Clinical validity and stability of active and passive cervical range of motion with regard to total and unilateral uniplanar motion

Study Design. A study of inter- and intra-examiner reliability and clinical validity using two instruments for assessment of spinal range of motion in healthy individuals. Objective. To assess the clinical validity, stability, and normative values for active and passive cervical range of motion as measured by the CA-6000 (Orthopedic Systems Inc., Union City, CA), an electrogoniometer. Summary of Background Data. The authors' early trials with the electrogoniometer yielded values that differed substantially from those in other reports. The authors sought to resolve those discrepancies and understand their sources. Methods. Axial rotations along the transverse, coronal, and frontal planes were measured as half-cycles (i.e., left-right or flexion-extension) that were repeated seven times per trial. Test-retest data were collected on the same healthy individuals for active and passive motion using men and women aged 20-39 years. For validity, simultaneous digital dual inclinometry and electrogoniometry were performed twice over a 1-week interval. In addition, a bench test was performed for validation of axial rotation. Results. Clinical reliability of the CA-6000 was high for inter- and intra-examiner studies of total active motion, and validity was high when compared with that obtained with dual inclinometry. Total range of motion had less between-trial variability than half-cycles, axial rotation and lateral bending measurements had greater reliability than did flexion-extension measurements, and active motion was more reliable than passive motion. Conclusion. The CA-6000 provides valid and reliable measures of cervical range of motion. Discrepancies reported elsewhere appear to have arisen from several sources, as discussed in this article.