Computer-aided video analysis of vertebrofemoral motion during toe touching in healthy subjects.

OBJECTIVE: Despite widespread use of the toe touch test, the relative contribution from vertebral and hip movements has not been clearly established, largely because of unsatisfactory measurement techniques. This study aimed to reinvestigate the kinematics of toe touching by combining computerized videotape analysis with a new model of reference marker placement.
METHOD: Twenty-two subjects were videotaped during active toe touching from upright standing. Computer software was then used to derive the sagittal thoracic, lumbar, and hip angles at .02-sec intervals throughout the movement.
RESULTS: Hip flexion was directly proportional to toe touch distance (TTD) (r2 = .71) but not lumbar flexion (r2 = .17) or thoracic (r2 = .20) excursion. On average there was .8 degree of thoracolumbar flexion for every 1 degree of hip flexion; however, there were wide variations between subjects. In 19 of 22 subjects the thoracic spine flexed and extended relatively equal amounts during the test resulting in a small total thoracic excursion of 4.8 degrees flexion in unsuccessful toe touchers and 4.0 degrees extension in successful toe touchers.
CONCLUSION: The separate contributions of hip, lumbar, and thoracic mobility to toe touching or any other vertebrofemoral motion can only be accurately determined by a measurement strategy that uses the plane of the pelvis to separate vertebral from hip motion and uses tangents at the limits of the thoracic and lumbar regions to separate lumbar from thoracic motion. Using this model the authors found that TTD is not a reliable indicator of either vertebral or hip mobility.