Dr. Rhonda Watkins presents "Ground Reaction Force: Common Overuse Injuries in Running Athletes (Patellofemoral Pain, IT Band Friction, Shin Splints, Stress Fractures)" at the UCSF Pediatric Musculoskeletal and Sports Medicine Conference 2023 in Berkeley, CA.
Next to me is Doctor Rhoda Watkins. On top of being a co-chair of this conference, she is a pediatric primary care sports medicine physician here at U CS F. She completed her Masters of Public Health at U C L A pediatrics residency at the University of California San Francisco Fresno, followed by sports medicine fellowship at Boston's Children's Hospital. Uh Doctor Watkins is also a former track and field Olympian who competed in 2008 Summer Olympics in Beijing and a former National Collegiate Athletic Association champion. She draws on her personal experiences with athletic training and injuries to shape the way she treats. All right. Thank you. Good morning, everyone. Thanks Tom for that introduction. Um I'm excited today to share with you on the topic of common overuse running injuries uh in, in young athletes. Ok. I have no relevant disclosures. Uh It is my goal that by the end of my presentation today, you'll be able to identify risk factors uh for overuse injuries and runners, you'll be able to discuss some of the common overuse injuries that we see in this population as well as discuss indications for imaging and referral. So kids are running, they're outside, they're inside, they're on the turf, they're running alone, running in groups with pairs of same ages or different ages. And I look at this and I'm like, what a sight. Ok. It takes me back to my origins and, and track. I started running competitively around age eight. And track is really, and running is really why I'm here today. It's what brought me into sports medicine and, and is giving me the experience to, to treat uh patients uh based on, on things that I've lived and experienced. But for some of you, you might look at this and you think well, injury risk, are they too young? Is it safe? So it's my goal with this presentation to, to share with you what the evidence really says in regards to some of the injury risk for these running athletes at this age. So as I mentioned, running is really popular worldwide, about 40% of pre adolescents and adolescents do running as their sport of choice in the US. It's the second most common uh physical activity for both boys and girls ages 12 to 15. And in the 2018 to 2019, high school year, almost 500,000 kids did cross country and just over 1.2 million participated in track and field. So these kids you see all the time, it's really common and that's great, right? Because it's accessible, it's cheap. Uh You don't really need a lot of equipment to do it and it promotes good bone health, good cardiovascular health, cognitive development, as well as um development of athleticism. But the injuries, right. So we know that running related injuries have been increasing over the past few years. This study looked at running related injuries coming to the emergency room between 1994 and 2007. And they found an increase by 34%. Another one looked at these injuries that occur in pe. So they looked at pe injuries in the same time frame. And what they found was that 70% of all pe related running injuries or not running injuries, but injuries occur in six activities and running of course was one of them. And when you looked at what percentage it accounted for it, it it disproportionately accounted for more injuries. So about 25% of all those injuries that we see in pe uh was from running, but there's good news, we can breathe a sigh of relief. But uh most of the running related injuries are, are minor. Ok. So there, there are strains, sprains things that people will overcome and are able to get back to sport easily with uh the more serious ones which we'll talk a bit about today, like stress fractures are far less common. So let's get into the risk factors. So when we think about overuse injury, risk factors, we can think of them as intrinsic factors. So things that we can't really modify that much like age sex and then they are also extrinsic factors like training foot strike pattern. So I'm gonna go through some of these, only some in the interest of time and, and try to share with you what the evidence actually states based on these risk factors for youth runners in particular. So when we think about sex, the evidence strongly suggests that female sex uh places you at higher risk for running related injuries and greater time loss uh from sport than boys. So in 2021 the first ever uh youth running consensus statement was published in the British Journal of sports medicine. And they looked at a lot of different studies and and sort of summarize what your risk where the risk lies for these runners. So of the 14 studies, they looked at that studied sex. Uh eight of them found that the girls, the cross country girls were at much higher rates uh or higher risk for injuries compared to boys. When we think about age, there's two things I want you to remember. So when kids get older, their bone, they grow, right? So their bones get longer, but the muscles don't necessarily stress at that same rate. So that places extra tension or tensile forces at the