Doctor and nurse looking at x-ray

Knee assessment and diagnosis

Understanding your symptoms is the first step to recovering from a knee problem. Once you know what’s causing your knee pain, you can work with your doctor to work out the best treatment option for you to help you make a speedy recovery.

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Assessing your pain

Knee injuries are common, especially if you take part in sport.

Understanding your pain

Injuries to the soft tissues in your knee, such as ligaments, cartilage and tendons, are the most common types of knee injury.

An acute injury means you have damaged the bone, muscle or ligaments in your knee suddenly, usually because of an accident.

If your knee pain has developed gradually over time or comes and goes, you may have a chronic or overuse injury. Osteoarthritis is an example of a chronic condition that that can affect your knee joints.

Just injured your knee?

Explore your symptoms

Explore the different types of knee pain and the possible causes and conditions associated with each type of pain.

Front of knee pain    Outer knee pain    Inner knee pain    Back of knee pain

front knee pain

Anterior (front) knee pain

Front knee pain may also be called anterior knee pain (AKP). Anterior just means front.

You may have pain:

  • below your kneecap (patella)
  • around the kneecap, on either side of it
  • behind your kneecap

Front knee pain may come from the kneecap itself or from the tendons that attach the muscles to the bones of the knee.

More information about anterior (front) knee pain: Expand all
  • There is no single cause, but there are a number of reasons why anterior knee pain may develop. It is more common in:

    • people who have had a dislocation, fracture, or other injury to the kneecap
    • people who exercise often, including runners and joggers, cyclists, skiers, football players and other athletes
    • people who are overweight
    • teenagers and healthy young adults, more often girls
    • people with flat feet
  • There are a number of medical conditions linked to front knee pain. Generally, they are caused by damage from a fall or a sports injury, from overusing the knee during exercise, or from getting older.

    Patellofemoral pain syndrome (PFPS) means pain related to the kneecap (the patella) and the thigh bone (the femur). Doctors sometimes call this ‘patella maltracking’ or ‘runner’s knee’. When you bend and straighten your leg, your kneecap slides up and down a groove at the end of your thigh bone. Damage or swelling where the kneecap and thigh bone meet stops the kneecap sliding smoothly and causes pain. The kneecap may also be unstable.

    Patella tendinopathy means wearing away of the tendons around the kneecap due to overuse and stress over time. Small tears in the tendon can cause inflammation (tendonitis). These tears are usually due to sudden injury. These conditions are sometimes called ‘jumper’s knee’ and are most common in athletes. Quadriceps tendonitis is a similar condition, but less common. It causes pain and tenderness where the tendon from the thigh muscle attaches to the kneecap.

    Infrapatellar fat pad syndrome is a condition where the fat pad behind the kneecap gets pinched between the kneecap and the thigh bone. It is most often caused by over-straightening the leg repeatedly, for example in weight lifting.

    Anterior cruciate ligament injury is overstretching or tearing this ligament, which runs across the knee from the thigh to the shin bone, either completely or partly. It is a sudden injury, caused by twisting or overextending the knee, and is nearly always associated with sports.

    Osteoarthritis of the knee is a common cause of knee pain. The smooth, shiny cartilage that lines the knee joint becomes worn and rough. This causes pain and increasing damage to the knee over time. It mostly affects people over 50. The older you are, the more likely you are to get it.

    Less common conditions causing front knee pain

    Bursitis is inflammation of the fluid sac that acts as a cushion behind the kneecap. It can be caused by kneeling a lot and is sometimes called housemaid’s knee or vicar’s knee. More commonly these days, it’s caused by overuse, a sudden increase in sports training, by being overweight, or by another condition such as rheumatoid arthritis, gout or infection.

    Chondromalacia of the patella is a condition where the smooth tissue under the kneecap (the cartilage) can soften and break down. It is most often seen in teenage girls.

    Recurrent partial dislocation (subluxation) of the patella is an uncommon condition that runs in families. It is most often seen in girls who tend towards being ‘knock-kneed’ – ie when the knees are together, the ankles are apart. This affects the tracking of the kneecap.

