Types of knee injuries
Knee ligament injuries
Your knee ligaments help to keep your knee stable by holding the bones together. You have two sets of ligaments in your knee. The collateral ligaments run down either side of your knee, while the cruciate ligaments lie inside your knee. Each can get damaged.
- Collateral ligament injuries – the medial collateral (MCL) is on the inner side of your knee and the lateral collateral ligament (LCL) is on the outer side. They limit the amount your knee can move from side to side. You can sprain or tear your MCL if your lower leg gets forced outwards; for example, if you’re tackled in rugby or when you’re skiing. Your LCL is less commonly injured but may be damaged if your lower leg gets forced inwards. Both ligaments may also be damaged if your knee twists too far outwards.
- Cruciate ligament injuries – cruciate means cross-shaped. Your anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) form a cross inside your knee. They help to keep your knee stable by controlling its movement backwards and forwards. ACL injuries are one of the most serious types of knee injury. They often happen when you twist your knee, for instance when you land on your leg then quickly turn. You might get this type of injury while playing football or basketball. Your PCL may get damaged if you fall on your knee while it’s bent. Another typical way of damaging your PCL is when your knees hit the dashboard during a car accident.
If you’ve injured one or more of your knee ligaments, a doctor will investigate and 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 through the ligament.
The knee ligaments that you’re most likely to damage are your MCL and your ACL.
Other soft tissue injuries
There are other soft tissues around your knee that can be injured (soft tissue means any tissue in your body that isn't bone). These include cartilage and tendons.
- Cartilage injuries – tearing a meniscus (one of the wedge-shaped pieces of cartilage lying inside your knee) is one of the most common knee injuries. It’s what people usually mean when they say they have a ‘torn cartilage’ in their knee. You can damage a meniscus if you play a sport that involves twisting, such as football or basketball, but it can also happen to runners, tennis players and skiers. As you get older, your menisci may become worn. This makes them more likely to tear during your normal daily activities. Your knee also has cartilage covering the parts of your bones which lie inside the joint. This articular cartilage can become damaged too, often at the same time as damage happens to the other soft tissues.
- Tendon injuries – if you’re a regular runner or take part in sports where you jump a lot, you may damage the tendons that attach muscles to your knee. You can irritate or tear the tendon that connects your kneecap (patella) to your thigh muscle. This tendon is called the quadriceps tendon. Or you may irritate soft tissue around your kneecap, including the patellar tendon, which is just below your kneecap (jumper’s knee).
Symptoms of knee injuries
Symptoms of a torn ligament in your knee are similar for most people. These include:
- instability – you may feel like your knee is giving way
You may also:
- feel or hear a popping or snapping when the knee ligament injury happens
- find that you can't put your full weight on the leg with the torn ligament
If you injure a meniscus in your knee, you may:
- feel severe pain and your knee may swell after a few hours
- have a ‘locked’ knee that you can’t move it in the usual way
- still be able to walk a little on the leg where you have the knee injury
If you’ve torn your tendons, as well as pain and swelling you may find that:
- your kneecap is lying higher or lower than it should
- you won’t be able to straighten your knee
If you’ve injured your knee and the pain is mild or moderate or has come on gradually, visit your GP. Seek advice if a torn ligament or knee injury is very painful or swollen, giving way, clicking painfully, locking or you can’t put your full weight on it.
If you’ve hurt your knee in an accident, are in severe pain, or the knee is severely swollen, go to your nearest A&E department.
Diagnosis of knee injuries
Your GP will ask about your symptoms and examine you. This may include feeling for fluid in your knee joint by pressing gently around your kneecap. They’ll also ask you to describe how your injury happened, where your pain is and what type of pain it is.
Your GP may ask you to walk, sit or lie down. This is so they can test for injury to your knee ligaments or soft tissues. They will bend and straighten your knee and move your leg into different positions.
If your GP believes you may have damage which would be helped by surgery, they’ll refer you to an orthopaedic surgeon. This is a doctor who specialises in bone surgery.
Your GP or your doctor may recommend other tests, which may include the following.
- An X-ray or CT scan – this may be used to check for a fracture or arthritis.
- An MRI scan – this is useful if your doctor is not sure about the diagnosis. It may help to show up damage to the cartilage or soft tissues of the knee after an injury.
- Knee aspiration – your doctor may remove a sample of fluid from your knee to look for blood.
- Knee arthroscopy – your doctor may look inside your knee using a telescope attached to a tiny camera. This can help show if there is damage to a meniscus, cartilage or ligament. Your doctor may treat your damaged knee at the same time as doing the arthroscopy.
Treatment of knee injuries
There are different types of treatment that a healthcare professional may suggest, depending on the type and severity of the damage to your knee. It’s frustrating, but it’s important to be patient when recovering from a knee injury – your injury may take time to fully repair itself. You may not be able to do all the things you’re used to doing for some time.
