Knee ligament injuries in male professional football players

Sammanfattning: ABSTRACT Knee ligament injuries are common in professional football and entail a significant time loss from football, but studies of knee ligament injuries other than anterior cruciate ligament (ACL) injuries are scarce. The aim of this thesis was prospectively to study the epidemiology and characteristics of medial collateral ligament (MCL), lateral collateral ligament (LCL) and posterior cruciate ligament (PCL) injuries in male professional football players with the main emphasis on MCL injuries. A further aim was to analyse whether professional football players are more susceptible to ACL injury after returning to play from any previous injury. The main sample in this thesis is from the UEFA Elite Club Injury Study (Studies I-IV) that has been ongoing since 2001. In addition, data from the English Premier League (Studies II-IV) and the Nordic Football Injury Audit (Study III) were used during 2011 and 2014 and 2010 and 2011 respectively. All four studies followed a prospective design using standardised methodology, which documents training and match exposure and time loss injuries on an individual basis. Injury severity was evaluated according to length of time loss. Injury rate and the rate ratio (RR) for injury between training and matches were calculat- ed. In Study II, further details on clinical grading, imaging findings and specific treatments were collected between 2013 and 2016 for all injuries, with MCL injury as the main diagnosis. In Study III, first-time complete ACL injuries were matched 1:1 according to team, age and playing position with control players who did not have a current injury and the 90-day period prior to the ACL injury was analysed for injuries and compared by using the odds ratio (OR) and a 95% confidence interval (CI). The match injury rates were significantly higher than the training injury rates for MCL injury (1.31 vs 0.14/1,000 h, RR 9.3, 95% CI 7.5 to 11.6, p<0.001), LCL injury (0.21 vs 0.02/1,000 h, RR 10.5, 95% CI 7.3 to 15.1 p<0.001) and PCL injury (0.056 vs 0.003/1,000 h, RR 20.1, 95% CI 8.2 to 49.6, p<0.001). There was a significant average annual decrease for MCL injuries of 6.9% (p=0.023) between 2001 and 2012 in Study I and for LCL injuries of 3.5% (p=0.006) be- tween 2001 and 2018 in Study IV respectively. For MCL and LCL injuries, the majority were mild to moderate injuries, i.e. the lay-off time was less than four weeks (71.7%, and 72.7%, respectively). On the other hand, most PCL injuries (57.1%) were severe injuries causing more than four weeks’ lay-off. In total, 75% (98/130) of all MCL injuries in Study II and 58% (63/108) of all LCL injuries and 54% (14/26) of all PCL injuries in Study IV were related to contact injury mechanisms. For MCL injuries, the agreement between clinical examination and magnetic resonance imaging (MRI) for grading was 92% in Study II. Using a brace in the treatment of grade II MCL injuries was associated with a longer lay-off compared with not using a brace (41.5 (SD 13.2) vs. 31.5 (SD 20.3) days, p = 0.010) in Study II. The odds of a player with an ACL injury sustaining an injury in the previous 90-day period did not differ significantly from that of controls (OR 1.20, 95% CI, 0.66-2.17, p = 0.65). A men’s professional team, typically with 25 players in the squad, can expect ap- proximately two MCL injuries a season and one LCL injury every third season, while a PCL injury can only be expected every 17th season. These knee liga- ment injuries typically occur during matches and are associated with a contact injury mechanism. Moreover, the collateral ligament injury rates have decreased significantly since 2001. For players sustaining a grade II MCL injury, using a stabilising knee brace was associated with a longer lay-off period compared with players who did not use a brace, indicating that routine bracing may not be an optimal therapeutic option and is better determined individually.