which permits unrestricted noncommercial use, provided the original work is properly cited. Open Access Journal of Sports Medicine 2012:3 17–20 Open Access Journal of Sports Medicine

Background: Osgood–Schlatter disease (OSD) is one of the common causes of knee pain in active adolescents who play sports. The common age for boys to have OSD is between 12 and 15 years and for girls, between 8 and 12 years. Radiographic studies are helpful in diagnosis and treatment of OSD. Purpose: We examine the age at onset of OSD in detail and investigate the relationship between clinical findings, radiographic bone morphology, and the severity of OSD in adolescents. Results: The average age at onset of knee pain was 12 years and 6 months – 12 years and 9 months in boys, and 12 years and 1 month in girls. Boys were significantly older than girls at onset. In addition, there were significant relationships between duration from first onset to visit to the clinic, radiographic bone stage, body morphology, and radiographic severity. The patients who delayed their visit to the clinic from the first onset of pain and who were older showed a later bone stage and more radiographic severity grade of OSD. There was significant differences concerning weight and body mass index between severity grade I and III. Conclusion: For the age at the onset of OSD, the mean age of boys was significantly older than that of girls. The patients at a later bony stage had a higher severity grade. The boys and girls with OSD who had less weight or body mass index showed less severity