Even after your knee injury has recovered, there’s still a risk that you may get arthritis in that knee in the future. This is called post-traumatic or degenerative arthritis. It usually occurs around five to 10 years after the initial injury. After a more severe injury, it can come on more quickly.
Different injuries require different rehabilitation, so it’s best to talk to your GP.
There’s a lot you can do to help yourself if you have a knee injury. You should follow the PRICE procedure for any soft tissue injury to your knee. PRICE stands for the following.
- Protect your knee from further harm.
- Rest your knee for the first two to three days, possibly by using crutches. Then reintroduce movement so that your knee doesn’t become stiff and you don't lose muscle strength.
- Ice the painful area with a cold compress, for example ice or a bag of frozen peas wrapped in a towel. Do this for 20 minutes every two hours during the day for the first two to three days. Don't apply ice directly to your skin as it can damage it.
- Compress the joint with a simple elastic bandage or elasticated tubular bandage to support the knee and help decrease swelling. Don’t leave the bandage on while you sleep.
- Elevate your knee by resting it above the level of your heart, keeping it supported.
There are certain things you shouldn’t do in the first three days after your injury so you don’t damage your knee further. You can remember these as HARM.
- Heat – don’t take hot baths, showers or saunas, or use a heat pack.
- Alcohol – don’t drink alcohol because it can increase bleeding and swelling in the affected area.
- Running or other forms of exercise – these may cause further damage.
- Massaging the injured knee – this can cause more swelling or bleeding.
Paracetamol, which you can buy over the counter, is the best medicine to use if you have a knee injury. Over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen can help to reduce inflammation and swelling, as well as relieve pain. However, you shouldn’t take oral NSAIDs (tablets) for the first two days after your injury because they may delay healing. NSAIDs are also available as gels, creams and sprays that you can put directly onto your skin and these are OK from the time of injury.
Your GP 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.
If your injury is more severe or complex or persists for over six to eight weeks, your GP may refer you to a physiotherapist. This is a health professional who specialises in movement and mobility. You can also choose to see a physiotherapist privately. They will develop a programme of rehabilitation exercises to gradually strengthen your knee and restore its normal function. These exercises will vary depending on the type of injury you have and how severe it is.
Some people have braces or strapping to support the knee during rehabilitation, usually when an injury has been severe.
For some types of knee injury, your GP or physiotherapist could refer you to an orthopaedic surgeon for assessment. They may recommend that you have surgery to repair the damage to your knee – especially if other forms of treatment haven’t worked.
Your surgeon is more likely to suggest surgery if you have one of the following injuries.
- You have torn your anterior cruciate ligament (ACL) and you do a lot of sport or have also torn a meniscus. ACL reconstruction involves taking a piece of tendon (usually from your patella tendon or hamstring) to replace the damaged ligament.
- Your knee remains painful or locks after an injury to your meniscus. Your surgeon may repair or partially remove your damaged meniscus.
- You have an injury to your medial collateral ligament (MCL) that hasn’t healed after three months of non-surgical treatment. Your surgeon will repair or reconstruct your MCL.
You may be able to have a type of keyhole surgery called knee arthroscopy to get to the damaged area of your knee.
Self-help for knee injuries
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; for example, football
- your knees hit the dashboard in a car accident; this is one way to damage the posterior cruciate ligament
- you have osteoarthritis of your knees; this may damage the ligaments as well as the bone
- you have poor training methods; this includes not warming up before activities, not cooling down afterwards, or failing to take appropriate rest periods between bouts of exercise.
Prevention of knee injuries
There are some precautions you can take to try to reduce the risk of damaging your knee ligaments and avoid sports injuries.
- Exercise regularly to maintain a good level of fitness, and include some resistance training (training with weights). 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 doing any exercise to increase blood flow to your muscles and reduce the chance of an injury. Most sports professionals advise stretching your muscles after warming up and again after cooling down. There is little evidence to show that stretching before or after exercise reduces injuries, but staying flexible is important for everybody.
- Wear the right footwear. If you have the right shoes, they will support your foot and ankle, and help to prevent twisting and injury. There are many different models of trainers available and it’s important to find some that fit well and offer the support and cushioning you need. If you’re not sure, it’s a good idea to go along to a specialist sports shop and ask for advice.
Exercises for knee pain
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FAQ: How long does it take for knee ligament injuries to heal?
The time it takes for your knee injury to heal depends on which part of your knee you’ve injured and how badly it’s affected. A mild sprain to your medial collateral ligament (MCL) may recover in as little as one to two weeks.
