Limited associations between passive range of motion and gross motor function in ambulant/semi-ambulant children and adolescents with cerebral palsy: A cross-sectional study

Background and aim: Cerebral palsy (CP) is the most common childhood motor disability, and the Cerebral Palsy Follow-Up Program (CPUP) in Nordic countries uses a traffic light system for passive range of motion (ROM) assessment to aid interpretation and guide decisions regarding interventions. However, the arbitrary chosen ROM threshold values and their potential clinical impact are uncertain. We investigated whether lower extremity ROM values were positively associated with gross motor function and whether gross motor function scores differ between the CPUP ROM thresholds. Methods: This was a cross-sectional analysis of CPUP data for 841 ambulatory children and adolescents with CP, at a mean (SD) age of 9 (3). Regression analyses were employed to explore the relationship between gross motor capacity and performance (using the Gross Motor Function Measure (GMFM-66) and the Functional Mobility Scale (FMS) 5/50/500 m, respectively) and lower extremity ROM, measured with a goniometer. ROM was assessed both as continuous and categorical variables. Results: We found that two out of ten continuous ROM measures were positively associated with gross motor function. Limited differences in gross motor function between the ROM thresholds were seen for seven out of ten ROM measures. The CPUP traffic light thresholds primarily differentiated gross motor function between the red and green categories, predominantly for the subgroup of participants with bilateral spastic CP. Conclusion: Limited associations between passive ROM and gross motor function in children and adolescents with CP were observed, indicating that there is more to consider than ROM when identifying whether interventions are needed.