So I'm very excited to introduce Dr. Zell, who is coming to us from Maryland. He actually started his training up in Connecticut, right here at UConn, and then subsequently has been recruited back down to Maryland, where he is now practicing. So he is a foot and ankle surgeon who is down at the University of Maryland, Upper Chesapeake. And thanks for being with us and sharing your thoughts. Great, thank you. All right, can everybody hear me? So, great. Yeah, thank you for the nice introduction. I know this session is focused on runners, but stress fractures occur in all different types of athletes, and they actually occur in all different types of patients, and it's always something you should have on your rear radar when you're seeing patients in the office. And they're not always runners, but sometimes they're older people that have stress fractures, and it's always a good thing to think about when you're evaluating your patients. I don't have any disclosures with this talk. So a stress fracture is a fracture of bone due to repetitive loading rather than a single traumatic event. It also can be termed a bone stress injury. It's probably a better term, which is the inability of a bone to withstand repetitive mechanical loading, resulting in fatigue, structural fatigue, and localized bone pain. And it really describes a continuum. Stress reactions, which are usually, we see them on MRIs, stress fracture, and then sometimes a stress fracture will become a complete fracture. This is actually a different term than an insufficiency fracture. Insufficiency fractures occur in abnormal bone subject to normal load, and I always think of our little ladies that we see with sacral insufficiency fractures. And a stress fracture is normal bone that's subject to abnormal load. So what's the pathophysiology here? So the skeleton is exposed to mechanical loading during running and other activities, and that leads to micro damage of the bone. And this micro damage is a stimulus for remodeling of the bone. And then on the cellular level here, with the micro damage, you get the osteoclasts, which resorb bone. And then this is followed by osteoblasts after that, laying down new osteoid and making a stronger bone. And this is what, really what Wolff's Law is, and we always talk about Wolff's Law as a process that bone responds to stress and becomes stronger with time. So the issue, though, is that this whole remodeling process can take a few months. And when people are doing more training or they're stressing an area, before the bone can remodel, that's when you get your bone stress injury and stress fractures. So what's the incidence of stress fractures? Many of the studies in the literature are from the military, and if you think about it, it makes sense, because you have a very captive audience of military recruits, and they're often a group of people that are forced to do a lot of extra activity when they weren't doing it, so they're really stressing the bone. So there have been good studies, and this is one of them from Israel that was a bone scan study. Bone scans are extremely sensitive for picking up stress reactions or fractures, and they found in this group that there was a 31% incidence of stress fractures. And many of these were in the longer bones, such as the tibia and the femur, but there was some also in the foot and ankle. So there have been studies looking at stress fracture incidence in runners, so in particular cross-country athletes and track and field athletes, and when they looked at this group over a year, there was up to a 21% incidence of stress fractures. Interestingly, you know, in other studies that have shown that 50% of track and field athletes have had a bone stress injury on more than one occasion, and these can often be in the tibia, but they also occur in the femur and throughout the ankle and the foot. There are studies in runners showing that depending on the type of run you are, it depends on where you're going to get your stress fracture, and Dr. Wasserman did a great job at really going through the mechanics of this, but our marathon runners are predominantly heel strikers, and a lot of them would load the longer bones, such as the femur and the tibia, and that's where they get their stress injuries. Other athletes such as sprinters that have a forefoot strike, they may have greater loads to different parts of the foot and would get stress injuries in the midfoot or the forefoot. So what are the risk factors for stress fractures? So there's intrinsic factors of the foot and the ankle. So in particular, any foot type or condition that causes stiffness or malalignment can lead to increased loading of a bone and eventually a stress injury. So this picture on the lower right shows a medial subtalar coalition, and you could imagine that the mechanics of this foot during running would be different than if you had a normal subtalar joint. So higher arched feet can have issues with stress fractures. Those with forefoot verus, tarsal coalition, charcot-marie-tooth, and even leg length discrepancies have all been shown to be intrinsic factors that can lead to stress fracture. There are extrinsic factors, and Dr. Wasserman went through some of these. I often see stress fractures in new runners. People will come in and say, well, I'm training for a 5K, and all of a sudden they have a stress fracture. Over vigorous training, the athletes that are doing a half marathon when they haven't done it before. Interestingly, people that run on harder surfaces haven't been shown to have a higher rate of stress fractures. But as Dr. Wasserman said, if there's any recent change in the type of running you're doing, such as going from a treadmill to running outside, more hills, altered train, that can all be a factor. And then change in footwear or orthotics. Dr. Wasserman also mentioned different medical conditions that you have to think about. The female athletic triad is something that's often written about. So menstrual irregularities with eating disorders can cause issues with the bone being able to resist load and to repair micro damage. Something to look for in elite female long-distance runners. And there's even been studies showing that