BACKGROUND: There is evidence that early return to competition post-anterior cruciate ligament (ACL) injury increases risk of re-injury. AIMS: To compare subsequent ACL and other injury risks following ACL reconstruction for Australian Football League (AFL) players returning to competition at different times post-injury.
METHODS: AFL players returning from ACL reconstruction in the 1992-2014 seasons were divided into three groups based on return to competition time (< 10, 10-12 and > 12 months). Non-reconstructed injuries and artificial ligament reconstructions were excluded. Subsequent ACL injury rates were calculated based on time since injury and number of return matches played. Risk of other knee and hamstring muscle injuries was also calculated.
RESULTS: There were 233 ACL reconstructions that returned to play in the AFL during the time period under study and met our inclusion criteria. The per-game risk of subsequent ACL injury decreased with a log decay from 1.2 to 0.15% during the first 20 games back (R2 = 0.43). Players returning at > 12 months had higher overall percentage of future career games missed through subsequent ACL injuries (4.8% vs. 2.4%), and through all hamstring and knee injuries combined (12.6% vs. 8.4%) than players who returned at ≤ 12 months (both P < 0.001). Players returning at > 12 months had higher risk of knee cartilage (3.7%) and patella tendon (0.6%) injury than those returning at 10-12 months (1.5%, 0.1%, respectively).
CONCLUSION: Players returning from ACL reconstruction at greater than 12 months had significantly higher rates of future games missed through both subsequent ACL injuries and through all hamstring and knee injuries combined. It may be true that both early and late return to play lead to suboptimal outcomes compared to average return-to-play times.