Anterior cruciate ligament (ACL) injuries are a serious and sometimes career-threatening injury for professional football players. Early ACL reconstruction (ACLR) is generally considered to be the gold standard treatment in most cases. While most professional players are able to return to football after ACLR, football performance may be negatively impacted post-injury and there is a risk of further knee injury. The primary aim of the paper highlighted in this FastFact was to quantify the risk of further ACL injury following ACLR among elite players.1
A prospective study involving 118 elite professional football players that sustained an ACL injury and subsequent ACLR was conducted. Players were recruited over the course of nineteen seasons as part of a sub-study from the Elite Club Injury Study (ECIS). Following ACLR, the players were tracked prospectively for a second ACL injury. Secondary outcomes were career length following ACL injury and related treatment. Analysis of potential predictors of subsequent ACL injury (to either knee) were carried out using a stepwise Cox Regression model.
All the players in this cohort returned to training (RTT) following ACLR and were evaluated at a median follow-up of 4.3 (IQR 4.6) years after surgical treatment. Among the 118 included players, there were 21 subsequent ACL injuries after RTT. The cumulative second ACL injury incidence was 17.8% (21/118), with 9.3% (11/118) ipsilateral graft ruptures and 8.5% (10/118) contralateral ruptures. This is similar to reported injury rates in other (non-elite) cohorts.
Non-contact or isolated index ACL injuries were independent risk factors for a second ACL injury with a 7-fold and 3-fold increased risk, respectively. Combined, 11 of the 26 players who sustained a non-contact isolated index ACL injury had a second ACL injury compared with 9 of the other 92 players (42.3% vs 9.8%, p<0.001). None of the 32 players that sustained a contact and non-isolated ACL injury sustained a 2nd ACL injury. Time to RTT was not an independent predictor of 2nd ACL injury in the multivariable analysis (HR: 0.87; p=0.446). However, none of the 13 players who had their RTT after eight months sustained a second ACL injury, whereas 10 of 49 players (20%) with RTT within six months sustained a second ACL injury. The median top-level career length was 4.1 (IQR 4.0) years after ACLR and 3.4 (IQR 3.9) years after RTT. The proportion of players still playing at highest level five years after ACLR was 60%.
This study illustrates that the risk of a second ACL injury is high among elite players. This finding underscores the importance of ongoing secondary prevention strategies, even after a ‘successful’ return to play. It would appear that this is especially important for players who have sustained a non-contact index ACL injury (44-66% in professional footballers) or an isolated index ACL injury. Delaying RTT for a minimum of eight months for players in these groups is one strategy that would be supported by this study’s findings. Finally, players who had an ACLR in this group only played for an average of 3.4 years after formal RTT, suggesting an important effect of ACL injury even at top level European football. It is difficult to interpret the significance of this last finding as there was no matched control groups to compare this with.
1. Della Villa F, Hägglund M, Della Villa S, et al High rate of second ACL injury following ACL reconstruction in male professional footballers: an updated longitudinal analysis from 118 players in the UEFA Elite Club Injury Study British Journal of Sports Medicine Published Online First: 12 April 2021. Doi: 10.1136/bjsports-2020-103555