Returning to play too early after anterior cruciate ligament (ACL) reconstruction surgery can pose significant risks.  There has been a transition in how long an orthopedic surgeon holds out an athlete from sports after ACL reconstruction over the last 2 decades.  20 years ago return to play at 4 months was advised as long as the athlete met certain criteria of performance.  As time has elapsed there are multiple studies that has refuted this time period and has changed the recommendations.  First, what are the risks of returning to play early:

1. Re-Injury and Graft Failure:  The ACL graft needs time to heal and become strong enough to withstand the stresses of sports activities. Returning too soon increases the risk of re-injuring the ACL or damaging other structures in the knee.  It has been shown that the ACL graft can take 12-18 months to fully mature.  Several studies have shown the increased risk of graft failure.  In a study out of University of Delaware where they looked at the rate of return to sports (RTS) and measured testing parameters prior to returning, the re-injury rate was significantly reduced by 51% for each month RTS was delayed until 9 months after surgery, after which no further risk reduction was observed. 38.2% of those who failed RTS criteria suffered re-injuries versus 5.6% of those who passed. More symmetrical quadriceps strength prior to return significantly reduced the knee re-injury rate.   In a study from 2022 looking at return to play at 6 months versus 12 months, the accelerated rehabilitation was significantly associated with graft elongation and graft reoperation.  In another study from 2022 among patients with RTS at >8 months, every month that RTs was delayed reduced the risk of re-injury by 28.4%.  
2. Decreased Performance: Returning before full recovery can result in decreased performance due to weakness, instability, and altered movement patterns. Athletes may not be able to perform at their pre-injury level, and their risk of further injury may be heightened.
3. Chronic Knee Problems: Early return to sports can contribute to long-term knee issues such as chronic pain, instability, and an increased risk of developing osteoarthritis in the future.  In a study from 2018 looking at return to sports at <10 months versus greater than 10 months an early return to sport was associated with significantly increased odds of bone marrow lesions.  Bone marrow lesions or bone contusions are associated with progression to osteoarthritis.  Also in those with poor lower limb function, early return to sport exacerbated the odds of bone marrow lesions.

To minimize these risks, athletes should follow a structured rehabilitation program under the guidance of a qualified physical therapist or athletic trainer. The timing of return to sport after ACL surgery varies depending on several factors, including:

1. Type of Surgery: The specific surgical technique used, as well as the type of graft used for ACL reconstruction (e.g., autograft or allograft), can influence the recovery timeline.  That said, there is no study showing graft type changes the increased risk of re-injury returning early versus late.  Some grafts have slightly lower re-tear rates but the re-tear rate is still higher for that specific graft when returning early versus late.  
2. Individual Healing: Each athlete’s body responds differently to surgery and rehabilitation. Factors such as age, overall health, pre-existing knee conditions, and adherence to the rehabilitation program can affect the rate of recovery.  
3. Rehabilitation Progress: Athletes must meet certain criteria before being cleared to return to sports, including achieving full range of motion, restoring strength and stability, and demonstrating proper movement patterns.  In a study published in 2024 by Walsh, et al.,  a total of 352 patients underwent RTS-testing, following ACLR.  The re-rupture rate was 6.6% after passing the RTS-test and 10.3% following failure, representing a 36% reduction. Contralateral ACL injury rate after surgery was 6% and was 19% lower in those passing the RTS test. Re-ruptures in those who passed the RTS test first time occurred late (>34 months), compared to those who failed first time, which all occurred early (<33 months).

In general, athletes are typically advised to wait at least 8-12 months before returning to sport after ACL reconstruction surgery. However, this timeline can vary based on individual circumstances, and clearance for return to play should be given by the surgeon and rehabilitation team based on objective criteria rather than solely on time elapsed since surgery.  At Total Orthopedics and Sports Medicine we have knee surgeons who are up to date with the literature helping to minimize re-injury and improve an athlete’s long term well-being.