Your ACL, also known as the Anterior Cruciate Ligament, is a key component of the human knee, and is composed of strong fibrous material and helps aid in restricting excessive motion. This is achieved by limiting mobility of the knee joint. The ACL is one of the four main ligaments of the knee, and is the knee ligament most likely to be injured.
ACL injuries occur most often while participating in sports or activities which include sudden stops or changes in direction. Sports where you see a lot of ACL injuries include:
- Downhill skiing
Types of ACL Injuries
There are two main types of injuries which can occur to your anterior cruciate ligament-- sprains, and the much more severe, tears.
When you hyperextend your knee and put too much stress on your ACL, it can cause a ligament sprain. Sprains come in three severities:
Grade 1: The ligament is lightly damaged. It has been stretched a bit, but is still able to help keep the knee joint in place.
Grade 2: The ligament is stretched to the point where it is loose. This is commonly known as a partial ligament tear.
Grade 3: Also known as a complete tear of the ligament. The ligament has been split into two pieces, and the knee joint is no longer held in place.
When you hyperextend your knee violently, the damage to your ACL can go beyond a mild sprain and can fully tear the ligament. Unfortunately, these are the most common injuries to the ACL, and require the longest recovery time.