Background/Objectives: LAS is common in adolescents, yet early management strategies differ. The traditional PRICE + NSAIDs protocol focuses on short-term symptom relief, whereas the PEACE and LOVE framework emphasizes education, early optimal loading, and progressive exercise. This study compared functional recovery between these two approaches. Methods: A prospective randomized study enrolled 76 adolescents (12–17 years) with first-time LAS, allocated to PRICE + NSAIDs or PEACE and LOVE using a computer-generated randomization sequence with concealed envelope allocation; 65 completed follow-up (PRICE n = 32; PEACE and LOVE n = 33). Functional performance was assessed at 1–2, 5–7, and 12–15 weeks using Biodex isokinetic dynamometry and the Y-Balance Test composite score (YBT-CS). Outcomes were expressed as side-to-side deficits (uninjured − injured limb) and analyzed using two-way mixed repeated-measures analysis of variance, with Group (PRICE + NSAIDs vs. PEACE and LOVE) as the between-subject factor and Time (1–2, 5–7, and 12–15 weeks) as the within-subject factor. Results: Significant main effects of time were observed for IN strength at 60°/s (F = 5.73, p = 0.006) and 120°/s (F = 10.15, p < 0.001), EV strength at 120°/s (F = 6.82, p = 0.003), ankle ROM at 60°/s (F = 12.79, p < 0.001) and 120°/s (F = 13.09, p < 0.001), and YBT CS (F = 6.91, p = 0.002), indicating progressive recovery across follow-up. No significant group effects or time × group interactions were detected for any outcome (all p > 0.05). Conclusions: Both rehabilitation protocols were associated with progressive functional recovery following adolescent LAS. No statistically significant between-group differences or differential recovery trajectories were detected over 12–15 weeks. These findings suggest that an active, education-focused rehabilitation approach yields functional outcomes comparable to traditional PRICE + NSAIDs management in the short term. Larger studies with longer follow-up are required to determine whether clinically meaningful differences exist between protocols. Trial registration: ClinicalTrials.gov: NCT07287020; registered 3 December 2025 (retrospectively registered).

Background/objectives: Lateral ankle sprain (LAS) is common in adolescents, but the extent to which structural injury severity is associated with recovery of objective functional measures remains unclear. This study explored the association between Grade I–III injury severity and short-term recovery of objective functional measures following adolescent LAS using a post hoc secondary analysis of a randomized controlled trial (RCT). Methods: This exploratory secondary cohort analysis included 65 adolescents aged 12–17 years with acute LAS who had participated in a RCT comparing two rehabilitation strategies. The severity-based analysis was not prespecified in the trial protocol. Participants were analyzed according to Grade I–III injury severity, irrespective of original treatment allocation. Injury severity was classified using clinical and imaging findings. Functional performance was assessed at 1–2, 5–7, and 12–15 weeks using Biodex isokinetic dynamometry for inversion (IN) and eversion (EV) peak torque normalized to body weight (PEAK TQ/BW) and ankle range of motion (ROM), and the Y-Balance Test composite score (YBT-CS). Outcomes were expressed as signed side-to-side differences (uninjured−injured), with values closer to zero indicating greater interlimb symmetry. Changes were analyzed using mixed repeated-measures ANOVA and covariate-adjusted LMMs including Severity, Time, Severity × Time, age, and treatment allocation, with participant as a random effect. Injured- and uninjured-limb values were examined separately. Results: Significant changes over time were observed for most outcomes. No significant Severity × Time interactions were identified for signed side-to-side differences in either repeated-measures ANOVA or covariate-adjusted LMMs. In the ANOVA, Severity main effects were observed for ROM at 120°/s ( p = 0.024) and YBT-CS ( p = 0.014); after adjustment, the Severity effect remained significant for YBT-CS ( p = 0.045) but not ROM at 120°/s ( p = 0.090). In injured-limb analyses, all outcomes improved over time (all p < 0.001), without significant Severity or Severity × Time effects. Conclusions: No statistically significant severity-related differences in short-term recovery trajectories were identified for the measured outcomes, including in covariate-adjusted analyses. The Severity effect for YBT-CS, but not ROM at 120°/s, remained significant after adjustment. Given the exploratory design and limited power for interaction effects, these findings should be considered hypothesis-generating. Trial registration: NCT07287020; registered 3 December 2025 (retrospectively registered).