Hello, and welcome to this session where we are going to discuss proximal hamstring tendinopathy, current concepts, and emerging technology. There will be three talks in this session. I will present the first talk. My name is Kelly McInnis, I'm an assistant professor of physical medicine and rehabilitation at Harvard Medical School and a sports medicine physiatrist at Massachusetts General Hospital. I help to take care of a number of professional and college teams, including the Boston Red Sox, the New England Patriots, and the Harvard Crimson. Our second speaker is Dr. Brian Heiderscheit. He is the Frederick Ganslin Professor of Orthopedics at the Department of Orthopedics and Rehabilitation at University of Wisconsin-Madison. He also exists in the Department of Biomedical Engineering. He is the Director of the University of Wisconsin Health Runners Clinic, as well as the Director of Research for the Badger Athletic Performance. And our third speaker is Dr. Adam Tenforty, who is an Associate Professor of Physical Medicine and Rehabilitation at Harvard Medical School and the Medical Director of the Spalding National Running Center. So with that, I will share my screen. I will start with a presentation regarding pearls for clinical assessment. I have no conflicts of interest. The specific objectives for the talk are listed here, and we will start with a review of hamstring anatomy. The hamstring myotendinous unit is a biarticular muscle group consisting of the biceps femoris, the semitendinosus, and the semimembranosus. It's responsible for hip extension and knee flexion. The biceps femoris origin is at the ischial tuberosity as the conjoint tendon with the semitendinosus. The proximal fibers are contiguous with the sacrotuberous ligament. The biceps femoris is the lateral hamstring that has its insertion on the fibular head. It also has some fibers that attach to the lateral collateral ligament, the lateral tibial plateau, and the iliotibial band. The semitendinosus is a medial hamstring that has its insertion on the pes anserinus. And finally, the semimembranosus has a separate, has its own origin on the supralateral ischial tuberosity, just anterior to the conjoint tendon. It has some attachment to the adductor magnus as it courses through the medial thigh to attach on the tibia with a broad attachment. This is the footprint of the proximal hamstring tendon at the supralateral ischial tuberosity. And you can see the location is really supralateral on the ischial tuberosity. So this brings us to our first clinical pearl related to palpation landmarks. When you're palpating the inferior aspect of the ischial tuberosity, you're actually palpating more of the adductor magnus and the ischiocondylar portion. And then along the pubic rami, you're palpating more of the pubofemoral portion of the adductor magnus. So the pearl is when you're palpating the ischial tuberosity, the hamstring tendon is located really lateral, supralateral on the ischial tuberosity. Another important anatomic relationship is the sciatic nerve, which lies an average of one centimeter from the lateral-most aspect of ischial tuberosity. So we can understand why if we have proximal hamstring tendon thickening with proximal hamstring tendinopathy, that that can result in sciatic neuralgia. We know that the hamstring unit is most active during the last 25% of the swing phase of running, when it eccentrically contracts to decelerate knee extension just prior to heel strike. This is also the point of peak stretch and maximal muscle tendon length. We also know that the highest eccentric load occurs at the muscle tendon junction and more so in the biceps femoris than the semimembranosus. Dr. Heiderscheidt described that speed running is the mechanism for most hamstring strains and that most of these injuries occur at the biceps femoris. But as described by Dr. Heiderscheidt, the mechanism for proximal hamstring acute injury is typically a bit different, involving more of the extreme of hip flexion and knee extension that can occur in dancing, in kicking sports, and in water skiing. The authors describe that this mechanism more often involves the semimembranosus portion of the proximal hamstring tendon. And this injury, proximal hamstring acute injury, can have a prolonged recovery compared to the running mechanism of strain that is more common. This is an example of a proximal hamstring acute injury in a major league baseball player where he has extreme knee extension, hip flexion, and at the end, trunk flexion. But what we're really going to focus on in this symposium is more the cumulative microtrauma and the overuse that can result in proximal hamstring tendinosis. We know that two forces generally contribute to tendinopathy. One, tendon compression, two, tendon tension. Compression increases with the wrapping that occurs of the proximal hamstring tendons around hip flexion. And tensile load, we know, increases with eccentric contraction. And activities that increase these two loads include sprinting, hill work, lunging, hurdles, overstriding, overstretching, more of an anterior pelvic tilt, and more trunk flexion that can occur with poor lumbopelvic stability and weak hamstrings. The location of pathology is most often insertional. Mid-portion has not been well described. And studies are mixed in terms of which of the two tendons are more frequently involved. In my experience, it's been the semimembranosus, especially in female runners. We all know that the non-inflammatory nature of tendinopathy with a degenerative cellular milieu that ultimately leads to altered viscoelastic properties. And we know that the tendon bone interface at the ischial tuberosity and thesis is generally a hypovascular zone with suboptimal healing potential. Patients with proximal hamstring tendinopathy typically present as running athletes with gradual onset of lower gluteal pain, worse with speed and hills, with poor sitting tolerance. And as discussed, sciatic neuralgia can occur due to the proximate location of the sciatic nerve adjacent to the proximal hamstring. This injury can cause significant