We often hear about this type of injury, yet it is assumed that the general public understands the cause, treatment, and rehabilitation that is involved. However, unless one has undergone ACL injury, this is usually not the case.
Let's begin with the basics. What is the ACL and why is it so important?
The ACL is one of four major ligaments within the knee, and connects the femur (thigh bone) to the tibia (shinbone). Its primary function is to act as a restraint for movement between the femur and tibia. In addition, another function of the ACL is to control and limit rotation at the knee, especially when the leg is near full extension (straightened).
As you can imagine, these functions are critical in multidirectional sports, where cutting, planting, and exploding are often required.
As mentioned previously, we hear a lot about ACL injuries, but just how common is a torn ACL? In the general public, it has been reported there is roughly 1 case in 3,500 people annually, resulting in 95,000 new ACL ruptures per year.
I knew I should have become an orthopedic surgeon.
In sports, females tend to be affected more than males, which we think is due to many factors, some of which include a wider pelvis, increased flexibility, narrower notches within the knee joint, and faulty firing patterns of the thigh musculature.
However, this does not mean that males are spared from ACL injury. Within just the last month, two Arizona football players have torn their ACL, as starting safety Adam Hall, and running back Greg Nwoko, are now both in question for the upcoming football season.
Now you may be wondering, how do all of these injuries occur, especially in sports? There are typically two types of injuries. Those that occur without contact involving another player (Non-Contact) and those that occur from a collision (Contact).
Interestingly, Non-Contact events make up roughly 70% of ACL injuries. This occurs when a person generates great forces at the knee that apply an excessive load on the ACL. This is typically seen in activities that involve sudden deceleration, rotational stress such as pivoting, and/or hyperextension of the knee. Some common sports for ACL injury to occur are football, basketball, soccer, lacrosse, and skiing.
Following injury of the ACL, most athletes require surgery to have a chance to return to their sport. These repairs are known as ACL reconstructions and involve grafting of either the individual's patella tendon, or hamstring, to replace the damaged ACL. Each type of graft has its pros and cons, but it usually depends on the demands of the athlete, along with the surgeon's preference, as to which graft is used.
Following surgical repair, the athlete will typically undergo at least 5-6 months of rehabilitation, involving physical therapy. The good news is that today's ACL repair and rehabilitation techniques are much more accelerated than protocols followed in the past.
Although the timelines vary by surgeon, there are overarching themes and goals involved in any rehab program. Initially, the emphasis is on regaining the athlete's knee range of motion. Following surgery the knee becomes very stiff and swollen, and it is important to target this very early.
Additionally, it is just as essential to regain activation and strength of the Quadriceps femoris muscles of the thigh. Once swelling builds up around the knee, these muscles quickly shut-down and begin to decrease in size and strength. The re-activation of these muscles not only helps to decrease swelling, but also helps improve range of motion and return the athlete to walking and strengthening.
A critical point in rehab comes around 6 weeks following surgery. This is the time period in which the athlete is beginning to feel "good" and thinks they can push themselves a little harder in the hopes of a quicker return to play.
That sounds wonderful, right?
Not exactly. The problem is that right around the 6-week mark, the ACL graft is actually at its weakest point, due to a lack of blood flow. It has been documented that this blood flow returns around 8-10 weeks and the graft is fully healed around 16 weeks. It is difficult for athletes to understand that they must continue the rehab process, in spite of feeling "good".
The remainder of the rehab program will continue to increase leg strength, while also incorporating balance, endurance, agility, multi-plane movements, and single-leg stability demands.
Finally, the athlete will be taken through a return-to-running protocol, and ultimately a return-to-sport test, to determine if they are ready to once again see the field, court, etc.
They are usually cleared for sports once they demonstrate at least 80% strength of their un-involved leg at all testing speeds. Additionally, they must successfully complete a series of functional tests, which include various hopping, jumping, and cutting tasks.
The entire process following ACL injury can last anywhere from 5-12 months, and varies greatly by individual. It is not uncommon for ACL tears to involve other damage within the knee as well, most notably injury to the meniscus. Any further injury beyond just the ACL will delay the time an athlete must wait to return to their sport.
It is not out of the question that both Nwoko and Hall will return during this upcoming football season and pick up where they left off. But, as already mentioned, this will depend on many variables, many of which are unknown to the public.
The next few months will not be easy for these athletes, but if they remain committed to rehabilitation and continue to be motivated, they can overcome the ACL epidemic that affects so many people each and every year.
Let's just hope no more Arizona athletes become a part of the statistic.
Preston Collins received a Bachelor of Science degree in Physiology, with minors in both Chemistry and Psychology while at Arizona. He is currently in Denver, CO where he is pursuing a Doctor of Physical Therapy (DPT) degree from the University of Colorado medical campus.