How do knees work?

The knee is the largest joint in your body. Your knees are complex joints which need to take your full weight. They allow your legs to bend and straighten.

There are 3 bones that meet at your knee:

1. the end of the femur (thigh bone)
2. the top of the tibia (shin bone)
3. the patella (kneecap)

The end of each of these bones is covered with cartilage which lets the parts move smoothly.

Between your femur and tibia there is a thicker cushion of cartilage called the meniscus.

Your knee also has 4 ligaments joining the bones as well as tendons which join bones to muscles in your leg.

What is a knee injury?

You might have a knee injury if there is damage to the bones, ligaments, cartilage or tendons.

Common knee injuries include:

• damage to the cartilage that lines the knee
• torn ligaments — these can be partial tears or complete tears
• torn meniscus — the cartilage between the shinbone and thighbone
• irritation to the kneecap

Less common injuries to the knee include:

• fractures (broken bones)
• kneecap or knee joint dislocations

What causes knee injuries?

Knees are easily injured because they take your full body weight. Knees come under stress when you run and jump. Knee injuries are particularly common when your knee is twisted whilst weight bearing.

It is common to injure your knee when playing sports such as:

• football
• netball
• basketball
• skiing

You may have a chronic knee injury due to:

• old trauma
• prior surgery
• chronic conditions such as osteoarthritis or rheumatoid arthritis

When should I see my doctor?

You should see your doctor if:

• your knee pain is very bad
• you have recently been injured or had an accident
• you cannot walk
• it feels like your knee is unstable or about to give way
• you can't straighten or fully bend your knee
• your knee looks deformed

How are knee injuries diagnosed?

Your doctor will examine you and ask about your symptoms. You will need to describe what happened at the time of the injury including:

• how you fell and if you made contact with other players or the ground
• any twisting of the joint
• any swelling or popping noises
• the location of the pain
• any previous injuries
• any loss of strength or feeling

Your doctor may order an x-ray, CT or MRI scan. These imaging tests are not always needed for knee injuries.

Talking about what happened and a physical examination by the doctor can be enough to diagnose the injury.

If there is a lot of swelling, some tests will not be able to be done until a few days after the injury.

Your doctor may refer you to a specialist doctor for treatment.

How are knee injuries treated?

Often knee injuries will get better using PEACE & LOVE:

• Protection — avoid activities that increase pain in the first few days after injury
• Elevation — lie or sit with your knee raised higher than your heart
• Avoid — avoid taking anti-inflammatories and icing
• Compression — firmly bandage your injury to reduce swelling
• Education — avoid unnecessary treatments and let your body heal

• Load — let your body guide you as you return to normal activities
• Optimism — be positive and confident
• Vascularisation — choose pain free activities to help repair your tissues
• Exercise — adopt an active approach to recovery

You can visit a physiotherapist for advice on knee injuries.

Don't use heat or massage to treat your injured knee. Avoid vigorous exercise while your knee is healing.

How are more serious knee injuries treated?

If you have a serious knee injury, you may need physiotherapy and a guided rehabilitation program.

Different treatments may be required for more serious knee injuries:

• ACL ruptures — will require a long period of rehabilitation. You may also need surgery.
• PCL ruptures — your knee may be immobilized (held still). Rehabilitation will be needed over a long period of time.
• Other ligament injuries — treatment involves physiotherapy and you may need a hinged brace or another support. Surgery is rarely required.
• Meniscal tear — rest and physiotherapy is usually recommended. Sometimes an arthroscopy may be needed.
• Dislocated kneecap or fracture — your knee joint may be immobilised and you may need arthroscopy followed by physiotherapy to prevent another dislocation.

Are there any complications of knee injuries?

Go back to your doctor if:

• the pain or swelling doesn't get better in a few days
• your symptoms become worse
• you develop a fever or redness in your knee

Resources and Support

You can use healthdirect's Service Finder to find a physiotherapist

Read our article about knee pain.

Musculoskeletal Australia can help with information about other causes of knee pain such as osteoarthritis.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.