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Kneecap Pain and Injury

HSS is the #1 orthopedic hospital in the U.S. and a national leader in rheumatology. This content was created by our physicians and experts.

A man holding his knee in pain

The kneecap, also known as the patella, is a small, triangular bone that sits in front of the knee joint. It helps to protect the knee joint and to keep the thigh muscles in line. Kneecap injuries are common, especially in athletes and active people. Other Conditions that affect the patellofemoral disorders

Types of kneecap conditions

Types kneecap injuries and conditions include:

  • Patellar fracture: This is a break in the patella. A broken kneecap is most commonly caused by a high-impact direct blow, such as a fall or a collision.
  • Patellar dislocation: This is when the patella slips out of place. It is most commonly caused by a sudden twisting motion of the knee.
  • Patellar tendonitis: This is an inflammation of the tendon that attaches the patella to the thighbone. It is most commonly caused by overuse of the knee.
  • Patellar bursitis: This is inflammation of the bursa in front of the kneecap. When this bursa gets injured from a forceful impact or by overuse (excessive kneeling), the inflammatory response can produces excessive fluid, causing swelling that puts pressure on the surrounding areas of the knee, causing pain.
  • Osteoarthritis of the kneecap: This is a condition in which the cartilage that cushions the knee joint wears away. It is most commonly seen in older adults.
  • Patellofemoral disorders: These are conditions that affect the patellofemoral joint, where the kneecap meets the femur (thighbone).

Kneecap injury symptoms

Symptoms of vary depending on the type of injury, but some common kneecap condition symptoms include:

  • Pain: This is the most common symptom of a kneecap injury. The pain may be sharp or dull, and it may be worse when you move the knee.
  • Swelling: The knee may become swollen and red after an injury.
  • Locking: The knee may lock up and become difficult to straighten.
  • Instability: The kneecap may feel unstable or give way, which may be due to patellofemoral instability.

Articles on patellofemoral disorders

Learn about various patellofemoral conditions, including runner's knee and patellar (kneecap) instability issues.

Articles on patellofemoral arthritis

Somewhat less common than typical knee arthritis, patellofemoral joint arthritis occurs when there is a loss of cartilage from the joint surface between kneecap and the groove on the thighbone in which it rests. Learn more in these articles.

Articles on surgical treatments for patellofemoral conditions

Learn about specfic surgeries for different patellofemoral conditions.

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