Noninvasive three-dimensional analysis of cervical spine motion in normal subjects in relation to age and sex. An experimental examination.

STUDY
DESIGN: Experimental examination in vivo.
OBJECTIVES: To determine the precision of the ultrasound-based Coordinate Measuring System (CMS 50; Zebris Medizintechnik GmbH, D-88316, Isny, Germany) and then to establish a reference range for the active range of motion of the cervical spine in normal test subjects grouped according to age and sex. SUMMARY OF BACKGROUND DATA: Many different devices such as inclinometers, goniometers, potentiometers, computer-aided devices, and radiographic procedures have been developed to examine the range of motion of the cervical spine. All of them have more or less inherent limitations.
METHODS: To assess the precision of this examination method, preliminary experiments were performed including intraobserver retest and two-observer repeatability, intraindividual variability, a daily profile, and a comparison between active and passive motions. In the subsequent main experiment 157 persons (86 women and 71 men) were examined during active motion. The sex groups were further subdivided into age groups of 10 years each. A comparison of weight and athletic activity was also performed.
RESULTS: The range of motion decreased with increasing age, increasing body weight, and decreasing athletic activity. The rotation in the upper cervical spine increases with age to compensate for the reduced range of motion in the lower levels. Women showed significantly better mobility than men of the same age, only above the age of 70.
CONCLUSIONS: The CMS 50 device provides precise reproducible measurements of the active range of motion of the cervical spine in all three planes. Criteria such as age, sex, body weight, and athletic activity influence the range of motion of the cervical spine.