The tendon from the knee cap, the patella tendon, attaches onto the tibia at the tibial tuberosity, which also happens to be where one of the major growth plates in your lower leg is (the proximal tibial epiphyseal plate). Many young students begin to develop painful and unsightly lumps on the front of their knee from constant pulling in this area during periods of growth, termed Osgood Schlatters disease.
Osgood Schlatters disease is not actually a disease, but a syndrome that was just named after the doctor who first described it, hence its rather scary name! It is very common in adolescent athletes, due to an unfortunate anatomical situation. In the knee, there is a tendon (the patella tendon), that connects the kneecap (patella) onto the shin bone (tibia). The knee cap is very important in acting as a pulley, to transfer force through the knee without the muscles and tendons rubbing over the joint. Unfortunately, where the tendon attaches onto the tibia is exactly where the growth plate is situated in young adults. During periods of growth, there is a lot of cell turnover happening in this area, and if the tendon is repeatedly pulled (as in running and jumping) an area of inflammation may occur around the growth plate. In severe cases, a small piece of bone may actually pull up, away from the shin bone, and a visible lump will be seen at the top of the shin.