Femoral Head Size in Legg-Calve-Perthes Disease

 

Measurement:

(1) Perform an anteroposterior X-ray of the pelvis with the patient supine and the legs in the neutral position.

(2) Measure the maximal lateral to medial distance in the horizontal plane for the normal femoral head.

(3) Measure the maximal lateral to medial distance in the horizontal plane for the affected femoral head.

 

femoral head size =

= (diameter of the affected femoral head) / (diameter of the normal femoral head)

 

Interpretation:

• The normal femoral head size is closes to 1.

• A femoral head size > 1.1 indicates coxa magna.

 

Limitation:

• The opposite side must be normal, so it is limited to patients with unilateral disease.