Knee Pain

What is Knee Pain?

The knee is one of the biggest and most sophisticated joints in the body. The knee links the thigh bone (femur) to the shin bone (tibia). The smaller bone that runs alongside the tibia (the fibula) and the kneecap (patella) are the other bones that make the knee joint. Tendons connect the knee bones to the leg muscles that move the knee joint. Ligaments join the knee bones and provide stability to the knee:

• The anterior cruciate ligament prevents the femur from sliding backwards on the tibia (or the tibia sliding forward on the femur).

• The posterior cruciate ligament prevents the femur from sliding forward on the tibia (or the tibia from sliding backward on the femur).

• The medial and lateral collateral ligaments prevent the femur from sliding side to side.

• Two C-shaped pieces of cartilage called the medial and lateral menisci act as shock absorbers between the femur and tibia.

• Numerous bursae, or fluid-filled sacs, help the knee move smoothly. Your knee joints serve a pivotal role supporting your bodyweight and are succumbed to even more pressure when walking, running or jumping.

Knee pain is very common and can be caused both from sports injuries and the wear and tear of the joint as we age. Knee pain can arise from impact injuries like sprains, swollen or torn ligaments (anterior cruciate ligament or ACL), meniscus or cartilage tears and runner's knee. Sports injuries tend to affect one knee at a time.

What are the Causes of Knee Pain?

Pain in both knees is more common with arthritis, osteoarthritis, gout or pseudogout that can develop later in life. Conditions that cause knee pain;

Tendonitis. This is an overuse injury and causes swelling of the tendons, the bands of tissue that connect your bones and muscles. This is sometimes called 'jumper's knee' as it is common in sports involving jumping, such as netball or volleyball

Bone chips. Sometimes, a knee injury can break off fragments from the bone or cartilage. These fragments can get cemented within the joint, causing it to seize up. You may also have pain and swelling.

Housemaid's knee or bursitis is caused by kneeling for lengthy periods of time or repetitive knee movements. Fluid can build in the bursa, the sac of fluid that cushions the knee joints. Swelling behind the knee is called a 'Baker's cyst' and may be caused by either injuries or arthritis.

Bleeding in the knee joint. This injury is also called haemarthrosis and affects blood vessels around the knee ligaments causing the knee to feel warm, stiff, bruised and swollen. This may require hospital treatment in severe cases.

Iliotibial band syndrome. This is an overuse injury to the iliotibial band of tissue that runs from the hip to the shin past the knee.

Medial plica syndrome. This overuse injury affects the plica, a fold of tissue in the knee joint.

Osgood-Schlatter Disease. This overuse condition is common in teenagers playing sport and causes swelling and tenderness over the bony bump just below the knee.

Partially dislocated kneecap (or patellar subluxation). This is usually due to a physical condition with the legs rather than a sports injury. The kneecap slides out of position and causes pain and swelling.

Light sprain or strain

If you believe your pain is the consequence of having engaged in more activity than you're used to, you've probably just sprained or strained your knee. This means that the knee tissues have stretched, but aren't permanently damaged. Read more about sprains and strains.

How can Knee Pain be Managed?

Most sprains and strains can be managed yourself using PRICE therapy (protection, rest, ice, compression and elevation) and painkillers. Read more about treating sprains and strains. You can prevent future injuries by:

• always warming up before exercising and stretching to cool down after exercise

• increasing your activity levels slowly over time

• replacing your sports shoes when necessary

You can also try low-impact exercises, such as cycling and swimming, to improve your health and fitness without harming your knees. Read about easy exercises. Anterior knee pain Knee pain felt at the front of the knee, around the kneecap, is called anterior knee pain or patellofemoral pain syndrome. It's not always obvious why this pain develops, but it's been linked to previous injuries, overuse of your knees, muscle weakness and your kneecap being slightly out of place. The pain tends to be dull or aching and often affects both knees at the same time. It's usually made worse by sitting for prolonged periods, squatting or kneeling, or using stairs.

You can normally treat this yourself using over the counter painkillers, an ice pack and rest. Exercises to strengthen the muscles around your kneecap can also help. You may be referred to a physiotherapist, who can advise you about specific exercises to try. Damage to the menisci or cartilage Sitting between the upper and lower leg bones at the knee joint are rubbery pads of tissue called menisci which cushion the bones, acting as shock absorbers. A meniscus can also be torn after suddenly twisting the knee joint, resulting in pain, swelling and occasionally locking of the knee. Rarely, the torn meniscus can flip into the joint and prevent you from straightening it. A meniscus can also be torn after suddenly twisting the knee joint, resulting in pain, swelling and occasionally locking of the knee. The cartilage covering the bones of the knee joint can also be damaged by injury (read more about cartilage damage). These symptoms may settle down with rest, although physiotherapy can sometimes help, and in the case of menisci damage, an operation may be needed to remove or repair the torn pad of tissue.

What is Osteoarthritis and How does it affect the Knee?

In older people, recurrent pain and stiffness in both knees is likely to be caused by osteoarthritis, the most common type of arthritis in the UK. Osteoarthritis causes damage to the articular cartilage (protective surface of the knee bone) and mild swelling of the tissues in and around the joints. The pain in your joints may be worse after putting weight on your knees and your knees may become stiff if you don't move them for a while. They may also occasionally become locked or feel as though they're going to give way. In some cases, osteoarthritis can also cause a painful fluid-filled swelling to develop at the back of the knee – this is known as a Baker’s cyst, or popliteal cyst.

