Carleen Baldwin presents "Cuff Enough: Blood Flow Restriction in the Treatment of Post-Operative Knee Injuries" at the UCSF Pediatric Musculoskeletal and Sports Medicine Conference 2023 in Berkeley, CA.
Our next speaker is Carlene Baldwin. Carly received her Bachelor's of Science and Exercise biology from U C Davis and went on to earn her doctor of physical therapy from Western University of Health Sciences. She joined U CS F Benioff Children's Hospital Sports Medicine Center for young athletes. In 2015, she's an orthopedic certified specialist. She has a special interest in working with over at athletes, returned to sports progressions, manual therapy and blood flow restriction training. In addition to her clinical work, she also teaches the strength and conditioning portion for our residency program. So with blood flow restriction training is Miss Gray. Hi, my name is Carly Baldwin and I'm a physical therapist at U CS F. Benioff Children's Hospital Sports Madison, our center for young athletes. I do not have any financial disclosures for today or affiliations to disclose. I wanna go over our overview for today. This is our outcomes and our objectives, but really, I like to use the kiss principle of keep it simple. We're gonna go over the, who's the, what's the, when and the whys for B F R and when to use it. So before we dive deep into this. I want to go over some things that are in your syllabus because your syllabus is different than the power point. Your syllabus reads like a script or an outline and it includes three key things that I think are really beneficial to walk away with. For today. One is, it's going to include a copy of the protocol for B F R. This is a universal protocol that goes through all our research as well. Number two, it goes through in a logarithm that's evidence based based on a recent research article that gives you risk for high, low medium for if someone's appropriate to use B F R. Lastly, there's a series of different links um leading you to different uh resources for how to get certified in B F R. So if you love this today and you're like, I want to go get certified, please do because this is by no means comprehensive of what B F R is in terms of actually applying it to your patient. So today, I'm guessing that, that we have a spectrum of people here in regards to knowledge of B F R anywhere from why in the world would you put a tourniquet on someone and have them exercise to? Yeah, I've been doing this for a while and I really enjoy it. I think it's super beneficial to our patients. So the most basic definition of B F R is that it's a brief and intermittent occlusion of venous blood flow while restricting arterial inflow using a tourniquet while either at rest or exercise. This next uh proposed mechanism is a little bit wordy here and we're gonna break it down. But there was a phrase I really liked that I came across in the research and that it has super physiological effects or benefits. So, when I saw that I'm like, wow, who wouldn't want to do this? Right. So what it does is it promotes cell signaling after promoting a hypoxic environment in the muscle, the hormonal changes activate protein synthesis, causing proliferation of myogenic satellite cells, stimulation of cells within a muscle connected tissue for muscle growth and regeneration and activation for the preference of type two muscle fibers. So let's break that down because that makes no sense. Just going on a big long paragraph. What's actually happening? The first thing that happens is you create a load, you have a tensile stress on the tissue. You include that Venus return and it restricts the arterial inflow and doing so there's a metabolic response. The metabolic expo response is that it decreases the P H stimulating satellite cells. Satellite cells are what is going to help us with hypertrophy. So, they're responsible for increasing protein synthesis, myofibril size and stimulates the muscle cells. Well, so these are the same metabolic uh markers that we would see with traditional resistance training next muscle. Uh And I want to go back to that metabolic um accumulation just for 11 point is that if you are looking at it on a cellular level, it's the same as when we're looking at lactate threshold, lactate threshold is that point when we see the dip in the P. So for muscle fiber recruitment, traditionally at rest and with aerobic activity, we have type one muscle fibers for uh B F R peripheral fatigue. And that hypoxic environment actually changes it from aerobic to anaerobic. So you're generating those type two fibers and recruiting them. Then there's a cell signaling that happens because of this. It stimulates the protein synthesis pathway via the rapamycin um pathway. And then it down regulates myostatin which actually breaks down tissue. Lastly, you get post exercise hormones. So you get a systemic proliferation of growth hormone, insulin, um growth factor one and testosterone, this happens even after exercise. So here's the bottom line. The magic of B F R is that it creates this acidic environment in the muscle cells that mimics higher loads of training at a lower resistance which promotes an increase in strength. This allows one to exercise with less load on