muscle tendon bone, uh unit junction, which places them at risk for things like apoyo injuries. At the same time that those bones are lengthening the bone mineralize is not necessarily occurring at the same rate, it's slower than the rate of growth. So what happens then is there's this transient period where the bone mineral density is lower while they're growing. So particularly at the peak height velocity time frame, uh which is about 12 for girls and 14 for boys. So in that period of transient uh decreased bone mineral density, it places them at much, much higher risk for things like bone stress injuries. So when you look at what the data says, however, uh on age as it pertains to youth runners, we don't have a lot of, of data to really support this. Um There's no consistent data that looks at age as a risk factor for youth runners. So, so one prospective study of high school cross country runners ages 13 to 18, uh looked at age and and injury risk and they really found no difference between the average age of those that were injured and, and not injured. So, what about height and weight? So, uh the evidence does not support height and weight as a risk factor for injury in adolescent runners. So, one study looked at 230 cross country runners and they found no difference in the rate of lower extremity stress fractures in relationship to height and weight for both males and females across a three year period. Another study looked at 421 cross country runners in a similar age group of 14 to 18 and they looked at the impact of height and weight on in season injury risk. And they also found that height and weight did not uh significantly differ between the injured and the non injured athletes. And that's for both boys and girls B M I. However, we think there is evidence, strong evidence to support that a low normal B M I is a risk factor for stress fractures in the adolescent female population. Higher B M I S uh is a risk factor as well. So the extremes uh entire B M I is a risk factor for stress, uh shin or a stress in uh cross country runners and we'll talk a little bit more about that. So this is one of the studies that, that uh bare for this brought forth this consensus. Uh They looked at 748 high school competitive runners ages 13 to 18 and they found specifically this uh 19 B M I range was uh cut off. So girls that had a B M I of of 19 had a nearly three times greater risk for bone stress injuries uh compared to those with higher B M I or B M I over 19. So remember 19, uh in your assessment of risk where B M I is concerned? Ok. So what about previous injuries? So we know in sport that previous injury is a risk factor for future injury. And the evidence strongly supports that being through true as well for a adolescent runners uh where lower extremity injuries uh is concerned. So a lot of cohort studies have looked at this and they found increased risk for lower extremity injuries for runners with previous uh lower extremity injuries versus those without. So, uh a word on training, so there's limited evidence to support some of the training things or training risk factors. Um but it seems that if you train for less than eight weeks during the summer, uh this is a risk factor for in season injury. So I remember where as a young athlete, I was always injured one thing after the next and a lot of coaches uh would tell me, you know, you need to train harder and longer in the off season to avoid injury next season and, and that there's some evidence in the literature to support that. So they weren't just crazy. So other things that people talk about is is um terrain. So we think running predominantly on hills or in frequent alternating of short and long distances. Um That is with your training mileage in the summer is, is a risk factor for in season injury. So you need to be alternating between long and short distances and mix it up, not just hill work. And, and this is especially true for adolescent and female girls also a low step rate we think is a risk factor for, for shin injuries. And we'll talk a little bit more about that coming up. So, foot strike. So there's been uh a lot of work or research on the concerns regarding the impact the foot takes in running in the running gate in particular. So this graph here describes the the vertical reaction force uh that the body absorbs when the foot hits or strikes the foot and running over time. So it compares that uh ground reaction force between four ft strikers and heel strikers for heel strikers, you'll notice they have this big aggressive loading or peak uh once that the foot hits with a heel strike and that is associated with increased forces. I'm not forces up through the joints, the ankle, the knee and the hip by extension, which can place you at risk for increased injury. The thought is you want to eliminate this first peak and have a more smooth uh distribution of the vertical ground forces which can be achieved with a more mid foot or four ft strike pattern. So there is not a lot of data in regards to how foot strike increases the risk for youth runners. A lot of this is out of adult studies. Um but for the studies that do exist for the youth runners, we think four for a four ft strike pattern may be more beneficial for a decrease facing