Interspinous gap change during lumbar flexion-extension motion for the detection of lumbar instability. Inspection of the low back to detect interspinous gap change. The patient is asked to stand with his/her feet shoulder-width apart, flex their back and place both hands on an examination table. The examiner inspects the patient’s back at flexion, focusing on the gaps between interspinous processes (A). Palpation of the low back at flexion. The examiner palpates individual interspinous spaces of the patient’s back and evaluates the width of individual interspinous spaces and the position of the upper spinous process in relation to the lower spinous process (B). Palpation of the low back at extension. The patient is asked to extend his/her upper body and push their buttocks toward the examination table as both hands are on the examination table, which reproduces lumbar extension from the flexion state. During this motion, the examiner evaluates interspinous gap change (C).