Summary
Among MLS players with ACL injuries, a faster return to sport was seen between 2016-2021, when compared to 2011-2015, possibly indicating an acceleration of ACL injury rehabilitation; player performance largely equaled or exceeded that of matched controls by the third post-injury season.
Abstract
Purpose
To examine (1) the incidence of anterior cruciate ligament (ACL) injuries in MLS athletes, (2) return-to-sport (RTS) following ACL injury, (3) investigate conditions that are associated with increased time to RTS (4) determine player performance after ACLR in elite MLS soccer players with a retrospective matched-cohort analysis.
Methodology
The MLS Injury Surveillance database was queried for athletes with ACL injuries from 2011-2021. An ACL injury was defined as an incident involving the ACL, with possible additional co-ligament involvement, that required medical attention. Demographic characteristics and injury characteristics (setting, activity, and re-injury) were used for descriptive analysis. The athletes were then matched by position, age, season of injury, baseline statistics and then compared to uninjured control players in a 1-to-3 ratio. The difference between performance metrics for the first 4 full seasons following injury were calculated by comparing to player metrics 1 season before injury. Univariate 2-group comparisons were performed by using independent t tests.
Results
146 total injuries were recorded between 2010 and 2021 in 132 MLS players, with 9 (6%) re-injuries. The median absence from sport per injury was 240 days (mean: 246.5). The average number of games missed, and practices missed per injury, were 17.4 +/- 13.3 and 52.8 +/- 50.6, respectively. The average injured player age was 24.8 +/- 4.3 years, with 93% undergoing ACL reconstruction. Time to RTS significantly decreased from 269.6 days in 2010-2015 to 219.0 days in 2016-2021 (p=0.044). Additionally, acute contact injury (vs non-contact), lead to increased games missed (20.7 games vs 15.6 games, p = 0.024). Concurrent ligamentous and meniscal pathology, position, home vs away games, weather, and field type, did not significantly affect time to RTS or average games missed.
51 total athletes, who at least played in one season prior to injury, were matched to 153 control athletes. Injured athletes played and started significantly fewer games, and recorded inferior performances for the first season after their injury (P < .05). However, in subsequent years the game performance of injured players was either not statistically significant in difference or had significantly improved compared to control athletes across several performance metrics, with the exception of attackers, who demonstrated a continued decline in performance beyond the initial 1-2 years following injury (P < 0.03). Notably, when compared to control players, a higher percentage of injured players had remained in the league for the first 1-2 years following the injury index year. However, by the 4th post-injury season, the rate of players still in the league were similar between both cohorts.
Conclusion
Comparing injuries between 2010-2015 and 2016-2021, there was a 50-day average decrease in days missed, and a 5-game average decrease in games missed. Given that 93% of MLS athletes with ACL injuries underwent surgery, the significant decrease noted from 2016-2021 may indicate an acceleration of ACL injury rehabilitation. With the exception of attackers, player performance largely equaled or exceeded that of matched controls by the third post-injury season, a result shared by prior studies investigating player metrics in UEFA soccer athletes.