A grade 2 MCL injury, which is quite common, usually heals in six to eight weeks if you wear a hinged knee brace. You can help yourself to heal by following the PRICE method immediately after the injury. PRICE stands for protect, rest, ice, compress and elevate. See our section on treatment of knee injuries for more details.
If your injury is more severe, or if you need surgery, return to sport can take up to 12 months.
If your symptoms don't improve, or any pain or swelling gets worse, talk to your GP about physiotherapy or other treatment. It may be that you will need to be assessed by a surgeon, who may recommend reconstructive surgery.
It’s also important to follow the advice and exercise recommendations your GP or physiotherapist give you.
FAQ: Can arnica help with my knee injury?
Arnica is often promoted as a treatment to help relieve soft-tissue injuries such as sprains and strains. It has been used for centuries as a herbal remedy. You may come across arnica in two main forms: as a homeopathic (very, very diluted) therapy taken by mouth, or as a cream or ointment for putting directly on your skin (a topical treatment).
Although a few studies have shown that applying arnica to your skin may help a little with sore joints, it probably has very little effect. Because of this, doctors don’t usually recommend it. There’s no convincing evidence that taking homeopathic arnica remedies can help with sprains and strains.
FAQ: I have osteoarthritis. Am I more likely to get a knee injury?
The pain from osteoarthritis may cause you to use your knee joints less, so the muscles can weaken. However, by keeping active and regularly exercising your knee, you can strengthen muscles to help prevent injury. Exercise may also reduce the pain of knee osteoarthritis and help to prevent longer-term disability.
Aim to do a combination of different types of exercise.
- Strengthening exercises – these will help the muscles around your joints. It’s helpful to do strengthening exercises on both legs, even if your arthritis is on only one side. Exercising your quadriceps (thigh muscles) will help to stop your knee giving way.
- Aerobic activity – this is activity such as swimming or cycling (or anything that increases your heart rate and makes you slightly out of breath). This type of exercise can help to reduce pain, and also improve your general health and wellbeing. Aerobic activity can also help you to lose excess weight or control your weight. This reduces your chances of your knee problems getting worse in the future.
- Range-of-movement exercises and stretches – these may help to keep you flexible and mobile. This type of exercise involves moving your joints through their full range of movement and then trying to move a little further beyond this.
Try to do exercise regularly – little and often is usually best. A physiotherapist can discuss with you which type of exercise is best for you in your circumstances. Always follow their advice.
FAQ: My GP says I have housemaid’s knee. What’s that?
Housemaid’s knee is the common name for the medical condition called prepatellar bursitis.
A bursa is a small fluid-filled sac which acts as a sort of cushion or lubrication. You have many bursae around your body, mainly in and around your joints to prevent friction between the tissues when they move. The bursa between your kneecap and the overlying skin is called the prepatellar bursa. Bursae can become inflamed – this is called bursitis. When a bursa becomes inflamed, it produces more fluid so it swells.
Prepatellar bursitis is often caused by the pressure of kneeling forwards for long periods. This is where the name ‘housemaid’s knee’ comes from – in years gone by, housemaids would spend a lot of time on their knees scrubbing floors. These days, it’s more commonly seen in tradesmen such as carpet fitters or roofers.
Prepatellar bursitis can also be caused by a direct blow or fall onto your knee. And it’s more common in people who have gout or rheumatoid arthritis. Occasionally, prepatellar bursitis is caused by a bacterial infection, especially in children.
Symptoms of prepatellar bursitis may include:
- swelling over the front of your kneecap which appears over several hours to several days
- pain in your knee which is worse when you bend it
- difficulty with kneeling and walking
- redness of the skin over your knee
If there’s an infection, your knee may look red, feel hot and painful, and you may have a raised temperature. Always see your GP if you have these symptoms.
In most cases, you can treat prepatellar bursitis simply at home. Your GP will recommend that you rest and apply an ice-pack to your knee. See our section on treatment of knee injuries for more details. While you have symptoms, don’t repeat the activity that caused the inflammation in the first place.
Your GP will probably also recommend over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, which will reduce the pain and inflammation.
You may find that a stick or cane is useful for a while to help you walk. Your GP may also refer you to a physiotherapist if you have a reduced range of movement in your knee.
If there are signs of infection in your knee, your GP will prescribe antibiotics. They may also take a small sample of fluid from the bursa through a needle (aspiration). They’ll send the fluid to a laboratory to look for and identify any bacteria. The laboratory may find certain crystals in the fluid if you have gout or rheumatoid arthritis.
You can reduce your risk of getting prepatellar bursitis by wearing knee pads while you work, or kneeling on a cushion. Also, try to take regular breaks, or change what you’re doing to give your knees a rest.
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- Personal communication, Leon Creaney, Consultant Physician – sport and exercise medicine, 24 March 2016
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