What is the best view for an X-ray (X-ray) of the knee?

Best Views for X-ray of the Knee

The standard radiographic examination for evaluation of the knee should include standing anteroposterior (AP), lateral, and axial/skyline views, with the AP view preferably obtained during weight bearing. 1

Standard Views and Their Purpose

Primary Views (Essential)

• Standing/Weight-bearing AP view

  • Evaluates tibiofemoral joint space
  • Assesses alignment in the coronal plane
  • Detects joint space narrowing, osteophytes, and subchondral changes

• Lateral view (25-30 degrees flexion)

  • Evaluates posterior knee compartment
  • Assesses patellar position and height
  • Detects osteophytes, loose bodies, and joint effusion

• Axial/Skyline/Patellofemoral view

  • Evaluates patellofemoral joint
  • Assesses patellar tracking and tilt
  • Detects patellofemoral joint space narrowing and osteophytes

Supplementary Views (Based on Clinical Indication)

• Weight-bearing PA flexed view (Tunnel view)

  • Better visualizes the intercondylar notch and tibial spines
  • More sensitive for detecting lateral compartment osteoarthritis than AP view 2
  • Improves detection of joint space narrowing and osteophytes 3, 4

• Full-length (hip-to-ankle) weight-bearing views

  • Provides optimal assessment of overall limb alignment
  • Essential for evaluating mechanical axis in suspected malalignment
  • Recommended as a baseline, with subsequent follow-up using targeted knee radiographs 1

Clinical Considerations

Acute Trauma

• For acute knee trauma, evidence suggests that four views (AP, lateral, and two oblique views) are more sensitive (85%) than just AP and lateral views (79%) for fracture detection 5
• When tibial plateau fracture is identified on radiographs, CT is frequently performed for better characterization of fracture severity 1

Osteoarthritis Evaluation

• Adding either a lateral or skyline view to an AP view yields high sensitivity (94-97%) for detecting radiographic osteoarthritis 6
• The PA flexed view better classifies the severity of lateral compartment disease in patients with mild valgus osteoarthritis compared to standard AP view 2
• The combination of weight-bearing AP and tunnel views significantly increases detection of joint space narrowing in both lateral (p<0.001) and medial (p=0.006) compartments compared to AP view alone 3

Post-Arthroplasty Assessment

• For total knee arthroplasty evaluation, standing AP and lateral views plus a tangential axial view of the patellofemoral joint are recommended 1
• AP views obtained in 10° of internal rotation improve interpretation of varus and valgus alignment compared to neutral AP views 1

Common Pitfalls to Avoid

1. Inadequate weight-bearing views: Non-weight-bearing images can miss joint space narrowing
2. Overlooking patellofemoral joint: Failure to include skyline/axial view can miss patellofemoral pathology
3. Poor positioning: Slight variations in positioning can significantly alter the appearance of joint spaces and alignment
4. Incomplete evaluation: Using only AP and lateral views may miss up to 15% of fractures in acute trauma 5
5. Neglecting mechanical axis: For alignment issues, full-length radiographs are necessary for accurate assessment

By following these guidelines for knee radiography, clinicians can optimize diagnostic accuracy while minimizing unnecessary radiation exposure and healthcare costs.