the joints, a higher ability to resist fatigue and lastly the ability to respect restrictions of pain. I'm gonna skip ahead one slide and come back to this one because what I want you to look at on this slide is if we're looking side by side traditional exercise versus B F R. And what's actually happening in the body. It's the same except for that very last line. And that's at 60 to 80% of load. For hypertrophy for traditional exercise versus B F R, it's at 30 to 50% load. So going back when we're talking about resistance exercise versus B F R, 20 to 50% of a one rep max can promote muscle hypertrophy similar to that traditional strength program along with reducing pain and adverse joint loading. B F R has been shown to increase fiber cross sectional area. We'll talk a little bit more about what the research is doing with that. It's also been shown to increase muscle size and strength compared to low load resistance training and as little as three weeks. So to break that down a little further, 3 to 8 weeks in traditional strength training at 30 to 50% on max for strength versus 12 to 16 weeks of uh strength training first at 60 to 80% for hypertrophy. You're getting those same results in about 2 to 3 weeks with B F R as far as application goes when compared to load load training, B F R is more effective. It also could be more tolerable for your patients, but it is not going to be superior to high load training. And it's important to still keep that in mind, especially with our uh our young athletes because muscle does adapt much faster than tendon. So we don't want a hypertrophy without having that load and impact to balance it out. So I emphasize this especially for our young athletes because we need to emphasize that um this is a great supplement because you can continue to train more frequently with less mechanical stress on the joints. So it does have a broader application that we can use in conjunction with other um forms of training. Lastly, and I will talk about this a little bit more. The fact the effects of B F R tend to happen distal to the site of inclusion. There are systemic benefits. There are crossover effects with B F R. But the main, the things that are getting the most benefit are distal to that inclusion site. So this highlights many of the benefits we already just talked about. But there's a couple other things I want to highlight. So there is an improvement in bone density and function in addition to um the mitigation of atrophy and the increase in strength. Um There's also a heightened neuromuscular activity with B F R. There's an increase in aerobic capacity which I haven't touched much on and we won't touch much on today because I really want to emphasize the hypertrophy and strength component, but you can use it for aerobic training as well. And then these last two points are huge for me. One is that it can help increase um strength and continue to keep strength during in season right now. If you look at the MLB season. It's crazy. It is super long. Those athletes still need to train, they still need to continue to get strong. How are you going to do that? When you're playing multiple games in a week, it's very hard to continue to do that. We don't want to encourage early specialization in our athletes but encouraging them to understand that when they are performing in these long seasons, they still need to work on their strength. So this could be something where they're resisting fatigue in like a traditional resistance training by doing B F R in addition to their season. And lastly, if you've been into my clinic in Oakland, you know that it's a nice cozy, intimate space. So the, the appeal of that, there's little requirements for space and equipment was huge for me. I don't have to have a big squat rack. I can use this in addition to like small ankle weights and still get a great bang for my buck. If you're an AC C here today, you guys are magicians with space. So this is a great resource for you. So this is the actual protocol. We're not going to dive too deep into it because it's a lot, there's really three protocols to highlight here. One is passive B of R. It's also called ischemic preconditioning. The second is aerobic or V 02 conditioning and lastly um is hypertrophy training and that's the one that we're really after. And the first one was ischemic conditioning or passive B of art. It's exactly what it sounds like, passive or very low load. So, isometrics you're putting it on for a set amount of time and a much higher resistance aerobic. It's similar to if you've worked with pots patients and having to find a graded area that you're going to train in. And then lastly hypertrophy. So, the hypertrophy training, this is the, it's same in all of the research. This is the protocol for B F R. It doesn't matter what certification you get. Um the way that they do hypertrophy training is, it's four sets. The first set is 30 reps. The second set is 15, 3rd set is 15, 4 set is 15, it's about 30 seconds to a minute, rest in between. So mind you, we're talking 20 to 30% of one rep max. So you're not supposed to be doing Olympic lifts on these, you're not supposed to be going to max resistance 20 to 30%. So there are contra indications and you are