Knee Surgery, Sports Traumatology, Arthroscopy https://doi.org/10.1007/s00167-021-06684-8 SPORTS MEDICINE Football‑related injuries are the major reason for the career end of professional male football players Matthias Koch1 · Martin Klügl2 · Borys Frankewycz1 · Siegmund Lang1 · Michael Worlicek1 · Daniel Popp1 · Volker Alt1 · Werner Krutsch1,3 Received: 15 October 2020 / Accepted: 29 July 2021 © The Author(s) 2021 Abstract Purpose Little is known about the consequences of injuries on professional male football players’ career and retirement period. The aim of this study is to investigate the impact of injuries that male professional football players endure during their career, reasons for the end of their career and the post-career phase of retirement. Methods In a retrospective cross-sectional cohort study, retired male professional football players of the German Bundesliga were investigated by a standardised questionnaire to analyse the history of injuries sustained during their professional football career, the reasons for ending their career, their current health status and their suggestions for future prevention strategies. Results Most of the 116 analysed players (n = 73 (62.9%)) stated an injury as the reason for ending their professional career. Relevant injuries were mainly located in the lower extremities (n = 587 (61.3%)) with a focus on the knee (p < 0.001) and ankle (p < 0.001). A signifcant majority of the participants who had retired due to injury described degenerative symptoms, such as pain or instability, and were diagnosed with osteoarthritis after retirement (p < 0.001). These players had also often been afected by symptoms of depression during their career, which had decreased signifcantly after retirement. Moreover, players who had not retired due to injury had signifcantly better overall health status and quality of life after retirement. Conclusion Football-related injuries have a signifcant impact on the career end of professional male football players and their health status after retirement. Future prevention strategies need to particularly address injuries to the knees and ankles and to implement measures for preventing osteoarthritis after retirement. Level of evidence Level III Keywords Retirement in football · Professional football player · Injury · Osteoarthritis · Knee injury · Football · Soccer Introduction professional football players have a high risk of sustain- ing injuries [1, 4]. Most injuries occur during matches and Football is the most common type of sports worldwide and afect the lower extremities [1, 3, 5, 6]. Besides the consecu- is associated with a high incidence of injuries [1, 2]. Many tive time loss [7], the negative efect on team performance studies have analysed injury patterns with regard to the dif- [5], and the possible long-term consequences, such as an ferent activity levels or training vs. match [1–3]. Overall, increased risk of osteoarthritis [8], football-related injuries may infuence a player’s career and quality of life [5]. Thus, many studies focus on specifc treatment and rehabilitation * Matthias Koch strategies to restore the sports abilities of athletes as soon as [email protected] possible to reduce the risk of long-term impairment. Martin Klügl Yet, little is known about the real impact of football inju- https://www.kardiologie-herzbewegt.de ries on the career end and the retirement period of profes- sional football players. 1 Department of Trauma Surgery, University Medical Centre Regensburg, Regensburg, Germany Thus, the aim of this study is to investigate the impact of injuries of professional football players during their 2 herz:bewegt - Praxis für Kardiologie und Sportmedizin, Bahnhofstraße 19, 94315 Straubing, Germany career, related reasons for the end of their career and their retirement with a special focus on the health status after 3 SportDocsFranken, Nuernberg, Germany Vol.:(0123456789)1 3 Knee Surgery, Sports Traumatology, Arthroscopy the end of the career. The knowledge about mid-term included all players stating that they had no medical reason and long-term consequences of football-related injuries for ending their professional football career. obtained in this study will help to improve the risk assess- ment for teams and players and enable the adequate devel- opment of prevention strategies to be already implemented Statistical analysis during the active career of professional football players. The hypothesis of this study is that not only the career Statistical analysis was performed using SPSS® (Version course of professional football players in terms of timing 25, IBM, Armonk, NY, USA). Because of the absence of the end of their career but also sports activities and the a specifc primary endpoint, no a priori sample size