The patellar tendon, the tendon that connects the patella to the shinbone of the lower leg, is called patellar tendonitis when it is damaged or inflamed. Symptoms of patellar tendonitis are characterized by pain, swelling, and limited function. The most common symptom of patellar tendonitis is pain, which often occurs due to squatting and jumping movements. The pain site is usually in front of or below the anterior part of the knee joint, and the nature of the pain can be soreness, swelling, or even stabbing pain. At the same time, due to the injury or excessive pulling of the patellar tendon, resulting in increased soft tissue exudation, there can be swelling around the patellar tendon area, and in severe cases, there may be an increase in skin temperature. The type of pain in patients with chronic patellar tendonitis varies greatly among individuals, with some patients experiencing pain after exercise; some experiencing pain before exercise, which is relieved during exercise; and some experiencing pain during exercise or walking in general. Patients with chronic patellar tendonitis may also experience limited knee extension due to pain. If the above symptoms occur, it is recommended to go to the hospital in time for early treatment.