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.

Indications

This view is the ideal projection to assess the presence of knee joint effusion or lipohemarthrosis as it demonstrates the suprapatellar 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.

Patient position

• the patient is supine on the table/bed 

• affected 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 

Technical factors

• 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

Image technical evaluation

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 

Practical points

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.

An interactive case correcting lateral knees can be found here

Correcting rotational errors

• 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

Abduction and adduction

• medial condyle is inferior to the lateral condyle

  • perform adduction

• medial condyle is superior to the lateral condyle

  • perform abduction