In the fast-paced world of fitness and sports, preventing injuries is crucial for both professional athletes and casual fitness enthusiasts. One common injury that plagues many is the Anterior Cruciate Ligament (ACL) injury. This article will provide a comprehensive understanding of ACL injuries, their prevalence, preventive strategies that can be taken, and risk factors that increase the risk of ACL injuries.
What are ACL injuries?
The Anterior Cruciate Ligament (ACL) is a critical structure in the knee that plays a key role in providing internal stability during movement. A tough, yet flexible band of tissue it connects the top of the shin bone (tibia) to the bottom of the thigh bone (femur.)
An injury to the ACL will occur when there is a sudden change in direction or pivot, causing a force that exceeds its threshold. The severity can range from mild strains to severe tears, or complete ruptures with symptoms including pain, swelling, and instability of the knee joint. Often the surrounding structures such as the Posterior Cruciate Ligament (PCL,) Medical Collateral Ligament (MCL,) and Lateral Collateral Ligament (LCL) are involved as well as the medial or lateral meniscus.
Recovery from an ACL injury is usually long and arduous, with management often a decision between a surgical or conservative approach. In a surgical ACL reconstruction, a new ligament is fashioned from either the tendon of the semi-tendinosis portion of the hamstring muscle or a strip of the patella tendon which connects the kneecap (patella) to the tibia. If a conservative approach is chosen, the focus of rehabilitation is on range of movement, strength, and stability training prioritising quadricep and hamstring control and co-contractions. Regardless of which approach is chosen, it will involve on average 12 months of rehabilitation before returning to activities such as running, hopping, and changing direction at high speed.
How common are ACL injuries in Australia?
Within Australia, ACL injuries are prevalent amongst professional athletes, club level players, and weekend warriors. According to the Australian Orthopaedic Association National Joint Replacement Registry, knee injuries, including ACL tears, are one of the most common orthopaedic injuries reported. Sports that involve cutting, pivoting, and jumping, such as soccer, basketball, and netball, have higher incidences of ACL injuries. Our culture of outdoor activity and recreational sports results in the country having one of the highest rates of ACL injuries worldwide. The rate of surgical reconstruction is also high in Australia as many patients want to return to sport and therefore seek a fix instead of living with potential lifelong knee instability.
How can ACL injuries be prevented?
Preventing ACL injuries is crucial for maintaining the long-term health and performance of athletes and fitness enthusiasts. By incorporating these strategies, coaches, and trainers can help to reduce their athlete’s risk of sustaining an ACL injury:
- a) Neuromuscular Training: focusing on balance, stability, and proper movement patterns can enhance proprioception and reduce the risk of ACL injuries.
- b) Strength Training: especially targeting the muscles around the knee, such as the quadriceps, hamstrings, and glutes. Strong muscles provide additional support to the knee joint.
- c) Plyometric Exercises: gradually introducing plyometric exercises to improve agility and power. These exercises should be executed with proper form and technique to minimise the risk of injury. A specific assessment known as the “Prepare to Play – Triple Hop Test” has been developed, using AI technology to analyse a player’s movements and determine if they are ready for the demands of their chosen sport or to return post-injury.
- d) Proper Warm-Up and Cool Down: dynamic warm-up routines prepare the muscles and joints for activity. Additionally, athletes should be encouraged to perform cool-down stretches to promote flexibility and reduce muscle tightness.
- e) Sport-Specific Techniques: coaching on proper techniques related to cutting, pivoting, and landing, as these movements are often associated with ACL injuries. Correcting form can significantly reduce the risk of injury during sports activities.
What increases the risk of ACL injuries?
Understanding the factors that contribute to the risk of ACL injuries is essential for tailoring injury prevention strategies. Some of the risk factors include:
Gender: Females are more prone to ACL injuries than males, possibly due to hormonal and anatomical differences. As hormone levels fluctuate throughout a woman’s cycle, is there a higher injury risk when ligaments have higher levels of laxity? This theory has not been proven and there is a need for more research. While this might be a contributing factor, it is not likely to be significant. Another previous theory was that a wider female pelvis places more strain on the knees however research has all but debunked this theory.
The AFLW has built an unfortunate reputation for high numbers of ACL injuries amongst its ranks of players. In the 2020 season, there were 7.47 new injuries per 1000 player hours (compared to 0.70 per 1000 hours in the 2019 men’s AFL competition). The incidence of Anterior Cruciate Ligament (ACL) injuries resulting in missed matches remained steady at 4.17 per 1000 player hours in the 2022 (S6) AFLW season. In the 2022 (S7) AFLW season, the incidence of ACL injuries resulting in missed matches decreased to 2.84 ACL injuries per 1000 player hours. Less funding in the sport compared to their male counterparts means female footballers can’t spend the same amount of time and effort training and building strength in the gym. Some female athletes have transitioned from other sports but haven’t been playing football all their lives and are still adapting to the 360-degree nature of the game. Hopefully now as more young girls are playing in the junior ranks they will be conditioned to the nature of the game from the beginning.
Previous Injuries: Individuals with a history of ACL injuries or knee instability are at a higher risk of experiencing a repeat injury.
Poor Biomechanics: Incorrect movement patterns and biomechanics during physical activities can increase the stress on the ACL.
Playing Surface: The type of playing surface, especially in outdoor sports, can impact the risk of ACL injuries. Surfaces that provide less traction may increase the likelihood of slips and twists. This factor may be another link to the increased risk in female athletes, as women’s football games are often played on smaller community grounds which are dry and hard compared to the carefully manicured grounds of the MCG or the Gabba.
Coaches, personal trainers, and physiotherapists play a pivotal role in promoting the well-being of athletes and individuals engaged in physical activities. By understanding the nature of ACL injuries, and their prevalence in Australia, and adopting proactive preventive strategies, fitness professionals can contribute significantly to reducing the occurrence of these injuries. Stay informed, implement evidence-based practices, and empower clients to move safely, ensuring a healthy and injury-free fitness journey.
References:
- Australian Orthopaedic Association National Joint Replacement Registry. (https://aoanjrr.sahmri.com/)
- Hewett, T. E., Myer, G. D., Ford, K. R., Paterno, M. V., & Quatman, C. E. (2016). Mechanisms, prediction, and prevention of ACL injuries: Cut risk with three sharpened and validated tools. Journal of Orthopaedic Research, 34(11), 1843-1855.
- AFL 2022 Annual Injury Report
Thanks to Caroline Jones for this article.
Caroline is a physiotherapist with two decades of experience spanning acute hospital care, oncology rehabilitation and lymphoedema management. She is passionate about using exercise as medicine and getting patients moving, especially those living with chronic conditions.
She also holds a Level 3 Certificate in Personal Training, owns a CrossFit box with her husband, and enjoys being a below-average runner.
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