uh injury risk. Ok. Certainly more, more injuries are associated with a heel strike pattern. And the reason for this is we think that there is improved strength and stiffness of the achilles tendon with a four ft strike pattern. You tend to load the anterior shin less when you run with a four ft or a mid foot strike pattern compared to a heel strike pattern. And there's reduced contact um with the ground. So less stress on the tele moral or the knee joint and this typically increases uh the, the step rate. Now, the next couple of slides are really gonna be based on expert opinion. So you can't talk about uh injury risks in youth runners without talking about running mechanics. But there's not a lot of data uh on this for the youth uh running population in particular. But it might have been some things that you've heard from coaches, if you're an athlete yourself or you have kids that are athletes. Um and it, it isn't always information that you solicited but they, they talk a lot about overriding. So have you guys heard of overriding? And the, the risk uh it poses for, for running. So, so the concept of overriding and it's featured here in this with the one is that the, the foot lands before the knee and, and that really places uh increased stress on the knee and it also gives you a stiffer foot. So it actually slows you down. So the thought is that if you can run with the foot more underneath the knee here uh you, you have a more stable stance and uh less aggressive forces through the lower extremity with the running. Uh The other thing we talk a lot about is uh hip alignment with the running mechanics. So this is something we look at with gate retraining. Um And it's no different for a youth athletes. So when, when you run and the hip falls in like, like pitch it here, uh what you can see is there's a dynamic collapse of the knee or valgus collapse. Doctor Pandia talked about this earlier and that places you at increased risk for injury as well. So the thought is trying to stabilize the hip um alignment uh it as a way to reduce injury. Uh So we know that poor bone health uh as reflected by low bone mineral density increases your risk for injuries and runners, particularly for females, menstrual dysfunction, low B M I prior bone stress injury or fracture and longer participation in in in endurance running um can increase their risk for low bone mineral density and we don't want to forget about the male. So they, they often are forgotten population, but they also can suffer from low bone mineral density and be at increased risk for running related overuse injuries, particularly if they have low B M I prior bone stress injury history. They have low dairy intake, they run 30 miles or more per week or they have a belief that being thin leads to faster performance. And that gets into this whole concept of re relative energy deficiency in sport, which we'll hear a little bit more about later today. So that brings us to some of the injuries that we see in these uh running athletes. So, bone stress injuries are one of the injuries that you'll be familiar with. And we commonly see them in running athletes. Uh, we'll talk about some of them today, but I want you to understand that they sit on a continuum. Uh the beginning of which is really something like and as it progresses, it continue to run, it could progress to more serious stress reactions and eventually a stress fracture. So I think about it like uh a paper clip. If you keep bending, it, it weakens in the middle. So you're bending, that's the impact of running and eventually it weakens so much that it snaps. That's when you have your stress fracture. So I want you guys to meet Sally. She's a 14 year old female who recently joined the track team. Uh She reports she has bilateral shin pain for six months and when you examine as she's tender over the distal third of the tibia on both sides, but she has no swelling, normal pulses and she also has pain with a hot test. Her x-rays are, are negative. So what do you guys think would be the most likely diagnosis? Uh, for Sally, is it shin splints takers for shin splints. Ok. And then what about stress fractures? Anybody concerned that she might have a stress fracture? Yeah, maybe. Ok. So she has shin splints and so shin splints or medial tibial stress syndrome, um, is, is really an early stress injury on the continuum of tibial stress fractures. It's caused from overload of the tibial bone and, and usually is associated with a periostitis. So a lot of times where they have pain is where that bone um attaches to the muscle. Uh and I'll show you that in the next picture and it's common in runners and up to 25% of runners will see it. So um they will present with exercise induced pain usually along the distal two thirds of, of the media to be border. So right here, I talked about where the bone attaches to, to the muscle and the pain is usually provoked with activity. It could be during or after. So don't let them say, ok, it only hurts after. So I think I'm fine. Um pain that's after activities is pain. Uh worth taking note of as well. Um It usually reduces with relative rest, but they don't have cramping, they don't have burning pain in the posterior compartments or in the calf here and they don't