Ep 379: Bone Stress Injuries: Risk Factors, Diagnosis & Prevention (Part 2)

[Music] Welcome to episode 379 of the Physical Performance Show. In this episode, our host Brad Biah sports an exercise physiotherapist by trade and training sit down with Pogo's physiotherapist Tim Studley to have the second of a three-part conversation about bone stress injuries. This extensive subject matter is essential for athletes to be aware of to stay in peak condition. A special thank you to our show sponsors Pilots performances range of sports nutritionals and Pogo Physios' telehealth consultations. Pilots performance have led new frontier in the sports nutrition industry through their micronutrition innovation. And as therapists who have spent their career working with endurance athletes managing injury, this one really caught our attention. You may have also recently seen Pilots launch some of their new product lines under the banner of performance health. 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I don't think it was just me at that time because this was in the mid 2000s, I graduated in 2005 and November. I think that was where the industry was at. But then over that last 20 years, two decades, the industry and sports medicine field has learned and now appreciates that arguably the greater driver of, in my opinion, or the greater risk factor, the greater side that we need to consider is this biological side. How well can that skeleton do its job? Yes, the training is going to come at it, but how well it equipped is skeleton. So considerations over on that side and it comes off the sheet that I'll give out to every patient and I'll go through an individually, if you want to call it risk stratifist fire, the patient's presentation. We have athletic history. So we need to know what did you do as an adolescent? There's a delineation in sports medicine if they've participated in the one sport for more than nine months of the calendar year, their deem to be specializing. And we know that early specialization in running increases the risk of bone stress injuries as an adult. I started triathlon at 10 and so that didn't help me in any way and I was probably energy deficient for the bulk of my adolescence when I went into running a triathlon again later in my life and ended up with 10 bone stress injuries and osteoporotic at 36 and osteoporotic after that. So we want to know about early specialization. Have they done that? Have they had other exposure or other sports because that can help their skeleton develop throughout a lessons? We know multidirectional sports helps the skeleton in simple terms be more robust, probably wider bones, better diameters. We want to know about their medical history team as a biological factor to consider so that can be medical conditions that may impair absorption of micronutrients. So celiacs disease, your thyroid, hyper and hyperec too, can change bone metabolism. Have they had cancer? Have they been exposed to then the other side of that is medications that can impair bone quality? So long term use of anti-inflammatories which can impair collagen synthesis and formation has it been cancer medications that have taken a toll on the skeleton. Long term exposure to corticosteroids. So we want to get biomedical history, prior medication use as part of this consideration. And then the big, big, big thing that I think we now appreciate is energy availability. And we probably need to dive into that, I suspect. Other quick considerations are asleep. We know that they can be impaired bone synthesis with reduction in sleep. The study is around this. And then life stress, which is a hard thing to quantify. I think some of the pain practitioners refer to as alastatic load, life loads, they're very real. I funny enough, I'm trying to do 100 ramp tests in a row on Zwift on my stationary bike. So it's the same training stimulus every time. And some days I, in my relative to my own, ability will perform well. And then on other days I'll perform miserably. And it's funny because it's the same training stimulus. But I'm tired. I'm stressed. I'm worried about something or I'm fresh and engaged. And so we all know that that stuff has an effect. When I went through my 10 femoral shaft bone stress injuries over about a five, six year window, there was a three legal battle that was going on at the time with a national franchise that we were removing ourselves from as a practice. And often see that in the clinic when people have bone injuries, they're often going through some psychologically stressful events. So that lives on that biological side, but the big one team is energy availability. Absolutely. So on energy availability, I am aware that it's becoming more and more known and understood problem within the running community that practitioners are aware of what risk factors are you screening for that might indicate an athlete is perhaps experiencing some lack of energy availability. And you're right. There's no blood test for it, per se. There's no light that pops up on your whore poor, any other data point. It's often found in the subjective