 Good afternoon everyone and thank you for staying around till the bitter bitter end. I thought it's been a really interesting and productive session so far and I'd just like to thank the organizers again for all of the work that you've done over the multiple months leading up to this and it's been a really great session so thank you very much for that. Today I'm going to be speaking to you about some ongoing research that's being done as part of the after the plague project under the umbrella of that and John Robb introduced that earlier today so we're just going to jump right in. So there are a lot of different reasons that have been talked about today for why an individual may experience a period of immobilization or have some kind of incident that would alter their gait. Congenital malformations for example, fractures to the lower leg have all been discussed and we are working as part of this project to try to come up with a way to understand what's happening in the bones a little bit better. So what we're trying to do by taking this biomechanical approach is explore the trabecular bone which is not something that has really been done so far. So just in case there's any non-bone people in here there are two types of bone tissue in the human body you have cortical bone and trabecular bone. Cortical bone is the dense outer surface and it protects the internal cavity which is where the trabecular bone lives and it's also called spongy bone and you can see it on the image here and we're assisted in the trabeculate. So generally within biomechanical studies physical impairment has been restricted to pretty much cortical bone and not a lot has been done on the trabecular bone because we don't as biologists know very much about it. What we do know about it is that it is highly plastic in response to loading history. Trabecular bone turnover rate is much higher than that of cortical bone so because the surface to volume ratio is much higher so that's why the trabecular bone remodels quicker than cortical bone. So as part of this project we've theorized that this higher remodeling rate of the trabecular bone may enable us to detect adaptations in mechanical loading that occur closer to the time of death and it might be closer to the time of injury so we can see not only that an individual has had some kind of traumatic event but also how the body has responded to this event. So if you've had some period of disuse you should be able to see it in the trabecular bone and hopefully we're still working on this we're going to start looking at the potential of trabecular bone to reconstructing activity that would have followed these types of traumatic events. So the aim of my talk today is to just talk about our understanding of physical impairment in medieval societies and how we're doing our CT scans to improve the biomechanical analysis of the trabecular bone and what potential ramifications that could have to studies of physical impairment and disability specifically within the medieval period. So for this course of this project I have analyzed 327 individuals from the center close enough to Medieval Cambridge so the individuals that we're going to be talking about today are either coming from an Augustinian friary, a parish cemetery or the hospital of St. John's the evangelist and again like I said before there's 12 people working on this project I did not do all this work myself. Bram Mulder our PhD student has done all of the CT scans Sarah and Skip and I sit in the lab all day working on skeletons so again this is very much a team effort. So in the course of this process we have analyzed four we found 14 individuals that had anti-mortem fractures to the lower limb or a musculoskeletal deformity and because we are running a tight ship on time today we're only going to talk about two of them we had an elderly female that had an intercapsular fracture which we're going to talk about and then a gentleman that had a tibial plateau fracture and they're going to be our poster children for this method so what we did was once we identified these individuals as having a traumatic injury or some kind of physical impairment we believe we took plain x-rays which were used to determine the degree of angulation the rotation of overlap of the fracture and if there are any secondary or complications of that fracture we then use micro CT scans to analyze the trabecular and cortical bone architecture of the femurs so we have 14 individuals that have been completely scanned so far so our two pathological individuals and then our 12 control samples that we're using to map a variation within the bone so cortical geometry was analyzed at the mid shaft and then the trabecular bone structure was quantified in two volumes of interest that were placed at the proximal and distal femur and you can see the areas on the screen the red is your proximal there and then the green is your distal area so what does all this mean we analyzed these individuals using a number of different parameters absolute cortical area bone shape so the ratio between the short and the long access cortical bone thickness curvature of the bone but for the sake of this presentation we are going to talk about the three most straightforward and most promising parameters that we are using to identify asymmetry that was caused by the periods of disuse so only focusing on three they are j values the relative cortical area and the bone volume fraction so there's definitions of these things are i'm just going to give you the j value and the bone volume fraction for now because they're they're the most interesting we think so the j value is the most common indicator of cortical bone quality and it's used to record things like loading history however it remains largely unchanged after an individual reaches peak bone mass so that usually occurs in the late 20s and early 30s a bone volume fraction is the key characteristic that we use to quantify trabecular bone strength and it's a it's a it's a good way to hopefully look at