    Osgood–Schlatter disease and Sinding-Larsen–Johansson disease are conditions seen mostly in teenagers who take part in a lot of sports. They both cause pain and tenderness just below the kneecap, at the top of the shin bone (the tibia).

  • Front knee pain may be dull and aching or sharp or shooting.

    If your knee pain is caused by wear and tear, it often affects both knees at the same time. But of course, if you’ve sustained a particular sports injury then it will only affect one knee. Front knee pain is usually made worse by standing up after sitting for a long time, squatting or kneeling, using stairs, or running downhill. Jumper’s knee may cause pain when you’re active, or may be a continuous dull ache.

    Your leg may sometimes just give way when you put weight on it. This instability of the knee happens in runner’s knee and partial dislocation (subluxation) of the kneecap.

    Pain from an anterior cruciate ligament injury may be sudden and you may hear a ‘pop’. The knee is likely to swell from internal bleeding and may feel as if it is going to give way.

    Stiffness and loss of movement, first thing in the morning or after sitting for a while is most common with osteoarthritis.

    Osgood–Schlatter disease and Sinding-Larsen–Johansson disease cause pain, tenderness and swelling just below the kneecap, at the top of the shin bone (the tibia).

  • Your doctor will examine your knee and take a history, asking about:

    • the type of pain you have, when it started and whether it comes and goes
    • how active you are
    • any activity, accident or injury that could have caused it

    They may suggest an ultrasound, X-ray or a magnetic resonance imaging (MRI) scan, but this is often not necessary. The examination and your history may be enough to diagnose you. If you have cartilage or ligament damage, your doctor may suggest a procedure to look inside your knee, called an arthroscopy (often referred to as ‘keyhole surgery’). This involves making a small cut in your knee and inserting a thin tube with a camera on the end. As well as diagnosing the problem, the procedure can also be used to repair or remove damaged tissue.

    Knee arthroscopy [link]

  • You can often treat anterior knee pain using an ice pack, resting your leg and taking ordinary anti-inflammatory painkillers, such as ibuprofen. Exercises to strengthen the muscles around your kneecap can also help. A physiotherapist can advise you about specific exercises.

    Don’t use heat or massage on your knee, or drink alcohol for the first three days after an injury. These increase blood flow which will make any swelling or bleeding worse. If your injury is mild, you may not need to see a doctor, but you should if:

    • you cannot put weight on the affected leg
    • you have severe pain, even when not bearing weight 
    • your knee buckles, clicks, or locks
    • your knee is deformed or misshapen
    • your knee is hot, red or very swollen or you have a fever
    • you have pain, swelling, numbness, tingling, or bluish discoloration in your calf
    • you are still in pain after three days

    In the longer term, you can help to stop knee pain recurring by making a few changes to your lifestyle and exercise regime. Try:

    • varying the type of exercise you take or trying a different sport
    • warming up and cooling down properly
    • strengthening your core muscles (back and abdominal), hamstrings and thigh muscles
    • losing weight if you need to
    • using the right sports equipment properly: well-fitting sports shoes, bike saddle at the correct height, for example
  • The treatment that you have for your front knee pain will depend on what condition is causing the pain.

    For information on treatments, please see the relevant knee condition page.