there's certain factors, such as BMI and greater than 12 hours exercise a week, that can be consistent with this. We all know that vitamin D and calcium are important for our bone health. Calcium combines with phosphate to form the hydroxyapatite crystals. Vitamin D is also important in calcium reabsorption and absorption in the GI system. So there have been studies that have shown that if you have adequate calcium level, and some studies in female distance runners have shown that's protective against bone stress injury. Vitamin D is a really area that has had a lot of study over the last several years. And it seems recently you can publish a paper just by looking at the vitamin D level in your particular patient population. But there have been some studies that have shown a lower risk of stress fracture in those who have adequate vitamin D levels. Some other studies have not shown this. How do these patients present? Usually they come to the office complaining of foot pain. Sometimes they're very specific, saying that it happens after I run a half mile, or sometimes they even say when I have a strike in the running cycle, all of a sudden I have pain. And with time, the pain can become more severe and localized. And often they'll say, well, I could run initially, but I can't do that now. On exam, there is usually tenderness to palpation. Very often there's swelling. And this picture here shows someone with a metatarsal stress fracture. And our patients often come in that way. They have swelling. Sometimes you get a little bit of an inflammatory response around a stress fracture. You get some increased warmth and redness. And it can be confused sometimes with gout or infection. And there are certain tests that you can do to load a part of the foot, and that would give you an idea that that area of the foot is an issue. In the office, we always get x-rays, but x-rays are not all that sensitive for stress fractures. Studies have shown that up to 85% of the time, our initial films are negative. And in follow-up, the x-rays continue to be negative. CT scans are also not all that sensitive. But CT scans are valuable in certain types of stress fractures, such as navicular stress fractures. If we're planning on operating on somebody, they can be helpful. And we often use them to see how patients are healing, especially after navicular stress fractures. So a bone scan is a study that we don't always order, but can be quite valuable. And in the past, I think it was more often used. But a bone scan is very highly sensitive for stress fractures, but not all that specific. And some people think that a three-phase bone scan may allow you to localize in more as bone as the tissue that's causing the uptake. And there can be a higher radiation dose with bone scans, but they still have a place. But MRI is really the gold standard. It's very sensitive and specific. You can identify stress reactions, which is basically edema in the bone without a fracture line. You can't see that on a regular X-ray. And MRI is good because it can rule out other conditions that could be causing pain, such as tendonitis, arthritis, better seen on an MRI. You have to be a little bit careful because just because an MRI shows something, if it doesn't match with the clinical symptoms, it doesn't mean you have to do anything about it. This was an interesting study that looked at college-level distance runners, and 43% of them had some signal change in their tibia consistent with the stress reaction, but none of them went on to develop symptoms or needed any treatment for it. So when we talk about stress fractures in the foot and the ankle, they're often divided into low-risk stress fractures and high-risk stress fractures. Low-risk have a favorable history, and they usually don't need any surgery or extended non-weight-bearing status. Some of these include the metatarsal, the calcaneus, and the fibula, which are common stress fractures that you'll see in the office. And they often occur on the compression side of the bone, which is an easier area for healing or easier side of the bone for healing. High-risk stress fractures can also occur and this is often on the tension side of the bone. They occur often in an area where the blood supply is not as good. They're prone to delayed union and non-union, and these include the tibia, medial malleolus, the navicular, and the proximal fifth metatarsal. You can also grade stress fractures by their MRI findings, and they can be graded as low-grade and high-grade. I know I read a little bit about this. It's not something I would typically look at myself on an MRI, but there have been studies that have shown that the return to sport can be different depending on how impressive the MRI findings are with your stress fracture. So how do we manage these? And we'll first talk about the low-risk stress fractures. So usually the first thing is some type of activity modification, and likely, since this is focused on running, stopping running for some time period. Occasionally patients have to be made partial weight-bearing, but sometimes they can weight-bear in a cushioned shoe and that's enough for them. Sometimes, depending on where the stress fracture or stress reaction is, a different type of shoe, a stiffer shoe, which is good for midfoot and forefoot problems, or a boot for more of the hindfoot low-risk stress fractures, such as the distal fibula or tibia. And then it's good to look to see what stress fractures, or what risk factors the patients have. So you ask them about changes in their training, changes in their diet, try to get a feeling on whether they're taking adequate vitamin D and calcium. And then it's also important in these type of patients that they maintain their physical conditioning. So get them in the pool, possibly cycling, because a lot of these patients, as you know, exercise is very important to them, and it's good for them to continue on with that in some form. Every once in a while, you'll hear about ultrasound as a treatment for stress fractures, and low-intensity ultrasound, you know, has released some growth factors, and it's been helpful in the past for non-unions and certain fractures, such as fifth metatarsal