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Meta-analysis of normative cervical motion.

STUDY DESIGN
Meta-analysis of normative cervical range of motion literature performed by applying summary statistics to range of motion and reliability values reported among studies.


OBJECTIVES
To identify reliable and valid methods for measuring active and passive cervical range of motion and to estimate normative values.


SUMMARY OF BACKGROUND DATA
Range of motion studies use a variety of measuring instruments and statistical analyses, making it difficult to select the most suitable instruments, procedures, and normative values for clinical application. Reviews of the literature, being limited in scope, have not quantitatively synthesized the literature.


METHODS
Range of motion and reliability data were grouped by technology and types of motion, then summarized by deriving means and variabilities. Clinical validity was assessed by examining discrepancies, variabilities, and correlations. Change in range of motion as a function of age was determined by comparing range of motion ratios (fourth:third and seventh:third decades).


RESULTS
Nine technologies were identified. Overall, passive motion was greater than active motion, and range of motion decreased as age increased, with women exhibiting greater range of motion than men. Variations within each technology were as large as or larger than those between technologies, indicating that clinical procedures are as important as the accuracy and precision of the technology itself. Reliability has not been adequately tested for the majority of technologies.


CONCLUSIONS
Clinical procedures appear to be as important as accuracy and precision in determining the reported range of motion values. Further research is needed to establish a gold standard for normative values and to identify an instrument that is reliable for all motions.