morbidity. Perhaps the most challenging group to treat is the hypermobile female runner. I call it the perfect storm of proximal hamstring tendinopathy, the combination of overload and overstretch with a runner that also does a lot of hypermobile activities such as yoga. This is our differential diagnosis for lower gluteal pain. We want to rule out lumbar radicular pain and sacroiliac joint pain. We want to rule out intraarticular hip joint pain, as well as other soft tissue pain generators. And in runners, we always want to rule out bone stress injury, and that includes sacral and inferior pubic rami bone stress injury in this particular anatomic location. Proximal hamstring tendinopathy is largely a clinical diagnosis, and muscle tendon pain is generally reproduced with three different modes on exam, palpation, stretch the muscle tendon unit, and activate the muscle tendon unit against resistance. However, tenderness at the ischial tuberosity is variable in this diagnosis. So I often ask the patients as I'm palpating the supralateral aspect of the ischial tuberosity if that is the index of their, if that is the location of their index pain because they may not actually be tender on exam. They may be more tender with running activities as well as sitting. The stretch tests are fairly reliable. I use the bent knee stretch test that's pictured here. And I find that patients generally have more pain with resisted hip extension than resisted knee flexion, but can certainly have reproduction of pain with both. If an athlete does not have pain with loading with manual muscle testing, you can also use these loading tests to try to reproduce their pain. And I have found that the supine plank test as well as a single leg deadlift can be quite predictive in terms of success with return to run when an athlete's able to do these maneuvers without pain. The straight leg raise is probably better than the seated slump test to distinguish radicular neural tension from proximal hamstring tendinopathy as there is less hamstring stretch to irritate the hamstring muscle tendon unit. You want to make sure that you do a good sciatic nerve assessment, both motor and sensory, and you want to hit on your palpatory gluteal landmarks, including the periformis, which can certainly coexist with proximal hamstring tendinopathy, but can exist in isolation, the sacrotuberous ligament, the PSIS, the greater trochanter, and the inferior pubic rami to name a few. Point-of-care musculoskeletal ultrasound can be very useful as an extension of our physical examination, and I use an approach described by Beccolini et al. which is to localize the hamstring triangle or Cohen's triangle on short axis, which is just distal to the gluteal crease, and if you can locate the sciatic nerve laterally, the conjoint tendon as the apex of the triangle, and the semimembranosus as the medial aspect of the triangle that looks tadpole-like with its membranous tail, then that's a great starting point for an ultrasound assessment. Then you can scan proximally to the gluteal crease, still on short axis, and you can see the insertion site on the ischial tuberosity, where you see the cortical margin of the IT, you see the conjoint tendon, the fascial plane between the conjoint tendon and the semimembranosus, as well as the sciatic nerve. Anisotropy can be a challenge in this region, so you really need to angle your probe medially, particularly to eliminate anisotropy in the semimembranosus tendon. A bilateral exam can be quite useful, and on the symptomatic or the pathologic side, you can often see tendon thickening, you can see hypoechoic regions within the tendon both on short axis and long axis, you can see cortical irregularity at the ischial tuberosity, and you can see the thickening of the tendon on the symptomatic side compared to the contralateral side. And this can also be visualized in long axis, where you can have a loss of the fibular pattern that we see normally with tendon echo texture. And you want to be aware of other pathology and mimickers at the ischial tuberosity. Ischial bursitis, which is actually quite rare, and is characteristically complex in nature in terms of bursitis, which can be multiloculated and can actually look quite scary on ultrasound imaging if you haven't seen it before. And certainly you want to look for calcific tendinopathy and calcium hydroxyapatite deposition in the critical zone, one to two centimeters distal to the insertion on long axis and short axis views. And this is really why I like to get plane radiographs of the pelvis when I'm assessing proximal hamstring tendinopathy, because I don't want to be surprised by calcific tendinopathy later, particularly if I'm doing an ultrasound-guided procedure in this region. So I usually use the ultrasound finding and correlate it with the plane radiograph to better define the region of calcific tendinopathy, which is often missed in MRI scans. These are my indications for MRI in the setting of proximal hamstring tendinopathy. If I have mild physical therapy, good rehab, which we're going to hear about in the next section of the talk. If I have a suspicion for tear or partial tear on ultrasound, and if I'm considering interventions beyond rehab, I really want to investigate for whether there's a partial tear or not, and I want to characterize that. And partial tears are seen as linear crescent-shaped signals deep to the tendon at the interface between the tendon and the initial tuberosity. Other MRI findings that correlate with pain include initial tuberosity edema, peritendinous T2 signal around both of the tendons, and thickening. Intratendinous signal intensity is a poor correlator for pain. Many asymptomatic patients have intratendinous signal intensity, particularly runners over the age of 45. We're going to end this discussion with a brief talk on exciting advancements in ultrasound technology that allow us to assess different muscle tendon properties that may improve the care of patients with hamstring injury in the future. The ever-advancing B-mode or brightness mode, which is standard function on all 2D ultrasound