history of a patient. So I'll ask questions related to the training hours. We know if you're training more than 12 hours per week, you've got a much greater, it's a risk factor for low energy availability. It's very hard for that athlete to get the caloric intake in that they need to keep a balance between energy in and energy out there. So what we call high energy expenders, I'll ask about the training. We also know team for every hour above five hours of training a week increases the risk of bone stress injuries by 5%. So once you start to get into the say multi sport world surf, life saving, triathlon, long course, 20, 30 hours a week. It's quite quickly. It's quite quickly. It's quite quickly. I want to know about their general mood and they feeling responsive or they frustrated irritable. They clear indicators. They call it the hair in the cereal test. Like are they just dog tired? Yes. And are they responding to training? We then have indicators such as, before I go there, I might mention gastrointestinal functions quite a big one. So often want to know, have you got an upset stomach? Patients might relate to that as irritable bowel type symptoms or the runner that has trouble when they're running. It feels like I have to go to the loop. Because if there's a deficit in fueling, then the gut function will be impaired. Sometimes it is foggy. I just forgetful, not quite sharp. It's often observed in the performance cohort, like dancers. They need to be cognitively really switched on. And if they're under fuel, they may struggle cognitively or the athlete that's sitting in class studying. But the big one is, for the female athlete, is the menstruation function. And it's really quite simple when you sit back and think about it. If there is not enough fuel on board for an athlete to fuel for their biology, then the reproductive function is probably not a high priority. The brains are high priority. It needs some fuel. The working muscles will take what they need. But reproduction is not a priority. So the hyperthalmic going at elaxes that's referred to will become downregulated. And you will see a downregulation in sexual function. And so for the female athlete, that can be any regularity of their menstruation cycle, their men's ears. So that can become irregular in nature. The time course for it, or it can become missed. An amenorrhea is a diagnosis. Is the classification given to three cycles or more that are missed? And if you're not, you're not. Athlete, a female athlete gets to that, then they will either have longer standing low energy availability exposure or a medical reason for that and those medical reasons can include pregnancy, Holisistic Ovarian PCOS syndrome or other reasons, pituitary disorders, etc. So if we find an athlete, a female athlete that's in that situation, I like to engage a sports physician to medically screen for anything else other than just underfueling that has potentially driven the cycle down regulation. And I've had athletes' team that have not had cycles for like six to ten, fifteen years. And back when I was a junior, it was almost a trophy for coaches to know that their athletes were missing cycles because it meant they were training hard enough. For the male athlete, they don't have the menstruation cycle to look towards. So in practice, I've just over the years coined a very corny statement that tends to capture the attention of most blocs and that is a bone or a day keeps the bone stress away. And the origins of that is that the male's reproductive function can be downregulated so that can include libido and morning rectal function is a good indicator of, they call it penaltum essence in the morning of fueling. So if the male athlete is an experiencing that and really McGregor, who's a prior guest of the show, dietitian gave the three mornings a week, I think it was fear. But without getting too needy-gritty, I think that is a question I want to know. And I've had athletes that keep bone or diaries as they then go in through their recovery from low energy availability or relative energy deficiency in sport. So there, there you're indicators, other one team would be bloods. So I'm a sports physio, I'm not a sports physician, but athletes will often have bloods and more often than not, if you look at their iron studies, their iron pallet of tests, you will see low iron serum ferritin will often be low. 25 is a threshold for typically an infusion. And you will see athletes sometimes living that low for a long time. And so that's a surrogate for under fueling often because if you're not getting enough food in, you cannot get enough iron in. So it's often a bit of a giveaway. Vitamin D, something to look at as well. And then of course, sex hormones. What is the sex hormone profile look like? I've had elite distance runners and athletes that have hormone profiles that are consistent with 67 year old men and women. And the sad thing about this is it's not just about the energy availability, it's about their performance and their adaptation to training. They are not going to be adapting to the train stimulus because the