    • Anterior knee pain. Medline Plus. www.nlm.nih.gov/medlineplus, last updated May 2016
    • Anterior knee pain. Patient Plus. http://patient.info/doctor/anterior-knee-pain, last updated June 2015
    • Patello-femoral Pain (PFS). Guy’s and St Thomas’ NHS Foundation Trust. www.gstt.nhs.uk, last updated June 2013
    • Patellofemoral Pain Syndrome. BMJ Best Practice. http://bestpractice.bmj.com, last updated June 2015 
    • Bass, E. Tendinopathy: Why the Difference Between Tendinitis and Tendinosis Matter. Int J Ther Massage Bodywork. 2012; 5(1): 14–17
    • Musculoskeletal problems. Oxford Handbook of General Practice (online, 4 ed.) Oxford Medicine Online. www.oxfordmedicine.com, published April 2014
    • Tendinopathy. BMJ Best Practice. http://bestpractice.bmj.com, last updated Dec 2015
    • Anterior cruciate ligament injury. BMJ Best Practice. http://bestpractice.bmj.com, last updated August 2015 
    • Osteoarthritis. PatientPlus. www.patient.info/doctor, last updated March 2014
    • Osteoarthritis. BMJ Best Practice. http://bestpractice.bmj.com, last updated February 2016
    • Bursitis. Medscape. http://emedicine.medscape.com, last updated October 2015
    • Pre-patellar Bursitis. Medscape. http://emedicine.medscape.com, last updated October 2015
    • Bursitis. Medline Plus. www.nlm.nih.gov, last updated September 2014
    • Patellofemoral Joint Syndromes. Medscape. http://emedicine.medscape.com, last updated October 2015
    • Knee Pain. Medline Plus. www.nlm.nih.gov/medlineplus, last updated November 2014
    • Calmbach WL, Hutchens M. Evaluation of Patients Presenting with Knee Pain: Part II. Differential Diagnosis. Am Fam Physician 2003 Sep 1;68(5):917-22
    • Knee Pain. NHS Choices. www.nhs.uk, last updated March 2015
    • Sinding-Larsen Johansson Disease. Patient Plus. www.patient.info/doctor, last updated January 2015
    • Dragoo JL, Johnson C, McConnell J. Evaluation and treatment of disorders of the infrapatellar fat pad. Sports Med 2012 Jan 1;42(1):51-67
    • Osteoarthritis. NICE Clinical Knowledge Summaries. http://cks.nice.org.uk, last updated April 2015
    • Knee Pain Assessment. NICE Clinical Knowledge Summaries. http://cks.nice.org.uk, last updated March 2011
    • Map of Medicine. Knee injuries. International View. London: Map of Medicine; 2012 (Issue 4)
outside knee pain

Lateral (outer) knee pain

Outer knee pain may also be called lateral knee pain (LKP). Lateral just means side. It refers to pain on the outer side of your knee. (So the right side of your right knee, and the left side of your left knee.)

You may have pain on the outside of your leg just around your knee or pain that spreads up your thigh.

You may have pain from damage inside the knee itself, or from swelling of a band of fibrous tissue that runs down from the hip to the knee.

More information about lateral (outer) knee pain: Expand all
  • There is no single cause, but there are a number of reasons why you may have outer knee pain. It is more common:

    • in distance runners or people who run a long distance each week
    • in cyclists
    • after an injury that pushes the knee outwards (away from the other leg)
    • in those who do activities that involve twisting or pivoting of the knees
    • in people who tend towards being ‘knock-kneed’ – ie when the knees are together, the ankles are apart, placing a strain on the outer knee
  • There are a number of medical conditions linked to outer knee pain. Generally, they are caused by damage from a sports injury, from overusing the knee during exercise, or from getting older.

    Ilio-tibial band friction syndrome is caused by a band of connective tissue rubbing on the outside of the knee. The ilio-tibial band is a thick band of fibrous tissue that runs from the hip to below the knee on the outside of the leg. Frequent bending and straightening of the leg can cause this tissue to become sore and inflamed where it passes over the bottom of the thigh bone, where it meets the knee. This type of injury is most common in runners and cyclists.

    Lateral collateral ligament injury is caused by stretching or tearing of the band of tissue that connects the thigh bone to the shin bone. (A ligament is a band of tissue that connects one bone to another.) The lateral collateral ligament runs down the outer side of the knee. This injury is most often seen in skiers, footballers or basketball players.

    Meniscal injury is damage to the cartilage inside the knee. The meniscus cartilages act like shock absorbers. The meniscus may tear when you twist your knee with your foot still on the ground. So this type of injury is common in sports where you have to change direction suddenly, such as football and skiing. The meniscus can also tear in older people because of wear and tear and without any particular injury having taken place.

    Anterior cruciate ligament injury is overstretching or tearing of this ligament, which runs across the knee from the thigh to the shin bone, either completely or partly. It is a sudden injury, caused by twisting or overextending the knee, and is nearly always associated with sports.

    Osteoarthritis of the knee is a common cause of knee pain. The smooth, shiny cartilage that lines the knee joint becomes worn and rough, and can eventually be worn down to bare bone. This causes pain and increasing damage to the knee over time. It mostly affects people over 50. The older you are, the more likely you are to get it.

