Osgood-Schlatter disease is a painful condition that affects the proximal end of the tibia (a long bone) just distal to the knee. It primarily affects athletically active children between the ages of 10 and 14. The condition develops when the patellar tendon places strain on this area of the tibia as the area is not as stable as other regions of the bone in children this age. Why would this region not be as stable as other regions of the tibia?