Knee pain is a common complaint that can affect people of any age, though it is more likely as we get older. Often knee pain can be managed with simple lifestyle changes, but for serious and chronic cases more treatment including the possibility of surgery is usually necessary to get a good quality of life back again.
In most cases, biomechanical elements, degenerative joint processes such as osteoarthritis, along with injuries to the knee are the primary factors that lead to knee pain, so if you're having problems with your knees and asking: "why do I feel pain in my knees?", this guide will point you in the right direction so you can find the causes and discover ways to help relieve it.
It will also offer guidance on how to keep your knee joints active and in the best condition so you can reduce the likelihood of accidental damage in the future.
Note that our Consultants and knee specialists are available to discuss your condition in detail and help you access the best possible treatment for your condition.
It comes as no surprise then to hear that knee pain (just like back pain) is very common, but while stress on our knee joints is one of the three major causes of knee pain, we need to know why we feel pain there in the first place.
The knee joint looks simple enough, but unlike other joints in the body, has some unique features, the principle one of which is the kneecap (or patella). This serves a number of functions including keeping the knee straight and protecting its inner workings.
Should the patella (which runs in a groove in the lower end of the thigh bone or femur) move out of place for any reason, and there are many reasons why that can happen, the pain can become intense, varying from moderate to severe.
This is because the tendons that keep the patella in place can tear, or in the worst case, become detached. The patella itself can also fracture with the possibility of small pieces of bone becoming detached and causing further injury and pain.
A number of bones as well as the patella make up the knee joint. At the top is the lower end of the thigh bone (the femur). This sits on top of the articular cartilage, which is a smooth white coloured tissue that helps the joints slide back and forth.
If this is damaged in any way, including through normal wear and tear, friction will increase between the joints resulting in swelling, stiffness, and, of course pain.
This cartilage sits on top of more cartilage called the menisci, and they in turn sit on another layer of cartilage, which sits on the top end of the lower leg or shin bone called the tibia.
The two menisci, the medial meniscus and the lateral meniscus, are the shock absorbers of the knee joint. The medial meniscus cushions the inside of the leg, and the lateral meniscus cushions the outside.
At the front of the knee we have the patella as discussed, and connecting and holding all these moving parts together are a range of ligaments, which we'll come to shortly.
If any part of this mechanism goes wrong, pain occurs. That pain can come on suddenly, or it can build up over time. It can be bearable, or it can become completely debilitating.
In general though, you might experience pain in your knee joint for a wide variety of reasons. These will generally fall within the categories of injury, overuse, or arthritis.
Not everyone will experience knee pain in the same way. You might have a sharp pain only when doing certain things, or your pain might be duller but more constant. Perhaps you feel pain at the back of the knee, while others might feel most pain at the front. You may find knee pain worse during the night or when you get up from a prone or sitting position.
As well as pain emanating from any of the parts that make up your knee joint, you might also experience swelling and a reduced range of movement, which then increases the level and area of pain.
Whilst some types of pain can point to certain knee conditions, this is not always the case, and sometimes a scan is necessary to pinpoint the precise problem.
Try resting your knee for a few days or placing a soft pillow between your knees whilst sleeping if you prefer to sleep on your side.
If the pain doesn't ease or go away, speak to your GP who will help you get a diagnosis.
If it feels more serious or you want a second opinion, then our trained Consultants and knee experts can help.
Osteoarthritis of the knee
Many people don't realise that the term arthritis can be used to describe most conditions where there's pain and inflammation in a joint. Arthritis is a condition that can affect any joint, and the knee joint is one of the most commonly afflicted.
There are two forms of arthritis, one of which is from general wear and tear of the bones. This is called osteoarthritis, and the more wear your bones get, the more painful they become, including to the point that you can no longer walk unaided.
Osteoarthritis is not curable, but you can still live a comfortable life if you're suffering from its effects on your knee bones thanks to modern knee replacement surgery.
Robotic arms can also be used to aid this type of surgery and can greatly improve the outcome by ensuring a better fit during prosthetic knee replacement surgery.
Rheumatoid arthritis of the knee
The other major form of arthritis is rheumatoid arthritis. Like all forms of arthritis this can affect any joint in the body, but is most common in the hands and feet. However, it can and does affect knee joints too, and can cause severe problems and pain if not treated.
The fluid that helps keep our knees working efficiently is called synovial fluid. This is produced from the synovial membrane that surrounds the knee joints.
Rheumatoid arthritis is an immune deficiency disorder, which attacks tissue in the body. In the case of the knee, the target is the synovial membrane, and when that happens, inflammation causes the membrane to swell, which then limits movement of the knee as well as causing pain.
