A Common Knee Injury
The knee is an extremely complex joint. It has to be. It’s responsible for flexing, extending and rotating the lower leg, and it carries most of the body’s weight.
The knee is a meeting of three bones–the femur (thigh bone), the tibia (shin bone) and the patella (kneecap)–surrounded by muscles. Holding it together are tendons (tissue that connects muscles to bone) and ligaments (tissue that connects bone to bone).
With between 120,000 and 200,000 per year in the U.S., injuries to the anterior cruciate ligament (ACL) are one of the most common knee injuries. But what is the ACL, who gets ACL injuries, and how are they repaired?
Function of the ACL
The ACL sits in the center of the knee and connects the femur to the tibia. Along with the posterior cruciate ligament (PCL), the ACL provides stability when rotating the knee joint and it keeps the tibia from sliding out in front of the femur. That’s why without an ACL the knee can feel unstable, particularly playing sports, but even with every day daily activities (such as stepping down a step or on uneven surfaces).
How ACL Injuries Happen
ACL injuries, especially among athletes, are sustained either by a direct blow like a tackle at the knee, or by a twisting motion or rapid change of direction. Most happen without contact. Sports with high incidences of ACL injuries include:
Most ACL injuries happen to high school and college athletes. They disproportionately affect girls and women, who are more than three times as likely as male athletes to sustain non-contact ACL injuries. After puberty, girls are at higher risk than boys to sustain an ACL injury.
Treating ACL Injuries
Initially, the treatment for an ACL tear is focused on managing your pain, swelling and range of motion, as well as any other associated injuries. This may include rest, icing, immobilization, crutches, pain medication and physical therapy. Generally, in order to return to sports and/or if you have functional instability (your knee gives out with normal activities of daily living), this will require a surgery to reconstruct the ligament.
This is accomplished by creating a new ACL ligament with a tissue graft. The goal of ACL reconstruction is to anatomically repair the ACL to create an environment to get you a stable knee. Generally, surgeons accomplish this by removing the damaged ligament, arthroscopically, and replacing it with a graft (ie, tissue) taken from the patient or one used from a cadaver. The graft then heals and incorporates, over time, to become a new ligament.
The surgery is performed arthroscopically, as an outpatient procedure. Physical therapy is, generally, started within 7-10 days after surgery. The focus in the first four weeks after surgery is to decrease swelling and improve range of motion. Typically, you are back to your normal activities of daily living by 4 weeks. Running is allowed at 3 months and most patients return to sports between 6 to 9 months.
I was set on the path to a career in medicine when I injured my own ACL as a high school athlete. I know firsthand what it’s like to be limited by a knee injury. That’s why I’ve dedicated my career to helping people with ACL injuries come back better than ever. If you are dealing with an ACL sprain, I can help. Feel free to request an appointment with me or one of our sports medicine specialists to discuss your treatment options.