Anterior Cruciate Ligament (ACL) Tear – Signs & Symptoms

Anterior Cruciate Ligament (ACL) Tear

The Anterior Cruciate Ligament (ACL) is one of the main stabilising ligaments of the knee. It is the most common knee ligament injury to occur, and is unfortunately associated with significant time out of sport/activity. The injury generally occurs from sudden change of direction, an awkward landing (especially after being bumped mid-air), or from direct contact at the front or side of the knee (e.g., in a rugby tackle).

If you have recently injured your knee and are wondering if you may have torn your Anterior Cruciate Ligament, here are some signs & symptoms to look out for:

1. The Knee Swells Up Quickly

There is a blood vessel near the ACL that may also get injured when the ACL is torn. With this, comes a lot of bleeding (known as a haemarthrosis) which is the cause of the rapid swelling in the knee. This can occur in as quickly as 30 minutes and usually progresses over the next 24 hours.

2. You Hear a “POP”

When you tear your ACL, you may hear, or even feel a POP. Knees cracking and making noise is generally considered normal and quite common. However, when instant pain and swelling occur after, this is a noise that simply cannot be ignored!

3. Inability to Weight Bear

If you are struggling to walk or bear weight on your injured knee, this is another sign that you may have injured your ACL. This can be due to a feeling of instability (like your knee is going to buckle), or as a result of pain and discomfort.

4. Positive Lachman’s Test

The Lachman’s test is an orthopedic examination to assess the integrity of the ACL. The ACL prevents excessive forwards (anterior) translation of the tibia (shinbone) on the femur (thigh bone). A mushy end feel, as opposed to a firm end feel when comparing both legs, may indicate the ACL is not doing its job because it has been torn. This is the most accurate orthopaedic ACL examination in an acute setting, and is the reason you will often see physio’s doing this out on the sporting fielding as soon as a suspected ACL injury has occurred!

5. Loss of Range of Motion (ROM)

Are you struggling to bend or straighten your knee due to pain or restriction?  This may indicate that you have had an injury to the ACL (and/or other structures in the knee joint).

What Next?

An MRI will confirm if you have had an ACL tear. It is important to note that some of these signs & symptoms are associated with injuries to other structures in the knee as well. If you have a knee injury, seeing a medical professional is crucial to get a quick and accurate diagnosis.  This may include a referral to necessary imaging if needed. Physiotherapists play a crucial role in the assessment, treatment, and rehabilitations of ACL tears. It is important to note that these injuries can be managed with or without surgery. A shared decision-making approach should occur between yourself and a team of medical professionals (surgeon, physiotherapist) in regard to management of the injury.

If you have injured your knee and are looking to have it assessed and/or rehabilitated, contact us today.  We will provide an evidence-based approach to managing your condition!

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