hormones drive that adaptation. And Brad, all the information you give and I think it just speaks to the complexity of relative energy deficiency in sport. But it's important to have those factors that we can easily consider and screen for training over 12 hours, understanding that every hour over five hours increases an athlete's risk. Having reduced mood or focus in the athlete, gastrointestinal disruptions and important consideration. And then of course, the big ones being menstrual cycle disruption or morning erectile function in males as big indicators for potential energy deficiency. There's a statistic I'm sure that I'm pretty sure a runner that doesn't meet their caloric requirements by only a hundred calories a day ends up having the equivalent of a month's worth of energy requirement not met per year. So I think just speaks to the importance of practitioners to screen the issue. Yeah, they came from I heard that from Trent Stellingworth, who has contributed to the scientific space of relative energy deficiency in sport enormously. And that was on Trent's expert addition back probably eight years ago now. And it is quite confronting when you think about that. So in other words, if you fly south of the required amount daily over the course of a year, that's like not eating for a month. And you would never know athlete would ever consider that's a good way to go. But this is just how challenging this space is. And to try and counter that, we need good education for the athlete that has had a bone injury because we know that they're more likely to get another one. I think they need to probably go a step further and actually work with sports dietitians to do things like body composition scans to identify their what's called fat free mass or lean muscle mass. So in other words, how much of you Tim is just pure muscle, which is so calorically hungry. And that, for example, let's say you're a 70 kilo male, that might be 50 kilos. With a high energy outputters, remember, we use that term before they will require some around 45 calories per kilo of that fat free mass. So if you multiply 45 by 50, that gives us I think about 2,200 calories. So that's what you Tim is a high output in athlete would need to be taken in every day. So sometimes I think when patients have had a history of bone, it's nice and have a bit of an idea on their target. I think we need to be careful though we don't have athletes saying go out and start counting calories because that can spawn like orthorexic behaviors with their food intake, which sometimes a risk factor in the first place. That desire to be lean lean is better for performance. Yeah, it's so easy to fly south of the border and it's invisible. You don't know. So in my view, you're better off to go too much than not enough. It's, you know, so I've sort of coined the phrase eat more than you think you need. Yes. You know, eat more than you think you need. If I could boil it down to one tip for bone stress injury, rehab slash prevention, that's probably that. Eat more than you think you need. Don't be seeking it to be lean. Absolutely. Absolutely. Brad, do you think it'd be helpful for listeners if we perhaps discuss the common sites of bone stress injuries where runners might be experiencing pain throughout the body? Absolutely. So there's a couple of diet like frameworks we could use. I break it down in my own mental construct to proximal and distal, distal being anything in my opinion below the knee. So we've got the shin, the tibia, and we can have bone stress there post-remediately. So at the back and behind at the back and inside margin, anteriorly at the front, we can then go down to the bones in the foot and ankle. So the tailors, the fibula, and then all of your midfoot. So you can a forms, an avicular. Then we go a bit further down to the forefoot. You've got the metatarsals. You could probably put sessamodes or sea samodes in there. And then above the knee, we've got the thigh bone, the femur. You've got the shaft. You can have bone stress anywhere along that. It's quite unusual, but I have seen cases to have it distally at the bottom. Most of it's in what we call the mid-diffice, the diaphyses, the shaft. And then you've got the femoral neck. Then you've got hip bones, if you like, the iliums. And you can get bone stress of the ilium. You can get it the pubic bone. The sacrum, many listeners will have seen cases of sacral bone stress, whether it's as a clinician or as an athlete or just on social media, people's stories. And then you've got the spine, the lumbar spine. So these are all running related sites of injury. And Rich Willie teaches this beautiful, who's one of my biggest influences in this space and Rich has featured on the podcast several times on prior expert editions. But Rich teaches this great, great tool that is the more distal, the bone stress injury, the more we need to be considering the biomechanics of the athlete, how they run in, how they move in, how they change footwear. But once we go above the knee, we're thinking fuel in, fuel in, fuel in, and specifically underfuel in. And once