For some young people who experience an ACL (anterior cruciate ligament) injury, delaying surgical repair is associated with a higher risk of new tears in the meniscus and cartilage after the initial injury. That’s according to a new study by Johns Hopkins Children’s Center researchers, who found that adults with the same type of ACL injury generally showed no significant increase in such risk.

The likely explanation? Adults are more likely to dial back physical activity and comply with calls for restrictions from a doctor, while children are more likely to continue strenuous sports and other play, and experience further knee damage that may not at first be obvious.

“What we have shown with children is that the longer you wait, the more damage may be done to the knee,” says pediatric sports medicine specialist R. Jay Lee, senior author of the study, which appeared in Orthopaedic Journal of Sports Medicine.

The researchers say they hope their findings will help inform decisions when adults and caregivers of children who experience ACL injuries are deciding if and when to have surgery.