Knee sprain and anterior cruciate ligament (ACL) tear

Synonym for sprain:

• Strain

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What is a knee sprain?

It is a stretch or tear of one or more ligaments in the knee joint.

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What are the ligaments of the knee?

A ligament is a tissue that serves to hold bones together. We have hundreds of ligaments in the body between each of our bones to stabilize the bones. 

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In the knee, there are four main ligaments:

• The anterior cruciate ligament (ACL)
• The posterior cruciate ligament (PCL)
• The medial collateral ligament (MCL)
• The lateral collateral ligament (LCL)

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Together, these four ligaments help stabilize the knee joint. During a knee sprain, one or more of these ligaments may be affected.

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The two most commonly affected ligaments are the anterior cruciate ligament and the medial collateral ligament.

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What are the causes of a knee sprain?

A sprain is always caused by an accident, a blow, or a twist. There must be a clear traumatic event.

Common causes of knee sprains include:

• Falling on the knee
• Pivoting trauma with the foot fixed on the ground (e.g., a sudden change of direction while running in soccer or football)
• A direct blow to the knee that causes it to twist

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Therefore, if the pain appeared slowly and gradually, without any clear accident, it is not a sprain.

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What are the symptoms of a knee sprain?

The common symptoms are:

• Knee pain (the location of the pain may vary) after a trauma
• Swelling of the knee that may appear immediately or in the following hours
  
  • If it is a minor sprain, it is very possible that there will be no swelling.
• There may be redness and warmth of the knee, which generally lasts 48 hours after the accident
• Slight to significant difficulty putting full weight on the leg

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Depending on the severity of the sprain, painful movements may vary from person to person.

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How is a knee sprain diagnosed?

Diagnosis is possible with a review of the symptom history and a clinical examination. In some cases, if a complete ligament tear is suspected, magnetic resonance imaging (MRI) may be necessary.

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However, be careful because not everything seen on this imaging is relevant.

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« Furthermore, in the majority of knee sprains, getting an MRI does not change the treatment plan at all, which remains physiotherapy first. »

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When should I consult a physiotherapist for a knee sprain?

You should consult a physiotherapist if you have symptoms as described above or if your doctor has already ruled out any other cause that may be responsible for your pain.

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You do not need to see a doctor before consulting a physiotherapist. If your condition requires you to see a doctor, your physiotherapist will be able to tell you.

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What are the physiotherapy treatments for a knee sprain?

As with all traumatic injuries, we must let the body do its natural healing work.

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"Inflammation is a normal and necessary process for proper healing. There is therefore no miracle way to speed up healing."

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However, it is very important to make sure to eliminate any factors that could slow down recovery.

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Here are some examples of things that could slow down healing:

• Worries or fears related to the injury or pain
• Improper dosage of exercises and daily activities
• Poor biomechanics of your movements
• Stiffness in the joints or muscles

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"That's why your physiotherapist can help you optimize the healing of the injury. Your physio will guide you in the best possible direction to ensure that the injury heals effectively."

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Think of healing from a traumatic injury like taking care of a plant. Pulling on the plant won't make it grow faster. However, you can make sure it gets enough water, sunlight, and fertilizer. We want to put the plant in a good environment to heal. It's the same for a traumatic injury.

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Your physiotherapist will perform an assessment to determine your limitations by evaluating the following elements:

• Your joint mobility
• The gliding of your nerves
• The quality of your movements
• Your strength and stability

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Based on the assessment results, your physiotherapist will:

• Mobilize your knee to reduce pain and improve your movement
• Give you specific exercises to retrain the control of your knee movements.
• Give you exercises to regain mobility, reduce pain and regain your muscle strength.
• Teach you how to properly manage your daily activities and hobbies to optimize healing
• Give you advice for your posture and movements.

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What to do at home for a knee sprain?

As with any traumatic injury, you must follow the PEACE and LOVE principles. Read the blog post on PEACE and LOVE (coming soon) and then read here for advice specific to knee sprains.

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PEACE and LOVE tips specific to knee sprains:

(make sure you have read the blog post that explains the PEACE and LOVE steps in detail)

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For C = Compression:

Use a compression bandage or taping to wrap your knee.

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For L = Load:

• Start walking and putting weight on the leg gradually without significantly increasing the pain.
• Wait until you no longer limp before increasing the duration of your walks.

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For V = Vascularisation:

Light to moderate, pain-free cardio exercise speeds up recovery. For a knee sprain, you can:

• Do stationary cycling without pain
• Swim without pain

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If you don't see any improvement after 10 days, you should consult a physiotherapist.

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If you are a runner, please refer to the blog post on running (link to come) for specific running tips.

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To learn more...

You can listen to the podcast created by one of our physiotherapists, Alexis Gougeon.

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Episode #1 discusses the prevention and treatment of running injuries.

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Find the episode on YouTube:

Click below to listen to episodes on podcast platforms:

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Sources

• Diagnostic validity of physical examination tests for common knee disorders: An overview of systematic reviews and meta analysis. Physical Therapy in Sport 23 (2017) 143-155
• Review article: Best practice management of common knee injuries in the emergency department. Emerg Med Australas . 2017 Dec 15.

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