Epidemiology of gradual-onset knee injuries in team ball-sports: A systematic review with meta-analysis of prevalence, incidence, and burden by sex, sport, age, and participation level.

OBJECTIVES: To systematically evaluate the literature and estimate the prevalence, incidence, and burden of gradual-onset knee injuries in team ball-sports. DESIGN: Systematic review with meta-analysis. METHODS: Six databases (MEDLINE, EMBASE, Web of Science, CINAHL, SPORTDiscus, SCOPUS) were searched from inception to June 2021. Cohort studies of team ball-sports reporting the number of gradual-onset knee injuries were included. Study quality was assessed using a modified Newcastle-Ottawa scale. Studies were pooled using a Freeman-Tukey Double arcsine transformation (prevalence) and a Poisson random effects regression model (incidence, burden). RESULTS: Forty-nine studies that captured gradual-onset knee injuries (unclassified, patellofemoral pain, tendinopathies, and iliotibial band friction syndrome) across 15 team ball-sports were included. For unclassified gradual-onset knee injuries, prevalence was 4 % (95 % Confidence Interval (CI) 2 % to 7 %, I2 = 96 %), incidence was 0.32 per 1000 player-hours (95 % CI 0.25 to 0.43, I2 = 88 %), and burden was 3.24 days lost per 1000 player-hours (95 % CI 1.95 to 5.37, I2 = 99 %). For patellofemoral pain, prevalence was 6 % (95 % CI 1 % to 13 %, I2 = 93 %), and incidence was 0.07 per 1000 player-hours (95 % CI 0.04 to 0.12, I2 = 67 %). For tendinopathies, prevalence was 1 % (95 % CI 0 % to 2 %, I2 = 68 %), incidence was 0.07 per 1000 player-hours (95 % CI 0.04 to 0.11, I2 = 76 %), and burden was 2.14 days lost per 1000 player-hours (95 % CI 1.23 to 3.71, I2 = 92 %). CONCLUSIONS: Estimates of prevalence, incidence and burden generated from this systematic review quantify the extent of gradual-onset knee injuries in team ball-sports. Further research is required to assess whether age, sport, and participation level are predictors of gradual-onset knee injuries.