Sprained Knee

A knee sprain is a common injury that can be quite disabling. The pain, swelling, and stiffness from a sprained knee can prevent you from doing your daily activities. It may even force you to change your lifestyle. Thankfully, simple measures like home exercises can help relieve your knee pain and increase the range of motion.

You can work on strengthening the knee and reduce recovery time. In this guide, we provide you with an overview of the causes, symptoms, and treatment of knee sprains. We also introduce you to some knee exercises that can help you treat your sprain and prevent future injuries.

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Juhi Modi Medical Writer
Medically reviewed by 


What is a knee sprain?
What are the causes of a sprained knee?
Symptoms of a sprained knee
Diagnosis of a sprained knee
Treatment for knee sprains
Other treatment options for knee sprain
Recovery time
Complications of knee sprain
When to see a doctor
Helping you heal from knee sprain

The knee is one of the largest and strongest joints in the body. It supports the body’s weight and allows us to perform many everyday activities such as sitting, standing, walking, and running. The knee is a complex joint made up of different kinds of structures including bones, muscles, menisci, and ligaments. An injury to any of these structures can result in symptoms.

A knee sprain is a common injury, especially among people who take part in contact sports like football and rugby. A sprained knee can also occur during high-intensity sports like skating and skiing.1 This does not mean that knee sprains cannot occur in non-athletes.

You can also be unlucky to suffer a knee sprain as you go about your normal day-to-day activities. This usually happens because of an unnatural movement, like twisting during a slip and fall. Knee sprains can cause crippling symptoms that make it impossible to do your daily activities, let alone take part in sports. The good news is that you can control your symptoms and recover from a knee sprain with simple measures like home exercises.

At Injurymap, we are committed to helping you live a life free of injuries and pain. With this comprehensive guide, we will help you understand knee sprains and how to prevent them. Please remember, this guide is for general informational purposes only. You should get professional medical care if your symptoms do not improve with rehab exercises and other home treatments.

Looking for a solution to knee sprain? Try the Injurymap exercise app now.

What is a knee sprain?

A knee sprain is an injury to a ligament. A ligament is a sturdy band of tissue that connects the different bones in the knee joint. When one or more ligaments are torn or overstretched, it is called a sprained knee. Four major ligaments support and stabilize the knee.2

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

The severity of the ligament tear in the knee can vary. When a ligament is stretched, leading to tiny tears, it is called a mild knee sprain. People with a mild knee sprain (grade I) can usually continue to bear weight on the leg. A moderate (grade II) sprain means the ligament is partially torn. This can lead to pain and knee instability (a feeling that the knee is going to give out while you’re standing or walking). Severe (grade III) knee sprains occur when the ligament is completely torn, resulting in an unstable joint and inability to bear weight on that leg.2

Severity of ligament tear

What are the causes of a sprained knee?

The most common cause of a knee sprain is an unnatural movement during physical activity. That’s why this type of knee injury is common among athletes who play sports that involve contact, jumping, running, and turning. For example, knee sprains are more common in people who play basketball, football, and rugby. Sprained knees can also occur during wrestling, gymnastics, and skiing.

Some of the movements that can cause a sprained knee include:1

  • Sudden stops
  • Sudden changes in direction
  • Twisting or pivoting
  • Hyperextension (over-straightening the knee)
  • Tackling

Knee sprain

Besides unnatural movements, a direct blow to the knee can also cause a knee sprain. For example, the ACL can be sprained by a direct hit to the outside of the knee. A direct impact on the front of the knee, for example during a car crash, can lead to a sprain in the PCL. Falls that cause the lower leg to twist outwards can cause an MCL injury. Knee sprains involving the LCL are uncommon because this ligament is protected by the opposite leg. But, a sharp blow to the inner knee can generate a force that stretches or tears the LCL.2

A poor physical condition, lack of flexibility, and decreased strength in the muscles and ligaments surrounding the knee are risk factors for a knee sprain. You can reduce your risk of knee sprain by using the Injurymap app to make your leg muscles strong and flexible.

Symptoms of a sprained knee

The main symptoms of a sprained knee are pain, swelling, stiffness, and tenderness. Many people hear a popping noise when the injury occurs. There can also be instability of the knee. Some people have trouble bearing weight on that leg when the knee sprain is severe.

Bruised knee

The ACL and MCL are the most commonly injured knee ligaments.1 The LCL is rarely sprained on its own. LCL injury is more likely during a severe knee injury that involves multiple ligaments.1 The symptoms of knee sprain can vary depending on the specific ligament involved.2

Symptoms of ACL injury

  • A popping sensation at the time of injury
  • Significant knee swelling that appears quickly after the injury
  • Severe pain
  • Discoloration (blue and black knee)
  • Instability (buckling or giving out when you stand)

Symptoms of PCL injury

  • Mild knee swelling
  • Minor difficulty with knee movement
  • Mild pain which is often worse with kneeling
  • Usually no knee instability

Symptoms of MCL injury

  • Pain
  • Swelling
  • Tenderness on the inner side of the knee
  • Buckling toward the outside

Symptoms of LCL injury

  • Pain
  • Swelling
  • Tenderness on the outer side of the knee
  • Buckling toward the inside

Diagnosis of a sprained knee

If you have symptoms of a knee sprain, some clues can point to the specific ligament that is injured. For example, if you suffered a direct blow to the outer knee, heard a pop, and developed severe pain and knee swelling within a few hours, it points to an MCL and / or ACL sprain. However, it is important to seek medical advice and not self-diagnose.

