Evaluation and Management of Knee Pain in a 13-Year-Old Female
Begin with plain radiographs of the knee (anteroposterior, lateral, and tangential patellar views) as the initial imaging study, then proceed to MRI without contrast if radiographs are normal or show only effusion and pain persists. 1, 2
Initial Diagnostic Approach
Imaging Strategy
- Start with three-view knee radiographs (anteroposterior, lateral, and tangential patellar) for all patients ≥5 years old presenting with knee pain 1, 2
- Proceed to MRI without IV contrast if radiographs are normal or demonstrate only joint effusion but symptoms persist 1, 3, 2
- MRI accurately detects meniscal tears, ligament injuries, articular cartilage abnormalities, bone marrow lesions, and popliteal cysts that may not be visible on radiographs 1, 3
Critical Red Flags to Identify
Rule out emergent conditions first, including:
- Septic arthritis or osteomyelitis (fever, inability to bear weight, severe pain) 4
- Malignancy (night pain, constitutional symptoms, progressive symptoms) 4
- Hip pathology presenting as knee pain (limited hip range of motion, groin pain) 1, 3, 5
- Lumbar spine pathology causing referred pain (back pain, radicular symptoms) 1, 3, 5
Age-Specific Considerations for Adolescents
Common Diagnoses in 13-Year-Old Females
- Patellofemoral pain syndrome (most common cause of anterior knee pain in adolescents) 6
- Osgood-Schlatter disease (tibial tubercle apophysitis) 1
- Sinding-Larsen-Johansson syndrome (inferior pole patella apophysitis) 1
- Patellar instability/dislocation (medial patellar tenderness, apprehension with lateral patellar translation) 1, 7
- Meniscal tears (joint line tenderness, mechanical symptoms) 7
- Osteochondritis dissecans (activity-related pain, possible mechanical symptoms) 1
Physical Examination Priorities
Assess for focal tenderness, effusion, and ability to bear weight to determine imaging urgency 1, 2
Examine the hip and lumbar spine if knee examination is unremarkable, as referred pain is common 1, 3, 5
Evaluate patellar tracking and stability with apprehension testing for patellar instability 1, 7
Management Algorithm
Conservative Treatment (First-Line)
Initiate physical therapy emphasizing:
- Quadriceps and hip strengthening exercises 1, 6
- Neuromuscular education and movement retraining 1, 6
- Load progression and activity modification 6
- Patient education about the condition and pain management strategies 6
Pharmacologic Options
Use NSAIDs (oral or topical) or acetaminophen (≤4 g/day) for pain control unless contraindicated 1
Avoid glucosamine, chondroitin, and acupuncture as they lack evidence of effectiveness 1
When to Advance Imaging
Order MRI without contrast when:
- Radiographs are normal but symptoms persist despite 4-6 weeks of conservative treatment 1, 2
- Radiographs show osteochondritis dissecans, loose bodies, or joint effusion 1
- Clinical suspicion for meniscal tear, ligament injury, or patellar instability exists 1, 7
- Radiographs demonstrate signs of prior injury (avulsion fractures, Segond fracture) 1
Common Pitfalls to Avoid
Do not order MRI without obtaining recent radiographs first (within the past year), as approximately 20% of patients inappropriately receive MRI without baseline radiographs 1, 5, 2
Do not attribute all knee pain to local pathology without examining the hip and lumbar spine, as referred pain is frequently missed 1, 3, 5
Do not assume all imaging findings are symptomatic, particularly meniscal tears in older patients, though this is less relevant in a 13-year-old 1
Do not overlook patellar instability in adolescent females, who are at higher risk for this condition 1, 7
Specialty Referral Indications
Refer to orthopedics when: