Discussion #4995

Understanding Knee Pain

25 min - Discussion
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Many people are nervous about the knee pain they might experience during a total knee replacement. In this discussion, Dr. Brent Anderson explains the purpose of pain so you can learn how to manage it when it is time for your recovery from knee surgery. He talks about what influences pain, how mediation controls it, and the latest management philosophies so you can decide what is best for you.
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Jul 07, 2022
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One of the greatest challenges that we find is understanding pain. This is, it doesn't matter if it's knee or shoulder or anything, but particularly understanding, what is the purpose of pain? And why do we have pain? And why are people afraid of the total knee replacement because of the rumors they hear about the pain, and what is that purpose? So this particular lecture or class, we're gonna be talking about the purpose of pain, where does pain reside, what influences pain, how does medication control pain, how does it work, and what are some of the latest management philosophies for pain that the medical practitioners are using, and then really coming back on to what's best for you or what's best for me as we go through this process.

Lorimer Moseley is a well-known physical therapist and a neuroscientist that specializes in understanding pain. And he said in a quote that, "The pain system is not very good "at being a physical damage meter, "but that is not the purpose of pain. "The important task is to break the image information "down into meaningful components, "and thereby perceive the need for action." So let me give you an example of what Lorimer Moseley's talking about. There are cases where people have severe trauma to tissue and they feel no pain, and there are cases where people have little to no trauma to tissue, and they experience severe pain. Pain, therefore, is defined as an interpretation in the central nervous system of what's going on in our body.

What risk do we have, right? Some people train themselves to not be affected by pain. So you could think of special ops and Navy SEALs that are trained not to experience pain. So they could have a major injury and their survival depends on them not having a painful episode. And on the other hand, we look at chronic pain, and even some of the neuropsychological pain, and we know that there doesn't even need to be tissue damage for the brain to perceive pain.

So one important thing I want to talk about is that pain, in order for it to exist, we must be conscious. If you think of an anesthetic or analgesia, what it typically will do is cause us to go into a coma if we're under anesthesia. And therefore we are not consciously processing the pain. However, the body is receiving and sending lots of messages of the surgery to the brain, and it's just not being interpreted by the frontal lobe or by the conscious part of the brain. So we're still experiencing a lot of pain, we just don't know it, right?

So we have to be conscious to know that we're having pain. That's the first lesson. And the second one is is that pain does not measure tissue damage. It basically tells us when we need to take action. So the next question is, what influences pain?

Where does pain come from, right? So we know that inflammation can cause pain, that there are nociceptors in our body, in our tissue, in our hands, in our skin, in our organs, that when they get stimulated are sending a message to the central nervous system, particularly the thalamus, and in the thalamus is being interpreted and sent to interpretation centers to see if there is something wrong. So inflammation is a biggie. We often talk about things like cytokines and bradykinins and things that can cause pain. We think of, you know, when we cut our hand or we have an inflammation or we have an infection.

Where does that pain come from? Typically from an inflammation. The next one that I have up here is a perception and fear of pain. Did you know that just being afraid can make our pain worse? Emotions can make our pain worse or better.

If you've ever noticed that you've been in pain and all of a sudden somebody gives you really good news or you have this romantic moment and all of a sudden the pain is gone while you're in that romantic moment. And when that romantic moment is gone the pain comes back. So emotions can influence pain interpretation. Knowledge is a very powerful tool. This is part of Adriaan Louw's work where he says education, education, education.

The research shows that patients who are educated about pain have a 30% improvement in their outcomes, just purely by being educated as I'm educating you now, to know where pain comes from, to know what it's related to, to know it's not related to tissue damage, to remove emotions that cause more pain. So for example, fear, anger, sadness, depression can all cause pain to be worse. Happiness, excitement, distraction can cause pain to be less, right? And then of course we have the pharmaceutical input of medications that are specifically designed to decrease our interpretation of pain. And that's really what they're doing, they're blocking the interpretation that's coming from our body that something's wrong.

And so we have to be careful, for example, an anti-inflammatory medication is going to influence the first one. It's going to decrease the inflammation. That's gonna decrease the messages going to the brain that there is an inflammation process. If that inflammation process was necessary for us to know that there's pain for us to change our behavior, that anti-inflammatory might be a problem. Some surgeons don't like anti-inflammatories because inflammation is also part of healing.

So we have to be careful and know what medications we would take if we're supposed to have inflammation. The one that I'm most interested in are the three middle ones. How can I influence my patients or my clients or my own perception of pain, my emotional influence on pain, and how can I enhance my knowledge to minimize my pain? So one of the questions that comes up is how does medication control pain? And so I'm just gonna go through a brief list of some of the pain medications that are out there that are used, especially during these types of surgeries or these types of pathologies that lead to surgeries.

So we've already talked a little bit about anti-inflammatories or non-steroidal anti-inflammatories. These are gonna be like your ibuprofen and a lot of the medications we take that are not steroidal, they're not cortisone or corticosteroids. And their primary approach is to block the inflammatory process. And so blocking the inflammatory process is going to decrease the inflammatory input of pain. Aspirin is an analgesic and an anti-inflammatory and a blood thinner.

So this is the one that quite often is used, baby aspirin for blood thinning and it also works as an anti-inflammatory and an analgesic. I've heard pharmacists say that if they had to run aspirin through the same rigors of research and studies, that it wouldn't pass these days, but because we've used it for so long, it's actually a quite successful pharmaceutical intervention. Another one that we use quite a bit is acetaminophen, and that's Tylenol, basically, the generic form of Tylenol. And that is an analgesic, right? So analgesic mean it's going to block pain.

It does not change inflammation. So for example, a surgeon that does a graft or a repair of a meniscus or a tendon or a ligament probably doesn't want us to be taking non-steroid anti-inflammatories, because they need the inflammatory response to have and secure good healing. And therefore they might use something like acetaminophen or Tylenol because the Tylenol will control the pain, but it allows the inflammatory process to continue as part of the healing process. Another drug that is used, they're steroids as I mentioned earlier, the corticosteroids are anti-inflammatories. We can't use too many of them because they do have some side effects.

I failed to mention that the non-steroid anti-inflammatory side effects typically are things like stomach and intestinal problems. Where it's too hot and it can cause bleed or damage to the internal organs. The next drug on the screen is the neurogenic drugs. And these are drugs that are used to, basically to manage the interpretation of the pain signals. So they tend to block the pain signals on the neuroceptive fibers, nociceptive fibers.

So they often, for example, like Lyrica and Gabapentin, these are drugs that are really helpful when it comes to pain, but they don't allow us to be very functional because they often will make us a little dumb, a little slow to react, and not feel great. But it does help with the pain, especially neurogenic pain. The next one is opioids and you've heard a lot about opioids. I just finished watching the series "Dopesick" and it sure makes you think about where these opiates come from. But these could include names like morphine, Dilaudid Percocet, codeine, Oxycontin, oxycodone, these are all examples of opioids.

Some of them are natural, some of them are synthetic. And these have really caused a major disruption into our world. Probably one of the greatest causes of drug overdose these days are these type of opioids, particularly the synthetic ones. And so we wanna minimize them. I mean, it's good that we have them.

I remember having a neck surgery and being on Dilaudid and thinking like what a great drug for that day that I was on Dilaudid, that I literally have no memory of. But the idea is that these drugs are incredibly addictive and they do, in some individuals, just ruin their lives. And so the goal is, if you know that you have an addictive behavior, or you've had an addiction problem before, there are alternatives. There are cocktails that physicians are putting together to be able to block and minimize the need for pain medication. And that's really important.

I know that when I had my hip surgery, they used a cocktail of a neurogenic drug, a steroid, and an anti-inflammatory to be able to make it so that there was not an analgesic injection to make sure that I did not have pain during the surgery, to minimize the messages that were going to my central nervous system while I was on a general anesthesia. The other thing they did is they did an epidural and they blocked all the messages from getting up into the brain through the spine. And so these are some of the techniques surgeons are using now. That's why I say, when you pick a surgeon, pick a surgeon who is going to minimize the need for opioids and optimize other alternatives that might work better for you in minimizing your pain, and allowing you to sleep, and allowing you to heal, without having the side effects of the opioids. So what are some of the latest medical management philosophies for pain?

I think this is again, when you're interviewing your physician, these are things you can ask them. You can ask the medical assistant, you can ask the nurse that's helping the physician. But what are some of the things that they're doing to manage pain? It's a very legitimate question to ask your surgeon. Some of the ones that I like is asking, what are some of your pre-surgery cocktails?

And are you using steroid Lyrica and some of these mixes? Are you doing epidurals? How do you manage the pain during the surgery? Some surgeons are using a lot of long lasting Marcaine injections into the surgical site before the surgery begins. That's sort of like the Novocaine that you would get in your mouth when you get a dental work and how you get numbed, right?

That's the same idea, that let's numb everything up before so there's no messages of pain that are getting to the central nervous system. We have to assume that the more messages the brain gets of traumatic pain, the harder it is to get over it and the more severe and longer lasting the pain is, seems to be the research. So even though we're on a general anesthesia, that's just a coma drug that makes it so that we're not conscious while the pain mechanism is is still reporting to the brain. But if we can decrease the amount of pain being reported to the brain by local pain meds, anti-inflammatories, neurogenic drugs, epidurals, seems that the recovery is so much better. I know that the long lasting Marcaines can last 24, 48 hours.

And with a steroid in there that then picks up after an hour, it could be that you have minimal to no discomfort or pain at all. And by the time you start having normal pain sensitivity, you're well beyond the healing phase, that you're already into a minimal pain that could be managed by Tylenol. That could be managed by an anti-inflammatory instead of any hard drugs. And that's really the goal. Some other things that are out there is there are some, you know, minimal opioids.

So I know that sometimes you can get away with things like Tramadol, or a Tylenol with codeine, or something like that, or Percocet, or two that would be just used in the first couple days only should be used. But there's other things that are out there now. So we know that the whole cannabinoid world is opening up and really helping to avoid a lot of the opiate addictions that often follow these total joint surgeries, right? One of the things that I like the most is the idea of sleeping. There's a recent study that was done that showed that lack of sleep following a knee replacement was the biggest complaint.

Like, you were unsteady and the knee kept waking you up. And that people were taking opiates because of the anticipation of not sleeping. And so if we could address the sleeping issue with something like CBN, cannabinol, which is very well known for inducing sleepiness, and we can use things that are not addictive and things that allow us to avoid opiates, much better for all of us, much better in preventing the the need, or the perceived need is really the better way of saying it, of the opioids. I mentioned some of the cannabinols and cannabinoids that are out there that are opiate alternatives. We're seeing more and more states and countries that are making it legal for people to use THC, CBD, CBN, CBG, CBC, and many, there's many different combinations of this.

And also the stronger doses of it with pure isolate forms mixed with broad spectrum forms of it. Again, it's not real well regulated yet, we're gonna see it regulated more and more. But I do believe that this is gonna be a very healthy alternative to avoiding the opiates, which I do believe have a high risk. Again, I don't want to give you the impression that opiates are never needed, they are needed. But how do we minimize them?

How do we prepare ourselves? What is our surgeon thinking of? How are we prepared on our own to be able to have some alternatives that can help us sleep, rest, control inflammation? So just looking at this list here on the slide, THC is what we often refer to as the cannabis and marijuana, right? So THC is d9 and d9 in the cannabinols is responsible for some psychoactive.

So I'm not as much a big fan of the psychoactive unless somebody's really in a lot of pain the THC can be beneficial, same with seizures. But I am very interested in CBN. It turns out that the cannabinol is the C of the THC. So when people used to talk about weed going bad and that all it was was called sleepy weed, it no longer had psychoactive effect. That actually is the cannabinol, that's the CBN.

And so there are a number of studies now showing that the CBN is actually very good for helping people restore natural sleep and to be able to have good deep sleep or REM sleep. The CBD is thought to be an anti-inflammatory. And so it actually directly links to the CB2 receptors in the immune system. And so it's going to, we've seen more and more now, as the research is showing that cannabidiol, CBD, is going to help with inflammation. The same thing with CBG.

CBG also is going to affect the immune system and decreasing inflammation. So if you think of the CBN going to the brain and helping to sleep, and CBD and CBG going to the body to decrease inflammation, we're starting to see some really healthy attributes of a plant that is very normal. Our body has endogenous cannabidiols and it also can benefit from exogenous ones as I'm presenting to you. So this leads us to another question, what is best for me? What do I need, right?

And I think this is an important question. It's personal. You know, what is your past medical experience with pharmacology? Have you ever had bad experience with any kind of addiction? With opioids, alcohol other drugs that you could have been addicted to?

It's very important that you talk openly with your physician, it's confidential, to let them know that you've had those addictions and that you prefer not to go down that pathway. I have a number of patients who have had addiction past and have gone through and done total joint surgeries and it was the total joint surgery that put 'em back in there because they were afraid to talk to their doctor about alternatives. But I want you to know that there are alternatives. There are high versus low pain tolerance individuals. If you seem to have a low pain tolerance then what we can do is work on pain modulation and education before the surgery.

And that also, as I mentioned, has shown, Adriaan Louw's work, that there is significant improvement in reducing pain just by educating people how the pain tolerance scale works, and how we manage fear, and how we manage emotions, that seem to lower the pain tolerance. And that we start working on increasing pain tolerance so that you're ready to go through the surgery and realizing that you're not in a tissue damage state anymore, you're in a healing state, and that you're gonna be able to perform more activities. There's no longer a restriction in your knee and that you can return to your normal participating activities. Other things that we want to know is things like allergies. Do you have allergies to certain medications?

Do you have any opposition maybe from your culture or your religion to certain drugs or pharmaceuticals? Making sure that you're picking the right plan ahead of time. Do not assume that the plan for pharma and for pain management is right for you that you're going into. Make sure you ask the doctor. If you have questions there's lots of great information out there.

The biggest resource I could give you is to look up Adriaan Louw's work who has a lot of education out there for patients and clients about explaining pain and understanding that. Also David Butler and Lorimer Moseley out of Australia are great resources for explaining pain and helping people who have a hypersensitivity to pain threshold and who are often afraid of these kind of things. The education can help prepare you so that you can, you know, have the proper surgery and return to function. And that's really what we're looking for. So in summary, when we look at pain, pain is not an indicator of tissue damage.

Pain basically tells us that we need to take a look and see what's going on, if we need to do more action of something that is a possible threat to us. So once we're educated to understand what is gonna cause pain, and what's not gonna cause pain, that helps a lot. The next thing is understanding that our emotions and our fears and our lack of knowledge are all things that can contribute to a low pain threshold. And we really, for this type of a surgery, we wanna bump that up. We want to be prepared for and understand the pain before we go into the surgery.

Third, we talked about really talking to our physicians about what are they doing to prevent and to minimize pain? What are they doing pre-surgery? What are they doing during surgery? What are they gonna prescribe to you after surgery? And individualizing it based on your experience, any past addictions, any allergies, any particular beliefs that you have, that might impact your ability to recover quickly, safely, and successfully.

So in conclusion of this section altogether, preparing for a total knee replacement, and knowing that it's time for you to have a knee replacement, you know who your physician is, you know what procedure you're gonna have, you've talked to them about the pharmacology in preparation for pain control, are all necessary steps in preparation for a total knee replacement. What we're gonna go now is we're gonna go into how do I prepare myself physically, right? What kind of activities and mobility and strength do I need to go into surgery? And what kind of things do I need to know and be prepared for after surgery? And this scenario really important, that I wish I had had, even as a physical therapist, after my surgery.

I wish I would've known some of these things beforehand. And I've noticed that when I've helped patients understand these things before surgery, it makes the transition so much easier, much less fear, much more confidence, and success. So we'll see you in the next section.


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