Ligamentous laxity of the knee during childhood and adolescence

BACKGROUND: There is little age- and sex-specific objective data concerning anterior knee translation in school-aged children. We aimed to establish age- and sex-specific baseline data for anterior knee translation of the knee in girls and in boys in grades 5 to 12. We also investigated whether a correlation exists between anterior knee translation and global joint laxity in girls in grades 5 to 12. METHODS: A sample of convenience from a local school was used. Fifteen boys and 15 girls were randomly chosen from each grade, 5 to 12, to undergo anterior translation measurements with the KT2000 knee ligament arthrometer at 15, 20, and 30 lb of force. In addition, Beighton scores and bone age were determined. RESULTS: Anterior knee translation decreased with age in both girls and boys. Girls had greater anterior knee translation and end-point compliance than age-matched boys. In girls, there was a positive correlation between increased global joint laxity and increased anterior knee translation at 20 and 30 lb. However, hyperextension of the knee by itself was not a predictor of greater anterior translation. CONCLUSIONS: Anterior translation of the knee showed age and sex variation in school-aged children. These data are important in establishing a foundation of baseline data to understand sex differences in ligament development and function and to help guide injury prevention strategies. LEVEL OF EVIDENCE: Level II diagnostic study.