This can lead to damage of other parts of the knee including the bones, cartilage, and ligaments, at which point urgent treatment will be needed.
As well as cartilage and the menisci to reduce friction and absorb shocks from the more strenuous activities we put out knee joints through, the knee also contains a number of small sacs of fluid called bursae.
These reduce friction in areas of the knee including the movement of ligaments and the patella, and can become inflamed and cause pain.
Even something as simple as kneeling for an extended period of time can cause problems to a bursa, but they can also become infected or inflamed by bacteria, gout, or arthritis.
The medical name for problems with the bursa sacs is bursitis and should be investigated if the pain does not go away after a few days in case there are any extenuating circumstances.
This injury is caused by overuse of the knee. It normally causes pain in the front of the knee and is sometimes called jumper's knee (the term refers to athletes who can suffer from this condition due to excessive training).
It happens when tiny tears in the tendons that hold the patella in place begin to form. If these tears are not allowed to heal, they will worsen. This is called tendinopathy, which increases the swelling around the knee causing further pain.
Anterior cruciate ligament (ACL) injury
This is the most common knee ligament injury, which is also frequently suffered by athletes. It can make your knee unstable and will usually need treatment.
It's one of the strongest ligaments in the knee joint, connecting the femur to the tibia, so as you can imagine, if this tears or ruptures, it not only causes severe pain, but can debilitate movement completely.
The menisci play an important part in absorbing shocks to the knee and thigh bone as we know, but they also help regulate the stability of our knees and provide lubrication and nutrients to the knee joint.
The term meniscus comes from the Greek and translates as 'crescent', which is more or less the shape of these two important parts of the knee. They are made up mostly of water (72%) and collagen (22%).
If we make a sudden turn, whilst playing sport for example, it's possible to tear either or both of the menisci, which results in swelling and stiffness along with pain, especially when trying to do anything involving movement of the knee (twisting or extending the leg).
Whilst it's possible for minor meniscus tears to naturally heal over time given enough rest and pain relief treatment, in more extreme cases, surgery may be required.
Runner's knee is a loose term covering a number of different conditions usually affecting the kneecap or patella and the tissue surrounding it. The most common of these conditions is called patellofemoral pain syndrome (PFPS).
Other associated terms you may hear include 'anterior knee pain', 'iliotibial band syndrome' (ITBS), and chondromalacia patella (the breakdown of cartilage behind the kneecap).
Runner's knee occurs when too much stress or shock is repeatedly put on the knee, such as when running on hard surfaces like roads or pavements or when performing squats with heavy weights, but it can also happen suddenly from direct trauma to the knee.
You'll know if you have runner's knee (or a related injury) because the first symptom you'll feel is pain in or around the kneecap, however if it persists despite rest, then it's a good idea to have it checked out by a knee specialist to make sure it's nothing more serious.
Baker's cyst (pain or lump in the back of the knee)
A cyst is a fluid filled sac that can form more or less anywhere in the body including the knee. There are primary cysts, which form without any underlying conditions, and there are secondary cysts which happen because of underlying conditions.
In the case of the knee, Baker's cyst is a secondary cyst formed by leakage of synovial fluid from the cartilage in the knee joint (from a torn meniscus or a bursa for example).
Baker's cyst happens when the fluid leaks into the popliteal space at the back of the knee (it's other name is popliteal cyst), resulting in a visible bulge and swelling, which can become quite painful depending on the severity of the trauma.
Baker's cyst was named after the 19th century physician, William Morrant Baker
Gout of the knee
Although most people think of gout as being a foot (and in particular, big toe) disease, it can and does affect other joints, including the knee.
Gout is a build up of uric acid that forms into small needle-like crystals within a joint. This build up then causes inflammation with increasing pain. In the worst cases, this can be debilitating and last from days to weeks.
As the crystals build up over time, they form into extremely painful nodules called tophi, which can affect movement of the joint too.
Uric acid is a waste product in the blood created from the breakdown of purines found in many food types. The kidneys usually deal with it as they clean the blood by extracting it and passing it out through our urinary system.
If the kidneys are unable to cope with excess uric, gout then becomes a possibility.
Dislocation of the knee
In severe accidents, the femur and tibia can become dislocated at the knee joint. This can result in extreme trauma, and surgery will be necessary to restore movement back to the knee.
Dislocation of just the kneecap is more common though. This is where the kneecap slips out of its groove at the lower end of the femur. That can happen if the cartilage and muscles around the knee become weakened or through an injury.
Fractures, strains, bruising, viruses, along with other diseases all play a part in the cause of knee pain, but to get the full picture, we also need to take into account things like our environment.
For example, the temperature can play a part, particularly during cold weather such as the winter months.