  • Other symptoms you may have with outer knee pain will vary, depending on the cause. Pain may be dull and aching or sharp and localised. You may have swelling from fluid collecting, or your knee may click or lock (get stuck in one position). 

    With ilio-tibial band syndrome, you may have pain all over the outside of your knee or the pain may be sharp and in one area. You may get pain when running and also when doing anything that causes you to bend and straighten your leg repeatedly, such as going up and down stairs.

    Lateral collateral ligament injury causes pain over the outside of the knee, which may focus on the mid-point of the knee joint. This ligament helps to keep the knee stable, so you may feel as if your knee is going to give way. Some people find the pain worse when walking or running on uneven ground.

    Symptoms of a torn meniscus cartilage generally come on up to a day after the initial injury. Pain and swelling may increase and you may have difficulty fully straightening your leg. Swelling may improve over days or weeks but get worse again after exercise. The knee may also feel stiff and lock or catch.

    Pain from an anterior cruciate ligament injury will be sudden and you may hear a ‘pop’. The knee is likely to swell from internal bleeding and may feel as if it is going to give way.

    Osteoarthritis usually causes pain when you are bearing weight, which is relieved by rest. You may have stiffness and loss of movement first thing in the morning or after sitting for a while. You may also have some swelling over your knee.

  • Your doctor will examine your knee and take a history, asking about:

    • the type of pain you have, when it started and whether it comes and goes
    • how active you are
    • any activity, accident or injury that could have caused it

    They may suggest an X-ray or a magnetic resonance imaging (MRI) scan, but this is not always necessary. The examination and your history may be enough to diagnose you.

    If you have cartilage or ligament damage, your doctor may suggest a procedure to look inside your knee, called an arthroscopy (often referred to as ‘keyhole surgery’). This involves making a small cut in your knee and inserting a thin tube with a camera on the end. As well as diagnosing the problem, the procedure can also be used to repair or remove damaged tissue. Most knee operations (apart from total replacement) are now done using keyhole surgery.

    Knee arthroscopy [link]

  • Immediately after an injury, you can help yourself by resting your leg, using an ice pack and taking painkillers, such as ibuprofen. If you can’t put weight on your leg, you may need crutches. Avoid twisting or bending the knee as far as possible.

    Don’t use heat or massage on your knee, or drink alcohol for the first three days after an injury. These increase blood flow which will make any swelling or bleeding worse.

    If your injury is mild, you may not need to see a doctor but you should if:

    • you cannot put weight on the affected leg
    • you have severe pain, even when not bearing weight 
    • your knee buckles, clicks, or locks
    • your knee is deformed or misshapen
    • your knee is hot, red or very swollen or you have a fever
    • you have pain, swelling, numbness, tingling, or bluish discoloration in your calf
    • you are still in pain after three days
  • The treatment that you have for your outer knee pain will depend on what condition is causing the pain.

    For information on treatments, please see the relevant knee condition page.

    • Khaund MD, Flynn SH. Iliotibial Band Syndrome: A Common Source of Knee Pain. Am Fam Physician. 2005 Apr;71(8):1545-50
    • Lateral Collateral Knee Ligament Injury. Medscape. http://emedicine.medscape.com, last updated March 2015
    • Knee Pain Assessment. NICE Clinical Knowledge Summaries. http://cks.nice.org.uk, last updated March 2011
    • Collateral Ligament Injury - aftercare. Medline Plus. www.nlm.nih.gov, last updated May 2015
    • Meniscal Tear. BMJ Best Practice. http://bestpractice.bmj.com, last updated May 2016
    • Anterior Cruciate Ligament Injury. BMJ Best Practice. http://bestpractice.bmj.com, last updated August 2015
    • Knee Ligament Injuries. Patient Plus. www.patient.info/doctor, last updated February 2014
    • Osteoarthritis. Patient Plus. www.patient.info/doctor, last updated March 2014
    • Calmbach WL, Hutchens M. Evaluation of Patients Presenting with Knee Pain: Part II. Differential Diagnosis, Am Fam Physician 2003 Sep;68(5):917-22
    • Calmbach WL, Hutchens M. Evaluation of Patients Presenting with Knee Pain: Part I. History, Physical Examination, Radiographs, and Laboratory Tests. Am Fam Physician 2003 Sep;68(5):907-12
    • Musculoskeletal problems. Oxford Handbook of General Practice (online, 4 ed.) Oxford Medicine Online. www.oxfordmedicine.com, published April 2014
    • Assessment of Knee Injury. BMJ Best Practice. http://bestpractice.bmj.com, last updated July 2013
    • Knee Pain. Medline Plus. www.nlm.nih.gov, last updated November 2014
    • Osteoarthritis. BMJ Best Practice. http://bestpractice.bmj.com, last updated Feb 2016
    • Meniscal Injury of the Knee. Up to Date. www.uptodate.com, last updated May 2015
    • Osteoarthritis. NICE Clinical Knowledge Summaries. http://cks.nice.org.uk, last updated April 2015
    • Map of Medicine. Knee injuries. International View. London: Map of Medicine; 2012 (Issue 4)
    • Personal communication. Dr Roger Tillman, 13 June 2016
inside knee pain

