Knee (horizontal beam lateral view)

Last revised by Andrew Murphy on 28 Oct 2021

The horizontal beam lateral view (cross-table lateral) is an orthogonal view of the AP view of the knee requiring little to no patient movement and is hence the lateral projection of choice for acute knee injuries.

This view is the ideal projection to assess for lipohemarthrosis as it demonstrates the region of subpatellar bursa and associated fat pads for possible displacement or presence of fluid levels from knee pathology 1. Knee pathology can include fracture or dislocation of the femur, tibia, fibula or patella.

  • the patient is supine on the table/bed 
  • affect knee is flexed slightly ≈ 30° (to the best of patient's ability)
  • the detector is placed against the medial side of the knee running parallel to the affected leg, often held by the patient or sandbags 
  • the long axis of the femur is running perpendicular to the beam 
  • lateromedial projection
  • centering point
    • center to the knee joint 1.5-2.0 cm distal to the apex of the patella or at the tibial tuberosity if the patella is affected by certain injury patterns
  • collimation
    • superior to include the distal femur
    • inferior to include the proximal tibia/fibula
    • anterior to include the skin margin 
    • posterior to include skin margin
  • orientation  
    • landscape
  • detector size
    • 35 cm x 43 cm
  • exposure
    • 60-70 kVp
    • 7-10 mAs
  • SID
    • 100 cm
  • grid
    • no

A true horizontal beam lateral projection will have the following characteristic:

  • superimposition of the medial and lateral condyles of the distal femur 
  • an open patellofemoral joint space 
  • slight superimposition of the fibular head with the tibia 

The distal femoral condyles have distinct features that can be used for differentiation and hence positional errors that can be corrected.

The medial condyle has a medial adductor tubercle, located superior to the medial epicondyle,  a bony protuberance that acts as the attachment point the adductor minimus and the hamstrings part of the adductor magnus.
The lateral condyle has the condylopatellar sulcus also known as the lateral notch, a groove in the lateral femoral condyle. The easy way to remember is femoral is flat.

  • medial adductor tubercle is posterior to the lateral condyle
    •  rotate the knee externally to bring it anterior
  • medial adductor tubercle is anterior to the lateral condyle
    • rotate the knee internally to bring it posteriorly
  • medial condyle is proximal to the lateral condylar
    • perform adduction
  • medial condyle is distal to the lateral condyle
    • perform abduction

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Cases and figures

  • Figure 1: horizontal beam lateral
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  • Figure 2: projection requiring caudal angle
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  • Figure 3: medial adductor tubercle in profile
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  • Figure 4: medial adductor tubercle in profile
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  • Figure 5: medial adductor tubercle seen anterior in the rotational plane
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  • Case 1: normal knee
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  • Case 2: normal knee
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  • Case 3: normal knee
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