Anterior cruciate ligament. ACL for short.
It’s the ligament that runs up from your shin bone and passes through the middle of the knee, attaching itself to the bony part of the femur, or thigh bone.
It’s not very big. Less than an inch and a half long and half an inch wide.
Regardless of it’s size, the ACL is crucial in keeping the thigh bone from sliding backward behind the shinbone and keeping the shinbone from sliding up behind the thighbone.
But that’s not all it does. The ACL also keeps the knee from turning, which is where we run into problems.
You tear your ACL when you plant your foot and the knee locks and turns at the same time. That’s why torn ACLs are very common in sports like basketball, football and soccer.
So how do you know if you’ve torn your ACL? The seven following tests you can perform yourself should help you decide if you need to visit a doctor.
1. Listen for a Popping sound.
If you tore your ACL your knee will pop. In fact, people near you may even be able to hear it. It’s a classic, telltale sign. Walk or simply try to bend your knee and listen for a pop.
2. Observe a Joint Shift.
Compare your injured knee with your healthy knee. Does the injured knee look like the knee cap is not in the position it should be? If it looks out of place, then you’ve probably torn your ACL. Go see your doctor.
3. Walk.
A torn ACL will inhibit your ability to walk. In fact, your knee may give out, causing you to stumble and fall. If you’re on the ground, stand up and walk.
4. Swelling.
It’s typical for fluid to flood the area of the knee when you tear your ACL. And if fluid floods the area, then it swells. You may also see bruising. Does the knee look puffy and discolored? If so, then it’s possible you’ve torn your ACL. See your doctor.
5. Evaluate Pain.
You may be in an extreme amount of pain if you’ve injured your ACL. Then again, it maybe subtle. It has a lot to do with your tolerance, but typically a torn ACL will be very painful, especially to the touch.
6. Unable to Bend Knee.
When you’ve torn your ACL you will lose a range of motion. Try bending your knee and then straightening it out. If you can’t bend your knee to a 90 degree angle or straighten out your leg because of pain, stiffness and swelling, then it is likely that you’ve torn your ACL. Set an appointment with your doctor.
7. Weak Leg Muscles.
A torn ACL will weaken your quadraceps (thigh muscles), making it difficult to lift your leg or even straighten it out. The culprit is the pain and swelling. If you can get to your feet, try to raise your leg. If it hurts too bad, call your doctor.
These seven tests aren’t meant to replace a professional evaluation by your doctor. Rather these tests will give you an indication–depending on the result of each test–of whether you should see your physician or not.