Background: Although tensile force on an immature tibial tuberosity is considered the main cause of Osgood-Schlatter disease (OSD), the relationship between bony maturity and the pathogenesis of OSD remains obscure. Purpose: To survey the bone maturation process of the tibial tuberosity by age and sex and clarify its relationship to OSD. Study Design: Cross-sectional study
Level of evidence, 3. Methods: A total of 731 Japanese basketball players aged 6 to 14 years were enrolled in this study. Ultrasonographic examination was performed in all participants (1462 knees) to evaluate the bony maturity of the tibial tuberosity by use of the Ehrenborg classification. The age- and sex-specific prevalence of each stage was investigated, and the prevalence of symptomatic OSD and its relationship with bony maturity were also assessed. Results: The process of bone maturation occurred 1 to 2 years earlier in female participants compared with male participants. Among female participants, 59.2% were already at the epiphyseal stage (stage E) by 10 years of age, and 47.4% were skeletally mature by 14 years. Among male participants, conversely, only 8.0% were at stage E by 10 years of age, and only 13.8% were skeletally mature by 14 years. The overall prevalence of symptomatic OSD was 6.8% (males, 6.4%
females, 7.2%), and the onset was 1 year earlier in the female participants. The prevalence of symptomatic OSD tended to increase with age and bony maturity, significantly increasing from the cartilaginous stage (stage C) to the apophyseal stage (stage A) (odds ratio, 9.48) and from stage A to stage E (odds ratio, 2.22). Conclusion: The tibial tuberosity matures earlier in female participants. The risk of OSD is greater in stage A than stage C and in stage E than stage A. The risk of OSD increases with age in males but not in females.