have any numbness and tingling in the foot. If they do have those things, you should be thinking more about compartment syndrome. So when you examine them, it's usually over, at least a five centimeter um range, it's not pinpoint pain and, and they usually will have no swelling or erythema or normal pulses. So, the question on when to image. So this can be a clinical diagnosis. You're really imaging if you're uncertain or you're concerned for a more serious stress injury. So, so some of you were like, yes, maybe she could have a stress injury or stress fracture. Um It's important to know though that x-rays are usually negative and, and shin splints and they can't even be negative in early stress fractures. Um So usually if you're concerned, you're ending up having to obtain an MRI, it's usually the modality of choice and, and for shin spins, you'd see something like perioe bone marrow edema. So it's managed really with rest and activity modification with less repetitive, um, load bearing exercises. You can use some air cast stirrups to help with pain if it's really painful, but it's not a requirement. Uh If you are concerned that they may have low bone mineral density, you can check vitamin D labs and optimize that that will help with recovery as well. And then you talked about some of the gate uh associated risk factors. You, you want to look at that and retrain that. So it doesn't continue to be a problem. There's no one modality that, that um is superior when it comes to treating shin splints. Um But a lot of the more recent uh, articles have surrounded have been on shock wave or extra corporal shock wave therapy as, as a treatment modality for shin splints. And this is a non invasive treatment that uses a shock at the site um to promote healing. So a few years later, Sally returns now she's 16 and she's the star of her cross country team, but she's lost a lot of weight recently and her right tibia continues to hurt. It had continued even after she recovered from her shin splints. Uh, but now she's like it hurts a lot. Ok. So you examine her and she has tenderness on the anterior tibia and a positive hot tusk again. So what do you think would be the most likely diagnosis this time? Stress fracture? Perfect. So what are stress fractures? So these are, are common overuse injuries and, and they really uh occur from overload and it's not the type of load you think that you need to break a bone, it's from submaximal forces that occur over time. Um, they can be classified based on risk. So low risk, stress factors are simple fractures that heal, uh, well, and they're able to get back to the sport. The, the high risk ones are, are ones that are at risk for nonunion or uh increased uh displacement and sometimes even need surgery and to allow these kids to get back to sport, they're also associated with a long, long break from their, their activities. So I won't go through this, but you have these as a frame. So uh it it is common in runners when we think about all sports, uh stress fractures are most commonly seen in runners. Uh high risk stress fractures in particular are more common in runners than others. So these are like your femoral neck stress fractures, your navicular bone stress fractures in any uh runner that comes in with groin pain and you're not able to, to get a diagnosis. Um a stress fracture of the femoral neck should be high on your differential. So, fracture, the presentation of it depends obviously on where the the fracture is, but usually the pain will be focal on the places that you can palpate and it's insidious onset. So it it kind of developed over time and it really progresses from pain with activity to pain just at rest. And that's what you should be looking for in sort of your history. Uh on exam, like I said, you'll have 0.10 point tenderness, sorry on the bones that you can palpate. There are some special tests that you can do. So I mentioned the hop test which is just having them hop on the affected leg, uh 4 to 7 times try to have them go as high as they can go and, and usually for lower extremity fractures, it will be painful to do that or they may not even be able to do that. Uh The test is pictured here and uh what it is is you're using your hand as a lever to put force on, on the femur and this can be positive in femoral shaft fractures. So when should you image a lot of times you're imaging all the time when you're concerned for a stress factor, particularly if they have a lot of the risk factors that I talked about here and, and it should include an MRI but all we usually will start with an x-ray. So remember you're not gonna see anything on x-ray uh early on for sometimes 2 to 4 weeks later, you're still not seeing anything that does not rule it out. So if you're concerned about that, you should be referring uh if you confirm the diagnosis, you should re refer um particularly if they, you have ephemeral neck fracture and it is uh a tension side. So a lot of um the reason why some of these stress fractures are high risk is because one they, they may not heal well. So they're at high risk for nonunion, but also because of location where they are, some of the muscle attachments put that site at 10. So it's almost as if it's constantly being detracted or distracted. So