going to get that in your syllabus. Um The article that kind of goes through um the high, the medium low risk, but these are the main things we're worried about. The big thing is we don't want a thrombotic events, right? We're worried about clots. So the conditions that you see up here are ones that we're most concerned about that would lead to that I have some asterisk on some of these things because um, it's not absolute. Some of these are relative. You can have a fracture site and do the B F R on the opposite side or you can do it on an upper extremity or a low extremity, whichever one um, with surgery, most surgeons have told me, please wait until the incisions are healed. And then the research says weil is about less than three centimeters of edema to put it on the actual surgical side could still potentially do it on the non involved side. So this is a copy of that article and you have it as well. So let's actually talk about the, the big elephant in the room, the risk for venous thrombosis, right? We're concerned about, we don't want to put a cuff on someone and then have this event. So the likelihood of B F R directly causing this is very low, especially on these third generation uh pneumatic devices. The third generation, most of them are automatic. Now they turn off if it gets too high, they also won't let you go to full collusion point, they're wider. So if you look at uh the point about the wider cuff pressure, if you compare a smaller cuff to a wider cuff, a smaller cuff is gonna cut you off um in circulation at a much higher rate than a, than a larger cuff. Well, um, so the actual risk is about 0.0.4 to 0.8%. So pretty low. If you're screening out, you can really capture that if we compare B F R to traditional resistance training and the likelihood of actually causing a clot to travel if it's already there. Um It's about the same. So you should be screening either way, even if you're about to start resistance exercise on your athlete. To this date, there's been no studies that have shown increase in markers of a thrombotic event with B F R and this includes all the way out to four weeks after using it. Uh B F R in itself. Some of the research has shown that there's actually a uh a breakdown of fibrin in the blood with its use, so it could potentially be beneficial. So there are other risk factors that we're concerned about in the use of B F R. Skin breakdown, temperature changes, nerve injuries. If that cuffs too tight, all of these things could potentially happen, right. So the main causes of these things are too high of pressure, a cuff that is too narrow and leaving it on for too long. Lastly, I put this in here and I would also put this in the contra indications and precaution slide is that you have to know your patient if this is the patient that comes in with a pain diagram that looks like they drew a couture gown on it. This is not the patient to do B F R in if this is a patient that comes in and tells you I have a super high threshold for pain, not an appropriate patient to do this on. This is someone that doesn't communicate well with. You probably earn that trust and then maybe go back and re examine. Um So I, I bring this up because I put no voodoo flossing. Voodoo flossing is a band that you wrap as tight as you possibly can. You will see it a lot in gyms. Um It, it has its uses but you're going to have, especially if they are young athletes, they're gonna see this stuff. So they're gonna come and ask you. Oh, well, I saw this guy do it in the gym. Can I do it? No, you cannot. Um And here's why you're not regulating how much actual pressure you're applying and that's why it's dangerous and that's why we're concerned. Um If you're a visual learner like me, this is just a flow sheet of what technique you might want to choose and why. So now we get into post op knees, the nitty gritty here. So these are the deficits we're seeing and this is general post op knees. These are the deficits that we continue to see post off. And a lot of this is going to piggy back on to a lot of what was you just heard with Dr Pandia lecture too. So the two main things are immobilization and atrophy it happens because you had surgery and now we have to combat the quad lag and the quad atrophy that we're seeing and a person that just has bed rest has not had surgery at all 7% atrophy in the quad after seven days and post op patients, it can be up to 33% at three weeks. Previous studies have shown the actual cross sectional quadri sep atrophy up to 18% even six years out post surgery. If you're looking at a total knee and a total um hip, I realize we're talking about young athletes, but I come from a previous adult background, so I couldn't not talk about our total uh joints. Um they have up to 80% which is huge lastly and this is more pertinent to our young athletes is the differences in strength in our quad uh to hamstring ratio can lead to episodes further down the line of pain and dysfunction. So we're concerned about patella dysfun, patellofemoral dysfunction as well as O A in those patients. They're at a major risk for new injury if they don't work on getting that ratio. And the hamstring weakness as itself is a marker for prevalence of high re injury rates. Now