fractures. There have been some studies that have shown that it can be helpful in a bone stress injury that has a delayed union. It's really unclear whether an acute bone stress injury would benefit from it, but that's something that occasionally patients will ask about. So once our patients have been followed, you know, they want to return to running. So some of the things that you can tell your patients is that once a runner is pain-free with regular walking, you can gradually reintroduce running. If they have a setback, then they should stop running for a few days and then go back at lower levels, so less often or lower distance. And then, you know, take advantage of our physical therapy colleagues who do running evaluations, and it's too much to get into a talk like this about whether rear foot or forefoot striking pattern would be more beneficial, and that's something Dr. Wasserman is an expert at. So we'll go through a couple specific stress fractures. Metatarsal stress fracture is extremely common. They're usually in the distal second metatarsal, but it can occur in the third or fourth metatarsal. During running, there is a high bending stress on the second metatarsal, and some of the reason for this is that the base of the second metatarsal is in this keystone of the cuneiforms, and it's thought that that plays a role in why second metatarsals more commonly have stress fractures. These patients have pain in their forefoot. They have dorsal swelling. As I mentioned before, X-rays can often be negative, but after three or four weeks, you usually see some callus formation, and they occasionally, these patients need a cam boot or a stiffer shoe, and they can go back to running, you know, around six weeks, although sometimes it can take longer than that. There are certain metatarsal stress fractures that are slower to heal. The base of the second metatarsal is more common in dancers, and sometimes you have to cast these. The base of the fourth metatarsal is also another area that may take some increased time to heal. You can have stress fractures nearly everywhere. I've seen them in the cuneiforms, the cuboid. They can occur in different areas of the talus as well, and the great majority of these, you know, heal with immobilization and some relative rest. A lot of the studies are from the military, and a lot of these papers that talk about these are older papers, and a lot of them are from, you know, military studies. Calcaneus stress fractures are also relatively common. We see them in long-distance runners. Usually the stress fracture is in the tuberosity. There's swelling and pain with compression in this area. It's common to have some stress injury or reaction in other tarsal bones at the same time, and again, usually not picked up on x-rays initially, but you can see some evidence of healing at three or four weeks. I often see these in most patients just benefit from some time in a CAM boot. Maybe the stress fracture is very common in runners. They can also occur in patients who are not running, but, you know, usually you see this transverse line, so whenever you see a transverse line, you know that it's not a typical rotational ankle fracture, and they often have a stress fracture. Again, x-rays are negative initially, and they heal with some time in a CAM boot with returned activities anywhere from six to eight weeks. So we'll spend a couple minutes talking about some of the high-risk stress fractures. The navicular is one of these. The navicular articulates with the cuneiforms, the cuboid, and the talus. It's part of our transverse tarsal arch. It has many ligament attachments, including the posterior tibial tendon. It has a poor blood supply, especially in its mid-aspect, which contributes to its high risk of nonunion stress fracture. So this area where the blood supply is not great is also an area in the navicular that sees significant shear stress. So the medial and the lateral side see different forces during walking, and this, you know, combination of the shear stress and the altered blood supply can cause the stress fracture. Very common in running and jumping athletes, but also seen in basketball players and runners. There have been some studies that show navicular stress fractures are common in those with a foot that's not all that flexible. They come into the office complaining of pain along the anterior aspect of their ankle. Sometimes it goes undiagnosed for some time. There is an area of tenderness sort of in the mid-aspect of the navicular. This is one of my recent patients, and I asked him to point where his pain was, and he's a little bit more medial than normal, but that's typically what they say when you ask them to describe their pain. As with all these stress fractures, x-rays are often negative initially. One study showed that only 18% of x-rays were positive when it was confirmed with a CT scan. MRI, CT, bone scan are all more sensitive studies. MRI is good because it can detect stress reactions, which are edema in the bone without a fracture line. CT scan is valuable, so we'll usually get both an MRI and a CT in these patients, and the CT is good for looking at bony detail, good for pre-op planning, visualizing coalitions, and other causes of pain. Some navicular stress fractures can have sclerosis, which may make some changes for our operative plan if they go to the OR, and we use the CT scans also to monitor healing. There have been different classifications of stress fractures. Type 0.5 is a stress reaction. Type 1 are dorsal cortex fractures. Type 2, some extension of the fracture into the navicular body, and Type 3 is a complete fracture. These CT scans on the bottom are one of my patients from a few years ago, not an athlete, but a longstanding navicular stress fracture with fragmentation, and so it can run the gamut of severity. There's still some debate on what's the best way to treat navicular stress fractures. There have been reasonable results with both nonoperative and operative treatment. A lot of the studies on this are older, and Dr. Torg was a sports medicine orthopedist in Philadelphia, wrote a lot about navicular stress fractures and fifth metatarsal stress fractures, and he even came to our