Episode 1771 - Arthrogenic muscle inhibition: should we ice?

Dr. Lindsey Hughey // #ClinicalTuesday // www.ptonice.com 

In today's episode of the PT on ICE Daily Show, Extremity Division leader Lindsey Hughey discusses the benefits of icing prior to exercise for patients dealing with arthrogenic inhibition. 

Take a listen to the episode or check out the full show notes on our blog at www.ptonice.com/blog.

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EPISODE TRANSCRIPTION

LINDSEY HUGHEYAll right. Good morning, PT on ICE Daily Show. How's it going? I am Dr. Lindsey Hughey, one of the division leads of our extremity management here at ICE. Welcome to Clinical Tuesday. It is awesome to be with you all here to share a little clinical tip. I'm going to try to keep it short and sweet this Tuesday. about arthrogenic muscle inhibition, and specifically after surgery like ACL or a total knee replacement, not things we get to usually talk about on our weekend extremity management. So really the big question I want to tackle today is should we ice for this? When you come to our class, we talk a lot about peace and love principles, and this came out of the British Journal of Sports Medicine in 2020 by Dubois and Escular. And they really highlighted that when we're managing soft tissue injuries, we actually don't want to ice or use NSAIDs anymore. And so the question comes up weekend after weekend. Well, what about after surgery? Should we be icing still? Well, because of arthrogenic muscle inhibition, it's kind of a completely different animal. And the evidence would tell us actually, yes, we should be icing for this. And so I'm going to discuss a little bit about that research briefly. But let's just briefly talk about before that, what is arthrogenic muscle inhibition? Well, what happens after surgery, what we see is that the normal activation of the sensory receptors within the joint and its surrounding structures, think ligament, tendon, joint capsule, and even muscle, And these are all responsible for detecting change in joint position, tension, compression. They send signals to the central nervous system. But in response to injury or controlled trauma like a surgery, these processes get disturbed and interrupted. So what happens is after a surgery like that, the central nervous system kind of goes into protective mechanism mode. And so a lot of inhibitory signals get sent to really protect. Big picture, if we step back, this inhibits our quadriceps activation. So after an ACL repair or a knee replacement, we see a lot of the quad swollen, it shuts down, and this leads to sequelae of functional deficits, big ones being like knee extension deficit, which means we miss our terminal knee extension, leads to quadricep atrophy. if we don't quickly regain that knee extension and proper activation, we'll tend to see persistent knee pain if this is not rehabbed appropriately and poor function in our stability as well. So what does ice do? Like what, why is icing potentially beneficial here? Because just to review one more time, that arthrogenics, inhibition that is happening, arthrogenic muscle inhibition, what is happening again is that we see that abnormal joint afferent input, which will decrease excitability of the spinal neurons controlling that quadriceps activity. And so that decreases motor unit recruitment and then even our firing rate. And we see this time and time again in our folks with ACL and it becomes persistent and people after total knee replacement. So what is icing doing? Like why is ice potentially helpful? And then I'll share two articles and point you in the direction to read to share how ice has been beneficial. What icing cryotherapy is thought to do is that it may prevent the activation of those inhibitory synapses that are happen in response to that arthrogenic muscle inhibition or AMI. And By disinhibiting, it actually increases the excitability of the anterior horn cells. We're getting a little nerdy this clinical Tuesday. And so what happens then is that there's less supraspinal control over the reflexive activity of like guarding. And so the icing serves as a strategy to just basically overcome and create disinhibition, right? Prevent that inhibition from happening. two articles specifically in the ACL literature that I want to share. And what's really, I want to give a shout out to Jonathan, because it was actually a course participant that asked this question. And, you know, I said, I actually need to do a lip search because I don't know the answer for sure. And he was so awesome. And he like sent me these two articles. So shout out to him for doing so. So what we see out of the British Journal of Sports Medicine in 2019, there was a scoping review by Sonnery Cotlett et al. And this included 20 RCTs that had moderate quality evidence where they looked at the efficacy of cryotherapy in combination, so let's consider not just alone, but in combination with exercises that activate the quad after ACL. And so what they saw is improvement in activation. These folks tended to do better when cryotherapy was a part of their care and those that had that AMI present. In addition, We see another article I want to point you to, and I'll tag these links for you. We see another article specific to ACL, but that timing might even matter. So there was a study done in the Journal of Orthopedic Surgery in 2019 where they actually compared putting ice on folks before they did quad activation, and they had a sham environment where they It was actually kitty litter that they put on the knee, and then they put ice on the knee. And they did this so that the person measuring output and torque was blinded to know whether they had ice or not. And what they found is the folks that actually had ice prior to had better firing in their quad because what happened is it had disinhibition effects, meaning it stopped that inhibition that usually happens and shuts the quad off. So consider, and that really surprised me, that the timing of our ice in combination with exercise or stim might be the thing we also need to consider doing it before we start a bout of exercise care after surgery. SUMMARY So as promised, keeping it short and sweet today, I wanted to give you all an update that we are, in fact, advocating for cryotherapy for our folks after surgery because it helps with long-term, down the road, better quad activation because of its disinhibitory effects. I'll put those links here for you today. I hope everyone has a wonderful Tuesday and that you'll consider cryotherapy still for your folks post-operatively, which is contrary to our peace and love principles. If you want to learn more just in how we manage knee pain, rehab in general, please join us at an extremity management course. What's coming up is July 20th and 21st. Cody will be in Hendersonville, Tennessee. That course is filling up, so join him there. And then I'll be in Bend, Oregon with Hannah, which is sure to be a blast. We're going to go visit Justin Dunway, our Total Spine Thrust faculty that weekend. It's going to be a blast. That is July 27th, 28th. And then we have two opportunities in August across the country, 24th and 25th. I'll be in Bismarck, North Dakota. Never been there, so join me there. And then Cody, again, will be putting on a course, but this time in Greenville, his home base, the same weekend. So opposite spectrums on August 24th and 25th. I hope you'll consider joining us as you end out your summer. Thanks for your time this morning, everyone. Take care.

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