Long-Term Injury Patterns and Trends in Elite Professional Football: A Nine-Season Retrospective Analysis of Prospectively Recorded Data.

Long-term injury surveillance in professional football is essential for understanding temporal changes in injury patterns. However, prospective studies spanning multiple consecutive seasons within the same professional club remain scarce. This study aimed to investigate injury epidemiology, temporal trends, and injury characteristics over nine consecutive seasons in an elite Croatian professional football club. This retrospective longitudinal study over nine competitive seasons (2015/16-2023/24) included 167 male players participating in the professional first-team environment from a single professional football club, contributing a total of 382 player-seasons across nine consecutive seasons. A total of 749 time-loss injuries were recorded according to the FIFA Medical Assessment and Research Centre (F-MARC) consensus recommendations. Temporal trends were evaluated using Joinpoint regression, while injury characteristics, anatomical distribution, tissue involvement, and injury burden were analysed descriptively. Overall injury incidence averaged 12.66 injuries per 1000 h of exposure (95% CI: 11.77-13.60), with substantially higher incidence during matches (50.13 injuries/1000 h) than training (7.97 injuries/1000 h). Joinpoint regression identified a non-significant annual decline in injury incidence before the COVID-19 season (2019/2020) (APC = -9.66%), followed by a non-significant increase thereafter (APC = 4.88%). At least one injury was recorded in 295 player-seasons, corresponding to 77.2% of all eligible player-seasons. More than 80% of all injuries involved the lower extremities, while muscle injuries accounted for almost half of all recorded injuries. Functional muscle disorders were the most frequent injury type, whereas meniscal and articular cartilage injuries were associated with the highest mean time loss per injury. The predominance of lower-limb muscle injuries, together with the substantial burden associated with less frequent intra-articular knee injuries, highlights key priorities for injury prevention in professional football. Long-term surveillance within the same club provides valuable insights into evolving injury patterns and supports the development of targeted strategies to maximise player availability.