The Facts About ACL Tears And ACL Injuries:
- 70% of all ACL injuries are non-contact injuries
- High school and collegiate female athletes are 3-4 times more likely to suffer an ACL injury, and 6 times more likely to suffer a second ACL injury in the other leg than male athletes.
- Each ACL tear results in $25,000 to $40,000 in surgery and rehab healthcare dollars.
- ACL tears, even after surgery and rehab, predisposes the knee to premature osteoarthritis. This further increases the cost of healthcare on the knee in the future.
- Incident rate of re-injury of a reconstructed ACL is 25%.
- Prevention of ACL injuries is KEY.
What is the ACL?
The ACL, anterior cruciate ligament, is a ligament within the knee that prevents the anterior translation of the tibia during motion. In other words, it is responsible for the passive deceleration of the thigh bone (femur) while the body is decelerating during motion.
How does the ACL get injured?
Most injuries happen for two reasons:
- The angle with which the knee and is decelerating is not healthy – the typical presentation of this is when the knee is not aligned in a straight vector with the ankle and the hip, and the knee saves downward and inward.
- When deceleration of the body includes concurrent knee hyperextesion, i.e. an overly straightened knee. This typically happens when the athlete is landing from a jump without bending her knee.
Why are females more likely to get injured?
Females have wider hips that therefore increase the unhealthy angle with which they land. (See reason #1 above) Females also have a narrower intracondylar arch where the ACL passes through. This increases the chances of the ligament fraying in the smaller space.
The most preventable reason is that these female athletes have not been properly trained and conditioned during training to educate the body and the brain to decelerate their motions appropriately. Some athletes complete this training with their conditioning and strengthening regimens, but especially with rigorous performance schedules and pressure nowadays, coaches and players are opting to skip over these important strength and conditioning practices and only work on field drills.
A combination of the two factors above culminate in the female athlete landing with excessive knee valgus, which puts the ACL in a very winded-up position. Add to this, the unpredictability of sport and cutting maneuvers in slippery conditions and the result is an injured ACL.
So how do we prevent ACL injuries from happening?
The biggest effect that we can make in ACL injury prevention is via proper training, strength and conditioning and also a proper warm-up program.
In a study made by La Bella et al in 2011, they used 1492 soccer and basketball athletes and split them into control and intervention groups. Coaches were trained in a prevention program involving proper neuromuscular warm-ups that they took their intervention group through throughout the season. The results were staggering:
- The intervention group had 56% reduction in acute noncontact injuries than the control (no warm-up) group.
- All of the athletes that ended up requiring ACL reconstructive surgery were in the control (no warm-up) group.
What does this warm-up session include?
The warm-up involves a 20 minute pre-practice session each time to dynamically increase range of motion of the trunk, hip and ankle with activation of trunk and hip musculature in weight bearing and semi-weight bearing postures. See a video sample of our dynamic warmup.
Exercises include not only flexibility-based dynamic warmups but also strengthening exercises, balance activities and jump-landing training during tri-planar motion. Muscle groups targeted are: the gluteus maximus, gluteus medius, hamstrings, core and soleus muscles. These are the main muscles that control (keyword control not eliminate!) pronation and knee valgus. Proper progression of these exercises will train the athlete to properly decelerate during running, sprinting and landing activities.
More specifically, quadriceps training is given to lessen fatigue and decrease incidences of landing with knee hyperextended. Studies have also shown that core activation have a feed-forward effect before action and provides a stable base with which the lower extremity can power off of – this is clutch to achieving a strong and effective bounce-back from landing and take-off usually seen in cutting maneuvers.
It usually takes 4-6 weeks to retraining a motor habit, and 6-12 weeks to gain muscular strength and power, so this practice needs to be incorporated in the time and training before an intense game begins. For optimum results, this warm-up and strengthening routine should be incorporated at every single workout, pre and post-season.
Hoover, Donald et al. The influence of core musculature engagement on hip and knee kinematics in women during a single leg squat. The International Journal of Sports Physical Therapy,Vol. 7, o. 1. Feb 2012.
LaBella et al. Effect of Neuromuscular Warm-up on Injuries in Female Soccer & Basketball Athletes in Urban Public Schools Archives of Pediatric & Adolescent Med. 165 (11), Nov 2011.
Patterno M.V. et al. Incidence of contralateral and ipsilateral anterior cruciate ligament (ACL) injury after primary ACL reconstruction and return to sport. Sports Health and Performance Institute, The Ohio University Medical Center.
By Alice Holland, DPT.
Alice’s Google + page.
Doctor of Physical Therapy, Director at Stride Strong Physical Therapy