Anterior cruciate ligament (ACL) tears are some of the most common forms of injuries encountered by athletes. They occur when one of the four main ligaments in the knee, called the ACL, tears, leaving the knee less stable. The knee has four ligaments that connect the thighbone (femur) to the tibia (shin). These ligaments are what give the knee and leg flexibility and allow them to move easily. When a person has an ACL tear, they can experience reduced mobility and difficulty rotating their knee. It is one of the most common sports injuries, with nearly 300,000 cases occurring each year.
The majority of people who experience an ACL tear are athletes. Females are more susceptible to this than males. Some researchers believe this is due to variable conditioning methods in females. Athletes are usually more prone to this form of injury because of the pressure put on the ACL during athletic training, such as fast turns when running, or being tackled from behind in football or hockey. There are different levels of severity in ACL tears, and some require surgery to treat. Without proper treatment from a trained doctor, other parts of the knee can become injured as well, causing further problems down the road.
Anatomy of the Knee
The knee is the bone that connects the thighbone to the shinbone and provides mobility. It consists of the following:
In order for the knee to function properly, it uses each of the ligaments to give it flexibility and allow the leg to move and work smoothly. The ACL is the most important of the ligaments because it is the one that provides the most stability to the knee and allows a person to walk properly.
Types of ACL Tears
ACL tears can be divided into three gradation levels depending on their severity:
Grade 1 – This is the mildest form of an ACL tear. When a person has a Grade 1 tear, they are still able to walk and maintain some stability from the knee. While the ligament is stretched, it does not tear enough not to provide some function.
Grade 2 – This is usually referred to as a partial tear. When a Grade 2 ACL tear occurs, the ligament is stretched to a point where it becomes loose, making it more difficult to fully support the knee as it should.
Grade 3 – This is the most severe form of tear and results in a complete rip in the ligament. When this happens, the knee is unstable. Unfortunately, this is the most common of all ACL tears.
Causes of ACL Tear
There are many causes of ACL tears. While most causes are associated with some sort of sports trauma, there are other ways a person can tear their ACL:
Symptoms of ACL Tears
Depending on the severity of the ACL tear, symptoms can change. Most people who have an ACL tear report hearing a loud pop when the rip occurs. They also feel the sensation of the knee giving out from underneath them.
The following are common ACL tear symptoms. Every person is different and not everyone will experience all of these symptoms when a tear occurs:
ACL tear symptoms may be confused with those of other sports injuries, such as a tear in the meniscus, which oftentimes goes along with an ACL tear. Generally, the person with the tear is in so much pain that they stop all activity. If this happens, it is important to see a trained doctor in a timely manner.
The multidisciplinary team of orthopaedic experts at North Shore-LIJ Orthopaedic Institute in New York treats ACL Tears as well as a broad range of conditions that affect the bones within the body.