Development-Dependent Gait Symmetry in Healthy Children: A Systematic Review and Quantitative Synthesis of Reliability and Asymmetry Magnitude

Gait symmetry in healthy children is frequently interpreted as a marker of biomechanical balance; however, its developmental trajectory and measurement stability remain incompletely defined. This systematic review with structured quantitative synthesis aimed to evaluate (i) the reliability of instrumented symmetry measures and (ii) the magnitude of physiological asymmetry across childhood. Following PRISMA guidelines, 500 records were identified, of which 297 met inclusion criteria for qualitative synthesis. Forty-six studies provided extractable numerical data for quantitative integration, representing approximately 9420 participants. Reliability aggregation demonstrated strong repeatability of plantar pressure symmetry measures (ICC = 0.88), whereas stabilometric indices showed lower consistency (ICC = 0.54), highlighting the importance of instrument-aware interpretation. Quantitative synthesis revealed small but consistent asymmetry in healthy children (Hedges’ g = 0.31 for plantar pressure; g = 0.18 for temporal–spatial parameters), with the magnitude decreasing progressively from early childhood to adolescence. These findings indicate that complete bilateral equivalence is not a normative standard in pediatric gait. Instead, symmetry represents a development-dependent continuum shaped by neuromotor maturation and measurement context. Age-specific reference ranges and standardized asymmetry indices are essential for clinical interpretation and future methodological harmonization.