Knee pain is a fairly common complaint. Most cases of knee pain stem from overuse and clear up on their own without treatment or with mild pain medications.

Significant trauma with torn or ruptured ligaments causes pain and an unstable knee joint. The knee is also the site of other types of injuries such as dislocation of the kneecap (patella), patellar bursitis, and joint effusions.

Pain in the knee may actually be a symptom of a problem with the hip, such as in Legg-Calve-Perthes disease, where the actual disease is in the hip but the first symptom may be knee pain. Other conditions that can lead to knee pain include the following:

• Infection in the joint (septic joint)
• Arthritis
• Blood in the knee joint (hemarthrosis)
• Bone tumors
• Baker's cyst
• Osgood-Schlatter disease

Moderate exercise such as walking does not cause knee problems. If the knee is not injured, exercise is generally good for the knee. Side stresses, which the knee is not engineered to withstand very well, cause most knee injuries.

Uneven cartilage wear can cause the leg to bow in or bow out. Being overweight can also contribute to knee problems.

• Ligament or cartilage damage due to trauma or injury:
  • ACL injury
  • MCL injury
  • LCL injury
• Osteoarthritis
• Rheumatoid arthritis
• Acute gouty arthritis
• Adult Still's disease
• Baker's cyst
• Bursitis
• Chondromalacia patellae
• Chronic gouty arthritis
• Gonococcemia (disseminated gonococcal infection)
• Osgood-Schlatter disease
• Pseudogout
• Psoriatic arthritis
• Reiter's syndrome
• Systemic lupus erythematosus
• Systemic sclerosis (scleroderma)

• You cannot bear weight on the knee.
• There is an associated fever.
• There is severe pain when not bearing weight.
• The pain is persistent after 3 days of home treatment.
• There is pain or swelling in the calf below the sore knee.

• Time pattern
  • When did the knee first begin to hurt?
  • How long has this episode of knee pain lasted?
  • Is the pain continuous or off and on?
• Location
  • Are both knees affected?
  • Is the pain in the entire knee?
  • Is the pain in the kneecap?
  • Is the pain on the outer side of the knee?
  • Is the pain on the inner surface of the knee?
  • Is the pain below the knee?
• Quality
  • Is the pain severe?
  • Does it feel bruised?
  • Can you stand?
  • Can you walk?
• Aggravating and triggering factors
  • Have you had an injury or accident involving the knee?
  • Have you overused the leg?
• Relieving factors
  • What home treatment have you tried?
  • How well did it work?
• Other
  • What other symptoms are also present?
  • Is there knee swelling?
  • Is there a fever?
  • Is there swelling in the calf of the leg?

The knee and other joints will be examined and taken through their range of motion (the area of normal joint movement).

Diagnostic tests that may be performed include the following:

• Fluid drawn from the knee and analyzed
• X-ray of the knee

Some knee problems can be treated with medication or with surgery.