My knee is swollen and bruised on the lower kneecap i fell rollerblading its been a week still it hurts to extend im 13 years old whats wrong?

Possible causes of your knee pain and swelling:

- Knee contusion (bruise): This is the most likely cause of your pain and swelling. A knee contusion occurs when the knee is hit or bumped, causing damage to the soft tissues, including the skin, blood vessels, and fat. Symptoms of a knee contusion include pain, swelling, bruising, and tenderness. Treatment typically involves rest, ice, compression, and elevation (RICE).

- Patellar tendonitis: This is an inflammation of the patellar tendon, which connects the kneecap to the shin bone. Patellar tendonitis can be caused by overuse of the knee, such as from running, jumping, or climbing stairs. Symptoms of patellar tendonitis include pain, swelling, and tenderness just below the kneecap. Treatment typically involves rest, ice, compression, and elevation (RICE), as well as physical therapy to strengthen the knee.

- Fracture: A fracture (broken bone) of the knee is a less common cause of pain and swelling. Fractures can occur from a traumatic injury, such as a fall or car accident. Symptoms of a fracture include pain, swelling, bruising, deformity, and difficulty walking. Treatment typically involves immobilization, such as a cast or brace, and sometimes surgery.

Because you are 13 years old, it is important to see a doctor if your knee pain and swelling do not improve within a few days. A doctor can evaluate your knee and determine the cause of your pain and swelling, and recommend the appropriate treatment.