The bone below the knee is the location of the proximal tibia, tibial plateau, tibial tuberosity, for the causes of pain, as follows: First, tibial tubercle, patellar tendonitis: If it is the place of the tibial tuberosity appears obvious pressure pain, swelling, this situation may be tibial tubercle, patellar tendonitis, because the patellar tendon is often pulled with the tibial tuberosity, especially the people who often do strenuous exercise of the knee joint is more common. This leads to aseptic inflammation of the tibial tuberosity periosteum, resulting in pain. Second, traumatic fractures: the most common is a fracture of the tibial plateau. Third, a swelling in the proximal tibia: commonly a bone cyst or malignant tumor, which can be diagnosed with a local x-ray.