units really allows for improving contrast and tissue echo intensities. It allows us to better quantify tissue composition. Low echo intensity values or darker tissue are considered to be associated with greater muscle quality. In contrast, high echo intensities or brighter signal intensity represent sound waves reflecting more off the fat and fascia and scar tissue, and they're thought to be related to muscle impairment. Echo intensity measures can be quantified and ultimately may help to identify an at-risk area of tissue. We can also measure architecture properties on B-mode, including muscle fascicle length as well as penation angle, and these can be associated with muscle function. And as we see here in the bottom right, an extended field of view can help us to better quantify muscle thickness and volume, which may have a role in hamstring injury prevention, especially in comparison to quadriceps volume or gluteus maximus volume. The basic principle of shear wave elastography is to create an acoustic radiation force impulse through the transducer displacing the underlying tissue. That results in a propagation of transient shear wave. The shear wave velocity or velocity by which the waves return to the transducer is then calculated and directly related to the elastic properties of the tissue, and we know that this correlates with muscle stiffness and is a measure of muscle elasticity. And this can be mapped on a pictorial elastogram that's superimposed onto the ultrasound B-scan. And so this picture on the right illustrates the biceps femoris on long axis in B-mode with the superimposed elastogram demonstrating greater stiffness in the picture B compared to A with the higher velocity colors, and we know that hamstring stiffness is a well-described risk factor for hamstring strength. This is a systemic review looking at 39 studies investigating elastography in assessment of tendon injury. Unlike muscle tissue, tendon stiffness is desirable. All 39 studies found decreased stiffness in pathologic tendinopathy and tendon degeneration. The authors found elastography can detect subclinical pathology before symptomatic or visible on conventional ultrasound, and studies included the Achilles, the patellar tendon, the rotator cuff, the epicondylar tendons, given their superficial access. The proximal hamstring tendon is more limiting as it lies under the larger glute max, but someday we may be able to measure it with shear wave if we're able to introduce percutaneous shear wave down at the level of the tendon, potentially with ultrasound guidance. This is an example of elastography in the evaluation of the common extensor tendon looking at conventional B-mode imaging showing tendinosis and the yellow areas, yellow arrows representing a partial tear, and then the corresponding elastogram showing the region of decreased tendon stiffness. Clinical application here is that including, improving our precision with guided procedures including PRP injections as well as ultrasound-guided shock wave to really localize the region of tendinopathy, particularly in cases where we don't see a partial tear as pictured on the right. We continue to investigate how these exciting advancements can help our athletes and all patients. Future directions include looking at performance-related factors, response to training, rehab interventions, identifying high-risk athletes, and monitoring return to sport and readiness to return to sport. But these studies do have methodologic considerations and limitations. The benefits are promising, but many are not yet ready for prime time. So in closing, we'll end with these take-home points. We defined the tendon footprint and the ischial tuberosity palpation map. We learned that hip flexion increases, compressive and tension loads, and provocative activities that can increase these loads. We learned that on exam, we need to stretch the hamstring and load it to reproduce pain, and that tenderness is often variable. We learned some imaging pearls in starting with visualizing the hamstring triangle, a musculoskeletal ultrasound, and then working proximally to the enthesis. We have to be aware of anisotropy, particularly in the semimembranosus, and we don't want to miss ischial tuberosity, ischial bursitis, or calcific tendinopathy. We learned the MRI findings that correlate with pain, and that simply intratendinous signal intensity does not always correlate with pain. And we learned about some advancements in ultrasound technology, and how our field can potentially be at the forefront of further advancements and translation to clinical care. So with that, I will turn over the presentation to our next speaker, Dr. Brian Heiderscheit. All right, thank you, Dr. McInnis, fantastic talk. I'm just going to get my screen loaded up here. There we go. All right, as Dr. McInnis mentioned, I'm going to be leading us through then a discussion on rehab principles as it relates to proximal hamstring tendinopathy. Now, surprisingly, or maybe not surprisingly, there's not a lot of research in this particular area related to hamstring tendinopathy. So we're going to take quite a bit of information from other areas that have been studied quite a bit more, like Achilles and infrapatellar tendinopathy, at least as an initial guide to some of our ideas and application. No conflicts of interest. And again, the objectives for the talk are to identify the principles of progressive loading of tendinopathies to promote recovery, and also to discuss some new innovations and technologies for use in monitoring recovery and load progression. So when we think about tendinopathies, in particular in an active running population, there are a variety of locations throughout the lower extremity that are common, and certainly high hamstring tendinopathy tends to be one of those that is always a little bit daunting to deal with. I remember when they used to be on my schedule, they were ones that I dreaded. I'd much rather take an Achilles tendinopathy or an infrapatellar tendinopathy any day of high hamstring. But I think we've gotten better at understanding how to best