Balance Performance After Mild Traumatic Brain Injury in Children and Adolescents: Instrumented BESS in the Acute Situation and Over Time.

: Mild traumatic brain injury (mTBI) in the pediatric population is a significant public health concern, often associated with persistent post-concussion symptoms, including postural instability. Current tools for assessing postural control, such as the Balance Error Scoring System (BESS), lack integration with objective metrics. Incorporating force plate sensors into BESS assessments may enhance diagnostic accuracy and support return-to-play or sports decisions. This study evaluates postural performance in children with mTBI compared to controls using an instrumented BESS and examines recovery trajectories after mTBI. : This prospective, longitudinal study included 31 children with mTBI (12.01 ± 3.28 years, 20 females) and 31 controls (12.31 ± 3.27 years, 18 females). Postural control was assessed using an instrumented BESS protocol during standing on a ground reaction force plate at three timepoints: within 72 h post injury (T1), at two weeks (T2), and three months after trauma (T3). Posturographic parameters derived from the displacement of the center of pressure included the ellipse area, path length, and mean velocity in the anterior-posterior and medio-lateral directions. Symptom burden was monitored using the Post-Concussion Symptom Inventory (PCSI). : The BESS total scores did not differ significantly between the groups at any timepoint. A significant reduction in BESS errors over time was observed exclusively in the two-legged stance on a soft surface ( = 0.047). The instrumented BESS revealed higher body swaying in the mTBI group compared to controls, particularly under demanding conditions. Significant between-group differences were most frequently observed in single-leg soft surface (38% of comparisons) and two-legged soft surface stances (29%). In those cases, path length and mean velocity differed between groups, respectively. Ellipse area did not show significant differences across conditions. : An instrumented BESS has the potential to enhance the detection of subtle postural deficits in pediatric mTBI patients. Specifically, more demanding conditions with altered sensory-proprioceptive input and path length as an outcome measure should be focused on. This study underscores the need for tailored and age-appropriate objective and quantitative balance assessments to improve diagnostic precision in pediatric mTBI populations.