Biomechancis

In recent years the scientific community has shown an increased significant interest in the relationship between biomechanics and diet in extant and extinct primates. Most of these conclusions were based on the analyses of cranial morphology or unworn teeth. However, while tooth morphology can suggest what type of food can be processed, dental wear can tell us how a tooth is used. In this study, we examine the stress distribution in a digital model of a second mandibular molar of Pongo pygmaeus during occlusal loadings, taking into account the macrowear pattern. We combine together two different digital approaches: Finite Element Analysis (FEA) for the study of stress distribution and the Occlusal Fingerprint Analysis (OFA) for the examination of dental macrowear. The OFA results show a flat wear pattern characterized by large Phase II and large buccal phase I facets. On the contrary, the lingual phase I facets are less developed with the exception of facets 5 and 7 that form along ...

Purpose: Determine if an athlete's natural or imposed foot strike posture influenced the magnitude and/or timing of peak Achilles Tendon forces during treadmill running. Conclusion(s): No differences in AT forces were observed between natural RFS and FFS runners. Differences in AT force characteristics were only observed when a runner transitioned from their natural to an imposed foot strike posture.

Pongo pygmaeus is a large great ape that lives in highly sea- sonal environments of Borneo, where the preferred foods, such as ripe and soft fruits, are often unavailable. During these periods orangutans rely on hard food items, such as nuts and seeds, which become particularly challenging to eat. Is their dental morphology designed to feed on these hard foods? In order to answer this question we employ an innovative digi- tal approach that integrates Finite Element Analysis with oc- clusal molar macrowear. Our preliminary results on a lower second molar (M ) suggest that the feeding behavior of orangutans manly involve crushing masticatory processes and
little shearing, typical of hard-object diets. The morphology of P. pygmaeus M2, with low cusps, thick enamel and a wrinkled occlusal surface seem to minimize tensile stresses in the tooth. The protostylid with its (moderate) buttress-shaped morphol- ogy seems to functionally suffer the high tensile stresses concentrated along the buccal groove of the crown by the extensive load applied on the buccal cusps during maximum intercuspation. Thus, it appears that non-preferred foods (also called fallback foods) such as nuts and seeds have played a major role in the evolutionary and morphological adaptations in P. pygmaeus molars. This new method can be further used to advance our understanding of the diet, morphology and evolution of extinct hominins.

This study compared the movement and coordination variability of the previously injured leg of ACL injured subjects (ACLr, n=9), against their non-injured leg and a control (nACL, n=9) leg. The variability of lower limb joint angles and couplings were calculated during a land-cut task (n=20). The previously injured leg had less variability than the non-injured leg in the knee rotation–knee abd-adduction coupling, and more variability than the nACL leg in frontal and transverse knee joint angles and hip rotation–knee abd-adduction coupling. Reduced coordination variability could produce a more repetitive loading pattern linked to cartilage degeneration. Increased movement and coordination variability may stem from proprioceptive deficits on the previously injured leg and decrease the ability to adapt to perturbations.