cal- health status after their career is dramatically infuenced culation was carried out. The number of included patients by football-related injuries. was based on the data available from the VDV. Data are presented as mean ± standard deviation (SD) and 95% confdence interval (CI) (continuous data) or absolute and relative frequencies (categorical data). Continuous Materials and methods data were compared between the two groups using the Mann–Whitney U test. Categorical data were assessed The design and methods of this study were approved by using cross tabulation methods with the χ2 test. A prob- the local Ethical Committee (University of Regensburg; ability (p) value of ≤ 0.05 was considered to be signifcant. Ref. 10-101-0075). A cross-sectional cohort study design was chosen for analysing injuries that caused the end of professional football careers and the consecutive health status of retired professional male football players. The Results study was conducted in cooperation with the German labour union of professional football players (Vereinigung N = 126 (63.0%) retired players returned the questionnaire, der Vertragsfußballspieler, VDV), which takes care of of whom n = 10 had to be excluded from the study because active and retired professional football players in Germany of an incomplete questionnaire. In general, the end of the and acts as a counsellor for players with legal, health and professional football career was followed by a signifcant economic issues. The VDV distributed the study guide- increase in mean BMI (p ≤ 0.001, Table 1). The epidemio- lines and a questionnaire to a series of 200 former elite logical data did not signifcantly difer between the two male football players and collected written consent forms groups (Table 1). for participation in the study. The players reported injury The most signifcant reason for football players to end diagnoses and additional medical data based on the infor- their professional career were medical issues (medical mation given by their physicians. vs. non-medical reasons for ending the career: p ≤ 0.001) Professional football players were defined as players followed by age-related issues as the main non-medical who had an elite contract with a team of the 1st or 2nd reason (Table 2). Bundesliga, which represent the two highest playing lev- Players in group 1 had a signifcantly higher number of els in Germany. Further inclusion criteria were a minimum injuries per player during their professional football career of one ofcial match in a team of these two professional than players in group 2 (p < 0.001). In group 1, knee inju- football leagues. Exclusion criterion was an incomplete ries (n = 155 (23.8%) vs. n = 41 (13.3%); p < 0.001) and questionnaire. ankle injuries (n = 67 (10.3%) vs. n = 18 (5.8%); p < 0.001) The questionnaire included information about the par- were signifcantly associated with retirement due to injury ticipant’s characteristics, career details, history of football- (Table 3). related injuries, reasons for ending the career, the current After retirement, the level of overall sports activities health and activity status as well as a retrospective assess- difered signifcantly between the two groups (p = 0.03). ment of the prevention strategies available during the play- With regard to football activities, however, signifcantly er’s professional football career. The questions are shown fewer players continued playing football after retirement in the corresponding tables. Overall, the questionnaire was in group 1 than in group 2 (p = 0.003). In addition, players based on standardised injury surveys previously imple- in group 1 more frequently required assistive equipment, mented by Fuller et al. [9] and Hägglund et al. [10]. such as taping, bandages or orthosis (n.s.), and analge- The participants were divided into two groups, depend- sics (p = 0.01), in accordance to the description of symp- ing on the reason for ending their professional career. The toms, such as pain (p < 0.001) or instability (p < 0.001). frst group (group 1) consisted of players who had retired The group of retirement due to injury was characterised due to one or more injuries, and the second group (group 2) with an almost twice as high prevalence of osteoarthritis 1 3 Knee Surgery, Sports Traumatology, Arthroscopy Table 1 Anthropometric and football-specifc data of former professional football players Total Group 1 Group 2 n = 116 End of career due to injury End of career due to n = 73 non-medical reasons n = 43 Age at end of professional career Mean ± SD (95% CI) [y] 32.2 ± 4.2 (31.5–33.0) 31.8 ± 4.1 (30.8–32.7) 33.1 ± 4.2 (31.8–34.4) Duration of complete football Mean ± SD (95% CI) 25.6 ± 4.5 (24.8–26.4) 25.0 ± 4.7 (23.8–26.1) 26.6 ± 4.0 (25.4–27.8) career [y] Ofcial