What are the treatment options for a 7-year-old with a knee injury?

Management of Knee Injury in a 7-Year-Old Child

For a 7-year-old with an acute knee injury, obtain knee radiographs (anteroposterior and lateral views) if the child has focal tenderness, knee effusion, or inability to bear weight; if radiographs are negative but significant injury is suspected, proceed to MRI without IV contrast to evaluate for occult fractures or internal derangement. 1

Initial Clinical Assessment

Evaluate for the following key clinical findings that determine imaging needs:

• Focal bony tenderness (particularly over the patella, tibial tubercle, or fibular head) 1
• Knee effusion (visible swelling or ballottement) 1
• Inability to bear weight (cannot take four weight-bearing steps) 1
• Inability to flex knee to 90 degrees 1
• Gross deformity, palpable mass, or penetrating injury (these override clinical decision rules and mandate immediate imaging) 1

Important caveat: A 7-year-old falls outside the validated age ranges for both Ottawa Knee Rules (≥18 years) and Pittsburgh Decision Rules (<12 or >50 years), so radiographs may be beneficial even without classic clinical symptoms if there is any concern for fracture. 1

Imaging Algorithm

Step 1: Initial Radiography

Obtain knee radiographs if any of the above clinical findings are present: 1

• Minimum of two views: anteroposterior and lateral 1
• Lateral view should be obtained with knee at 25-30 degrees flexion to visualize joint effusion and lipohemarthrosis 1
• Consider additional patellofemoral view if patellar injury suspected 1

Step 2: Advanced Imaging if Radiographs Negative

If radiographs show no fracture but clinical suspicion remains high for significant injury, MRI knee without IV contrast is the next appropriate study: 1, 2

• MRI is particularly important in skeletally immature children (like a 7-year-old) to detect occult fractures, ligamentous injuries, and meniscal tears 1
• Critical consideration: 70% of children aged 9-14 with traumatic knee hemarthrosis have serious intra-articular injuries, and 56% of these show no visible injury on plain radiographs 3
• MRI can identify lateral patellar dislocations, ACL injuries, tibial spine fractures, and meniscal tears that are radiographically occult 2, 3

Treatment Based on Findings

If Radiographs Show Fracture:

• Tibial plateau fracture: Consider CT or MRI without IV contrast to evaluate extent of bone and soft-tissue injury 1
• Tibial spine fracture or other displaced fractures: Orthopedic referral for potential surgical management 3

If MRI Shows Soft-Tissue Injury:

Ligamentous injuries: 2, 4

• MCL injuries (Grades I-II): Non-operative management with bracing and physical therapy
• MCL Grade III: May require surgical repair if unstable 2
• ACL tears: Complete tears typically require surgical reconstruction, especially in active children 2
• PCL injuries: Surgical intervention for multi-ligament injuries or persistent instability 2

Meniscal tears: 4

• Most acute traumatic meniscal tears can be managed non-operatively initially
• Recent evidence shows non-operative treatment can be as successful as surgery at 1 year 4

Patellar dislocation: 2, 4

• Short period of knee bracing in extension
• Progressive weight-bearing as tolerated 2, 4
• Trial of conservative therapy can give good results and avoid surgery 5

If Significant Trauma or Knee Dislocation Suspected:

• Evaluate for vascular injury with CTA lower extremity with IV contrast 2
• Popliteal artery injuries require prompt surgical intervention 2

Key Clinical Pitfalls to Avoid

• Do not rely solely on radiographs in children with hemarthrosis or significant mechanism of injury - serious intra-articular injuries are frequently radiographically occult 3
• Do not apply Ottawa or Pittsburgh rules rigidly to 7-year-olds - they fall outside validated age ranges and may benefit from imaging despite lack of classic criteria 1
• Always consider hip pathology presenting as knee pain in this age group 6
• Monitor for osteonecrosis in cases of severe bone marrow edema/contusions on MRI 2
• Physician judgment should supersede clinical guidelines when gross deformity, altered mental status, multiple injuries, or unreliable examination exists 1