Can morphological variables be used to predict hip joint function? An examination of the anthropoid proximal femur and range of abduction (919.10)

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Femoral morphology is often been used to make inferences about hip mobility in fossil anthropoids, abduction ability in particular. However, no study has shown that variation in hip morphology is actually related to hip mobility. If hip joint mobility is predicted by morphological variation, this would provide a new tool to more specifically evaluate locomotor adaptation in fossils.We present results of an in silico model of anthropoid hip joint mobility that has been validated on a large sample of extant taxa (hominoids, cercopithecids, Ateles, Cebus). Pelves and femora of the same taxa were laser scanned and polygonal models were digitally articulated. Maximum hip abduction was modeled using PolyWorks software using strict morphological criteria for joint movement. Several morphologies of the femur that are hypothesized to relate to hip mobility were quantified from the laser scan data using PolyWorks. Regression was used to assess the relationship between morphologies and functional abilities.Neck‐shaft angle and femoral head orientation were significantly related to degree of abduction. However, the majority of morphologies quantified were not significant predictors of hip abduction ability, suggesting that many of the morphologies attributed to high joint mobility may not relate to increased abduction ability. This work has applications to reconstructing locomotor abilities in fossil anthropoids.Grant Funding Source: Study supported by NSF (BCS 1232393, 0647557, 0716244), Wenner Gren Foundation, LSB Leakey Foundatio