Jordy Nelson, a wide receiver for the Green Bay Packers, recently tore his ACL. This, unfortunately, is a season ending injury. ACL tears are one of the most common sports-related knee injuries and occur most frequently in athletes who play football, soccer and basketball.
What is the ACL?
• ACL stands for anterior cruciate ligament and is inside the knee joint. It connects the thigh bone (femur) to the shin bone (tibia).
• It is a strong stabilizer of the knee and helps prevent forward movement of the shin bone relative to the thigh bone.
• There is also a PCL (posterior cruciate ligament) which is not injured as often in sports.
How do you injure your ACL?
• Most commonly the ACL is torn following a pivoting mechanism when the foot is planted but the knee is not (cutting, decelerating, hyperextension, landing improperly from a jump). It can also be due to a contact injury.
What does an ACL tear feel like?
• Typically there is immediate pain with a large amount of swelling.
• Athletes often report hearing a “pop” then have difficulties with instability.
How are ACL tears diagnosed?
• Usually they can be diagnosed with a health history and physical exam.
• There is a test performed on the knee called Lachman’s test in which the shin bone moves forward much more than it should when the ACL is torn.
• ACL tears are confirmed on MRI.
Does everyone need surgery?
• No, ACL tears do not have to be surgically reconstructed but will greatly limit the type of activity a person can do if left alone. There are braces to help with stability for those who do not want surgery.
• Most athletes elect to have ACL reconstruction.
Why does an ACL tear mean an athlete will be out for so long?
• Surgery should not be done immediately because it increases the risk of a condition called arthrofibrosis which is when scar tissue forms inside the joint which could cause long term loss of motion at the knee.
• Delaying surgery after an ACL tear allows for the inflammation and swelling to resolve thus allowing for improvement in motion before surgery. It is important to have good motion before surgery to serve as a good starting point for after the surgery.
• Another reason why ACL tears are often season-ending is because of the length of time the ligament needs to regrow. ACL tears cannot be stitched back together (that’s why the term “reconstruction” is used, not “repair”). A graft must be used. Grafts are usually taken from another site from the person’s body and generally are taken from the patellar (kneecap) or hamstring (muscles on back of the thigh) tendons. The graft acts as a foundation or scaffolding to allow the ligament to regrow.
• Ligament regrowth takes 6-9 months. Physical therapy (PT) is needed along the way to restore motion, strengthen the surrounding muscles, as well as, a program to help strengthen the new ligament. PT focuses on hamstring strengthening, correction of knee mechanics and a progressive return to sport-specific drills.
Is there a way to prevent ACL tears?
• Yes, there are many ACL-prevention programs available and should be done as part of preseason conditioning.
• ACL prevention programs are very important for female athletes who have up to a 9 time higher risk for ACL tears when compared to males. The increased risk is due to anatomic differences, as well as, decreased neuromuscular control.