Less commonly, osteoarthritis can affect younger people, especially those who are overweight or have had serious injuries to the knee in the past. You should see your GP if you think your knee pain may be caused by osteoarthritis. They may recommend wearing suitable footwear to reduce the strain on your joints, using assistive devices such as a walking stick, losing weight, taking painkillers, or having physiotherapy. Read more about treating osteoarthritis.

What is Tendonitis and How does it affect the Knee?

Overusing or injuring the tendon that connects the kneecap to the shin bone can cause patellar tendonitis (inflammation of the tendon). This condition is sometimes called "jumper's knee", as it can be brought on by jumping activities such as basketball or volleyball. As well as feeling painful and tender, your knee may also be swollen, red and warm. The pain can often be relieved with rest, ice packs and painkillers at home. Read more about treating tendonitis.

What is Bursitis and How does it affect the Knee?

Repetitive movement of the knee or kneeling for long periods can cause a build-up of fluid over the knee joint, known as bursitis or "housemaid's knee". This particularly affects people with certain jobs that involve kneeling (such as carpet layers), or sports players (such as footballers). It typically causes pain in the knee that gets worse when you kneel or bend your knee fully. Your knee will also probably be swollen and may be tender, red and warm.

Bursitis can often be treated at home. Resting the affected area and using an ice pack helps reduce the swelling and ordinary painkillers can help relieve the pain until your knee heals. Read more about treating bursitis. If you develop redness that spreads, a high temperature (fever), or persistent pain, this may be due to infection of the bursae. You should see your GP urgently, or go to your nearest accident and emergency (A&E) department.

What is Torn Ligament or Tendon and How does it affect the Knee?

Knee pain may be caused by torn ligaments or tendons. Ligaments are robust strands of tissue that join the bones at the knee joint; tendons connect the muscles to the bone. You can tear these tissues during running sports which require sudden changes of direction like Football and Tennis.

Injured tendons or knee ligaments at the side of the knee may cause pain even when the knee stationary, which may get worse when you bend the knee in one direction or apply weight on it. If you feel that your knee is wobbly or keeps "giving way", you may have torn the anterior cruciate ligament (one of the main knee ligaments). This probably resulted from a sudden change in direction or a twisting movement. You should see your GP if this happens, and you may be referred to an orthopaedic specialist for advice and treatment. In some cases, surgery may be recommended.

What is Bleeding into the Joint and How does it affect the Knee?

An injury that causes significant damage to the knee joint may cause bleeding into the joint spaces, known as haemarthrosis. This can occur if a cruciate ligament is torn or if there is a fracture to one of the bones of the knee. Signs of haemarthrosis are swelling of the knee, warmth, stiffness and bruising.

You should go to hospital immediately to have your knee assessed if you have a significantly swollen knee. Surgery may be necessary to repair the damage. If you take anticoagulant medication such as warfarin, bleeding into the joint can happen without any obvious damage. You should see your GP in this case as you may need treatment to reverse the effects on your medication.

What is Gout and How does it affect the Knee?

If you experience sudden attacks of severe knee pain and your knee also becomes red and hot, the cause is likely to be gout, which is a type of arthritis. Gout is caused by a build-up of uric acid (a waste product) in the body, which can form crystals in the joints. These crystals cause the joints to become inflamed and painful. Gout will cause severe pain in the knee and limit movement of the joint. You may feel pain even when you're resting, including at night.

Gout can affect any joint in the body and sometimes other joints such as the joint of your big toe may be affected before your knees. You should see your GP if you think the cause of your knee pain is gout. They may recommend using ice packs and taking non-steroidal anti-inflammatory drug (NSAID) painkillers. You may also need to change your diet or receive additional treatment to prevent attacks if you experience them frequently. Septic arthritis (infected knee) Septic arthritis is a serious condition that causes a very painful, hot, swollen knee. You may also feel generally unwell and have feverish symptoms. The condition can easily be mistaken for gout (see above). You should see your GP urgently, or go to your nearest accident and emergency (A&E) department if you suspect you have septic arthritis. Septic arthritis is treated by draining fluid from the knee prior to administering antibiotics. Intermittent arthroscopic surgery is needed to remove the infection.

When to see your GP

You should see your GP if:

• you cannot put weight on your knee at all

• you have severe pain even when you're not putting weight on it, such as at night

• your knee locks or painfully clicks (painless clicking is OK)

• your knee keeps giving way

• you're unable to fully bend or straighten your knee

• your knee looks deformed

• you have fever, redness or heat around the knee, or it's very swollen

• you have pain, swelling, numbness or tingling of the calf beneath your affected knee

• the pain doesn't start to improve within a few weeks or you have pain that's still severe after a few days of caring for your knee at home.

Your GP will do a careful examination of the knee and take your medical history. They may also arrange further tests such as blood tests, an X-ray or a magnetic resonance imaging (MRI) scan to help identify the problem. In some cases, you may need to be referred to an orthopaedic specialist.