Medial (inner) knee pain

Inner knee pain is also called medial knee pain. Medial just means middle – so the side of the knee nearer the middle of the body. (The left side of your right knee and the right side of your left knee.)

You may have pain over, or just below, the inner side of your knee. It may be worse when you bend and straighten your leg and your knee may feel unstable.

More information about medial (inner) knee pain: Expand all
  • There is no single cause, but there are a number of reasons why you may have inner knee pain. It is more common in:

    • footballers, skiers, rugby players and those who play other sports
    • other activities that involve sudden twisting or pivoting of the knees
    • those who suddenly become much more active than they usually are
    • older people
  • There are a number of medical conditions linked to inner knee pain. Generally, they are caused by damage from a sports injury, from overusing the knee during exercise, or from getting older.

    Medial collateral ligament injury is caused by stretching or tearing the band of tissue that connects the thigh bone to the shin bone. (A ligament is a band of tissue that connects one bone to another.) The medial collateral ligament runs down the inner side of your knee. It helps to stabilise the knee.

    Meniscal injury (commonly known as torn cartilage) is damage to the cartilage inside the knee. The meniscus cartilages act like shock absorbers. The meniscus may tear when you twist your knee with your foot still on the ground. So this type of injury is common in sports where you have to change direction suddenly, such as football. The meniscus can also tear in older people because of wear and tear, without any particular injury.

    Anterior cruciate ligament injury is overstretching or tearing of this ligament, which runs across the knee from the thigh to the shin bone, either completely or partly. It is a sudden injury, caused by twisting or overextending the knee, and is nearly always associated with sports.

    Osteoarthritis of the knee is a common cause of knee pain. The smooth, shiny cartilage that lines the knee joint becomes worn and rough. This causes pain and increasing damage to the knee. It mostly affects people over 50. The older you are, the more likely you are to get it.

    Patellofemoral pain syndrome (PFPS) means pain related to the kneecap (the patella) and the thigh bone (the femur). Doctors sometimes call this ‘patella maltracking’ or ‘runner’s knee’. When you bend and straighten your leg, your kneecap slides up and down a groove at the end of your thigh bone. Damage or swelling where the kneecap and thigh bone meet stops the kneecap sliding smoothly and causes pain. The kneecap may also be unstable. PFPS is one of the commonest causes of front knee pain but can also cause inner knee pain.

    Pes anserine pain syndrome (or pes anserine bursitis) causes pain on the inside of the knee, over a fluid-filled sac called the anserine bursa. This sac is also sometimes inflamed (bursitis).

    Medial plica syndrome is when a small piece of tissue (the plica) inside the knee becomes inflamed. It tends to come on when you’ve suddenly become more active and causes acute pain across the inside of the knee.

  • Other symptoms you may have with inner knee pain will vary, depending on the cause. You may have swelling, pain with particular movements and your knee may click or lock (get stuck in one position). 

    Medial collateral ligament injury causes pain over the inner knee, which may focus on the mid-point of the knee joint. Pain and swelling usually come on straight after an accident or injury. The ligament helps to keep the knee stable, so you may feel as if your knee is going to give way.

