Understanding the Risk of ACL Retear After Reconstruction: What You Need to Know

Anterior cruciate ligament (ACL) tears are one of the most common and feared injuries in sports. An ACL tear often requires surgical reconstruction, followed by months of rehabilitation.  Understanding the factors that contribute to this risk and the measures that can be taken to minimize it is crucial for anyone who has undergone or is considering ACL reconstruction.

1. The Reality of ACL Retear Rates

Despite advances in surgical techniques and rehabilitation protocols, retear rates after ACL reconstruction remain a concern for many athletes and their medical teams. Studies have shown that the retear rate can vary widely depending on several factors, but generally, it is estimated that the risk of retearing the reconstructed ACL ranges from 5% to 15%. When considering the risk of tearing the ACL in the opposite knee, the overall retear rate can rise to 20% or more in some populations, particularly among young, active athletes.

2. Factors Contributing to ACL Retears

Several factors can influence the likelihood of an ACL retear after reconstruction, including age, activity level, surgical technique, and rehabilitation practices.

• Age and Activity Level: Younger athletes, particularly those under 25 who participate in high-demand sports like soccer, basketball, and football, are at a higher risk of ACL retears. Their intense activity levels and the physical demands of their sports increase the likelihood of reinjury.

• Graft Choice: The type of graft used in the ACL reconstruction can impact the retear rate. Common graft options include patellar tendon grafts, hamstring tendon grafts, and allografts (donor tissue). Some studies suggest that certain graft types may have slightly higher retear rates, though the differences are often small and depend on other factors like surgical technique and rehabilitation.

• Surgical Technique: The precision and skill of the surgeon play a critical role in the success of ACL reconstruction. Factors such as proper graft placement, tensioning, and fixation are essential to ensuring the stability and function of the reconstructed ligament.

• Rehabilitation Compliance: Adhering to a structured, progressive rehabilitation program is crucial for a successful recovery. Patients who do not fully commit to their rehab or who return to sports too quickly are at a higher risk of retearing their ACL. A typical rehab program lasts at least 6 to 12 months and focuses on restoring strength, stability, and neuromuscular control.

• Neuromuscular Control: Even after a successful ACL reconstruction, some athletes may continue to have deficits in neuromuscular control, which can lead to improper movement patterns that place additional stress on the knee. These deficits must be addressed during rehabilitation to reduce the risk of retear.

3. Retear Risk in the Opposite Knee

Interestingly, the risk of tearing the ACL in the opposite (contralateral) knee is also significant after an initial ACL reconstruction. In some studies, the rate of contralateral ACL tears can be as high as or higher than the rate of retears in the reconstructed knee. This phenomenon is particularly common among younger athletes, possibly due to their high activity levels and the biomechanical challenges that contributed to the first injury.

4. Preventive Strategies to Reduce Retear Risk

While the risk of retear cannot be completely eliminated, several strategies can help reduce the likelihood of reinjury after ACL reconstruction:

• Comprehensive Rehabilitation: A thorough rehabilitation program that emphasizes not only strength but also balance, proprioception, and neuromuscular control is essential. The program should be tailored to the individual’s needs and progressions should be carefully monitored by a physical therapist.

• Gradual Return to Sport: Rushing back to high-impact sports too soon is a common cause of ACL retears. Athletes should follow their healthcare provider’s recommendations regarding return-to-play timelines, often waiting 9 to 12 months post-surgery, depending on their recovery progress.

• Injury Prevention Programs: Participating in injury prevention programs, such as those focusing on proper landing mechanics, agility training, and lower body strength, can help reduce the risk of retear. These programs are particularly important for young athletes who are at higher risk.

• Addressing Biomechanical Factors: Identifying and correcting any underlying biomechanical issues, such as improper jumping or cutting techniques, can help prevent future ACL injuries. This often involves working closely with a physical therapist or sports medicine specialist.

• Continuous Monitoring: Even after returning to sports, athletes should continue to monitor their knee health and participate in ongoing strength and conditioning programs to maintain the stability and function of the knee.

5. The Emotional and Psychological Impact of ACL Retears

Beyond the physical challenges, the emotional and psychological toll of an ACL retear can be significant. The fear of reinjury, loss of confidence, and the prospect of facing another lengthy rehabilitation can be daunting for athletes. Psychological support, including working with a sports psychologist, can be beneficial in helping athletes cope with these challenges and regain their confidence.

Conclusion

ACL reconstruction is a highly effective procedure that allows many athletes to return to their sports and active lifestyles. However, the risk of retearing the ACL, whether in the same knee or the opposite one, remains a serious concern. Understanding the factors that contribute to this risk and implementing preventive strategies can help minimize the chances of reinjury. By focusing on comprehensive rehabilitation, gradual return to sport, and ongoing injury prevention, athletes can better protect their knees and reduce the likelihood of facing another ACL tear.

Author

Peter Wenger, MD Peter C. Wenger, MD, is an orthopedic and non-operative sports injury specialist at Princeton Sports and Family Medicine, P.C., in Lawrenceville, New Jersey. He is board certified in both family medicine and sports medicine. Dr. Wenger brings a unique approach to sports medicine care with his comprehensive understanding of family medicine, sports medicine, and surgery. As a multisport athlete himself, he understands a patient’s desire to safely return to their sport.