the more rapid adaptations that occur over the course of a person's life so our first individual is a mature adult female who is buried at the hospital of st john's the evangelist her psn number is 335 this individual presented with a healed intercaptural femur fracture on the right side and then secondary ankylosis of the hip joint and you can see the posterior view up on the screen and then the x-ray where you can kind of see how the the epithesis has slipped and you can see the line of the fracture as well so based on the macroscopic examination of the x-rays we hypothesize that this individual would very likely have evidence of asymmetry in the trabecular and the cortical bone which resulted of her not being able to load that right leg properly you can't tell but this this hip has essentially fused at a 45 degree angle making it pretty much it's pretty pretty unlikely that she would have been able to exert a lot of force through that limb which is why we chose her as our very first sample so these graphs show the j values and the relative cortical area of the pathological individuals and then compare it to the control so we can see that 335 is well outside the two standard deviations in terms of j values so this indicates their substantial asymmetry suggestive of disuse atrophy so she wasn't loading her right side essentially is what that is when we look at the trabecular bone these are actually quite quite drastic reduction in bone mass this is more than 10 standard deviations outside of the norm so this is this is pretty solid evidence that our our method is is working to at least be able to identify the differences in trabecular bone certainly in within the same individual so we don't see the drastic difference in asymmetry in the distal femur which is really interesting so if you look at the graph oh good it's used to stick so this is where we have in the proximal so this is the femur of the femoral head this is the distal portion but this is perfectly within our our our natural variation and we can't really explain why this is so forthcoming research is going to have to enlighten us but for now we we don't know why it would only show up in the proximal and not in the distal part of the bone but when you look at these cross sections here you can see that more than twice the amount of trabecular bone exists in the left side when you compare it to the right so this is still overwhelming evidence that the right side was largely unloaded for an extended period of time and then you can also just take a look here at the gradual reduction of the trabecular bone and everyone agrees there's a lot less on the right side so great the method works we think we're going to move on to our next individual seven two three he's an old adult male he was buried at a parish cemetery uh called Holy Saints by the castle we also called Converse Place he had a left tibia that was five centimeters shorter than the right side because he had a growth plate fracture that occurred on that left side at some point during his adolescence this is why it resulted in it being five centimeters shorter so for this individual we hypothesized that we would see evidence of uneven loading because he's probably not able to again exert as much force through that left side as is the right there's certainly would have been a situation where this individual would have presented with an altered gait he would have had he would have had a noticeable length when we looked at this the cortical bone and the j values were completely normal which is not at all what we anticipated that we would find but the relative cortical area which is on this side over here is an outlier and this is really interesting because the relative cortical area offers insights into remodeling after the individual reaches peak bone mass which again is in your late 20s into your early 30s well with this case that tibial plateau fracture would have occurred much earlier than this so I have a theory about this because we're among friends I'm going to tell you about in just a minute so when we look at the trapecular bone again we don't really see any asymmetry in the loading so this again is unusual because it means that during childhood and up to the point of skeletal maturity he was loading his legs relatively evenly which again because this fracture occurred in adolescence it shouldn't be the case so I thought about this for a while and if we accept the trapecular bone is reflective of the last couple of years of life before this individual died one possible interpretation of this data is that this individual would have been using some kind of device like an elevated shoe for example to achieve equal loading of his legs so I went into the medieval literature and there are a number of depictions of walking aids in the medieval period I have not yet found any kind of platform shoe maybe somebody has come across one if you do email after the play project and let us know but it is clearly common practice certainly in the medieval period to have these kinds of walking aids we saw a number before from the from the Dutch painting so it is perfectly possible that some kind of device was used by this individual which would result in his legs being loaded evenly so in conclusion I think that both corticobone and trapecular bone can be changed as a response to altered loading conditions and there seem to be telling different parts of the same story so we could potentially start looking at different aspects of impairment that occurred or changes in circumstances that changed over the course of an individual's life so the study of both trapecular bone and corticobone together should be able to give us a more sensitive tool for detecting cases of fiscal change in the past rather than just relying on the corticobone which has been done up until this point I'd just like to thank everybody again for coming to this session and also all of the people who have helped us with this research the welcome trust for funding it and thank you very much