Incidence and Risk Factors for Lumbar Spondylolysis in Adolescent Rugby Players: A Prospective Study

OBJECTIVE: The aim of this study was to investigate the incidence and risk factors of lumbar spondylolysis in adolescent rugby players. DESIGN: A prospective cohort design over a 9-month season (June 1, 2021-February 28, 2022) was used. SETTING: A set of adolescent rugby players of male sex participated in this study and physical function examination were measured before injury surveillance. PARTICIPANTS: A total of 185 adolescent rugby players participated in this study. ASSESSMENT OF RISK FACTORS: Bilateral passive range of motion of the hip, rectus femoris muscle flexibility, hamstring flexibility, and thoracic kyphosis angle were assessed. MAIN OUTCOME MEASURES: All participants were followed for a 9-month season (from June 2021 to February 2022) to determine the injury incidence during matches and training. RESULTS: A total of 25 players (14.4%) had a lower back injury. The 18 players (72.0%) who reported injuries of the lower back were diagnosed with spondylolysis. A smaller passive hip external rotation range of motion on the right side and larger thoracic kyphosis angle were associated with lumbar spondylolysis. CONCLUSIONS: Restricted hip external rotation flexibility and round posture may be risk factors for lumbar spondylolysis in adolescent rugby players. LEVEL OF EVIDENCE: Prospective cohort, level 2.