Knee injuries

Published by Bupa's Health Information Team, October 2011.

This factsheet is for people who have a knee injury, or who would like information about it.

Knee injuries are common, especially when taking part in sport. Injuries to soft tissues, such as ligaments, cartilage and tendons, are the most common, although damage to the bones is also possible.

About knee injuries

There are many different structures inside and outside your knee. These include ligaments, which connect your bones together, articular cartilage, which covers the end of your shin bone and thigh bone in your knee joint, and a crescent-shaped disc called a meniscus. This is made from cartilage and acts as a shock absorber and helps to stabilise your knee. Injury to your knee may damage any one of these structures.

Knee ligament injuries

Your knee ligaments help to keep your knee stable.

The medial collateral and lateral collateral ligaments are found on either side of your knee joint, and act to limit the amount it can move from side to side. You can sprain or tear your medial collateral ligament if you twist your leg while it's straightened, for example, when being tackled in rugby. Your lateral collateral ligament isn’t usually damaged on its own, but you may need to have it repaired if you have damaged other ligaments.

Your anterior cruciate ligament and posterior cruciate ligament form a cross (cruciate) inside your knee. They help to keep your knee stable when the joint is moving backwards and forwards. Anterior cruciate ligament injuries are one of the most serious types of knee injury.

If you have injured your medial collateral or lateral collateral ligaments, your doctor may grade your injury according to how severe the damage is.

• Grade 1 is a stretch of the ligament without tearing.
• Grade 2 is a partial tear of the ligament.
• Grade 3 is a complete tear of the ligament.

Other soft tissue injuries

Apart from ligaments there are other soft tissues around your knee that can be injured. Soft tissue means any tissue in your body that isn't bone.

You may tear the meniscus in your knee. You can damage it if you play a sport that involves twisting your upper leg while your foot is planted on the floor. As you get older, your meniscus may become slightly thinner or have micro tears (degenerates). This makes it more likely to tear after a very minor injury.

If you use your knee a lot, for example if you run, you can irritate or tear the tendon that connects your kneecap (patella) to your thigh muscle. This tendon is called the patella tendon and the condition is patella tendonitis.

Symptoms of knee injuries

You may feel or hear a popping or snapping sensation at the time of the injury. You may also find that you can't stand properly on the affected leg, or put your full weight on it.

The symptoms for most ligament injuries will be similar, no matter which one has been damaged. These may include:

• pain
• swelling
• instability - you may feel like your knee is giving way

You may feel a tearing sensation and severe pain if you injure the meniscus in your knee. Pain may develop towards the inside, outside or back of your knee joint (depending on which meniscus you injured) and you may see some swelling.

If you have any of these symptoms, visit your GP or physiotherapist for advice.

Causes of knee injuries

You may injure your knee if:

• an impact moves your knee beyond its usual range of movement, for example if you have a fall or land awkwardly
• you play a sport that combines running, jumping and stopping with quick changes of direction, such as football
• you have a condition such as arthritis or gout, which can affect your joints, or are very overweight, which can put pressure on your knees
• your knees hit the dashboard in a car accident - posterior cruciate ligament damage is sometimes called the 'dashboard injury' as this is often how it occurs
• you wear footwear that doesn’t match the shape of your feet or have poor training methods or flexibility, which can lead to overuse injuries of your knee

Diagnosis of knee injuries

Your doctor or physiotherapist will ask about your symptoms and examine you. This may include feeling for fluid in your knee joint by pressing gently around your kneecap. He or she will also ask you to describe how your injury happened, where your pain is and what type of pain it is.

Your doctor or physiotherapist may ask you to walk, sit or lie down so he or she can test for injury to your knee ligaments or soft tissues. He or she will bend and flex your knee and move your leg into different positions. Your physiotherapist may also ask you to step, squat or hop.

Your doctor may refer you for other tests in a hospital or clinic. These may include an MRI or ultrasound scan, and occasionally an X-ray. These tests can help to diagnose more complicated or severe injuries.