specific to AC L rehab and, and quad weakness, there's a couple different things that happen that are concerning. One is that if you have that quad weakness, there's gonna be a change in the biomechanics of the knee and change in their actual movement patterns that can decrease the muscle function and effectiveness. It can increase their risk of re injury and then further down the line, the thinning of the articular cartilage of the femur and then lastly a lower return rate for sport, which is something we don't want to see on our young athletes if we can avoid it. So this is where B F R kind of bridges that gap B F R rehab um is beneficial for our post op patients. For two main reasons. It resists muscle atrophy. It helps build muscle strength, post op protocols that involve any kind of cartilage require a much longer time of inactivity or partial weight bearing. So that would be the time that I would really want to use B F R to our advantage in a study by no and associates. It showed that patients with severe weakness, deficits post knee surgery. Um the majority of them made increases in strength with just within nine sessions of B F R and the protocol is 2 to 3 times a week. So that's not very much time. It goes back to that three week period. Uh Early studies have also shown up to a 50% of overall reduction in atrophy. So when we talk specifically about our AC L patients, there's a couple different things that B F R can help with. We just talked about uh resisting muscle atrophy A, the AC L population is probably the most, it was definitely the most well researched of the groups for B F R. Um And so that's why the research looks a little different for general population versus AC L. So in resisting muscle atrophy, um it increase it quad strength after 12 weeks compared to the control group. But there was also an increase in overall muscle strength at the 8 to 12 week mark compared to a control group. It does improve bone density and function. I spoke about this as an overall benefit earlier on. But this is something that's um important because it, it helps us in the long term health of our athlete. The re the reason and rationale that they think that it helps with bone density and function is it's thought to be interlinked with the skeletal muscle, me, mechanical, systemic, systemic and local signaling factor. So remember those satellite cells we talked about in the beginning that it's helping a lot with those pathways. Um The research has shown that there's improved pain and perceived function and the use of B F R. So compared to a control group and doing outcome measures, uh they found that the overall report of pain and then the overall report of function was better in the B F R group. Lastly improved hypertrophy and strength. So compared B F R at 30% 1 rep max to those training without B F R at 70%. So big difference there, the B F R group showed more rapid gains in quad and hamstring strength. Uh patients on average five years, post op AC L with mild quad atrophy uh still benefited from B F R. So if you have a patient that's just coming in because they're having some pain, uh they would still benefit from this. So there are some needs for some future studies. Uh There's a study that's currently going on right now. It started in 2017. And so hopefully it will be published soon. But there some it's a prospective cohort and it's looking at what's actually happening more at the cellular level of the quadra. So they're looking at torque, they're looking at um the rate of torque and then secondary objectives of what's happening with knee biomechanics, the quad muscle, a morphology and the quad um physiology. Uh the proximal effects are something I talked about earlier and that we know that it helps more distal to the site of inclusion. Uh the proximal effects, it does have a systemic benefit. But they're looking specifically right now on how we could use this for slap repairs and hip repairs um just because it is proximal to the inclusion site. So there's a couple of studies in the works with that. All right. So in summary, couple of key points here, number one, B F R creates a hypoxic environment, promoting metabolic and physiological changes that stimulate muscle hypertrophy. That's the big one right. Number two, B F R promotes muscle hypertrophy at a lower load of 20 to 50%. 1 rep max compared to traditional resistance training. Third B F R is ideal for those who are post stop injured, limited weight bearing status, prolonged season or with pain as it decreases stress on joints while still promoting strength. Four B F R can be beneficial for patients post op uh to prevent atrophy, improve strength, decrease pain and improve bone health. Here are the links to some of the supplemental material and resources. These are all four groups that I would highly recommend for training. Um They also have some of them have their own cuffs as well. And then there's a link for the risk factor assessment and then lastly a copy of the B F R Protocol. I wanna thank you all for letting me come join you today and talk about this subject. It's a subject I feel very passionately about. So if you have any questions, please feel free to contact me or talk to me today. Thank you.
