The effect of age and sex on the cervical range of motion - A systematic review and meta-analysis.
Cervical-flexibility examination is routinely performed in neck-pain patients. However, diagnosis of cervical-flexibility impairment requires physiological reference values, which vary widely among the population. Although there is a general understanding that the cervical range of motion (RoM) alters with age and sex, the consolidated details of these variations remain lacking. A systematic review and meta-analysis was performed to evaluate the difference of cervical RoM in different age and sex populations. The quality-assessment tool for quantitative studies was applied to assess methodological quality. We identified 4,034 abstracts through a database search and 3 publications through a manual search. Thirty-four cross-sectional studies were selected for the systematic review and measuring technologies were identified. The difference in age descriptions was substantial and a strong discrepancy existed between the mobility measured by radiological and non-radiological devices. Therefore, only 11 non-radiological studies with similar age descriptions were selected for meta-analysis. Cervical RoMs varied considerably among the populations and generally decreased with age. However, this diminishment started earlier and ended later in males, and was not continuous across age in both sexes. Females normally displayed a greater RoM than males, except in lateral bending. In young subjects, the difference between males and females was not significant. For subjects in their 50s, males displayed a non-significantly greater RoM than females. The variability of cervical RoMs can be explained by different devices as well as age and sex. However, the age-dependent reduction is not continuous and differs between males and females. These findings lay the foundation for a better understanding of the incidence of age- and sex-dependent cervical disorders, and may have important implications for the long-term success of different clinical interventions.