Common Knee Injuries

Written By: Chloe Wilson, BSc(Hons) Physiotherapy
Reviewed by: KPE Medical Review Board

Common knee injuries and how to treat them

Common knee injuries vary from minor falls which may settle quickly to major accidents which may take months to recover from.

Some injuries result from massive forces going through the knee, whereas others may be the result of simply twisting slightly wrong. The most common knee injuries are:

1) Ligament Injuries: damage to the ligaments that support the joint
2) Muscle Injuries: damaged to the muscle fibres
3) Kneecap Injuries: damage to the patella bone
4) Cartilage Injuries:
damage to the cartilage lining the joint

The knee ligaments and cartilage are the structures most commonly damaged.

Knee Injury Diagnosis

Knee injury diagnosis involves looking at the cause of your knee injury and the symptoms you are experiencing. The most common symptoms of knee injuries are pain and swelling, but there may also be other symptoms such as instability, locking, clicking and giving way.

Knee injuries can be diagnosed by both history and physical examination. Often, your doctor will be able to diagnose a knee injury from what you tell them and what they can see, but in some cases, they may also send you for tests such as an x-ray or MRI scan.

Here, we look at the 8 most common knee injuries: including how they occur, the symptoms for each one and the best knee injury treatment options.

Knee Ligament Injuries

Knee ligament injuries can affect any of the four knee ligaments. Knee ligaments are usually injured either by sudden twisting movements, or when a great deal of force goes through part of the knee e.g. from a sporting tackle.  Ligament injuries are the most common knee injuries in sports.

There are four ligaments in the knee, which work in the pairs. The anterior cruciate ligament and posterior cruciate ligament control the forwards and backwards movement of the knee and are really important for providing stability. The medial and lateral collateral ligaments provide sideways stability for the knee.

1. ACL Knee Injuries

ACL Knee Injury Diagnosis, Symptoms & Treatment

What is an ACL Knee Injury: Anterior cruciate ligament gets overstretched and tears/ruptures

Causes: Knee bending the wrong way, pushing back too far or twisting of the knee

Immediate Symptoms: Popping sound, swelling, pain, giving way

Long Term Problems: Lack of stability with pivoting and twisting

ACL Knee Injury Treatment: Exercise rehab and/or surgery. See ACL Injuries section for more information.

2. MCL Tear

Medial Collateral Ligament Tear: Causes, symptoms and treatment for an MCL Knee Injury

What is an MCL Tear: Damage to some or all of the fibres of the medial collateral ligament on the inner side of the knee

Causes: Force through the outside of the knee e.g. tackle, sudden twisting of the knee e.g. skiing

Symptoms: Inner knee pain, swelling, instability, difficulty bending the knee

MCL Knee Injury Treatment: PRICE, exercises, knee brace. See the MCL Tear section for more info.

3. PCL Knee Injury

Classic presentation of a PCL injury - one of the less common knee injuries

What is a PCL Knee Injury: Tear of the Posterior Cruciate Ligament that sits inside the knee joint.  One of the less common knee injuries

Causes: A force through the top of the shin bone causing the knee to bend backwards e.g. car accident or fall on to a bent knee

Immediate Symptoms: Usually fairly mild pain and swelling.  Often not noticed immediatelyThe shin bone tends to drop back from its normal position as seen in the picture here

Long Term Problems: Instability, particularly with activities when the knee is bent e.g. stairs, problems with running

PCL Knee Injury Treatment: Knee brace, physical therapy and/or surgery. See PCL Injuries section for more information.

4. Knee Sprain

Common Knee Ligament Injuries: Causes, Diagnosis & Treatment

What is a Knee Sprain: Over-stretching any of the knee ligaments which tears some of the fibres. This is one of the most common knee injuries

Causes: sudden force through the knee or sudden twisting

Symptoms: knee pain, swelling, instability, difficulty bending and straightening the knee

Knee Sprain Treatment: PRICE, exercises, knee braces. See the knee sprain section for more info.

Knee Cartilage Injury

One of the most common knee injuries is damage to the knee cartilage. The knee joint is lined with two types of cartilage, articular cartilage which lines the bones, and then a second special layer of cartilage known as the meniscus. The meniscus works like special cushioning to reduce the force going through the knee bones.

