Knee pain is a very common condition for which are complaining people from all of ages. This pain can be result of an injury such as torn cartilage or a ruptured ligament. Medical conditions such as infections, gout and arthritis can also lead to knee pain. There are many types of minor knee pain which are responding well to the self – care measures. Knee braces and physical therapy can also give you a relief from the knee pain. But also there are some cases in which your knee will need surgical repair. If you have a fever in addition to redness, pain and swelling in your knee, then you need to talk with your doctor. If you feel as if your knee is unstable or your knee gives out, then visit your doctor.
Symptoms of knee pain
The severity and location of knee pain can vary, which is depending on the cause of the problem. Signs and symptoms that sometimes accompany this knee pain are including:
- Inability to fully straighten the knee
- Popping or crunching noises
- Weakness or instability
- Redness and warmth to touch
- Swelling and stiffness
If you have marked knee swelling or you cannot bear weight on your knee, then you need to visit your doctor. Also you should talk with your doctor if you are unable to fully extend or flex your knee or see an obvious deformity in your leg or knee.
Causes for knee pain
This type of pain can be caused by types of arthritis, injuries, mechanical problems and other problems.
- Types of arthritis: More than 100 different types of arthritis exist in the world. The most common types of arthritis which cause knee pain are including:
- Septic arthritis: In some cases, your knee joint can become infected which is leading to redness, pain and swelling. There is usually no trauma before the onset of pain. This type of arthritis is happening with a fever. 
- Pseudogout: This condition is often mistaken for gout. This condition is caused by calcium – containing crystals which develop in the joint fluid. Knees are the most common joint which is affected by this type of arthritis. 
- Gout: This condition is happening when the uric acid crystals build up in the joint. The gout in the most cases is affecting the big toe but also it can happen in the knee. 
- Rheumatoid arthritis: This is an autoimmune condition which is affecting almost any joint in your body in which are also included our knees. This is a chronic disease. It tends to vary in the severity and it can come and go. 
- Osteoarthritis: This is the most common type of arthritis. It is a wear and tear condition which is happening when the cartilage in the knee deteriorates with the age and use. 
- Injuries: Here are the most common knee injuries:
- Patellar tendinitis: This is inflammation and irritation of one or more tendons, the thick and fibrous tissues which are attaching muscles to bones. Cyclists, skiers, runners and people who are involved in the jumping activities are prone to develop inflammation in their patellar tendinitis which is connecting the quadriceps muscles on the front of the thigh to the shinbone. 
- ACL injury: This type of injury is common in people who play soccer, basketball or other sports that require sudden changes in direction. 
- Mechanical problems: The most common mechanical problems are:
- Hip or foot pain: When we have foot or hip pain, then we can have changes in the way we walk to spare these painful joints. But this altered gait can place more stress on the knees. There are some cases in which foot or hip can refer pain to the knee. 
- Loose body: In some cases degeneration or injury of the cartilage or bone can cause a piece of cartilage or bone to break off and float in the joint space. This may not cause any problems unless this condition interferes with the knee joint movement.
- Other problems: Patellofemoral pain syndrome is a general term which is referring to pain that is arising between the patella and femur. This is common condition in young adults (it is very common in those who have a slight maltracking of the kneecap), athletes and in older adults (they develop this condition as a result of arthritis of the kneecap). 
 Mue DD, Salihu MN, Awonusi FO, et al. The epidemiology and outcome of acute septic arthritis: A hospital based study. Journal of the West African College of Surgeons. 2013;3(1):40–52.
 MacMullan P, McCarthy G. Treatment and management of pseudogout: insights for the clinician. Therapeutic Advances in Musculoskeletal Disease. 2012;4(2):121–31.
 Howard RG, Samuels J, Gyftopoulos S, et al. Presence of gout is associated with increased prevalence and severity of knee osteoarthritis among older men: Results of a pilot study. Journal of Clinical Rheumatology. 2015;21(2):63–71.
 Zhang A, Lee YC. Mechanisms for joint pain in rheumatoid arthritis (RA): from cytokines to central sensitization. Current Osteoporosis Reports. 2018;16(5):603–10.
 Alshami AM. Knee osteoarthritis related pain: a narrative review of diagnosis and treatment. International Journal of Health Sciences. 2014;8(1):85–104.
 Reinking MF. Current concepts in the treatment of patellar tendinopathy. International Journal of Sports Physical Therapy. 2016;11(6):854–66.
 Friel NA, Chu CR. The role of ACL injury in the development of posttraumatic knee osteoarthritis. Clinics in Sports Medicine. 2013;32(1):1–12.
 Hospital for Special Surgery. Foot pain? New study says look at hip and knee for complete diagnosis. Science Daily. 2017. Retrieved from www.sciencedaily.com/releases/2017/09/170919181533.htm
 Thomee R, Augustsson J, Karlsson J. Patellofemoral pain syndrome: A review of current issues. Sports Medicine. 1999;28(4):245-62.