ACL Injury

When you hear that your favorite athlete has an ACL injury, you know it’s not good. You probably know they will be out for a long time, and you may know that surgery will be needed. But what exactly is an ACL injury? Let’s discuss.

ACL stands for anterior cruciate ligament, which is an important structure in the knee. It plays a critical role in knee stability, and injury to it is of great concern to athletes. The ligament’s role is to resist forward movement of the tibia (shin bone) in relation to the femur (thigh bone), as well as to provide rotational control. Many times an ACL injury is a “non-contact” injury, which means it happens without impact from another player. ACL ruptures have a non-contact mechanism of injury about 70% of the time. They usually occur during deceleration (slowing down), pivoting, changing direction, or landing from a jump. The athlete commonly hears or feels a “pop” in the knee, which is followed by pain and swelling.

There is some debate about treatment for an ACL rupture, depending upon age, activity level, type of sport, associated injuries, etc. Some individuals can regain stability with rehabilitation and therefore avoid surgical reconstruction. However, given the nature of most sports like football, these players should have ACL reconstruction if they want to play again. The type of activity (e.g., pivoting, cutting, changes in speed) required in football would not do well with non-operative treatment; an ACL-deficient knee would likely have too much instability to endure these activities. That being said, it should be noted that ACL reconstruction is not a guarantee that they will be able to return to sport.

The surgery for an ACL rupture involves forming a new ACL from another tendon. It is performed arthroscopically, which means it’s done through poke holes and small instruments rather than through a big, open incision. Which tendon graft to use as the “new” ACL is also a subject of debate in the literature, however, the most commonly used tendons are hamstring (back of the thigh), patellar (knee), or allograft (cadaver) tendons. The timing of the surgery after the injury depends on other factors, such as the amount of swelling or if there were other injuries in the knee, such as a meniscus tear. It is common for an athlete to undergo rehabilitation before the surgery to work on swelling, quadriceps strength, and range of motion. This is commonly called “prehabilitation.” After surgery, rehab is important to reduce swelling and regain range of motion, strength, and balance. This is followed by more functional and sport-specific exercises. Progression through rehab should be tailored to each athlete, so timeframe for return to sport is variable. Maturation of the tendon graft alone takes up to 6 months, so most athletes don’t return until at least 9 months after surgery. Getting back into the game too early could put them at risk for reinjury.

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