we get to the sacrum, which is this trebecular spongy bone, like the heel bone, the calcaneus, that's really spongy as well. If you see bone stress in those really spongy bits, even other heel bones below the knee, or the sacrum, you're just thinking underfueling every day of the week as their main probable driver. So that's one way. Look at it. Above the knee, below the knee. Yeah. Speaks to the complexity, Brad, of the risk factors and how they interact that it's not just again, the contribution of someone's training that will lead them to have a bone stress injury. It's also their fueling. Hints on that can be indicated by where their bone stress occurs. Yeah, definitely. Now, common terms, thrown around around bone stress injuries are high risk and low recites. Perhaps returning back to the pathophysiology, the disease process of bone stress injuries, can you elaborate on the distinction between those two types of bone stress injuries? Yeah. High risk low risk distrued relates to how well those bones will bounce back if you like from injury. So, you know, it's breaking down very simply, but your high risk bone sites, sites like the nevicular, certain part of the fifth meditarsal, the tuberosity, the femoral neck, these are interior cortex of the tibia. These are deemed high risk because if there is a compromisation of that bone tissue, an injury, then those areas can have reduced ability to repair. And that can be due to reduction in blood flow. So, like the, they call it a Jones location on the fifth meditarsal or the fifth toe bone. There's a watershed area there where there's just not any arteries that innovate that bone. So if you damage it, that's going to take longer because blood supply at all bones good. And so that's one reason that a bone might be classified as high risk, bone location might be high risk because there's not a lot of blood flow or reduced blood flow compared to other sites. And then you've also got to consider the demands that go on the bone. So in sites like the femoral neck, when a bone gets loaded, you've typically got a compressive load and a tensile load. And it's the tensile loads that can be more problematic. So in something like the femoral neck, if there's a bone stress injury that develops on the upper side of it, then that can propagate right through to split through the femoral neck. And I've seen that in probably three runners over my 20 years. Whereas if it happens underneath it, this is compressive. So as the body gets loaded, it squishes it together. That ain't going to necessarily easily crack all the way through. Understood. Yes. So there are main reasons from my understanding as of why we term some bone sites high risk and some low risk. And my experience in my career so far, the more common sites, Brad, that I've run into runners, excuse the terminology, have been the shin end through that femoral neck. As demonstrating the literature, those are the most common sites where a run-on-art experience of bone stress injury. Most common sites for bone stress injuries are the tibia and the metatarsals. Understood. And then there would be papers we could reference in data sets that would show the distribution of the other bone injuries. But if I just had to reflect on my clinical practice, I think the other key locations are femoral shaft that gets missed, I think, more often than it could be. The sacrum. Certainly seeing a lot of sacrabone stress injuries in practice in the last several years, probably more than ever. Occasionally the fibula, distal fibula. And then in often more younger or youth-based athletes, the tassel bones, so inoviculars, you can have forms, it's salis at times. Because they're more related to once again, the biomechanics and the higher intensity running the sprint in that sort of exposure to load. And you mentioned there, Brad, that some of these bone stress injuries are probably missed more often than they should be. Are there any key principles that practitioners potentially listening should be considering for the objective examination of suspected bone stress injury that you like to apply? Yes, so if we talk about what the practitioner that greets an injured runner will then do, because this is what we call the objective exam or the physical exam, there are loading tests that we can do for each of these sites that we've just touched on. And I'll look back to those loading tests. But I think if I just walked through it and don't get too lost in the detail, but I like to observe the athlete, come on down, come on in, have a look at how they're moving out, they off-loading, limping to one side. Do they have a look of pain on their face? So you can get these subtle cues. Can they sit down okay? Are they? Oh gosh, helping the selves get sit down with their arms. And then physically, we want to know, I'll say it's something like point with one finger to where the pain is. And you get a bit of a sense then quickly and easily where the issue is. Is it localised? Like a very small point, like on the chin or is it more widespread? Pell patient. Pell patient's useful for bones if they're