ACL Tear

ACL tears are commonly classified into three grades depending on their severity:

1. Grade I Sprain: The ACL is mildly damaged. It has been slightly stretched but can still keep the knee stable. These can often be managed without surgery if you are able to perform the activities you would like to do without feeling instability or your knee shifting.
2. Grade II Sprain: The ACL has been stretched to the point where it becomes loose, often referred to as a partial tear. These often require surgery to remain active. However, some patients may be able to cope with this injury and be able to participate in sports without issue.
3. Grade III Sprain: This is a complete tear of the ACL. The ligament has been split into two pieces, and the knee joint is unstable. This will usually require surgery for those who wish to return to higher level activities or ones that require turning and pivoting.

ACL injuries typically occur during sports that involve sudden stops, changes in direction, or jumping — such as soccer, basketball, football, or skiing. Direct impact, like a football tackle, can also result in an ACL tear. For instance, if you’re running and abruptly change direction, your foot is planted, but your momentum carries your body to the side. This force can cause an ACL tear.

At the moment an ACL tear occurs, you might hear a “pop” sound and feel your knee give out from under you. You may feel immediate pain, almost as if you’ve been hit in the knee. The pain is often severe and is usually followed by swelling within a few hours due to bleeding from the torn ACL. Your knee may also feel unstable or like it’s giving way when you try to stand or put weight on it.

Over time, if your ACL is damaged, you might feel a painful catching or locking sensation in your knee when you try to move it certain ways. You might also notice that your knee tends to give way during physical activities that involve twisting or turning at high speeds.

Unlike other ligaments, or tissues in the body, the ACL usually cannot repair itself effectively. This is primarily due to the lack of blood supply to the ACL. However, a partial ACL tear might improve over time with non-surgical treatments like physical therapy and the use of a brace. Non-surgical treatment may be an option for patients with specific tear types, or older patients and those with a very low activity level. But for young, active individuals, especially those involved in sports, an ACL tear often needs surgical intervention for optimal recovery.

The diagnosis of an ACL tear is a multistep process. It starts with understanding the patient’s medical history, including the specifics about the knee injury – how it occurred, what was felt or heard, and the symptoms experienced immediately after. This is followed by a physical examination where your knee surgeon Dr. Mayo will check your knee for signs of instability and injury to other components of your knee. A common test is the Lachman’s Test, where the doctor pulls on your shin bone to see if it moves forward — a sign of an ACL tear.

To confirm the diagnosis, imaging tests such as X-rays (to rule out fractures) and Magnetic Resonance Imaging (MRI) scans (to visualize the soft tissues like ligaments and tendons) are used. The MRI can provide a clear image of the ACL, and it is particularly effective at revealing partial and complete tears, as well as to determine if any other structures in the knee were damaged during or after the injury.