Study Summary

30 adolescent athletes aged 14–18 years who underwent primary unilateral anterior cruciate ligament (ACL) reconstruction were randomized to receive either standard postoperative rehabilitation or Both Sides Up (BOSU) ball training combined with standard rehabilitation. Two participants (one per group) withdrew due to noncompliance, resulting in 28 athletes included in the final analysis (14 per group). The primary outcome of interest was anterior–posterior knee laxity; secondary outcomes included dynamic balance assessed with the Y-Balance Test, quadriceps and hamstring limb symmetry index, hamstring-to-quadriceps ratio, and psychological readiness to return to sport measured by the ACL-Return to Sport after Injury (ACL-RSI) scale. Outcomes were assessed preoperatively and at 12, 24, and 48 weeks postoperatively. Overall, the results of the study revealed that adolescents receiving BOSU ball training demonstrated significantly greater improvements in knee stability, balance, strength symmetry, and psychological readiness compared with standard rehabilitation alone, with differences most pronounced at 24 and 48 weeks. These findings suggest that incorporating unstable-surface training enhances neuromuscular recovery following ACL reconstruction in adolescent athletes.