rehab these individuals and how to make sure that we're not prone to as much of a recurrence as was once the case. So again, thinking about general tendinopathology and not just specific to high hamstring, but there are these stages of breakdown that have been described by Jill Cook's group between reactive tendinopathy into tendon disrepair, and then finally tendon breakdown that may be more or less permanent. It's when it's in that reactive tendinopathy and into tendon disrepair that I think we have the best chance of being able to make some changes for these individuals. So when we think about how best to promote recovery of the tendon or to stop the cascade of breakdown, resistance exercise is by far and away the foundational approach to make that occur. And so again, thinking of that resistance exercise is a positive stimulus for tendon cell activity and matrix restructuring. So we need to be able to understand how and what type of load to expose to the tendon. Now, as Dr. McInnis already mentioned, there are certain types of loads that do not promote tendon recovery. If it's a compressive type load, for example, where the tendon wraps around the bone and exposes to a local compression or as well as shearing, that ends up, the tendon does not promote recovery under those sort of loading circumstances. Tendons are designed to transmit tensile load. And so when exposed to a tensile load is when you have your best chance of promoting recovery. And so when we look at mechanical loading and its exposure to a tendon that's injured or even through an unloading situation, you can see that a loaded tendon has all positive factors with respect to its mechanical properties, as well as to its cellular and molecular properties. Now, how we go about exposing this load. Well, when we look back at some of the foundational work from the mid 90s describing heavy load eccentric exercise, and again, this is specific to Achilles, this be kind of opened up the door to say, okay, we're going to treat tendinopathies in an eccentric way. And the early work was very promising in that manner, but there's always room for improvement, right? Is this one that's always going to work for every sort of tendinopathy? As Dr. McInnis already mentioned, high hamstring tendinopathies, we think of many times as being mid portion, but the reality is they are essentially, we need to be thinking of them as insertional tendinopathies. They have not been described in mid portion manner the way that Achilles tendinopathies have. So because of that, we really need to be thinking about how we best approach insertional tendinopathies for the recovery of this sort of injury. And so case in point, when we apply this to Achilles tendinopathies, one of the ways that we differentiate our rehab program between an insertional tendinopathy versus a mid substance tendinopathy is that for insertional tendinopathy, we automatically limit the range of motion that it's exposed to at the beginning, right? We do not want to expose them to end range dorsiflexion motions because of that wrapping that was described earlier, where the tendon makes contact with the bony surface as exposed to the compression and shearing loads. So during this process of insertional recovery, we want to make sure that we're exposing it to tensile loads for sure, but minimize that compression and shearing load. And so we need to take that same approach then to our high hamstring tendinopathies and make sure that we're very careful about the amount of hip flexion that's exposed and what sort of hip flexion is occurring during these loading exercises. Another approach to think about is do we need to stay exclusively with heavy eccentrics? These eccentrics need to be done every single day. Well, again, some earlier work that was done with Achilles rehabilitation showed that heavy slow resistance training done only three times a week was just as effective at reducing the symptoms and improving the structural recovery of the Achilles tendon as compared to more of a traditional heavy load eccentric program. So I don't think we need to be thinking exclusively eccentrics when we're talking about a recovery and load progression for these tendons, but making sure that it's the proper load magnitude and dosing that we're using effectively. In addition, we need to be careful about thinking about high loading versus heavy loading. We use the term heavy load to think about making sure that we have adequate magnitude of load exposed in terms of the amount of resistance being applied, but we want to apply that in a fairly slow manner. And the idea being that if you apply a heavier load in a rapid manner, because of the viscoelastic nature of the tendon, you will end up with a spike in the stiffness and expose it to a very high tensile or high stress with minimum strain. One of our goals is to induce a bit more mechanical strain to the tendon, and we can achieve that by a heavy load and or a slow loading application. All right, so now let's tie this back to proximal hamstring tendinopathy. So as Dr. McInnes mentioned, the anatomy of the high hamstring insertion is a bit complex, and we need to be always thinking about the amount of wrapping that's occurring. In essence, anytime you flex the hip beyond zero degrees, 10 degrees, 20 degrees, you're talking about a good amount of bone to tendon contact that happens. And as soon as that's present under a loading situation to the hamstring, you're going to have compressive loads applied to that tendon. So we want to make sure that we are careful to minimize those compressive loads throughout the rehab process, but especially during those initial weeks when getting compliance and pain control is of the utmost importance. When we think about running mechanics in general, this was already described in the first lecture a bit, we need to be conscientious of the amount of hip flexion that's occurring with running. And again, running up hills, hill repeats, running faster, doing sprinting mechanics, running with an anterior pelvic tilt or a bit of a excessive lumbar lordosis, all can contribute to elements