupture and septic spread 3
• Obtain blood cultures if fever is present or there is acute symptom onset 3

Determine Joint Distribution Pattern

The number and pattern of affected joints fundamentally changes your diagnostic approach and workup. 2, 4

• Monoarticular (single joint): Consider trauma, septic arthritis, crystal disease (rare in adolescents), or mechanical derangement 1, 5
• Polyarticular (multiple joints): Suspect viral infection, reactive arthritis, early inflammatory arthritis, or systemic rheumatologic disease 2, 4

Mandatory Initial Imaging

Obtain plain radiographs (minimum two views: AP and lateral) before any other diagnostic or therapeutic intervention. 1, 3

• For knee involvement, obtain AP, lateral at 25-30° flexion, and tangential patellar view to exclude fracture, loose bodies, or chronic pathology 3
• Apply Ottawa Knee Rules: radiographs are mandatory if age >55 years (not applicable here), isolated patellar tenderness, fibular head tenderness, inability to flex to 90°, or inability to bear weight for 4 steps 3
• Approximately 20% of patients inappropriately receive advanced imaging without baseline radiographs—do not skip this step 3

Initial Laboratory Workup

For Monoarticular Pain with Concern for Infection

Perform joint aspiration with synovial fluid analysis (cell count, Gram stain, culture, crystal analysis) if septic arthritis is suspected. 2, 6

• Ultrasound of the hip allows quick diagnosis of joint effusion and can guide aspiration 1
• A false-negative ultrasound is uncommon but can occur within 24 hours of symptom onset 1

For Polyarticular Pain or Inflammatory Symptoms

Order CBC, ESR or CRP, rheumatoid factor (RF), anti-CCP antibodies, and ANA as the initial laboratory panel. 2, 6

• ESR or CRP quantifies inflammation and predicts persistent/erosive disease 2
• RF and anti-CCP positivity predict severe disease and poor prognosis in rheumatoid arthritis 2
• Morning stiffness >30 minutes supports inflammatory rather than mechanical causes 2
• Swollen metacarpophalangeal (MCP) or metatarsophalangeal (MTP) joints strongly suggest inflammatory arthritis 2
• A positive "squeeze test" (pain with compression of MCP or MTP joints) indicates inflammatory joint involvement 2

Add HLA-B27 testing if symptoms suggest reactive arthritis or affect the spine (seronegative spondyloarthropathy). 2, 6

Common Pitfalls in Laboratory Interpretation

Infections (mononucleosis, cytomegalovirus, parvovirus) can cause false positive RF, as can other autoimmune diseases and vasculitis. 2

• Always interpret RF in conjunction with anti-CCP and clinical findings 2
• Palpable synovitis (warm, swollen joints) indicates true inflammation 2

Advanced Imaging Indications

When to Order MRI

Order MRI without contrast if radiographs show fracture/bony abnormality, or at 5-7 days if symptoms persist with normal radiographs. 3

• MRI has 96% sensitivity and 97% specificity for detecting meniscal tears 3
• Indications include: inability to bear weight after 5-7 days, mechanical symptoms suggesting meniscal injury, joint instability suggesting ligamentous injury, or knee effusion >10 mm on lateral radiograph in patients <40 years old 3
• MRI is superior to CT for evaluating bone marrow lesions and ligamentous injuries 3

When Ultrasound or MRI Complements Radiographs

Use ultrasound with power Doppler or MRI when clinical examination is equivocal or to detect early synovitis not visible on plain films. 2, 6

Initial Management Strategy

Conservative Management for Traumatic Effusion with Normal Radiographs

If radiographs are normal and the patient has traumatic effusion but can bear weight fully and perform straight leg raise without difficulty, conservative management with close observation is appropriate. 3

Pharmacologic Management

Consider NSAIDs (such as naproxen 500 mg twice daily) after evaluating gastrointestinal, renal, and cardiovascular status. 2

• Acetaminophen is appropriate for mild pain without significant inflammation 1
• Avoid starting DMARDs (like methotrexate) until rheumatology consultation, as these require specific monitoring protocols and should be initiated by specialists 2

When to Refer to Rheumatology

Refer to rheumatology within 6 weeks of symptom onset if arthritis involves more than one joint with swelling not caused by trauma or bony enlargement. 2, 6

• Earlier treatment initiation improves outcomes in inflammatory arthritis 2
• Refer sooner if symptoms persist despite initial management or if there are systemic symptoms 6

Specific Considerations for Adolescents

In adolescent girls, consider sacroiliac joint misalignment, especially in young athletes with low back pain that mimics radiculopathy. 7

• Development of the pelvic girdle makes the SI joint prone to misalignment in adolescent girls 7
• Repeated stress from athletics can result in lasting pain from even minor trauma 7

Juvenile idiopathic arthritis (JIA) is the most common chronic rheumatic disease in childhood and presents with persistent pain as the most common symptom. 8

• Pain in JIA is multifactorial and significantly impacts physical, emotional, social, and school functioning 8
• A multi-modal approach including aggressive treatment of underlying disease, physical therapy, and psychological interventions is recommended 8