    Symptoms of a torn meniscus cartilage generally come on up to a day following the initial injury. Pain and swelling may get worse and you may have difficulty fully straightening your leg. A more severe tear will be more painful from the start and you may even feel it go. The knee may also lock, feel stiff or feel unstable, as if it is about to give way.

    Pain from an anterior cruciate ligament injury may be sudden and you may hear a ‘pop’. The knee is likely to swell from internal bleeding and may feel as if it is going to give way.

    Osteoarthritis usually causes pain when you are bearing weight, which is relieved by rest. You may have stiffness and loss of movement first thing in the morning or after sitting for a while. You may also have some swelling over your knee.

    Patellofemoral pain syndrome causes pain that is sharp or aching. It’s made worse by running, climbing stairs, squatting, or after sitting for a long time. Your knee may feel unstable, as if it’s going to give way.

    Medial plica syndrome typically causes pain on climbing stairs, running or squatting. The knee may also catch or click when you bend your leg.

    Pes anserine pain gets worse when you repeatedly bend your leg, such as when going up and down stairs. Some people have pain at night, from one leg pressing on the other, which can disturb sleep.

    There may be slight swelling, but not usually a collection of fluid on the knee.

  • Your doctor will examine your knee and take a history, asking about:

    • the type of pain you have, when it started and whether it comes and goes
    • how active you are
    • any activity, accident or injury that could have caused it

    They may suggest an X-ray or a magnetic resonance imaging (MRI) scan, but this is not always necessary. The examination and your history may be enough to diagnose you.
    If you have cartilage or ligament damage, your doctor may suggest a procedure to look inside your knee, called an arthroscopy (often referred to as ‘keyhole surgery’). This involves making a small cut in your knee and inserting a thin tube with a camera on the end. As well as diagnosing the problem, the procedure can also be used to repair or remove damaged tissue.

    Knee arthroscopy [link]

  • Immediately after an injury, you can help yourself by resting your leg, using an ice pack and taking painkillers, such as ibuprofen. If you can’t put weight on your leg, you may need crutches. Avoid twisting or bending the knee as far as possible. 

    Don’t use heat or massage on your knee, or drink alcohol for the first three days after an injury. These increase blood flow which will make any swelling or bleeding worse.

    If your injury is mild, you may not need to see a doctor, but you should if:

    • you cannot put weight on the affected leg
    • you have severe pain, even when not bearing weight 
    • your knee buckles, clicks, or locks
    • your knee is deformed or misshapen
    • your knee is hot, red or very swollen or you have a fever
    • you have pain, swelling, numbness, tingling, or bluish discoloration in your calf
    • you are still in pain after three days
  • The treatment that you have for your inner knee pain will depend on what condition is causing the pain.

    For information on treatments, please see the relevant knee condition page.

    • Knee Pain Assessment. NICE Clinical Knowledge Summaries. http://cks.nice.org.uk, last updated March 2011
    • Medial Collateral Ligament Injury. BMJ Best Practice. http://bestpractice.bmj.com, last updated April 2016
    • Calmbach WL, Hutchens M. Evaluation of Patients Presenting with Knee Pain: Part II. Differential Diagnosis. Am Fam Physician 2003 Sep 1;68(5):917-22
    • Osteoarthritis. Patient Plus. www.patient.info/doctor, last updated March 2014
    • Knee Ligament Injuries. Patient Plus. www.patient.info/doctor, last updated February 2014
    • Meniscal Tear. BMJ Best Practice. http://bestpractice.bmj.com, last updated May 2016
    • Anterior Cruciate Ligament Injury. BMJ Best Practice. http://bestpractice.bmj.com, last updated August 2015
    • Patello-femoral Pain (PFS). Guy’s and St Thomas’ NHS Foundation Trust. www.gstt.nhs.uk, last updated June 2013
    • Patellofemoral Pain Syndrome. BMJ Best Practice. http://bestpractice.bmj.com, last updated June 2015
    • Musculoskeletal problems. Oxford Handbook of General Practice (online, 4 ed.) Oxford Medicine Online. www.oxfordmedicine.com, published April 2014
    • Plica Syndrome. Up to Date. www.uptodate.com, last updated April 2014
    • Knee Bursitis. Up to Date. www.uptodate.com, last updated January 2016
    • Assessment of Knee Injury. BMJ Best Practice. http://bestpractice.bmj.com, last updated July 2013
    • Knee Pain. Medline Plus. www.nlm.nih.gov, last updated 26th November 2014
    • Bursitis. BMJ Best Practice. http://bestpractice.bmj.com, last updated 25th April 2016
    • Osteoarthritis. BMJ Best Practice. http://bestpractice.bmj.com, last updated Feb 2016
    • Meniscal Injury of the Knee. Up to Date. www.uptodate.com, last updated May 2015
    • Osteoarthritis. NICE Clinical Knowledge Summaries. http://cks.nice.org.uk, last updated April 2015
    • Map of Medicine. Knee injuries. International View. London: Map of Medicine; 2012 (Issue 4)
Back knee pain

