Lateral knee positioning

Case contributed by Mr Andrew Murphy

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 whilst the lateral condyle has a lateral condylopatellar sulcus. 

When the resultant image does not demonstrate superimposition of the two condyles in the rotational plane, look out for these anatomical landmarks to determine if the knee needs to be externally or internally rotated. 

 

Annotated image

Ideal horizontal beam lateral

Condyles perfectly aligned, no adjustments need to be made.

Although these lateral knee radiographs are of diagnostic quality, they can still be used as a teaching point.

Annotated image

Medial abductor tubercle superimposed

Medial abductor tubercle is overly superimposed; the leg must be internally rotated slightly to achieve correct superimposition of the condyles.

Annotated image

Medial abductor tubercle in profile

Medial abductor tubercle is not superimposed . Hence, the leg must be externally rotated slightly to achieve correct superimposition of the condyles.

Annotated image

Medial abductor tubercle superimposed

Medial abductor tubercle is overly superimposed; the leg must be internally rotated slightly to achieve correct superimposition of the condyles. Note the comminuted fracture of the patella in this case. 

Case Discussion

To summarise, if the medial adductor tubercle free from superimposition,rotate the knee externally

If the lateral condyle significantly superimposes the medial adductor tubercle the knee must be internally rotated.

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Case information

rID: 48121
Case created: 20th Sep 2016
Last edited: 26th Sep 2016
Inclusion in quiz mode: Excluded

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