of increased hip flexion more than you may otherwise need to still run effectively. In addition, an overstriding landing posture, meaning landing well ahead of your center of mass also has that same propensity for increasing the amount of hip flexion. So with that in mind, there are ways that we can modify the running mechanics to enable individuals to continue to run while they're undergoing rehabilitation for the tendinopathy. But a caution, of course, is that we don't want running to be an aggravating activity. We wanna make sure that it's loading the tendon, but in a way that does not slow the recovery. And so to start with, again, our pain management approach and tendon load reduction is step number one, right? We need to make sure that the tendon load is at a controlled level and at a non-aggravating level. And so that may involve reducing or will typically involve reducing running volume, as well as the load exposed to the tendon during running. And in this case, we wanna avoid hills, we wanna avoid speed work. We may have them increase their step rate, which in effect reduces their overstriding tendencies. And the idea is that is to avoid exacerbation of the symptoms and allow individuals to maintain some semblance of normal activity, albeit in their not typical manner. For some individuals, that may not be enough. We may need to eliminate running altogether for a period of time, or put them in an activity that is less provoking, whether that's some sort of non-weight bearing running mechanics, cycling or deep water running. But even those thinking about the tendinopathy may aggravate the condition. So we need to make sure that it's a non-aggravating form of activity. One of the paramount ways that we can help control pain management early on is through the use of tendon loading. And so resistance exercise in and of itself, it not only helps promote the recovery of the tendon, but also has a bit of an analgesic effect. And one of the ways that's been suggested, although not exclusively, is the use of isometric exercise. I found this to be particularly effective in those who are a little more reactive or a little more aggravated as a way to both gauge or to both enable the patient to have confidence in what you're prescribing to them and because it's a non-aggravating form of tendon load, as well as the advantage that it ultimately helps them feel better, both immediately and for a prolonged period of time. So using a pain monitoring model has been advocated by Connor Silvernagle, among others, and it's a fantastic way to go about informing your patient and educating your patient on how much loading is the proper amount of load. And so using a cutoff point of saying no more than five out of 10 is absolutely the maximum amount of pain that you're allowed to be exposed to, with the idea that you're gonna stay closer to around a two out of 10 or lower. But some activities that are maybe a three or a four out of 10 are acceptable. We just gotta be very careful about how frequently and often we expose our tendon to that magnitude of load. When you're using isometrics for pain modulation, there's been some good work, again, not necessarily for the high hamstring tendinopathy, although we've seen similar response with our patients. But using isometrics in a way that is a high magnitude of loading, so typically at least 70% or higher of their MBI-C or their maximum volitional contraction for sustained periods of contraction, 40, 45 seconds, has the advantage of reducing the amount of pain, both immediately after the exercise, as well as for hours and multiple hours following that exercise. Now, early on, it was suggested that we need to do 40-second holds five times or 45-second holds five times, but some recent work has suggested you don't need to use that long of hold times and still get the same pain modulating effect. You can do holds of only 10 seconds in nature, but of course you have to have more repetitions. So one of the constants is that it seems that to be roughly around four minutes of isometric load time is necessary to get some of these pain modulating effects. And so again, in the case of heavy load isometrics, we're gonna, for the high-anchoring telomopathy, we're gonna start them in a neutral posture, right? Zero degrees of hip flexion. So they are prone on a table and we're doing manual resistance loading anywhere from 10 seconds, multiple repetitions, to upwards of 20 or 30 seconds for fewer repetitions. And as they're able to tolerate, as their pain reduces and they're able to produce more and more force, we begin to move their hip angle to 20 degrees of hip flexion and then to 30 degrees of hip flexion. And then once we're able to get them pain-free through that range of motion, now we're ready to progress into short range, concentric, eccentric type of loading circumstances. And so that's where we move into exercises. Again, these are some other example exercises for isometrics where we hold them in particular angles and a fixed position with the idea of starting at zero to begin with and progressing toward 10, 20, 30 degrees. These are images out of a fantastic paper by Tom Goom who was published a number of years ago in JOSPT, really good clinical commentary leading through the rehabilitation progression for high hamstring telomopathy. When the pain is controlled and they're able to produce a reasonable amount of load, you're able to progress them into the isotonic loading circumstances. And so again, this would be going through the range of motion, but through the available range of motion that is pain-free. We don't wanna push them into that painful range that pushes them beyond that four or five out of 10 magnitude of pain. So we may start with limited hip flexion, concentric, eccentrics through that range to begin with, and then moving more toward greater hip flexion as pain allows. Then finally, after several weeks and confident that their pain is now controlled, we're gonna reintroduce plyometric loading or that stretch shortening cycle. So important to tendons, that's how tendons function. We need to make sure that