superficial. So the shin, you know, most notable example, I take my time to start right down the bottom of the shin and just go thumb width by thumb width. And I'll use a highlighter to mark when the pain starts. And it's tricky one, Pell patient with an athlete, I say, is it painful or just pressure? And sometimes they can't answer that. So you do need to then compare it to their unaffected side so they can go, oh no, that's painful. Yes. All right, there's my mark. And I'll go up the shin, Pell patting, we'll press in on the shin, taking note of where I am. So you want to be clear on your right around the back side of it or you're just on the inside border. And I'll map out the length of symptoms so we can differentiate between MTSS and bone stress quite well if the Pell patient length or the length of soreness is greater than 10 centimetres. That's periostitis, which we've mentioned before, the athlete MTSS shin splints, the athlete can keep running. And I'll need certain help and care. But if it's less than 10 centimetres and certainly less than five, you're thinking more potential bone stress. So you can palpate the shin's a classic one like we just said. You can palpate things like the sacrum so you can put pressure over that. Things like the femoral shaft, they're typically too deep, deep to push and see if there's pain. The foot is a nice site and the ankle for pressing bone. So the fibular, the navicular, there's the end spot they call it, that you can press on, the metatarsals, great. And I didn't mention the second metatarsal, the base of that as a high response site because of that compromised blood flow. But yeah, you can palpate those sites really readily and go, is that sore, painful, yes? So that's a key physical exam item. So we've looked at how they move, just generally, we've palpated them. Then we go to these load tests. And so there's actually not that many for bone. But we can do, most people will be aware of some sort of hopping test. And I like to just ease into that. So can they do double leg calf raises, single leg calf raises, are they dealing with that? Okay, can they stand on one leg or do they look apprehensive? My antennas up already that they could have a stress fracture because they're offloading as they hobble in or their history suggests that this, you know, could be that. And I suspect that they might already have a stress fracture. I might not even hop test them. That was my next question. I had a gentleman present recently who clearly could barely walk. So I wasn't going to hop test him mid-buttic pain and sent straight to an MR confirmed a high degree sacral bone stress injury. So I'm not going to hop test every patient. I'd start with double leg pogos and then I'd go to single leg hops. And if I'm suspecting femoral knack, which is a high risk side, you can go from hero to zero in one hop. So as time's on, I won't get that patient to hop either. So because I'm like, this is just, you can barely stand on it. Or lesser than that. You just, no, it doesn't feel right. So hop testing though is useful. Hop testing has 100% sensitivity for tibial bone stress injuries. So if you've got a patient that can hop test on their leg without symptom reproduction, they don't have a tibial bone stress injury. So that's quite a nice knowledge. Yeah, absolutely. So you can rule out bone stress of 100% sensitivity with the hop test. You still need to work through your differentials. Could be various status, but pretty confident it's not bone. You have the fulcrum test for the the femoral shaft where you lay someone over the edge of a table, push down on their leg and try basically bow the leg. You know, I had six to 10 femoral shaft bone stress injuries and maybe two or three occasions that ever produced symptoms. So I don't hang my hat on that. You know, days of evolve, they used to be tuning fork stuff, but I've never used one of those in clinical practice. I think there may be practitioners that still do and probably some use there, but they're my main physically exam items. And of course, we've got to rule out other potential as practitioners you need to go, well, is this just hip joint osteoarthritis or labral pain in the hip or is it in the shin? Is it a calf strain, calf muscle strain injury? So you need to work through that structure in a structured manner as a clinician, but that's what we should be doing, the general ones. Thanks for that again, Brad. Some helpful principles that we can apply when we're examining a client to observe them when they're walking in. Are they limping? Are they really sore? Do they have local pain, which we can confirm with the pal patient? And then of course, we've got our loading tests, double leg to single leg, of course, being careful to be nice and safe. Yes. We're going to pull this episode up here and leave you wanting more. Thanks so much for listening in and thanks again to our show sponsor, pillar performance, who we highly recommend. You can find the details and discounts in our show notes below. See you next week for the third and final episode of our mini series on bone stress injuries.