Treatment of knee injuries

There are different types of treatment that your doctor or physiotherapist may suggest, depending on the type and severity of the damage to your knee. It’s important to be patient when recovering from a knee injury. Your injury may take time to fully repair itself, so you may not be able to do all the things you are used to doing for some time. 

Self help

You should follow the PRICE procedure to manage any type of soft tissue injury to your knee. PRICE stands for the following.

• Protection. Protect your injury from further harm.
• Rest. Rest the injury for the first two to three days, then reintroduce movement so you don't lose too much muscle strength.
• Ice. Apply a cold compress such as ice or a bag of frozen peas wrapped in a towel to help reduce swelling and bruising. Do this for 15 to 20 minutes every two to three hours. Don't apply ice directly to your skin as it can damage your skin.
• Compression. Compress the joint by bandaging it to support the injury and help decrease swelling. Don’t leave this on while you sleep.
• Elevation. Elevate your knee by resting it above the level of your heart and keeping it supported.

There are certain things you should not do in the first three days after your injury so you don’t damage your knee further. These can be remembered as HARM.

• Heat. This includes having a hot bath or using a heat pack.
• Alcohol. Drinking alcohol can increase bleeding and swelling in the affected area.
• Running or other forms of exercise.
• Massaging the injured knee. This can cause more swelling or bleeding.

If you’re having difficulty bearing weight on your knee, you may need to use crutches or wear a brace to make sure that you keep weight off the affected knee.

Medicines

You can buy over-the-counter painkillers such as paracetamol to treat mild and moderate pain. Over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and ketoprofen can help to reduce inflammation and swelling, as well as relieve pain. NSAIDs are available as gels, creams and sprays that you can put directly onto your skin and gently massage in, as well as tablets or capsules that you take by mouth.

Your doctor may prescribe stronger painkillers if your pain is severe. Always read the patient information that comes with your medicine and if you have questions, ask your pharmacist or doctor for advice.

Physiotherapy

If your injury is more severe or complex, your doctor may refer you to a physiotherapist (a health professional who specialises in movement and mobility). You can also choose to see a physiotherapist privately. He or she will develop a programme of rehabilitation exercises to gradually strengthen your knee and stretch your muscles. These exercises will vary depending on the type of injury you have and how severe it is. Your physiotherapist may also use various techniques to help speed up the healing of your knee.

Braces or strapping to support your knee are occasionally used during rehabilitation, usually when an injury has been severe.

Surgery

For some types of knee injury, your doctor or physiotherapist may recommend that you have surgery to repair the injury to your knee – especially if other forms of treatment haven’t worked. Your doctor will refer you to an orthopaedic surgeon for assessment.

The surgeon is more likely to suggest surgery if you have one of the following injuries.

• You have torn your anterior cruciate ligament and you do a lot of sport or have also torn the meniscus or your medial collateral ligament. Anterior cruciate ligament reconstruction involves taking a piece of tendon (usually from your hamstring) to replace the damaged ligament.
• Your knee remains painful or locks after an injury to your meniscus.

Rarely, surgery may involve opening up your knee joint to repair it, or you may be able to have a type of keyhole surgery called knee arthroscopy to access the damaged area of your knee.

Prevention of knee injuries

There are some precautions you can take to try to reduce the risk of damaging your knee ligaments.

• Exercise regularly to maintain a good level of fitness. This will mean your muscles are stronger and better able to support your joints, including your knees. If you haven't been active for a while, start gently and gradually increase the intensity.
• Spend five to 10 minutes warming up before exercise to increase blood flow to your muscles and reduce the chance of an injury. Many sports professionals advise stretching your muscles after warming up and again after cooling down; however, the benefit of stretching before or after exercise to prevent soft tissue injuries is unproven.
• Wear correct footwear. There are many different models of trainers available, but the best is one that matches the shape of your feet. If you’re not sure, it’s a good idea to go to a specialist sports shop and ask for advice.

Video

See our video about knee injuries:

• How can I treat muscle sprains and strains at home?

For answers to frequently asked questions on this topic, see FAQs.

For sources and links to further information, see Resources.