we have those tendons exposed to that stretch shortening cycle in a controlled rehab setting before we just turn them loose into full support participation. So when we think about the tendon load progression, again, what we have are the number of weeks to progress through with the way that you would progress them through the angles and through the number of days and weeks that may be involved. A couple of quick treatments to avoid is a good review editorial by Jill Cook. One of the most important take-homes from here is stretching should be avoided. It's not something we wanna do for tendons, and we do not wanna rush rehabilitation knowing that many weeks of recovery are necessary beyond the pain-free mechanism. We're talking about needing several months to restore full tendon structure at that time. A couple of quick notes on future directions, then we'll turn it over to our next speaker, Dr. Tenforty. A couple of things, the shear wave elastography is one thing that we've begun to explore as well in a more dynamic situation. Certainly the imaging side of it's effective for imaging and identifying changes in tendon energy absorption and stiffness. We began to see this as well with hamstring injuries that suggest that certain injuries, both at the muscle and tendon level, are able to be detected effectively with shear wave imaging. One of our challenges and one of the advances that we wanna be able to use is can we use shear wave imaging effectively to assess tendon readiness for load progression? That's one of our key goals. Some new technology that's begun to develop is the use of tendon tensiometry. This is a wearable device that essentially during activities, not just through an imaging technique, but using mechanical vibrations to the tendon and measurements of the acceleration allow us to measure the tendon, the stiffness of the tendon, specifically during a variety of dynamic tasks, including sprinting. And then finally, thinking about activity, progression and recovery, what sort of load individuals are being exposed to, we wanna make sure that we're embracing wearables to monitor that sort of load exposure, but making sure that we don't assume that load exposure that we're measuring through these more global wearables are a direct measure of tendon loading. Again, these are a more global measure of activity with the potential for tendon load, but certainly not a direct measure of tendon loading. Thank you for your time. And I'd like to turn it over to Dr. Tenforty. Thank you so much. So I'm excited now to share my talk on innovations and management of proximal hamstring injuries. I have no conflicts of interest to disclose related to this talk. So the objectives of my talk are to discuss the innovations with treatment approach for proximal hamstring tendinopathy, recognizing that, as Dr. McInnis outlined, it's important to make the correct diagnosis. And as Dr. Heiderscheid has outlined, it's very important to have an appropriate loading program to rehabilitate the tendon. So what we're really getting into are, what is the evidence for other forms of interventions when we have these more refractory cases? So just in brief, we do recognize the initial management of these injuries does include some degree of activity modification, oftentimes a consideration for ice or heat, just different ways to help with the pain that the individual is experiencing that may get in the way of their rehabilitation. One topic we haven't covered is the role of non-steroidal anti-inflammatory medications. And as was outlined earlier by Dr. McInnis, a majority of these hamstring injuries oftentimes are not purely an inflammatory condition, but really represent intra-substance tearing and damage. So using an anti-inflammatory medication may not be the most prudent course for facilitating the remodeling, which we believe needs the inflammatory cascade. As Dr. Heiderscheid outlined, it's very important to address biomechanical and strength deficits. So what we're gonna get into in the following slides is what do you do in these chronic refractory cases? Or you could also consider these in the cases of individuals that really need a more predictable rapid return to sport. So we're gonna get into the relative role of corticosteroid injections, the use of different forms of orthobiologics and the level of evidence, and finally on shockwave treatment. So I want to caveat my comments with stating that if we really look at the research, there is very little guidance for an evidence-based approach. In this recent review from 2021, reviewing all of the available interventions in the management of proximal hamstring tendinopathy, there were two randomized control trials that were identified and from reviewing the literature, authors concluded there was a very low level of evidence in long-term gains with shockwave and in considering different interventions, similar outcomes potentially with whole blood versus platelet-rich plasma injection in midterm outcomes. So let's get into a few of these different topics. The first I'm gonna cover is the role of corticosteroid injection. So historically, and still a common in practice, steroid injections are oftentimes considered to address pain with the goal that this may improve function. When considering the role of a corticosteroid injection, image guidance at this stage has become standard of practice with the goal that the steroid is deposited peritendinously or targeting adjacent bursa, in this case, perhaps the ischial bursa in the management of proximal hamstring tendinopathy. We do recognize that an intratendinous steroid injection could actually be damaging to the long-term health of the tendon and something that we want to avoid. So when we think about steroid injections, I like to commonly cite this paper by Zeeson et al, and this was looking at a clinical cohort of 65 patients who received one or more ultrasound-guided corticosteroid injection for the management of proximal hamstring tendinopathy. In this large case cohort, the type of procedure received either consisted of 40 milligrams of triamcinolone with five milliliters of bupivacaine or the use of a mixture of 40 milligrams of triamcinolone with two milligrams of dexamethasone and five milliliters of bupivacaine. There was a standardization of the protocol for how an individual was allowed to return to sport, primarily running, with a goal to limit activity for two weeks if the ultrasound did not demonstrate evidence of tendon injury and three weeks if there was evidence of tendinopathy with partial tendon tearing. What did investigators find? Well, 23.7% of the cohort experienced no relief with a peritendinous steroid injection at any time following the procedure. 