that increases your risk for prolonged healing or nonunion. So we know this to be true of the the superior side of the femoral neck, femoral neck stress fractures. So if you see this, you should be referring, if there is a compression side and that displaces over time. You should also be referring because this is associated with increased risk for A B N of the femoral head. So management is really based on type and and severity. So there is a a classification system that can grade stress fractures uh based on severity. It's usually based on MRI, which is why you're usually getting MRI to diagnose it and then the time frame off from impact, which is the treatment for stress fractures, uh varies by, by grade and location. And after whatever time frame of rest, always, always, they should undergo a gradual reintroduction to activity and impact. Because what we know about stress injuries is if you go back after that prolonged rest too quickly, you put yourself at increased risk for repeat stress fracture again and then usually they are doing physical therapy as well to work on any strength deficits, uh flexibility deficits um and gate retraining. And so how do we prevent some of these things? So you wanna limit the total mileage? So 40 miles per week, no more than that. We talked earlier about 30 miles per week being a risk factor for male adolescent runners. So you wanna keep the range in that 30 or less. Um You want to limit running to no more than four or five days a week, they should have one rest day and they should be doing cross training or something like biking, swimming, yoga whatever they choose as well. If they do marathons, they should limit how many they do to no more than two or three per year. So, now I want you to meet Paula. Uh, she's 12 and she has, uh, an tyranny pain. It's been going on for two years. She doesn't have any injury history but it started after she started doing youtube, uh, hit workouts during the pandemic. Ok. So she was not alone. A lot of us was doing this. Uh She doesn't have any swelling. Uh you examine her and she has no tenderness. So you're like, what's going on here? The only thing you notice is that her quads are tight and she has flat feet. So, thoughts on what the diagnosis of Paula might be. So, does she have a meniscus here? Anybody think her meniscus can be torn? A lot of squats and lunges with these hip workouts at home? Uh Does she have pale pain syndrome? Good? And any, any takers for painful syndrome or O CD? F? No takers for O CD? Ok. So she does have patella formal pain syndrome um which is uh uh an oh, it's named for runners, so also called runners knee. Um and it's really friction of the patella as it moves in its groove in the femur. Uh it's characterized by anterior knee pain of insidious onset. So they don't have any injury history usually. And it's exacerbated by things that load the patella oral joint. So a lot of squats, lunges, step ups seas uh or things that you might hear them report in their history. Uh Important things that I didn't really talk about earlier um that can increase your risk for something like patella, formal pain or lower extremity malalignment. So we learned a lot about this yesterday. Uh One that we didn't hear so much about was the Q angle. You heard a little about it with Doctor Pandia earlier. So that's the angle between the quad tendon and the patella tendon. If that's increased, that puts you at increased risk for instability of the, the patella and and paal associated knee pain. Uh Other things that I didn't really address are foot hyper pronation. So when the feet fall in either um statically or dynamically that can increase how much load goes through the patella for moral joint and, and um cause knee pain. Uh So this can be unilateral or bilateral. A lot of times people will say it feels like burning or aching pain. So if you hear these things, you, you think of this um worse with stairs running, squatting um and usually it starts with just pain with activity, then it progresses to a which is really the pattern of all these overuse injuries. Your exam can be normal. But one thing you might look for is this dynamic. You have them do a squat either double or single leg squad and you can see uh or look for the knee falling in. We talked about that earlier today as well. Uh So when to image really, you should be imaging if you are concerned that it could be something else, right? So one thing that it could be is an O CD. So for the people that acknowledged that O CD was a possible diagnosis that was very prudent. Um O CD is a, is a great mimic uh of Pam pain because they, a lot of times they'll just have anterior knee pain, no swelling, it hurts, it's going on for a long time. No injury. So you wanna think about that as well? For me, I always get four views of the knee, which includes the notch view, uh which is really the view where you'd be able to see uh osteochondral defect in the femoral condo if they have other things that make you concerned for other pathologies. So locking or catching some mechanical symptoms, you typically don't see this with uh Patel, oral knee pain if they have a big e fusion. So a lot of them might have swelling like puffiness at the front of the knee, but not a huge big