Sit-up Leg Length Test determine if there is Sacroiliac (SI) joint pathology.


  1. Patient supine with leg straight.
  2. Examiner stands at the foot of examination table places one ankle in each hand & evaluates leg length by comparing side to side (maleoli length).
  3. Examiner then instructs patient perform a sit-up (which induces flexion of the hip).


Leg that was shorter supine becomes longer when the patient sits up Sacroiliac joint dysfunction (Posterior Inferior ilium on the leg that went from short supine to long sitting, or an Anterior Superior ilium on the opposite ilium).

Clinical Notes

Clinician Option:

To avoid examiner caused error, examiner may elect not to grip the patient’s ankles as they sit up, but rather simply observe leg length change (helps reduce examiner bias).