50% had resolution of their pain for one month and looking out to six months or longer, which was the case cohort endpoint, 23.7% had sustained relief at six months. The one prognostic finding across participants was the findings of a normal ultrasound is having a greater predictive value for whether a peritendinous steroid injection would provide longer-term relief. Now, when we think about why steroid may not be as effective, we need to think about the pathophysiology. And as outlined before, very few of our patients that we're seeing have a true tendonitis, which would be a primary inflammatory condition, which really doesn't involve the long-term pathological changes. So more often, we're dealing with a tendinosis, which is a more chronic form of tendon injury, which is primarily without inflammation and thought to be more of a failed healing response. So when we really consider the topic of steroids and tendinopathy, there really is a lot of concern that this may not be the best course of action. This relatively recent review by Dean et al looked at 15 human subject studies, 36 animal studies, and one that was combined. And what the investigators concluded was there was concern for long-term harm of tendon tissue with corticosteroid injection. This included at the pathological level, the loss of collagen organization, a reduction in collagen synthesis, which may be suppressed by steroid, and changes in cellular proliferation, which may actually lead to tissue necrosis. There's also concern that steroid may actually negatively influence the mechanical properties of tendon over the long-term. So while the investigators did identify that there was no high quality level of evidence to confirm or refute the increased risk for tendon rupture, which is one of the risks that we have to consider when performing this type of a procedure, there was strong evidence that oral steroids are associated with a higher risk for tendon rupture. So I think the big takeaway from looking at the very limited level of evidence in the role of steroid in the management of proximal hamstring tendinopathy is you really need to approach this with caution. So my approach, I really don't like steroid. I think that the risks oftentimes are well higher than the reward for most of our patients, and you really need to be selective. So let's consider some alternative injection-based interventions. And I think the one that we more commonly talk about is the role of platelet-rich plasma. And what this is is an autologous use of one's own blood products in the management of tendinopathy. The basic science of platelet-rich plasma suggests there are anabolic effects which may promote cellular proliferation and an anti-inflammatory effect at the tissue level. So when looking at the studies, there really are mixed results in the role of PRP and the management of proximal hamstring tendinopathy. And what we have to recognize is that there's quite a bit of variability in the study design, the number of patients, the formulation of PRP, the length of follow-up time, and even the outcomes that are used to measure. So looking at these five studies, you can see the first by Levy et al, which was a retrospective cohort study found no improvements using the BCH as an outcome measure. And there was no difference in outcomes based on grade of tendinopathy. In contrast, a study by Krauss, which was a prospective study, demonstrated a mean improvement in lower extremity functional scale of 13. Fader, using a retrospective design, demonstrated a mean subjective improvement in the visual analog scale for pain. Whereas Davenport, using a randomized control trial of platelet-rich plasma versus whole blood, demonstrated improvement in both groups without significant between-group differences. So again, that earlier review article on evidence-based treatment that suggested PRP and whole blood could be similarly effective. This is likely the study they were drawing from. And finally, the Wenzel study was a retrospective study showing a similar return to sport in the use of PRP versus other interventions. So I'd like to briefly discuss our experience in evaluating outcomes with platelet-rich plasma injections for proximal hamstring tendinopathy. The senior author on this paper was Dr. McInnis, and this was a single operator of Dr. McInnis performing a PRP injection for the management of proximal hamstring tendinopathy in 22 patients. You can see these were individuals close to their six decade of life, 12 female and 10 male, with duration of symptoms exceeding two years. Each received a leukocyte-rich platelet-rich plasma injection with a standard post-procedure protocol, and the outcome of interest was the VSA-H. What we identified across this cohort was that 68% of individuals had greater than a 50% pain relief, and that there did appear to be a general improvement in VSA-H subscales over time for individuals. Now, another finding from our report is the role of a standardized protocol post-PRP procedure. And I think this is really important when you evaluate the outcomes of platelet-rich plasma injections or other forms of orthobiologics. If you don't standardize the post-procedure protocol, you may actually create some variables that could potentially confound outcomes and results. So what we published was that it was important to restrict individuals from the use of non-steroidal anti-inflammatory medications for a minimum of 10 days following their PRP procedure. There was a brief relative rest