A Delay in ACL Surgery May Be Safe for Adults, Less So for Children, New Study Finds

A study from the Johns Hopkins Children’s Center concludes that in some children, delaying surgical treatment of anterior cruciate ligament (ACL) tears is associated with a higher risk of new tears in the meniscus and cartilage after the initial ligament injury.

Adults with the same type of ACL injury face no significant increase in the risk of these tears, the researchers found.

Why the difference? The researchers speculated that adults with an ACL injury would be more likely than children to dial back physical activity in accordance with recommended restrictions. Children would be more inclined to continue strenuous sports and other play, they said, thus experiencing 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,” said R. Jay Lee, MD, senior author of the study and a pediatric sports medicine specialist at the Children’s Center.

The researchers say their findings, published by the Orthopaedic Journal of Sports Medicine, reinforce the need for timely surgical treatment in pediatric patients to prevent ongoing damage to the knee, while older patients’ surgical treatment may be safely delayed.

MRI vs. Arthroscopic Findings

An estimated 100,000 to 200,000 people experience an ACL tear annually in the US. Historically, physicians have recommended that ACL reconstruction be delayed in younger patients until the child is finished growing. However, ACL tears leave the knee unstable and more prone to further injury in all patients, regardless of age.

For the new study, Dr. Lee and colleagues retrospectively identified 542 patients – 173 pediatric patients and 369 adult patients – who had undergone ACL reconstruction between 2013 and 2022 at Johns Hopkins and who had had an MRI of the affected knee within 3 weeks of injury.

Overall, 66% of patients had a meniscal tear that was observed arthroscopically, nearly one-third of which were new injuries not present on the initial MRI. This included 36 new medial meniscus tears and 97 new lateral meniscus tears. New medial meniscal tears were noted in 15% of children and 16% of adults, with new lateral meniscal tears found in 48% of children and 34% of adults.

Informed Decision Making

The researchers said that adults were more likely than children overall to delay ACL reconstruction, but among adults, the delayed reconstruction was not associated with a higher risk of meniscal tears at the time of injury or at the time of surgery. Therefore, delayed ACL reconstruction may be acceptable in adults, they said.

The researchers noted that their study was limited by the potential for selection bias: Surgeons may have been more likely to operate sooner when patients had more severe knee injuries. In addition, the level of a person’s physical activity after ACL injury is likely a major contributor to the development of further knee damage, but its specific contribution is challenging to measure. Lastly, meniscal tears that were missed on the initial MRI could have led to an overestimation of the incidence of “new” meniscal tears in some cases.

However, the researchers said they believe their findings will help inform decisions when adults and caregivers of children who have experienced ACL injuries are deciding when to have surgery.

The researchers will continue their investigation, particularly looking at whether restricting patients’ mobility has an effect on new meniscal tears.


Gupta A. Badin D, Ortiz-Babilonia C, Davidson AJ, Lee RJ. Is delayed anterior cruciate ligament reconstruction associated with a risk of new meniscal tears? Reevaluating a longstanding paradigm. Orthop J Sports Med. 2023 Oct 6;11(10):23259671231203239. doi: 10.1177/23259671231203239. eCollection 2023 Oct.

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