Timing of Noncontact Anterior Cruciate Ligament Injury According to Developmental Stage in Japanese Female Athletes.

OBJECTIVES: This study aimed to identify the timing of high incidence of noncontact anterior cruciate ligament (ACL) injuries in female athletes by developmental stage. DESIGN: Cross-sectional study. SETTING: Orthopedic clinic specializing in sports injuries. PARTICIPANTS: The study included 335 female athletes, from elementary school to college, diagnosed with ACL injuries by orthopedic surgeons at our clinic. ASSESSMENT OF RISK FACTORS: The developmental stage at the time of noncontact ACL injury. MAIN OUTCOME MEASURES: The primary outcome was noncontact ACL injury incidence by developmental stage. Using the Pubertal Development Scale, a multiple-choice self-administered questionnaire, we assessed the developmental stage at the time of ACL injury, and having classified participants into 5 stages-prepubertal, early pubertal, middle pubertal, late pubertal, and postpubertal-we identified the period with highest incidence of ACL injuries. RESULTS: Noncontact ACL injuries by developmental stage were 0 in prepuberty and early puberty, 5 (1.9%) in middle puberty, 221 (84.0%) in late puberty, and 37 (14.1%) in postpuberty. The distribution significantly deviated from an even distribution (χ2(2) = 310.02, P < 0.001), with more than expected in late puberty (adj. residual = 2.6) and fewer in middle puberty (adj. residual = -3.1). Contact injuries also deviated (χ2(2) = 26.34, P < 0.001), with fewer in late puberty (adj. residual = -2.6) and more in middle puberty (adj. residual = 3.1). CONCLUSIONS: In female athletes, late puberty seems to be the period of highest incidence of noncontact ACL injuries, suggesting that it could be 1 of risk factors for ACL injury.