knee. Uh You should be imaging. If they have limitations in range of motion, you should be imaging as well. I think it's why. So this is something you can treat well. You see it all the time in the primary care setting. But if they have alignment concerns as well, particularly if they're older, you should refer because you wanna know how that's at play um for increasing their injury risk as well. And of course, for anyone that you've sent to P T and they continue to have pain, you want to refer as well. So the treatment for this is, is relative rest. Um you can use nsaids, et cetera P T, particularly to strengthen V M O core and hip A B doctors. You can use a patella stabilizing knee brace, but it is not necessary. Uh If they do have flat feet and art support might be helpful because you can see here it helps with correcting um per of the foot and they rarely ever need surgery for this. Uh How do you prevent it? So, a lot of training programs uh aimed at hip and core strength for, for me, this was my first introduction to, to knee injury or injury prevention as an a young athlete ever. Everybody told me to do leg extensions and leg curls because I also suffered from moral pain. And then I don't want us to ever forget the importance of maintaining healthy body weight. So we see a lot of overweight athletes don't overlook that as a cause for their knee pain because that does uh overload the the knee joint as well and to wrap up quickly, I'm already over time, but we'll talk about I T Van syndrome, uh which is a common cause of lateral knee pain in uh young runners. So it's the second, the second only to Ella Hoor pain. Um it's caused we think from inflammation or compression of the tissues underneath the I T van. Uh when the I T van gets too tight. And so the I T band is a long, long band starts up on the hip and then comes down and it starts at the proximal tibia at Gerdes tubercle. So people will present with sharp or burning pain in the lateral knee, but it can really be anywhere along the track. Um And they typically will report symptoms with downhill running or when the knee gets into about that 30 degree of flexion range. Um It often will occur at a reproducible time in their, their running or distance of running. So on exam, they will have tenderness. Uh like I said, it could be anywhere on that track, but it, it is most commonly in this area at the lateral femoral Conal. Uh There are two special tests that you can do. If you come to the exam workshop, we can go through these. Um But over a test is pictured here where you uh get them into the lateral decubitus position and you try to extend the hip and then let go. It should add duct if it stays A B ducted, it suggests that the I T band is too tight. Uh A Noble test is putting your hand here on that lateral femoral condal era of tenderness and then trying to reproduce that 30 degree of knee flexion pain at that point. Uh uh in that range uh is sensitive for I T man problems. So it, it's managed with activity modification. They don't have to stop, but they should probably stop downhill running. And all the things that they know are aggravating their pain, um P T in particular to address uh hip abduction weakness, any I T band, so, or calf and flexibility. And then here's this shock wave again, this is emerging um work, but it's really based on just case studies at this point um for managing I T ban syndrome. This foam roller here, I often will encourage all my athletes to get in the primary care setting. You can do that as well. Sometimes that's all people need is foam rolling after and before um running. And so when do you image? So usually you don't need to image for this if you want something to confirm an ultrasound is probably the best thing. Uh And you might see some thickening of the I T band with an ultrasound. Um And you rarely ever need um MRI x-rays only if you're concerned about uh the pathologies. And when should you refer, if you've tried all these things we talked about, they've been doing it for six months and they still have pain. And so how do we prevent this? So, increasing pace. So we talked about uh pace and, and foot strike and, and stride or step rate and how that uh lower step step rate in particular increases your risk for injury. So when you increase your pace, you have, you increase your step rate and that in particular for I T band takes you out of that 30 degree of knee flexion range. Um Other things, uh particularly important I think is maintaining glute media strength. So a lot of these lateral leg lifts, that's something they can start to do at home before you get them to, to P T can be helpful. So, uh to summarize female sex, low normal B M I higher B M I, as well as previous injury, uh are well supported in the literature as risk factors for young runners. Um, common overused injuries that you see are I T syndrome, paleo moral pain as well as shin splints. You should have a high index of suspicion for stress fractures. And we know some of the risk factors that should pique your interest for that suspicion. Uh If you suspect it, they usually need advanced imaging. So you should be referring if, if that's hard to get and with that, I wanna thank you. This is a picture of me at World Juniors doing launches.