Pain in the back of the knee
Baker's cyst is an obvious contender for conditions that cause pain in the back of our knees, but there are many other possibilities, most of which are more common.
Gout can affect all parts of the knee as well as the back of the knee, as can damage to the ligaments and muscles. There is even something called pseudogout, which is similar to gout, but is the formation of crystals of calcium pyrophosphate as opposed to ural acid crystals.
Joint infections such as septic arthritis can cause severe pain anywhere in the knee including the back of the knee as can pulling a hamstring, and the pain from both of these can come on suddenly as well.
That's why it's important to see a specialist knee consultant sooner rather than later if you're in any way worried about it, or if your knee pain starts affecting your quality of life.
Once the causes of your knee pain have been diagnosed, your knee Consultant will work with you on a treatment plan that's best for your individual circumstances.
"Knee pain can occur for many reasons. An injury might damage the cartilage, the meniscus, the ligaments or the tendons of the knee.
There are also many common conditions that can cause pain in the knee. For example, the knee can wear out over time and this can lead to osteoarthritis.
The most common symptom of knee damage is knee pain itself. The pain can be very varied. Often the level and type of pain can give us an idea of the type of problem that's occurring.
Swelling is another symptom. If the knee starts swelling up, it's a sign that there's something in the joint that's irritating it; it's your body's way of telling you there's something wrong with your knee.
The three most common problems that I tend to see are:
- Tears to the meniscus
- Damaged or torn ligaments, in particular the anterior cruciate ligament (ACL)
- Osteoarthritis of the knee
When should I seek help for knee pain?
If you develop pain in your knee, try resting it for a few days. You can also use an ice pack and/or use mild over-the-counter painkillers. Your local pharmacist will be able to give you advice on these options.
If your pain and swelling persist after this, it's best to speak to your GP, a physiotherapist, or a specialist consultant. They'll help you identify what's wrong.
Most knee pain is not caused by anything serious, however it is still best to get it checked out sooner rather than later in case you need a particular treatment or a prolonged period of rest.
What treatments are available for knee pain?
The type of treatment you are recommended for your knee pain will depend on the cause as well as the severity of your symptoms.
For example, if you have an injury, you may be given a recovery plan that will help you get back to normal as soon as possible. If your pain is due to mild wear and tear, the first step may be to build strength in the muscles around the joint with exercise.
If you have very advanced osteoarthritis, you may be recommended more invasive treatments such as surgery.
For example, losing weight can ease the pressure on your knees, while non-strenuous exercise can help strengthen the muscles around your joints and increase synovial fluid production that lubricates your knee.
Making small changes like this can significantly reduce your pain in the long term, and even stop you from needing more invasive treatments in the future.
Non-surgical knee pain treatment
Sometimes you will need a little more than lifestyle changes to get your knee pain under control. There are various non-surgical treatments you may be prescribed.
Your consultant might first recommend physical therapy. A physiotherapist will show you movements and exercises that can reduce pain and improve flexibility without further damaging your knee.
There are also medications that might be recommended. These include painkillers (both over the counter and prescription), anti-inflammatories and joint injections.
There are many different types of knee surgery available. The one you are recommended will depend on what condition is affecting your knee, as well as your personal circumstances.
For example, procedures to repair a torn anterior cruciate ligament or meniscus are quite common after these injuries, which can't always heal on their own.
If you have very advanced arthritis and your pain or lack of mobility is stopping you from doing the things you love, you might be recommended knee replacement surgery. This involves removing part or all of your damaged knee joint and replacing it with a prosthesis.
Knee replacement surgery can have huge benefits to a person's quality of life, but it won't be recommended unless you've tried less invasive methods and they haven't worked.
"Surgery is not the only treatment option for patients who have problems with their knees.
The first step is to obtain an accurate diagnosis of the condition. This involves seeing a specialist, having a history taken, a thorough examination and then appropriate imaging.
A small percentage of patients will benefit from surgery for knee pain, but this is a decision that should only be taken once other avenues have been exhausted and after the surgeon and patient have had an extensive discussion of all the options.
Complications from knee surgery are quite rare. We occasionally see problems, but the vast majority of patients will not have any complications.
The recovery time from surgery depends on the type of knee surgery performed and also on the patient.
For example, keyhole surgery where we trim away the damaged part of the meniscus is a very common operation and I'd typically expect to see patients up and about within a day or two.
Other procedures, such as knee replacement surgery, take a lot longer to recover. Some patients can recover from a full knee replacement within six weeks, but typically recovery from this type of surgery takes between three and six months.
We look forward to speaking with you and hope that we can help improve your quality of life by getting you back on the road to recovery as soon as possible.