of two days prescribed, followed by range of motion exercises for the first two weeks. Cardiovascular exercise was allowed to resume at day three, but impact activities were limited for the first two weeks. There was also a formal physical therapy program that was assigned starting at two weeks. And this was standardized similar to the way that Dr. Heiderscheidt has outlined the importance of having a very thoughtful, standardized approach for the management of proximal hamstring tendinopathy. So I'd also like to briefly discuss another form of intervention, and this is a non-injectable intervention of shockwave therapy. I like to refer to this review article that I was the senior author on, published in 2018 in PM&R Journal. Again, this is an open access article which describes a lot of the current science and understanding for the role of shockwave in the management of upper and lower extremity musculoskeletal conditions. Now, when we start to think about shockwave, we wanna understand the mechanism for action. And to understand that this is a mechanism and that this is not just some type of a passive modality, but there is actually some science and multiple studies that have documented changes at the tissue remodeling and at pain modulation. And I'm not gonna go through each of the individual studies here, but you can see a number of different proposed mechanisms for how shockwave treatment may actually have biological effects, again, on tissue remodeling and pain modulation. So I would argue the best controlled study in evaluating shockwave for hamstring tendinopathy was performed by Cascio. This was published in the American Journal of Sports Medicine in 2011. And in this investigation, Cascio and colleagues studied 40 professional athletes, all had MRI confirmed findings of proximal hamstring tendinopathy. 20 athletes were randomly assigned to receive four weekly sessions of radial shockwave treatment. And the other 20 athletes were assigned a typical activity modification, short trial of analgesics and a gradual return to play. What were the two outcomes of interest was finding the number within each cohort that experiences a 50% or greater pain reduction and returning to pre-injury level of sport. At three months and sustained out to a year, 85% of those who received radial shockwave treatment compared to 10% with conventional treatment achieved a 50% reduction in pain. 80% of those who received radial shockwave returned to pre-injury level of sport versus none with the conventional treatment. And what was notable despite the fact that you're applying these pressure waves around the sciatic nerve as outlined by the anatomy covered by Dr. McKinnis, there were no adverse events reported with shockwave including no evidence of sciatic nerve injuries or long-term irritation of the sciatic nerve. So my experience with shockwave, we recently published in the journal MLT. This was a cohort of 63 runners of mean age, 42.8 years, 16.9 average month of symptoms. These were individuals who elected to receive either radial shockwave, which again is a pressure wave or the combination of radial shockwave with focus shockwave, which is a higher energy shockwave therapy. All were recommended to continue a standardized physical therapy program. And what we measured in my clinic as a patient related outcome measures was VSA-H. What we identified is that regardless of whether someone received radial or combined shockwave, we had an overall 60% treatment response, which was a change in the VSA-H of 22 or higher. There appeared to be a ceiling effect of six sessions, which helps to guide expectations on the duration and number of treatment sessions that are received in clinic. And there were no adverse events discovered. What we present in the dumbbell model are individual subjects and arrows that illustrate where the individual started and their change. Again, the diamonds representing their baseline VSA-H function and the circles representing their endpoint VSA-H. Now, briefly on surgical considerations, I'm not gonna go into great detail, but if you do have someone with an acute hamstring injury, particularly a significant tear with three-tendon involvement or a significant two-tendon tear with retraction or the presence of an avulsion injury, it would be reasonable to obtain advanced imaging and obtain a surgical consultation to discuss whether surgical management may be recommended. Although I will say that in general, we typically like to exhaust non-surgical management for proximal hamstring tendinopathy without significant tearing given the variability in outcomes with surgery. So in summary, hamstring tendinopathy typically responds to non-operative management. And when we think about these different interventions, we should think about how they work in conjunction with the correct diagnosis and with an appropriate physical therapy progression. The goal is to ultimately achieve a pain-free status and advance the individual back to full return to sports using symptoms to guide their progression. Steroid really has a limited level of evidence and can cause harm. So you should really be approached with great caution. When we think about PRP or even the use of whole blood, proper rehabilitation programs are necessary to see the good long-term efficacy. Shockwave is another intervention to consider. It has a good safety profile and doesn't require activity modification. So it's also one of the procedures I like to consider earlier on, particularly in athletes that are eager to get back to sport quickly. And finally, I will state that there is a growing interest in how we might think about these different interventions, such as the role of platelet-rich plasma combined with shockwave and how these may work in synergy. But I would say that right now, there's insufficient evidence to suggest a routine use of both. Thank you so much for your attention.

proximal hamstring tendinopathy

management

accurate diagnosis

progressive loading program

rehabilitation

sciatic neuralgia

tensile loads

corticosteroid injections

platelet-rich plasma (PRP) injections