The disease is most common in active boys and girls aged 11-15 and is usually self-limiting
The condition is caused by stress on the patellar tendon that attaches the quadriceps muscle at the front of the thigh to the tibial tuberosity. Following an adolescent growth spurt, repeated stress from contraction of the quadriceps is transmitted through the patellar tendon to the immature tibial tuberosity. This can cause multiple subacute avulsion fractures along with inflammation of the tendon, leading to excess bone growth in the tuberosity and producing a visible lump.
-Dude, What is that huge ass lump on your knee??
-Oh that is just my Osgood-Schlatters Disease also known as jumpers knee