Developmental changes in lower limb joint ranges of motion in Japanese children aged 6-15 years

Assessing lower limb ranges of motion (ROMs) is crucial for diagnosing and treating musculoskeletal and neurological disorders in children. Although prior studies examining decline in flexibility among school-age children suggest potential age-related changes in lower limb ROMs, this hypothesis remains unproven. Therefore, in this study, we aim to examine age-related differences in lower limb ROMs among school-age children.

The passive ROMs in the lower limbs of 572 typically developing children aged 6-15 years were measured by physiotherapists using goniometers. To examine developmental changes in lower limb ROMs, participants were categorized into four groups: 6-7 years (189 participants), 8-9 years (147 participants), 10-11 years (124 participants), and 12-15 years (112 participants).

We observed a consistent trend of decreasing ROMs with age across all measures (hip flexion, popliteal angle, knee flexion, knee extension, ankle dorsiflexion, and ankle plantar flexion), excluding hip extension. Notably, only the popliteal angle exhibited values indicating clinically significant sex differences.

Lower limb ROMs in school-age children generally decrease with age, with notable sex differences observed in the popliteal angle. The lower limb ROM values presented herein can serve as reference values to identify disease- and injury-related changes in lower limb ROMs during this developmental stage.