Twenty-year-old Sarah is a sport-obsessed amateur football player. She enjoys the social side of playing in a team sport, but most of all she loves the physical and mental challenge of game day. There is no better feeling than winning. She works hard on her skills and fitness, training twice a week with the team, and most other days on the cycle commute to the University and with her own gym programme. Maybe it was her young age1 and dodgy biomechanics2 that conspired against her. Perhaps it was the type of grass on her home pitch.3 But she winds up at your clinic clutching an MRI report that bears the dreaded diagnosis—she's ruptured her ACL.

Return to play is a fundamental concern for athletes and sports medicine clinicians—one important benchmark for judging treatment success. For many athletes with ACL injury, their most pressing concerns are about meeting their own expectations, or those of significant others (eg, coach, team mates, family), for returning to their pre-injury level or sports performance. Sarah will be faced with three options when she is ready to return to play—return to the pre-injury level sport, change sports participation (either change sport or change level) or retire.