5. Meniscus Tear

Meniscus tears are common knee injuries: causes, diagnosis & treatment

What is a Knee Cartilage Injury: Tear in the cartilage, aka meniscus, lining the knee joint. Meniscus tears are one of the most common knee injuries

Causes: a) Suddenly - force through the knee or sudden twisting of the knee, or b) Gradually - through wear and tear e.g. arthritis

Symptoms: knee pain, swelling, locking, instability, difficulty straightening the knee, difficulty walking

Knee Cartilage Injury Treatment: PRICE, exercises, knee brace, tubigrip, sometimes requires surgery. Can take a long time to heal - see the Cartilage Injuries section to find out more.

Muscle Injuries

Another group of common knee injuries is muscle damage.  If the muscles around the knee are suddenly overstretched, some or all of the muscle fibres can tear. 

These are commonly referred to as muscle strains.  Treated correctly, and a full recovery is usually made in a few weeks, but if you try to return to activity too quickly, you are likely to suffer from long term problems

6. Calf Strain

Calf tears are common knee injuries, particularly for runners. Learn about the causes, symptoms and treatment options

What is a Calf Strain Injury: Tear to some or all of the muscles fibres in one or both of the calf muscles

Causes: a) Suddenly - sudden acceleration e.g. jumping or sprinting, or b) Gradually - repetitive overuse e.g. running

Symptoms: calf pain, swelling, bruising, difficulty walking, cramp

Calf Injury Treatment: PRICE, exercises, tubigrip, sometimes requires surgery. Visit the Calf Muscle Strain section to find out more.

Knee Cap Injuries

Kneecap problems are less common knee injuries as they require a great deal of force through the knee.

7. Dislocated Patella

A dislocated patella is a fairly common knee injury. Learn about common causes, symptoms and treatment options

What is a Knee Dislocation Injury: Knee cap get pushed out of place. This is one of the least common knee injuries

Causes: Usually caused by major, high impact injury e.g. car crash

Symptoms: Deformed leg - won’t be in a straight line. Very painful and swollen. Occasionally you lose feeling below the knee

Knee Dislocation Injury Treatment: Relocation of the bones, exercises, knee brace, may require surgery.  Find out more in the dislocated patella section.

8. Patella Fracture

Patella fractures are one of the less common knee injuries. Learn about common causes, symptoms and treatment options

What is a Patella Fracture: When the kneecap bone breaks into two or more pieces.

Causes: A great force through the front of the knee e.g. falling from a height or impact from a car crash.

Symptoms: Pain and swelling at the front of the knee. Difficulty moving the knee and walking

Kneecap Fracture Treatment: May require surgery, exercises, knee brace and/or cast.  Find out more in the kneecap injuries section

To find out more about each of the specific types of knee injury, including simple and effective treatment options for each, choose from the links above.

Other Common Knee Injuries

As well as common knee injuries there are a number of other causes of knee pain which tend to come on gradually rather than suddenly.

If you have a longer term knee condition or have been having knee pain for a while but don’t know what’s wrong, then go to my section devoted to common knee conditions or visit the knee pain diagnosis section for help working out what is causing your knee pain.

You can also find a wide range of treatment options in the knee pain treatment section. 

  1. Knee Pain Guide
  2.  ›
  3. Injuries

Page Last Updated: 25/04/19
Next Review Due: 25/04/21

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1. British Journal of Sports Medicine: Injuries around the knee - Symposium. Sancheti P, Razi M, Ramanathan EBS, et al. December 2010

2. Orthopedic Journal of Sports Medicine: A Nationwide Follow-up Survey on the Effectiveness of an Implemented Neuromuscular Training Program to Reduce Acute Knee Injuries in Soccer Players. Malin Åman M, Larsén K, Forssblad M, Näsmark A, Waldén M, Hägglund M. December 2018

3. Arthritis Research & Therapy Journal: Down on one knee: soft tissue knee injuries across the lifespan. Thorlund J, Culvenor A, Ratzlaff C. December 2014

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