Here’s a transcription excerpt of our webinar with Jay Dicharry on this interesting ACL case:
“I basically stuck a sensor on one of our athletes, who I knew had an ACL tear about 11 months ago. He was the ginny pig of our gait assessments, and we looked at his data and found some things that were really really important. And I said hey, let’s talk about something. I said “how are you doing”, and he said, my ACL tear was 11 months ago”. And, his physiotherapist released him back to running and said, “you’re doing pretty well”. Well, we know from research that things aren’t completely healed after all, 12,13 months, or even a year and a half window—following a tear. But, if you just look at the range of motion or raw strength numbers, you miss some things“.
I’m not going to get too ‘deep in the weeds’, but I’ll give you really quick some numbers here. On the left side of the screen in the top corner we have ‘Impact Magnitude’, and this is somewhat reflective of the strength your athlete brings to the table when they’re running. So we can measure the amount of impact they have every time. If he’d have a strength imbalance you might see a large asymmetry here, but we don’t see a large asymmetry here.
If we look at impact duration (top right corner metric), though, things are actually very large—we see a huge shift. Things are out the green and we’re now around the caution level. We’re almost in the very high number on that left leg. So, what we found was—this runner—11 months post ACL tear, was not able to dampen impact loads. We talk about strength, (i.e., how much force you can put out), but is time a factor? Nope! Power is about how quickly you can put out forces, and because running happens quickly, this is a way you can look stride for stride if you’re seeing adequate power output to dampen these impact loads. So if we find asymmetries here, that’s telling to know what’s really going on. We can see very clearly that he can’t dampen loads very effectively on his left leg, so what he did was threw extra loads over to his right leg. And, even though the therapist told him he was ‘strong’, he lacks the functional ability to dampen loads symmetrically. And we’re releasing him back to running? Would we really do this if we had better tools to say, ‘hey, here is where we are’?
I know that this individual is strong, they just can’t generate this force fast enough. And it comes back to the key aspect of the rate of force development. So I know I’m not going to spend time doing strength work with this individual. I’m going to spend time improving his impact capacity—so how he learns to dampen those loads symmetrically over time, and how I can make sure that translates over to running gait. So, this information is just like a ‘aha this is cool, things are asymmetric’. They’re actually very telling about what you need to work on.