annual meeting a few years ago to represent some of his data. He and some other authors at that time showed that navicular stress fractures would do well as long as they were casted and not weightbearing, and there was studies from Dr. Torg and other studies here that have shown that nonweightbearing in a cast will allow patients to return to sports. The important thing here is that they have to be nonweightbearing. In some of these studies, weightbearing in a cast was not associated with good results. So the concerns with nonoperative treatment would be noncompliance with weightbearing status. A lot of our patients want quicker solutions, and patients are more programmed to want surgery for these type of issues, and then there's cast disease. We don't use casts as often as we would in the past because of the atrophy and stiffness, and patients be more prone these days to be in a boot rather than a cast. So surgery for navicular stress fractures is usually for complete or displaced fractures, fractures in elite athletes and high-activity-level patients. So for the stress reaction, probably not surgery, but for the other types, most likely surgery these days, and some studies have shown an early return to sports with surgery versus non-op care. So what happens in surgery? Usually, we go ahead and place cumulated screws, and these are 4-millimeter screws, and they are partially threaded and they compress the area of the fracture. This can be lined with some type of bone grafting, and none of this is really standardized. Sometimes you'll use some bone marrow aspirate, which you often take from the iliac crest. Other times, you can percutaneously put graft in, and in the fractures, which are larger, then sometimes you have to open up the area and use some iliac crest or other type of graft. We follow the patients with CT scans at 6- to 10-week post-op and return to activity when there's healing, and there can be a high rate of nonunion treating these fractures. So that's something you have to let the patients know. A few slides on fifth metatarsal stress fractures. The great majority of fifth metatarsal stress fractures now are avulsion fractures, and that's not what we're talking about here. The Jones fracture is a metaphyseal-diaphyseal fracture that has a prognosis of slow healing, and this describes a fracture that extends into the 4- or 5-intermetatarsal facet, and Jones fracture is usually an acute fracture. Stress fractures are different. They're usually a little more distal, and they're not as common as the other two. So these patients usually have some pain before they present with their stress fracture. Sometimes they have ongoing pain and then an acute event that makes them come in. Common in football, basketball players, soccer players, but can occur in any type of running or jumping athlete. Traditionally, we thought that patients with fifth metatarsal stress fractures had a cavus foot, but this often occurs in NBA basketball players, many of which don't have a cavus foot but more of a flatter foot. There's been work on looking at the angle between the 4th and 5th metatarsal. This may play a role. So there's also been a classification system for stress fractures. Again, Dr. Torg from Philadelphia wrote about this. Acute fractures with no sclerosis. Type 2 fractures are showing that they want to heal, but they quite haven't gotten there. They have some new bone formation and a little bit of beaking at the fracture site, and then type 3 are non-unions with wide gaps at the fracture site and sometimes some sclerosis in the intramedullary canal. So the treatment for these, again, you can consider non-weight-bearing in a cast, but most of the time these days we are taking people to the LOR for percutaneous screw fixation. For type 2, screw fixation does work well. There's been a couple studies that talked about a tension band construct, which I'll show you a picture of. It's good because they can usually weight-bear it around two weeks when you do an intramedullary screw and there's good results reported in the literature. Type 3 are less common, and usually you need to open up this fracture and place some type of bone graft. So this is one of my patients from a few years ago, and you can see that this fracture was having a little bit more in the Jones fracture area, not as distal, but an intramedullary screw and some percutaneous iliac crest aspirate graft showed that this eventually healed, and the patient went back to their activities. If you read the literature on this, you'll see sometimes you'll talk about a planar plate, which is another way to fix these, the plates on the tension side of the bone, and that can be helpful. And then just a picture of what a tension band construct looks like. It's not a very typical technique for this area these days. Finally, just two slides on medial malleolus stress fractures. Again, in runners and those participating in jumping sports, there's some impingement of the talus on the medial mal during ankle dorsiflexion and rotation. Often this can be in patients who have some early DJD or impingement in their ankle, and you get this vertical fracture line. So for these patients, if it's just seen on an MRI, they can usually be cast or put in a CAM boot, but if it's seen on plain radiographs, it's typically good to do an ORF, and there's many different ways to do it. I think that this technique demonstrated here is good because it's a vertical fracture line, and you get an anti-glide plate, and it's a nice way to make sure that these are stable and will heal. And if there's any issues with impingement, if they have, you know, anterior springs, such as in our soccer players, then a scope to remove the impingement is helpful. Thanks for your attention. Great. That was perfectly on time as well. Nice job. So thank you. That was a really nice overview, and I think that kind of separating what you focused on, the difference between those high versus low risk stress fractures is really important as far as management. So with that said, let's all head back again to the main room and meet our physical therapist.

stress fractures

pathophysiology

risk factors

incidence

management

repetitive loading