Posterior (back) knee pain

Pain behind the knee is also called posterior knee pain. ‘Posterior’ just means behind.

As well as pain, you may have swelling just at the back of the knee or that extends into the calf. The swelling may be large enough to stop you bending your leg properly.

More information about back knee pain: Expand all
  • There is no single cause, but there are a number of reasons why you may have pain behind the knee. It may be linked to:

    • increasing age and presence of osteoarthritis
    • knee injury (especially ligament injury)
    • a cyst
    • inflammation or infection in the joint
    • a growth or tumour (though this is very rare)
  • There are two main conditions that cause pain behind the knee:

    • a popliteal cyst, also called Baker’s cyst
    • posterior cruciate ligament injury

    A cyst is a collection of fluid inside a thin layer. A popliteal cyst is a cyst in the shallow depression at the back of the knee. It is often linked to other conditions affecting the knee, including osteoarthritis, rheumatoid arthritis, cartilage injuries and inflammation of the knee joint. Many types of injury can cause a collection of fluid. Often it will be a heavy blow to the front of the knee, from falling forwards or playing a contact sport. The natural mechanism of the knee pushes this excess fluid backwards and it collects in the depression at the back of the knee, over time, causing a cyst to form.

    A posterior cruciate ligament injury is caused by overstretching or tearing of this ligament, which runs across the knee from the thigh to the shin bone. It often results from a heavy blow to the front of a bent knee, sometimes from falling forwards or during a contact sport, such as rugby. A typical injury is when the knee hits the dashboard during a car accident. Or it may be caused by over-straightening the leg and bending the knee backwards. Doctors call this hyperextension.

    Osteoarthritis of the knee is a common cause of knee pain. The smooth, shiny cartilage that lines the knee joint becomes worn and rough. This causes pain and increasing damage to the knee over time. It mostly affects people over 50. The older you are, the more likely you are to get it.

  • Other symptoms you may have with pain behind the knee may vary, depending on the cause. You may have swelling or pain with particular movements.

    A popliteal cyst causes swelling at the back of the knee, which can be quite noticeable. A very large swelling may stop you from fully straightening your leg. 

    The swelling may get bigger or shrink over time. If the cyst bursts, you may have swelling and pain in your calf.

    NOTE: If you have a swollen, tender calf, it is very important to see a doctor. It could also be caused by a clot in your leg (deep vein thrombosis), which needs to be treated urgently.

    If your cyst bursts, you may hear a pop and feel warmth spread down your calf. You may develop what looks like bruising anywhere from the back of your knee down to your ankle and the top of your foot.

    With a posterior cruciate ligament injury, you may have no symptoms at first. You may feel pain behind your knee, but some people have pain at the front of the knee as well. You may also have pain when kneeling. 

    Osteoarthritis causes pain and stiffness. This is often worst first thing in the morning and eases once you start moving around.

  • Your doctor will examine your knee and take a history, asking about:

    • the type of pain you have, when it started and whether it comes and goes
    • how active you are
    • any activity, accident or injury that could have caused it

    If you have signs of a popliteal cyst, your doctor may suggest an ultrasound scan. If they suspect a posterior cruciate ligament injury, they may suggest an X-ray or a magnetic resonance imaging (MRI) scan.

