Knee pain is common in all age groups as the knee joint takes the full weight of your body and is vulnerable to injury. You are more susceptible to knee pain if you are overweight. Common causes of knee pain are:

• Simple strain/sprain: This happens as a result of increased activity or the overstretching of tissues.
• Anterior knee pain syndrome: Knee pain felt at the front of the knee is most commonly due to irritation of the cartilage under your knee cap due to abnormal bio-mechanics, poor flexibility, weakness in your muscles or arthritis. Pain generally associated with kneeling, going up or down stairs, sitting on a low seat or running long distances.
• Damage to the meniscus or cartilage: The meniscus is the cushioning pad in your knee joint. This is a very tough tissue hardened to withstand wear and tear. Like every other material it has a limit and can be damaged with high levels of force. In older age groups lower levels of force can also damage the meniscus.
• Osteoarthritis: is a common cause of knee pain in older people. It may also cause swelling in the knee which can be felt at the back of your knee joint (commonly called a 'Baker's Cyst'). Osteoarthritis can also affect younger people, those who are overweight or have had injuries to the knee in the past.

There are a few other less common reasons why you can get knee pain:

• Patellar Tendonitis/ tendinopathy: The patellar tendon connects the kneecap to the shin bone and can be inflammed with repeated over use. Also known as "jumper's knee", as it can be brought on by jumping activities. This can be easily managed with a guided self-treatment programme.
• Housemaid's knee/pre-patellar bursitis: Repetitive or prolonged kneeling can cause a build-up of fluid inside the bursa over the front of the knee joint.
• Torn ligament or tendon: Knee tendons and ligaments are very tough structures. However you can tear these tissues during contact sports such as rugby or football.
• Osgood-Schlatter's disease: Commonly seen in teenagers involved in sporting activities. A swelling is seen below the knee joint which rembles a bony lump. This can be painful to touch or to kneel on. This usually settles with rest, ice, compression and activity-modifications.
• Gout and pseudogout: Gout is caused by a build-up of uric acid in the body which forms crystals in the joints which causes inflammation, severe pain and slight fever. Pseudogout is a similar condition to gout in that crystals of calcium are deposited in and around the knee joint. 

When do I see my GP?

• If you have severe pain or are unable to put weight on your knee 
• If you have severe pain even at rest
• if your knee locks and you cannot straighten your knee or it clicks painfully (painless clicking is OK)
• If you have fever, redness or heat around the knee, or it is very swollen