Knee pain is a common condition, and is usually a result of overusing or injuring the knee. This tends to be more common in those who do a lot of sport, and older or overweight people who are more prone to arthritis.
Pain is the most common symptom, and can be most noticeable during simple activities such as walking or going up/down stairs. Sometimes the knee joint may become swollen or red.
Some of the most common causes include the following:
Simple sprain or strain - this is when the tissues have been stretched, but not permanently damaged, e.g. due to doing more activity than normal or a minor injury.
Anterior knee pain - this is pain felt at the front of the knee, often affects both knees, and can be due to previous injuries, overuse, muscle weakness or alignment problems.
Damage to the menisci or cartilage - these structures support the knee joint and offer cushioning to the joint. Injuries tend to cause pain, swelling and sometimes locking, which can settle with time but occasionally may need an operation.
Torn ligament or tendon - this can cause a painful and swollen knee, which can 'give way' and is usually a result of a sporting injury. You may need specialist referral and an operation for this.
Osteoarthritis - this is due to 'wear and tear' of the joint and more common in older people.
Septic arthritis - this is a serious condition which causes a very painful, red, hot and swollen knee, usually associated with fever. It can be confused with Gout which is a less serious condition, but you should always seek medical review for these symptoms.
Depending on the cause, several types of knee pain can improve with rest, pain killers and physiotherapy. You should see your GP if your symptoms are not settling within a few weeks, or if you have sustained an injury. There are instances in which an X-ray, blood test or specialist referral may be needed.