What is the management for a 6-year-old with left knee pain following a fall?

Management of Left Knee Pain in a 6-Year-Old After a Fall

Obtain knee radiographs (anteroposterior and lateral views) if the child has focal tenderness, effusion, or inability to bear weight; otherwise, radiographs may still be appropriate given the child's age falls outside standard clinical decision rules. 1

Initial Clinical Assessment

Perform a focused examination looking for:

• Focal tenderness at the joint line, patella, or fibular head 1
• Joint effusion (visible swelling or ballottement) 1
• Ability to bear weight (can the child take four weight-bearing steps) 1
• Range of motion (can the child flex the knee to 90 degrees) 1
• Gross deformity, palpable mass, or penetrating injury (these mandate immediate imaging regardless of other findings) 1

Imaging Decision Algorithm

If ANY of the following are present, obtain radiographs immediately:

• Focal tenderness (joint line, patella, or fibular head) 1, 2
• Visible effusion 1
• Inability to bear weight or take four steps 1
• Inability to flex knee to 90 degrees 1
• Gross deformity or palpable mass 1

If NONE of the above are present:

Still consider radiographs because a 6-year-old falls outside the validated age ranges for both Ottawa Knee Rule (≥18 years) and Pittsburgh Decision Rule (<12 years or >50 years), making clinical decision rules less reliable in this age group. 1

Important caveat: The Pittsburgh Decision Rule suggests radiographs for children <12 years old regardless of clinical findings, which would include this 6-year-old patient. 1

Standard Radiographic Views

When imaging is indicated, obtain:

• Anteroposterior view 1
• Lateral view with knee at 25-30 degrees flexion in lateral decubitus position (demonstrates patella in profile and allows evaluation for joint effusion) 1
• Cross-table lateral view with horizontal beam if available (visualizes lipohemarthrosis, which indicates intra-articular fracture) 1

If Radiographs Are Negative But Clinical Suspicion Remains High

MRI knee without IV contrast is the next appropriate imaging study for skeletally immature children when radiographs do not show fracture but there is concern for: 1

• Occult fracture 1
• Internal derangement (meniscal tears, ligament injuries) 1, 3
• Bone marrow edema or contusions 3

MRI is superior to CT for detecting bone marrow edema, occult fractures, meniscal tears, and ligament injuries in pediatric patients. 2, 4

Common Pitfalls to Avoid

• Do not rely solely on ability to bear weight to exclude fractures—focal tenderness alone is sufficient indication for radiographs. 1, 2
• Do not skip imaging in children ages 5-12 years even with minimal symptoms, as they fall into a gray zone where clinical decision rules are less validated. 1
• Do not use CT as initial imaging—it is not routinely appropriate for acute knee trauma evaluation in children. 1
• Do not use MRI as first-line imaging—radiographs must be obtained first. 1
• Physician judgment should supersede clinical guidelines when clinical concern warrants more imaging, not less. 1, 2

Conservative Management If Imaging Is Normal

If radiographs are normal and clinical examination is reassuring:

• Activity modification and rest 5
• Ice application 6
• Anti-inflammatory medications as appropriate 6
• Follow-up in 2-3 days if symptoms persist or worsen 7
• Return precautions for increased pain, swelling, inability to bear weight, or new deformity 7