The knee is the joint where the thigh bone, or femur, and shin bone, or tibia, meet. Knee pain refers to any pain or discomfort in this area of the body.
Pain in the knee can occur for many reasons. It can be mild or severe, and involve one or both knees. Some cases of knee pain pose a serious risk of disability, especially if the person is an athlete, but do not threaten life or overall health. Some others are not serious at all. Very rarely, the condition is life-threatening.
When a person complains of knee pain, the healthcare professional will ask questions such as: exactly where the pain is locatedwhen the pain startedthe type of pain, such as sharp, dull, or throbbingwhether the pain is constant or only occurs sometimeswhether there has been any injury to the painful areawhether anything makes the pain better or worsewhether there is any difficulty in bending the affected knee or kneeswhether or not there has been any other symptoms, such as swelling, skin rash, or feverwhat other medical conditions a person has, if anywhat medications, drugs, or herbs a person takes, if any
Other questions may also be asked in some cases.
There are many possible causes of knee pain, including: trauma or injury, possibly producing a torn cartilage or ligamentoveruse of the kneearthritis infections in or around the knee, such as septic arthritis disease or infection throughout the body, which may produce generalized joint pain. Examples include sexually transmitted infections (STIs) and flu.gout or pseudogout, disorders that can deposit crystals into the joint spaceautoimmune disorders, conditions in which a person produces antibodies against his or her own body for unknown reasons. Autoimmune disorders such as rheumatoid arthritis or systemic lupus erythematosus can cause knee pain.Baker's cyst, a small abnormal sac that may develop behind the kneeOsgood-Schlatter disease, a condition that usually occurs in teenage boys often producing a bump and the front of the leg just below the knee joint.deep venous thrombosis (DVT), which is a blood clot in the lega tumor or cancer affecting the bone
Eating a healthy diet and avoiding alcohol can prevent some cases of knee pain due to gout. Avoiding overuse of the knees can help prevent cases from this cause. Some knee injuries can be prevented by following sports safety guidelines for children, adolescents, and adults. Many cases cannot be prevented.
Often, the cause of the knee pain is obvious from the history, such as if the healthcare professional watched the person twist his body to the turf with a planted foot. A careful, systematic examination of the knee joint is important to distinguish possible injury to the various structures.
Next, x-rays of the knee are commonly taken. These can help diagnose a bone fracture, or break, and a bone tumor or cancer. Blood tests may also be ordered, such as a test called an antibody titer, if an autoimmune disorder is suspected. Other imaging tests, such as an MRI, may be done to look at the knee in more detail. If arthritis is suspected, a procedure called arthrocentesis is often done. The procedure involves inserting a needle through the skin and into the knee joint to remove a sample of joint fluid for analysis.
Long-term effects are related to the amount and the cause of the knee pain. An injury may cause no long-term effects at all if minor, or may cause permanent deformity of the knee. Arthritis may slowly destroy the knee joint over time. Autoimmune disorders can affect many different organs of the body. Cancer, especially bone cancer, may cause death if treatment is not successful.
Most cases of knee pain are not contagious and pose no risk to others. If the cause of knee pain is an infection, such as a sexually transmitted infection or the flu, that infection may be contagious.
For common knee pain, such as that from injury or osteoarthritis, over-the-counter pain medications are often used. Occasionally, braces and splints of various types may be helpful in resting and/or protecting the joint. If an infection is present, antibiotics may be needed.
If a serious injury occurs, surgery may be needed. Long-term arthritis may destroy a joint and require a total knee replacement. Autoimmune disorders are often treated with medications to suppress the immune system and reduce inflammation. If a tumor or cancer is the cause of pain, surgery, chemotherapy, or radiation therapy may be needed.
Side effects depend on the treatments used. For instance, aspirin and antibiotics can cause stomach upset and allergic reactions. Surgery can be complicated by bleeding, infection, or a reaction to the anesthetic.
Pain medication can be increased, changed, or decreased as needed. An injury often heals with treatment and needs no further monitoring. A person with a tumor or cancer may need regular monitoring for years after treatment.
Those with autoimmune disorders may need repeat blood tests to help monitor their disease. Any new or worsening symptoms should be reported to the healthcare professional.
Harrison's Principles of Internal Medicine, 1998, Fauci et al.