Knee Pain

Knee pain is one of the most common joint complaints, affecting people across all age groups for very different reasons depending on age and activity level.

Causes of Knee Pain

Injuries — ligament sprains (including the ACL), meniscus tears, and fractures, often from sports or a sudden twisting motion, typically cause sudden pain and swelling.

Overuse conditions — including patellar tendinitis ("jumper's knee") and iliotibial band syndrome, common in runners and athletes, tend to build gradually with activity.

Mechanical problems — such as a dislocated kneecap or a loose piece of cartilage or bone catching in the joint.

Degenerative and inflammatory conditions — knee osteoarthritis, the gradual breakdown of cartilage with age, is the most common cause of chronic knee pain in older adults; inflammatory forms of arthritis and gout can also affect the knee specifically.

Self-Care and Diagnosis

For pain without red-flag features, rest from the aggravating activity, ice, over-the-counter pain relievers, and gentle range-of-motion exercise are reasonable first steps. Diagnosis usually starts with a history and physical exam; an X-ray or MRI is added when a fracture, ligament tear, or another specific structural cause needs to be confirmed.

When to See a Doctor

See a doctor for knee pain following a significant injury, an inability to bear weight, visible deformity, significant swelling, or pain that persists or worsens over more than a few weeks despite rest. Seek prompt same-day care if the knee is also accompanied by fever, warmth, or redness — these can be signs of a joint infection that needs urgent treatment.