Knee injury? Do this assessment!

Returning to sport after knee injury

Have you hurt your knee and want to know if you’re ready to return to sport (RTS)? Here are some quick and dirty tests to assess if you’re ready! Note these have historically been used for ACL RTS criteria, nevertheless are great tests for other knee injuries as well (other cruciate ligaments + meniscus tears). 

1. quad strength 
2. single leg hop distance 
3. triple hop distance 
4. triple crossover hop for distance 
5. 6m timed hop 

We like greater than 90% limb symmetry for these tests. This means if you scored 190cm for the single hop for distance test on your uninjured leg, you would need >90% / >171cm on your injured leg to pass/RTS. Or, if your single-leg leg extension 1RM (the heaviest weight you can perform a single rep with) is 40kgs on your uninjured leg, you would need >36kgs on your injured leg. 

This is why a physio who has gone down the rabbit hole of knee rehab is useful to have in your corner! 

This is important as sports-specific tasks / training may not be sufficient to catalyse needed adaptations. In other words, when RTS following an ACL tear or other significant knee injury, it’s not enough to simply test yourself with drills and tasks used in the sport. You may need information from tasks outside the sport to inform you. This is because the nervous system is clever; you can mask deficiencies and look like you are back to 100%. But in reality, you are hiding a deficit with altered movement strategies (see the image below).

The task in the above image was to stop, change directions and head back where you came from. The image on the left shows a strong knee (evidenced by the torque needed to overcome the large moment arm at the knee), whereas the image on the right shows a ‘hip-strategy’ that masks weakness in knee extension. The knee is doing a lot of work on the left, whereas the hip is doing most of the work on the right.

Now of course there’s a lot more to the picture than these simple RTS criteria! There are other tests I like to perform and there’s some complexity regarding interpretation of the results. Moreover, there’s early management (in the first days and weeks after injury), there’s intermediate management in the months following injury, and then there’s ongoing maintenance after you have returned to sport.

I have guided over 20 clients (including a mix of those who did not have ACL-R, those who did, and a slew of other traumatic knee injuries) back to high level sport including powerlifting, BJJ and MMA fighters, and those involved in team sports (soccer, NRL, netball).