Knee pain can be caused by:
• Arthritis -- including rheumatoid, osteoarthritis, and gout
• Baker's cyst -- a fluid-filled swelling behind the knee that may accompany inflammation from other causes, like arthritis
• Bursitis -- inflammation from repeated pressure on the knee, such as kneeling for long periods of time, overuse, or injury
• Connective tissue disorders such as lupus
• Dislocation of the kneecap
• Iliotibial band syndrome -- a hip disorder related to injury of the thick band that runs from your hip to the outside of your knee
• Infection in the joint
• Knee injuries -- may cause bleeding into your knee, which worsens the pain
• Tendinitis -- a pain in the front of your knee that gets worse when going up and down stairs or inclines
• Torn cartilage (a meniscus tear) -- pain felt on the inside or outside of the knee joint
• Torn ligament (ACL tear) -- leads to pain and instability of the knee
• Strain or sprain -- minor injuries to the ligaments caused by sudden or unnatural twisting
Less common conditions that can lead to knee pain include the following:
• Bone tumors
• Osgood-Schlatter disease