  • You can help yourself by keeping weight off your leg as far as possible, using an ice pack and taking painkillers, such as ibuprofen. If you can’t put weight on your leg, you may need crutches.

    Don’t use heat or massage on your knee, or drink alcohol for the first three days after an injury. These increase blood flow which will make any swelling or bleeding worse.

    Popliteal cysts often get better on their own and you may not need any further treatment. But it is a good idea to see a doctor if you have pain behind the knee. It may be something more urgent (such as a blood clot in the leg). With posterior cruciate ligament injury, you can develop complications later if you are not treated.

  • The treatment that you have for pain behind your knee will depend on what condition is causing the pain.

    For information on treatments, please see the relevant knee condition page.

    • Knee pain assessment. NICE Clinical Knowledge Summaries. http://cks.nice.org.uk, last updated March 2011
    • Popliteal cyst. BMJ Best Practice. http://bestpractice.bmj.com, last updated 17 July 2015
    • General evaluation of the adult with knee pain. Up to Date. www.uptodate.com, last updated April 2016
    • Osteoarthritis. PatientPlus. www.patient.info/patientplus, last updated March 2014
    • Osteoarthritis. BMJ Best Practice. http://bestpractice.bmj.com, last updated Feb 2016
    • Musculoskeletal problems. Oxford Handbook of General Practice (online, 4 ed.) Oxford Medicine Online. www.oxfordmedicine.com, published April 2014
    • Baker’s cyst. PatientPlus. www.patient.info, last updated June 2015
    • Knee Ligament Injuries www.patient.info, last updated February 2014
    • Posterior cruciate ligament injuries. www.uptodate.com, last updated March 2016
    • Map of Medicine. Knee injuries. International View. London: Map of Medicine; 2012 (Issue 4)

Getting a diagnosis

Who you may see

You may meet different doctors and health professionals if you have a problem with your knee. Below is a description of some of the people you may meet, depending on the type of problem that you have. Expand all
  • Bupa members have access to musculoskeletal physicians when required. They are experts in their field, skilled in the diagnosis and treatment of a range of muscle, joint and bone conditions ranging from acute sprains and muscle tears to long standing joint problems, including arthritis.
  • A physiotherapist is a health professional who specialises in maintaining and improving your movement and mobility. They can help to treat or improve the symptoms of a number of conditions including asthma, cystic fibrosis, brain or spinal cord injuries, multiple sclerosis, back pain, arthritis and stroke.
  • A GP is a doctor who is trained to support and help you manage your health within the community. Your GP can assess, diagnose, treat and manage most illnesses to ensure that you receive the most appropriate care for your health. If necessary, he or she can arrange for you to be referred to specialists for tests and treatments and arrange if you need to be admitted to hospital.
  • A rheumatologist manages patients with arthritis and other musculoskeletal conditions, including disorders affecting bones, joints and muscles. A rheumatologist works closely with other medical specialists and healthcare professionals.
  • Trauma and orthopaedic surgeons treat musculoskeletal conditions. They may use surgery to treat injuries, degenerative diseases, infections, tumors, and congenital disorders of the bones, joints and their associated soft tissues. Most trauma and orthopaedic surgeons specialise in a particular aspect of orthopaedic conditions, often based on a region of the body, for example spine, knee, ankle and foot.

Typical tests

There are a number of tests and exercises your doctor or physiotherapist will use to help determine the cause of your knee pain. Expand all
  • 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.

  • There is no single test that can check for osteoarthritis. Your doctor will ask about your symptoms and examine you. He or she may also ask about your medical history.

    During the examination your doctor will look for bony growths and swelling and any creaking in your joint. He or she will also check how well your joint moves and how stable it is.

    Occasionally your doctor may also arrange for you to have an X-ray of the affected joint. An X-ray can help to show whether the normal joint space is reduced because of a loss of the protective cartilage. It can also show if you have any extra bone growth around your joint or any roughening or thickening of the joint surface. Sometimes calcification of the cartilage can be seen (this is when calcium builds up in the joint). It can be a sign of a type of osteoarthritis that can quickly become severe and cause more severe pain from time to time.

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