Knee XRay

Aka: Knee XRay

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II. Indications

  1. See Knee XRay Indications in Acute Injury

III. Views: Acute Injury Evaluation

  1. Anteroposterior View (Standing if possible)
    1. Distal femur
      1. Medial and lateral epicondyles (extraarticular)
      2. Medial and lateral condyles (intraarticular, articulate with tibial plateaus)
    2. Proximal Tibia
      1. Tibial Spine (ACL and PCL insertions)
    3. Proximal Fibula (including Fibular head)
    4. Patella
  2. Lateral view
    1. Distal Femur
    2. Proximal Tibia
      1. Tibial Tuberosity (Patellar tendon insertion)
    3. Proximal Fibula
    4. Patella
      1. Patella distance from inferior pole to tibial tuberosity
        1. Should be 80% to 120% of Patella length
        2. A shorter distance suggests a low lying Patella (quadriceps Tendon Injury)
        3. A longer length suggests a high riding Patella (Patellar Tendon Injury)
    5. Tendons (visible as linear soft tissue shadows)
      1. Quadripceps tendon (inserts at Patellar superior pole)
      2. Patellar tendon (between Patellar inferior pole and tibial tuberosity)
  3. Axial View (Sunrise View, Merchant View)
    1. Additional view (beyond standard 2 view knee, indicated in Patellar tenderness, pain or deformity)
    2. Axial view at 30 degrees knee flexion
    3. Views patellofemoral joint

IV. Views: Specific Indications

  1. Tunnel or notch view
    1. Postero-anterior view with knee flexed to 50 degrees
    2. Perform standing if possible
    3. Indicated for Osteochondritis Dissecans evaluation
      1. Shows femoral condyle radiolucencies

V. Evaluation: Systematic XRay Review

  1. See Musculoskeletal XRay ABCs
  2. Adequacy and alignment
  3. Bones
  4. Cartilage (joint)
  5. Soft tissues and spacing
    1. Consider rotating lateral images to horizontal (the supine plane in which they were taken)
    2. Observe for joint effusions
    3. Lipohemarthrosis (lipid effusions from Bone Marrow disruption)
      1. Layer out over the surface of tendons forming straight linear edge

VI. Findings: Acute Injury

  1. Fracture
    1. Tibial Plateau Fracture
    2. Patellar Fracture
    3. Fibular Head Fracture
  2. Knee Osteochondral Fracture
    1. Knee Osteochondritis Dissecans
    2. Knee Osteonecrosis
  3. Other findings
    1. Knee Osteoarthritis
    2. Knee Subluxation or Knee Dislocation (Tibial Femoral Dislocation)
    3. Knee loose bodies
    4. Bone Tumor signs

VII. References

  1. Tubbs and Janicki (2025) Adult Lower Extremity - Knee/Hip, Mastering Emergency Imaging, CCME, accessed 5/12/2026

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