Return to play testing protocols have become a mainstay of ACL rehabilitation guidelines. The logic is that passing the tests reduces your risk of consequent ACL injuries. However a recent review starts to look into the idea that maybe the outcomes of passing these tests are not as straightforward as we may believe, Webster and Hewett 2019.
What are the tests?
Over recent years there have been a number of investigations put together that have explored the use of two key areas of testing. The first is a functional testing protocol that includes jumping, landing, change of direction and balance tasks and the other testing scheme has typically used isokinetic dynamometry testing (muscle strength testing using an instrument to measure the force outputs of the legs muscles through different ranges and at different speeds). These investigations typically suggest that the better you perform on your reconstructed leg (with a typical pass mark of >90% of the uninjured side) then you are considered safe to return. There are other factors such as graft maturity, time and confidence to return, however we may leave that for another discussion.
So what is the outcome of the systematic review. For those who are unaware a systematic review is a research study that looks to compile all of the evidence in a particular field, so that potential trends can be seen, giving strength to the evidence. This is done as often you may get conflicting studies and it is generally accepted that if a significant portion of the evidence is leaning in one direction then it is more likely (however not always the case) that overall the research can be more certain of the results. The review completed highlights some interesting findings, they suggest that passing the return to play testing does in fact reduce the chance of rupture of the ACL graft, however it does not clearly reduce the risk of further knee or ACL injuries, with the most surprising finding that passing the return to sport testing may increase the risk of ACL injury on the other, uninjured leg.
So what does this all mean?
Essentially it showed that passing the tests in the return to sport following ACL injury is a key step to reducing graft rupture. However it does not mean that you are less likely to have further knee injuries on that side and it also may suggest that the uninjured leg remains at risk of ACL injury in a change of direction sport.