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 fall into four groups:

  1. Ligament Injuries
  2. Muscle Injuries
  3. Kneecap Injuries
  4. Cartilage Injuries

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

Here, we look at nine of the most common knee injuries, including how they occur, the symptoms for each one and the best knee injury treatment options. Once you've identified your knee injury, you can find out loads more detailed information by visiting the relevant section. 

1. 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.

ACL Knee Injuries

ACL Knee Injury Diagnosis, Symptoms & Treatment

What is an ACL Knee Injury: Anterior cruciate ligament gets overstretched and tears or 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. Visit the ACL Injuries section for more information.

MCL Tears

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. Visit the MCL Tear section to find out more

PCL Knee Injuries

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 immediately. The 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. Visit the PCL Injuries section for more information.

Ligament Sprains

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. Visit the knee sprain section to find out more

2. Knee Cartilage Injuries

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.

Meniscus Tears

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: Suddenly - force through the knee or sudden twisting of the knee, or 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.

3. Muscle Injuries

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

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

Quads Strains

What is a Quads Strain Injury: Tear to some or all of the muscles fibers in one or more of the quadriceps muscles

Causes: Sports involving sprinting, jumping and kicking, muscle tightness, weakness and fatigue 

Symptoms: thigh pain, swelling, bruising, "popping" sensation and difficulty walking, climbing stairs and getting in and out of a chair

Quads Injury Treatment: PRICE, exercises, tubigrip, physical therapy and occasionally surgery. Visit the Pulled Quads section to find out more.

Quads Tendon Rupture

Quads Tendon Rupture: Causes, Symptoms & Treatment Options

What is a Quads Tendon Rupture: Full or partial tear of the quadriceps tendon that attaches the quadriceps muscles to the kneecap

Causes: Sports injuries, fall, twisting, tendon weakness, underlying medical condition, corticosteroids

Symptoms: immediate pain above kneecap often with audible "pop", limited knee extension, difficulty walking, knee swelling

Quads Tendon Rupture Treatment: Immobilisation, crutches, physical therapy or surgery for a complete tear. Visit the Quads Tendon Rupture section to find out more.

Calf Strains

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: Suddenly - sudden acceleration e.g. jumping or sprinting, or 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.

4. Knee Cap Injuries

Kneecap problems are less common knee injuries as they require a great deal of force through the knee. As a result, they tend to be more serious knee injuries.

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.

Patella Fractures

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.

Knee Injury Diagnosis

Common knee injuries are diagnosed by a combination of your history, physical examination and radiographic scans.

Doctors and physical therapist can diagnose many common knee injuries from what you tell them about how you injured your knee and your symptoms, and what they can see.

In some cases, they may also send you for tests such as an x-ray or MRI scan to look directly at the bone and/or soft tissues.

Other Common Knee Injuries

As well as these nine common knee injuries there are a number of other causes of knee pain which tend to come on gradually rather than suddenly, such as tendonitis and bursitis.

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 the section devoted to common knee conditions.

Page Last Updated: 09/09/20
Next Review Due: 09/09/22

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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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