Busting ACL Myths with Erik Meira
All your burning questions answered.
I'm incredibly grateful for the opportunities I get to sit down and chat with some of the brightest minds in our profession, and my recent interview with Erik Meira was no exception. I'm a huge fan of Erik's work and have modelled so much of my own physical therapy practice on his teachings. He has a way of cutting through the noise and focusing on what truly matters.
Our full, unedited conversation is an exclusive for our paying members of The ACL Hub, but the insights Erik shared were just too important not to share some of them with our entire community.
So, I’ve pulled out some of the golden nuggets from our chat. Here’s a Q&A-style breakdown of Erik's key philosophies on testing, rehab milestones, and his invaluable advice for clinicians.
Q: Do you have a specific philosophy when it comes to ACL rehab?
A: My biggest takeaway from the thousands of ACL reconstructions I've seen is that no two are exactly the same. The organism in front of you is a lot smarter than you are, and our role is more about poking, prodding, and nudging things in the right direction.
I think about the end-stage first - what are the common issues we'll face? - and then track and stimulate progress towards that. It’s more about being a guide and keeping things honest rather than trying to drive all the change ourselves.
Q: You mention "keeping things honest" with testing. How do you view pass/fail test results?
A: Testing is crucial, but I've seen people take it to the wrong extreme where it's a black-and-white "pass" or "fail." I prefer to think of rehab as a series of gates you have to move through.
My philosophy on testing is this: you can only fail a test, you cannot pass it. If a patient fails a test - say, a manual muscle test on their quadriceps - I clearly know we have a problem. But if they "pass" it, it doesn't mean the issue is resolved. It just means that specific test didn't show me anything useful, so I need to find another test that might. It's about gathering information, not just ticking a box.
Q: So, what about the common 90% limb symmetry index (LSI) goal for quad strength or hop tests before returning to play? Is that the ultimate goal?
A: No, I don't think it's the be-all and end-all. I work with professional athletes where sometimes, returning by a specific date is critical for their contract. There isn't one day you're not cleared and the next day you are. It's a spectrum.
An athlete could go back with a 70% quad index, but they need to be acutely aware of their limitations. My job is to educate them on how that deficit will show up in a game and what situations to shield themselves from. Every return to play is different because every case is different.
Q: What are your non-negotiables in the first 12 weeks after surgery?
A: The 20% of work that gets 80% of the results in the early phases is swelling control. Swelling inhibits muscle activation, restricts range of motion, and drives pain. Everything comes back to swelling.
So, my non-negotiable is getting that under control with elevation, compression, and yes, even ice. I know ice gets debated, but it makes patients feel better, and that has value. If we see chronic swelling, I'm immediately looking at their activity levels. Sometimes the best thing to do is back off and let the knee calm down.
Q: What are your thoughts on modalities like Blood Flow Restriction (BFR) or neuromuscular electrical stimulation (NMES) in the early stages?
A: These tools can be useful, but they don't fall into my "non-negotiable" category. We know the joint is protecting itself after surgery - what we call arthrogenic muscle inhibition (AMI) - and it's shutting the quad down. You can think of using BFR or NMES as trying to do CPR on a muscle that isn't getting a stimulus otherwise.
I’m not opposed to it, especially for high-level athletes, but these interventions are classically uncomfortable when done properly. While some studies show they can give you a big burst of progress early on, things tend to even out by the end of rehab. I think this thing is going through its process, and our job is to stimulate it how we can and get the strength back later.
Q: Knee extensions have been controversial. What's your approach in the first 3 months?
A: We start with isometrics right away, usually at a 60 or 90-degree knee bend. As we progress, I use a partial arc for weighted (isotonic) extensions. I don't do full-arc extensions, not because they're dangerous, but because I think it’s a more efficient use of time. Patients aren't as strong near full extension, so by shortening the arc, we can add significantly more load to the system where it can handle it.
If you face pushback from surgeons, change your vocabulary. You're not doing "open-chain knee extensions"; you're doing "multi-angle quad sets." No surgeon is afraid of a quad set.
Q: A 9-month return-to-sport timeline is often cited. How strictly do you adhere to that?
A: Time is secondary to criteria. I was once asked what the soonest I'd clear an athlete is, and my answer was 4.5 months. That shocks people, but I interpreted the question as, "What if all criteria are met?" If an athlete has an amazing quad index, great power, and has passed every test at 4.5 months, why would I hold them back?
That said, for most athletes, I tell them to plan for 12 months. It takes the pressure off and gives us a fantastic window to work on skills, strength, and other aspects of their game without the demands of competition.
Q: What are some of your key return-to-sport tests?
A: The first major hurdle is that isometric quad index, getting within 90% over a 5-second hold. After that, we look at the rate of force development and isokinetics.
Once the dynamometer testing looks clean, my personal favourite is the 505 test. It’s a max-effort sprint with a 180-degree turn. It’s fantastic for revealing deficits in deceleration. What surprises people is that the issue often appears on the inside leg during the turn, not the plant-and-pivot leg. The surgical leg fails to decelerate properly, dumping excessive load onto the contralateral leg, which could be a reason we see so many opposite-side ACL injuries.
Q: Finally, what is one piece of advice you have for early-career clinicians working in ACL rehab?
A: Have a good, solid process. That's what you will always fall back on when things aren't going well. Bad outcomes happen to everyone; it's part of the job. But you can sleep at night if you can look at a bad outcome and know you did everything within your power and followed your process.
Nine times out of ten, when I'm consulting on a difficult case, the therapist got lost chasing complicated issues and forgot the basics. Don't make things harder than they have to be. Do the simple things exceptionally well, and you will be extremely successful.
Final Thoughts & Watch the Full Interview
What a conversation!
My key takeaways are to respect the healing process, prioritise swelling control early, test intelligently (remembering you can only fail a test), and let criteria, not the calendar, guide your biggest decisions. And above all, master the basics.
If you found these insights valuable, this is just a fraction of the knowledge Erik shared.
In the full one-hour interview, we dive much deeper into specific testing parameters, managing athlete psychology, differences between graft types, and so much more.
And if you're not already a member, please consider joining The ACL Hub to get exclusive access to this and our entire library of expert interviews, research reviews, and clinical resources. We'd love to have you.
You can watch the full, unedited interview at the link below.
➡️ Link to the full interview on The ACL Hub below
Keep reading with a 7-day free trial
Subscribe to The ACL Hub to keep reading this post and get 7 days of free access to the full post archives.