Kids going through a rapid growth spurt are vulnerable to anterior knee pain. This is pain that occurs at the front of the knee and is often due to tendinitis, overload of the knee cap or stress of the growth plate where the patellar tendon inserts (often referred to as Osgood-Schlatter disease).
This is often characterized by a painful bump just below the knee that is worse with activity and better with rest. Osgood-Schlatter disease most often occurs in adolescents during growth spurts, when bones, muscles, tendons, and other structures are changing rapidly. Because physical activity puts additional stress on bones and muscles, children who participate in athletics — especially running and jumping sports - are at an increased risk for this condition. However, less active adolescents may also experience this problem.
Sometimes, simple measures like rest, over-the-counter medication, and stretching and strengthening exercises will help relieve pain. In addition, I highly recommend wearing a knee compression sleeve or wrap. If the pain is below the knee cap I would suggest a Patella Helix. If the pain is not diffuse, then an Adjustable Knee Helix would be best.
WHY COMPRESSION WORKS
When your child is growing, quickly they lose flexibility and they need time for the muscles to strengthen to catch up to the longer levers (limbs). Applying compression takes some of the stress off of the area that becomes mechanically overloaded by these imbalances.