THE INFLUENCE OF BODY-SIZE ON LINEAR MEASUREMENTS USED TO REFLECT CERVICAL RANGE OF MOTION

Background and Purpose. The purposes of the study were to demonstrate that linear measurements of cervical range of motion are confounded by differences in body size when comparisons are made between groups and to introduce an alternative measure of range of motion that adjusts for variation in body size. Subjects. The sample consisted of 42 subjects (25 female, 17 male) with chronic posttraumatic headaches. Methods. Using a tape measure, a physical therapist measured the distance between two anatomical landmarks with the subject's neck in the anatomical neutral position and with the subject's neck fully laterally flexed, rotated, and forward flexed. Range of motion was effected with two measurements: the distance between the landmarks at full flexion/rotation and the proportion of distance traversed between the landmarks. Results. The end-of-range values were significantly correlated with body size. No significant correlations emerged between the proportion-of-distance values and body size. Conclusion and Discussion. Linear measurements of cervical motion are potentially confounded by body size when subjects of nonequivalent size are compared. Proportion-of-distance measurement is presented as a more valid alternative to end-of-range measurement.