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ACL Injuries and What You Can Do ABout It?

It is one of the most dreaded sounds nobody wishes to hear during exercise or sports – a popping sound, or sensation, in your knee.

Whether you are an athlete or someone looking to keep fit, knee injuries are never fun, and it feels scarier when your knee makes a popping sound during the injury.

Although it may turn out to be nothing serious, there are some reasons that it may be advisable to get your knee checked out by a doctor or physiotherapist. In this article, we will discuss what is an ACL injury, some of the common signs and symptoms, and an overview of some early treatment options.

Understanding your knee and the role of the ACL

The knee joint consists of two main bones: the thigh bone (femur) and the shin bone (tibia). Besides the leg muscles that support the knee and generate movement, there are also ligaments around the knee that help provide extra stability. Think of ligaments as stiff rubber bands that help bind and keep the joints aligned even when the muscles are relaxed.

The anterior cruciate ligament (ACL) is an important ligament inside the knee joint between the femur and tibia. It helps prevent the tibia from sliding forward of the femur, especially during kicking movements. The ACL also prevents stability to the knee during twisting movements, such as sudden changes of direction during running.

An ACL injury occurs when the ligament is strained, or torn. As such, an ACL injury indicates a reduction in the stability of the knee joint. It is important to differentiate an ACL injury from other types of knee injuries due to the different management and treatment plans. Here are some signs and symptoms that you may have injured your ACL.

Signs and symptoms of an ACL injury

Injury history:

How the injury happened is an important factor in determining whether an ACL injury has occurred.

Most ACL injuries occur during movements when the knee and foot move in different directions, resulting in a twisting motion at the knee. Common motions where this may occur include sudden changes of direction when running, or landing awkwardly after a jump.

An ACL injury can also occur when an external force is applied to the side of the knee, such as during a soccer tackle, or being kicked from the outside of the knee.

Although a popping sound is usually heard when the ACL injury occurs, it is important to note that ACL injuries can also occur without it. How the injury happened is more important than the absence or presence of a popping sound.

• Swelling and pain:

The knee usually rapidly swells after an ACL injury, and may occur almost immediately after the injury. There is also usually sudden onset of pain felt during the injury, rather than a gradual onset of knee pain. In instances where the injury is mild, it is possible that no pain or swelling is noticed.

• Stiffness:

You may notice difficulty with bending or straightening the knee after an ACL injury. This limited movement is usually due to pain, or swelling. Increased walking or exercises tends to worsen the stiffness and swelling.

• Difficulty with putting weight, or instability:

You may also experience difficulty with putting weight on the injured leg, or a feeling of the knee giving way when weight is put onto the injured leg. This feeling of instability is worsened when going down stairs, or when trying to walk quickly.

Management of an ACL injury

Dealing with an ACL injury can be frustrating as your mobility and independence is frequently affected. Here are some simple and effective ways to address some of the symptoms and help you on your recovery.

• Appropriate rest and swelling management:

It is important to strike a balance between rest and movement early in the recovery process. Too much rest and avoiding usage of the injured leg results in muscle weakness and joint stiffness, which hinder the recovery process. Although early movement is important, excessive walking or exercise can lead to swelling in the knee, which limits movement or may even cause pain.

Striking an appropriate balance between doing too much, or too little, will ensure you make consistent progress in your recovery.

• Joint protection:

During the early phase of the injury, it may be helpful to use an appropriate knee brace to provide additional support to the knee, especially during prolonged walking or when managing stairs. This may be helpful if you have an unstable knee or sense of giving way. Depending on the extend of the injury, you may also be advised on the use of crutches to reduce the load on the injured leg.

It is important to note that the use of braces and crutches is temporary, and you will gradually reduce your need for them as you improve.

• Restore knee flexibility:

Restoring full flexibility of the knee is an important goal to achieve in the first few weeks after injury. A knee that cannot full straighten and bend will reduce the effectiveness of the exercises, as well as make it difficult to perform simple movements, such as getting up from a chair, or getting in and out of a car.

Keeping the knee moving throughout the day, such as doing knee bends when sitting or lying down, and performing knee squeezes with the knee straight will help with restoring full movement of the knee quickly.

• Exercise rehabilitation:

Exercise will be the cornerstone of any ACL rehabilitation program. It is important to improve the strength and control of the leg muscles to compensate for the injured ACL. Rest, while effective for reducing pain and swelling, will not help with improving the strength and endurance of the muscles. A graduated rehabilitation program will start with restoring full knee flexibility first, and progressing to improving the strength and control of the leg muscles. Although the thigh muscles, such as the quadriceps and hamstrings, are the biggest and closest to the knee, and thus key muscles in providing stability to the knee, it is also vital not to ignore the hip and calf muscles as the entire leg will have to work together when returning to normal activity or sports. As your strength improves, the exercises will progressively increase in difficulty to incorporate elements of fast movements, and balance or changes in direction to prepare for return to sports.

In the early phase of the injury, some simple exercises to quickly get the muscles working again include quadricep squeezes with the knee straight, and gluteal bridges to help target the hip muscles.

It is important to note that ACL rehabilitation is a process that will take months, and will require patience and dedication.

ACL injuries can feel scary, and frustrating initially. If you think you may have injured your ACL, it is advisable to seek out a doctor or physiotherapist for an assessment. In some cases, surgery may be needed for the knee to feel stable, whereas an intensive course of rehabilitation may be all that is needed for return to normal activity in others. A qualified healthcare professional will be able to assess and advise you on the treatment options based on your presentation and individual needs.

With consistency and dedication to an appropriate rehabilitation program, most individuals with an ACL injury are able to regain full function of their knee and return to their regular activities. If you are looking for help to manage your ACL injury, feel free to contact our team of dedicated therapists at or 6581 9688.


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