Return to Sport After Injury: Why Criteria Beat the Calendar

Why the Calendar Is a Weak Guide

Healing timeframes are averages, and they describe how quickly tissue repairs rather than whether an athlete can tolerate the specific demands of their sport. Two players with the same injury at the same point in time can differ substantially in strength, movement control, fitness and confidence, and in the level of sport they are returning to. A consensus statement from the First World Congress in Sports Physical Therapy describes return to sport as an exercise in risk management, and as a continuum that runs alongside rehabilitation rather than a single decision made at the end (Ardern et al., 2016).

The same statement notes that research evidence to support return to sport decisions in clinical practice is scarce, which is a reason for humility about any rule, including the criteria discussed below.

What Return-to-Sport Criteria Try to Measure

Criteria typically assess strength, often compared between limbs, along with hop or jump performance, movement quality and how confident the athlete feels, and they are increasingly combined with tolerance of sport-specific training. Their value is that they ask whether the athlete currently has the capacity the sport demands, rather than how long ago the injury occurred.

The best-studied example is anterior cruciate ligament (ACL) reconstruction. In 158 male professional athletes, those who did not meet all six discharge criteria, a battery of strength and hop tests, before returning to team training had about four times the risk of ACL graft rupture, and a lower hamstring to quadriceps strength ratio was also associated with rupture (Kyritsis et al., 2016). In a cohort of 106 patients who played pivoting sports, more symmetrical quadriceps strength before return was associated with a lower knee reinjury rate (Grindem et al., 2016).

Time Still Matters, but as a Proxy

None of this means time is irrelevant. In the same Delaware-Oslo cohort, the reinjury rate fell with each month that return was delayed until nine months after surgery, after which no further reduction was observed (Grindem et al., 2016). One reasonable interpretation is that extra time allows strength and function to improve, since time and capacity are closely intertwined, and the ACL-specific findings cannot be assumed to apply to every injury.

The evidence also has limits. It comes from observational cohorts of modest size, and the authors of the criteria study noted that commonly used criteria had not been validated (Kyritsis et al., 2016).

What This Looks Like in Practice

A return usually moves through stages: pain-free daily function, then progressive strength work and running or sport-specific drills, then non-contact and contact training, and finally competition, with load increased gradually and symptoms monitored at each step. The decision is shared between the athlete, clinician and coach, and takes account of the athlete’s confidence, the level of sport and what is at stake in the season.

Because the right criteria depend on the injury, the sport and the individual, a return-to-sport plan needs an individual assessment.