Last weekend, during Real Madrid’s match against Osasuna, fans and players were shaken as Eder Militão suffered a painful knee injury. Hours later, a medical report confirmed a contralateral anterior cruciate ligament (ACL) tear—a complex injury that can end an athlete’s season. ACL tears are common worldwide, affecting about 68.6 per 100,000 people annually, but the risk of a second injury in the previously healthy leg (contralateral ACL injury) is particularly high, affecting nearly 42% of athletes who return to sport after ACL surgery.
Why Do Contralateral ACL Injuries Occur?
Many ACL injuries are due to non-contact mechanisms. Following surgery, strength imbalances and overreliance on the uninjured leg are two key factors that increase the risk of contralateral ACL injury. Athletes may develop strength asymmetries by depending more on the healthy leg, which puts additional strain on it, increasing the likelihood of a second ACL tear. For example, a 2024 study by López de Dicastillo found that about 80% of patients did not achieve a proper Limb Symmetry Index (LSI)—a critical metric for measuring leg strength symmetry—within six months post-surgery. Strength deficits, especially in the quadriceps, were even more pronounced in low-speed tests, indicating that full strength recovery remains challenging.
Comprehensive Rehabilitation and Prevention
Mark V. Paterno’s 2015 study highlights the limitations of existing recovery practices, showing that many current systems don’t effectively prevent second ACL injuries, especially among young, active athletes. Paterno points out that both modifiable factors (like muscle weakness) and non-modifiable factors (such as genetics) play a role in injury recurrence. He argues for a more comprehensive approach, which could involve assisted stretching, balanced strengthening, and biomechanical corrections, to improve overall recovery and reduce injury recurrence.
The Role of Assisted Stretching
Assisted stretching can be a game-changer for ACL recovery. It aids flexibility, reduces muscle tension, and ensures that both the previously injured and uninjured legs are treated and strengthened. This approach is especially important for preventing future injuries, as it helps athletes return to sports with greater balance and mobility. Working on both legs through assisted stretching can reduce strength imbalances, improve recovery, and lower the risk of a second ACL tear.
Conclusion: A Balanced Recovery Approach for Safe Return
Research underscores the importance of a comprehensive, well-rounded rehabilitation program for athletes recovering from ACL surgery. For those aiming to return to sports, an effective program will include attention to the uninjured leg, balanced strengthening, and assisted stretching to prevent muscle imbalances and further injuries. These strategies may prove essential to ensuring a successful and long-lasting return to physical activity after an ACL injury.
References
- Villa, F., et al. High rate of second ACL injury following ACL reconstruction in male professional footballers: an updated longitudinal analysis from 118 players in the UEFA Elite Club Injury Study.
- López de Dicastillo, L., et al. Higher Unilateral Muscle Imbalance at the Contralateral Knee 6 Months after Anterior Cruciate Ligament Reconstruction.
- Paterno, M. V., et al. Incidence and Predictors of Second Anterior Cruciate Ligament Injury After Primary Reconstruction and Return to Sport.
Alfredo, the author of this blog, is a highly experienced professional in the fields of sports science and rehabilitation. With a solid academic background, including a master’s degree in sports science, Alfredo is dedicated to providing in-depth, evidence-based insights into the importance of recovery in athletic performance. As the founder of StretchUs, TheRecoveryCoach, a company specializing in assisted stretching services, which combines expertise in therapeutic training with a strong commitment to promoting balanced recovery.
I hope it helps to understand the importance of reducing muscle asymmetries.