TESTING THE EFFICACY OF ASPARTIC ACID RACEMIZATION FOR AGING ADULT HUMAN SKELETAL REMAINS

Few problems have confounded bioarchaeological research as that of aging older (\u3e 40 years) adult human skeletons. Researchers have targeted virtually every area of the skeleton and dentition in order to develop sequences of morphological and microscopic changes that can be correlated with chronological age. The key problem is that the morphological and microscopic changes are more variable with increasing age and this variance reduces their correlation with chronological years. In the past three decades molecular research has impacted virtually every research area in bioarchaeology except aging. The main objective of this thesis is to test aspartic acid racemization in human dentine as a means of obtaining age-at-death estimates from skeletonized remains. I found that without standard operating procedures this methodology is problematic. Suggestions are given in order to standardize this methodology for use in future bioarchaeological research projects

The Human First Metatarsal in Bioarchaeological Research: New Insights into Human Variation and Bone Health Research from Kellis 2, Dakhleh Oasis, Egypt (50-450CE)

Objectives: This research tests the efficacy of using the human first metatarsal (MT1) in bioarchaeological research, specifically to investigate human variation (nonmetric traits and sexual dimorphism) and skeletal health (Osteo-Volumetric Density and µCT analysis) in antiquity. To date, this bone has had limited applications in bioarchaeology. Materials and Methods: This study used human remains from the Kellis 2 (K2) cemetery, located in the Dakhleh Oasis, Egypt (50-450CE). Specifically, 377 MT1s, representing 212 individuals were used to investigate human variation and osteo-volumetric density (OVD) in the K2 skeletal population. Additionally, skeletal health was further assessed in a female sub-sample (n=44) of the population using µCT analysis. µCT imaging of the MT1s was conducted using eXplore speCZT scanner, and analyses were done in MicroView with the Advanced Bone Analysis Application software add-in (Version 2.1.2, GE Healthcare Biosciences, London, ON) Results: The intermetatarsal facet had a prevalence of 28% in the K2 skeletal population. Moreover, significant sexual dimorphism was observed for MT1 metrics, and logistic regression models could predict the sex of an individual from K2 between ~80-90% of the time. The novel OVD method was found reliable/reproducible through intra-/inter-observer statistical analyses. The OVD patterns differed significantly between males and females, as well as between age-cohorts. The inverse relationship between age and the estimated OVD in K2 females was much more pronounced than was seen in K2 males. Additionally, an inverse relationship between biological age and the standard measures associated with bone strength/architecture using µCT analyses was observed for the female sub-population. The T-scores of individuals previously diagnosed with osteoporosis (based on age and fractures) were significantly below the mean of the “healthy” population using both OVD and µCT analyses of the MT1. Conclusions: The first metatarsal is a suitable element for the study of human variation and skeletal health in antiquity. Although not an area normally associated with osteoporosis related fractures, this research shows that the MT1 is not spared from age-related bone loss, and may prove useful for investigating skeletal health when the more traditional elements are not available

Limiting the impact of destructive analytical techniques through sequential microspatial sampling of the enamel from single teeth

A fundamental research concern within contemporary bioarchaeology is the sensitive balance between the preservation of human remains and the use of destructive techniques to collect information. Here we describe one example of how multiple microspatial destructive/semi-destructive techniques may be carried out in sequence using only the enamel of a single tooth. With careful planning of both sample preparation strategies and sequencing of sampling methods, it is possible to produce multiple datasets, and yet to retain material for future analyses. In this case, enamel from the teeth of 27 individuals who lived during the early medieval period (AD 1170-1198) in Bergen, Norway, were subjected to histological, trace element (LA-ICP-MS), diagenetic (FTIR), and isotopic analyses (δ18O and δ13C, via micromill/multiprep/IRMS)

Impact of surgeon’s hand and ocular dominance on right and left total knee arthroplasty alignment

Postoperative alignment is an important modifiable confounder that contributes to the longevity of total knee arthroplasty (TKA). Studies have shown that surgeon’s handedness can affect surgical performance; however, no studies have assessed the effect of surgeon’s hand or ocular dominance on TKA alignment. The purpose of this study was to evaluate the effect of surgeon’s hand and ocular dominance on coronal plane alignment in TKA. We retrospectively evaluated 138 patients who underwent sequential bilateral TKA by the same surgeon, using the Genesis II PS knee (Smith & Nephew, Memphis, TN). We assessed postoperative alignment by measuring and comparing anatomical tibiofemoral angle (TFA) bilaterally on standard postoperative knee radiographs, as well as Knee Society function and pain scores to determine any functional differences. Lastly, we evaluated whether a crossed hand-ocular dominant surgeon had greater accuracy when performing a TKA on the side opposite their hand dominance compared to uncrossed hand-ocular dominant surgeons. All surgeons were right-hand dominant and there was a significantly larger anatomical TFA on left TKAs (mean [SD], 4.6° [2.8°]) compared to right TKAs (3.8° [2.5°]) (P = 0.003). There was no significant difference between right and left Knee Society function (P = 0.09) and pain scores (P = 0.86). When comparing left TKAs, surgeons with uncrossed hand-ocular dominance (4.5°) performed with equal accuracy compared to surgeons with crossed hand-ocular dominance (4.8°) (2-tailed test = 0.597), indicating no effect of ocular dominance. In summary, hand but not ocular dominance was shown to have significant postoperative alignment effects on TKA