Your doctor will diagnose a knee sprain based on your medical history and physical examination. They will test the steadiness of your knee and your ability to bear weight on that side. The doctor will compare the sprained knee to the other side and check for discoloration, deformity, and tenderness.2

If your doctor suspects a severe knee injury, he or she may order imaging studies, such as MRI. This will show if one or more of the knee ligaments are torn.

Exercises for knee sprain

A rehabilitation program is the best way to strengthen the muscles around the knee and stabilize the joint. You should always start slowly and gradually increase the intensity of your exercise program. Never push yourself to the point of pain. Here are some exercises that can help you become stronger and regain motion faster.

  1. Cycling exercise

    Cycling exercise with back on floor
    40 sec.

    This browser does not support the video element.

    • Lay down on your back.
    • Bike with your feet in the air.
    • Bike "forward" for 20 seconds then "backward" for 20 sec.
  2. Skiing exercise

    Forwards neck stretch
    30 sec.

    This browser does not support the video element.

    • Sit on a chair.
    • Merge your hands in the back of your neck and slowly pull your head as far forward as possible.
    • You should feel a stretch in the neck muscles.
    • Keep the stretch for 30 seconds.
  3. Pelvic lift

    Pelvic lift
    5 reps

    This browser does not support the video element.

    • Lie on your back with bent knees and your feet placed flat on the floor.
    • Lift the pelvis up align your body with it with your thighs.
    • Pull up your pelvis and suck in your navel and slowly stretch one leg while you keep it aligned with the body and thighs without losing the pelvis.
    • Use your hands to make sure you are not dropping the pelvis to one of the sides.
    • Repeat the exercise 5 times to each side.

Other treatment options for knee sprain

RICE Therapy: If you have suffered a sprained knee, it is important to allow a period of rest to allow the knee to heal. For mild to moderate sprains, doctors recommend RICE therapy. This includes R (rest), I (icing to reduce swelling), C (compression with an elastic bandage), and E (elevation of the injured knee).

Pain Medications: You can use nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen. They provide short-term relief of pain and swelling. These drugs can help reduce symptoms and allow you to begin a rehabilitation exercise program. This is important to strengthen and stabilize the knee and prevent you from injuring it again.2

Bracing: Sometimes doctors recommend wearing a knee brace for a short period. This takes the load off the ligaments and supports the knee while it heals.2

Surgery: A torn ligament sometimes needs surgical repair. This can usually be done with a minimally-invasive approach (keyhole surgery) called arthroscopy. A tiny camera is inserted into the joint to guide the surgeon in repairing the ligament.2

Recovery time

Luckily, the vast majority of people with knee sprains recover fully. All you need is the proper treatment and a good rehabilitation program.

How long does it take to recover from a knee sprain?

In general, mild to moderate knee sprains usually heal in 2-4 weeks. People who need surgery for ligament repair can take up to 6 months to return to baseline.3 After operation, 80% of patients with ACL injuries, return to some form of sport, 65% return to the same sporting level and only 55% return to sport at a competitive level..1 MCL and LCL strains also heal well with conservative treatments like home exercises.

How do you know that you have recovered from a knee sprain?

You will know you have recovered from a sprained knee when you have no pain or swelling. You can move your knee freely in all directions. There is no problem with doing daily activities. You can play sports without any symptoms.

Complications of knee sprain

Even with proper treatment, a knee sprain can lead to other problems over time. People with long-standing knee sprain can develop degenerative joint disease (osteoarthritis) in the injured knee. This can lead to long-lasting pain and instability.2,3

When to see a doctor

Most people can manage a mild knee sprain at home and recover fully with home exercises. However, it is important to get the opinion of a medical professional if you suspect your knee injury is something more serious. How can you tell if your symptoms are worthy of a visit to the doctor? Here are some telltale signs that your knee injury needs to be looked at:4

  • Your knee is locked (you’re unable to straighten it)
  • You have severe pain and/or significant swelling
  • You cannot put weight on the injured leg
  • Your knee buckles (gives out or feels unstable)
  • You have sharp pain in a specific location
  • Your symptoms do not improve with home remedies

Helping you heal from knee sprain

A knee sprain is a common injury that can prevent you from living a full life. The pain can make it difficult to do your normal daily activities. You may not be able to play the sports you love.

Fortunately, a sprained knee is treatable. The injury heals quickly in most people. For mild sprains, doctors recommend that you continue using your knee normally even if it feels a little stiff and painful.5 Once the initial symptoms ease off, stretching and strengthening exercises are the quickest way to recover from a knee sprain. Remember to gradually increase exercises as the pain and swelling reduce. It’s a good idea to build strength with rehab exercises before returning to sports which can potentially cause a re-injury.

The Injurymap app has a range of effective exercises that can be performed at home with little to no equipment. If you have suffered a knee sprain, you should focus on exercises that will make your leg muscles stronger. This will not only speed up recovery from a sprained knee but also prevent future injuries. The Injurymap app demonstrates each exercise so it’s easy to follow along and workout at your convenience. A sprained knee should never prevent you from living the life you want and doing the things you love. Start using the Injurymap app today to become the strongest version of yourself.

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About the author

Juhi Modi has two decades of experience as a medical writer with varied interests and an enduring passion for health, biology, and science. She uses her educational background in medicine to write science-backed articles for clients around the world.


  1. https://now.aapmr.org/medial-and-lateral-collateral-ligament-injuries/ 

  2. https://www.health.harvard.edu/a_to_z/knee-sprain-a-to-z 

  3. https://www.healthline.com/health/sprained-knee#outlook 

  4. https://flexcin.com/6-telltale-signs-your-knee-injury-is-serious/ 

  5. https://www.gosfordhillmc.co.uk/wp-content/uploads/2017/03/101108kneesprain.pdf