Substantial ACL ruptures are not common in adolescence or childhood. During this period, ACL tibia avulsion fractures are more common than substantial ACL ruptures are. However, recent advancements in MRI and increases in adolescent sports activity have led to increased diagnosis of substantial ACL ruptures. Many physeal-sparing ACL reconstruction methods have been reported. However, some physeal-sparing ACL reconstructions are associated with poor outcomes because of laxity in the reconstructed ligament and discordance in the isometric point. We report a 14-year-old male patient with a chronic substantial ACL rupture and a longitudinal medial meniscus tear who was treated with ACL reconstruction and all-inside meniscal repair, which spares the femoral physis and reduces tibia physeal injury with an Achilles allograft.