The pain inside the bone when the knee hits the bone may be caused by edema, subcutaneous bruising and other trauma reactions, fractures, ligament and meniscus injuries. 1. Trauma reaction: after the knee hits the bone, it usually leads to the rupture of small blood vessels under the skin at the injury site, the body starts the coagulation system for repair, and there is subcutaneous bruise or blood clot, which affects the blood circulation around the injury. At the same time, the normal cells at the injury site rupture, and the intracellular material is free in the extracellular or interstitial space of the cells, resulting in edema of the tissues, causing increased pressure in the joints and leading to pain symptoms. 2. Fracture, ligament, meniscus injury: patients who do not see obvious relief of symptoms for a long time after trauma, and patients with limited joint function need to be alert to the presence of patella fracture, anterior and posterior cruciate ligament injuries in the knee, meniscus injuries, etc. These injuries can cause the peripheral bone of the knee to become damaged. These injuries can cause damage to the continuity of the bone around the knee joint, decrease joint stability, affect normal joint movement, and may also cause pain in the knee joint. If the symptoms of knee pain are not relieved or are accompanied by other symptoms, you should go to the hospital in a timely manner to clarify the cause of the pain and then give targeted treatment.