Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study

Grindem H, Snyder-Mackler L, Moksnes H, Engebretsen L, Risberg MA. Br J Sports Med. 2016 May 9:bjsports-2016.doi:10.1136/bjsports-2016-096031

Take Home Message: Athletes who wait at least 9 months after an anterior cruciate ligament reconstruction and/or regain quadriceps strength compared with the uninjured limb may be at lower risk for reinjury than those who fail to meet these criteria.

Despite advances in treating an anterior cruciate ligament (ACL) injury, a patient after a recent ACL reconstruction is at risk for reinjury. A reinjury could increase an athlete’s risk for long-term knee disability and pain. It is unclear if delaying a return to sport or requiring a higher level of knee function prior to return to sport may reduce the risk of reinjury. Hence, Grindem et al. assessed if the 2-year risk of knee reinjury after an ACL reconstruction was associated with either timing or knee function when returning to jumping, pivoting, and cutting sports. The researchers included 100 participants from the Delaware-Oslo ACL Cohort Study who had a recent ACL reconstruction in Norway (average age 24 years). Before their injury, participants had no history of knee injury and competed in level I (very strenuous activities like jumping or pivoting as in basketball or soccer) or level II (strenuous activities like heavy physical work, skiing or tennis) sports. All participants completed a rehabilitation program before undergoing ACL reconstruction with either a patellar tendon or hamstring autograft. After surgery, participants completed an individualized progressive rehabilitation protocol. Study personnel collected data on isokinetic quadriceps strength, single-leg hop testing, and two self-reported outcomes at 6 months, 1 year, and 2 years after surgery. A participant passed the return-to-play criteria if they regained ≥90% muscle strength and hop performance compared with the uninjured leg. Researchers found that 89% (74/83) of participants who previously competed in level I sports returned to level I sports within 2 years of ACL reconstruction. The median time to return to play was 8 months after surgery. However, only 24% (18 of 74) of participants passed the return-to-play criteria. Physicians diagnosed 24 individuals with a reinjury during the first 2 years after surgery. A participant who returned to a level I sport was 4.3 times more likely to reinjure a knee compared with someone who did not return to a level I sport. In addition, for each one month delay in return to sport the reinjury rate was reduced by 51% up until 9 months after surgery. After 9 months, waiting longer to return to play was unrelated with less risk of injury. Only one participant that met the functional return-to-play criteria suffered a reinjury. In contrast, 38% (21/55) of those who failed the return-to-play criteria suffered a reinjury. Specifically, for every 1% increase in quadriceps strength symmetry the researchers estimated a 3% reduction in injury rate.

As ACL reconstruction increasingly affects families across the United States and the world, it is important to have accurate information that clinicians can use to educate patients. This component of the Delaware-Oslo ACL Cohort Study is valuable in helping athletes make smart decisions post-surgery. The authors provide evidence that patients risk reinjury by rushing recovery and not fully completing rehabilitation protocols. While most active individuals want to get back to playing sports, Grindem et al suggests that athletes should weigh the risks before quickly going back to certain activities that require quick changes of direction. Modern medicine has made it possible to overcome ACL tears and to return to high level athletics, but it still takes a long healing process and challenging rehab to minimize the risk of a second injury. Clinicians should consider using the milestones presented in this study of waiting 9 months after injury and at least 90% return of quadriceps strength compared with the uninjured side to minimize risk of reinjury after ACL reconstruction surgery.

Questions for Discussion: Do we return our athletes to play to soon after an ACL reconstruction? What criteria do you use to determine if an athlete is ready to return to play after an ACL reconstruction?

Written by: Joshua Baracks
Reviewed by: Jeffrey Driban

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Altered Lower Extremity Biomechanics Following an ACL Injury and Surgery May Increase the Risk of Reinjury
Increased Re-Injury Risk after ACL Reconstruction
Predictors of Failure After ACL Reconstructions
Graft Type May Influence ACL Reinjury Rates
Fear of Re-injury in People who have Returned to Sport Following ACL Reconstruction

Grindem, H., Snyder-Mackler, L., Moksnes, H., Engebretsen, L., & Risberg, M. (2016). Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study British Journal of Sports Medicine DOI: 10.1136/bjsports-2016-096031