1Department of Evolutionary Anthropology, Duke University, 2Institute for Human Evolution, University of the Witwatersrand
Thursday All day, Plaza Level
Osteoarthritis (OA) is a degenerative joint disease promoted by a diverse array of genetic, somatic, environmental, and temporal factors. Approximately 27% of the American population suffers from OA of the hip, but signs of OA are rare in the hominin fossil record. It has been hypothesized that joints most commonly affected by OA, including the hip and knee, are those that have evolutionarily undergone significant morphological change increasing loading. Few morphological risk factors for OA in modern humans, however, have been determined. Recent research has suggested that gross morphological deformity of the hip predisposes the joint to OA in later life. Minor variation in hip morphology may have no functional ramifications, but could influence the biomechanics of the joint, altering the load and potentially fostering OA. In the present study, 115 radiographs of patients suffering from OA of the hip were examined and biomechanically relevant metrics were recorded. In patients with one affected hip, femoral biomechanical neck length and neck-shaft angle were significantly bilaterally asymmetrical. Relative biomechanical neck length, relative femoral head diameter, and neck-shaft angle were also significantly different between the pathological and control samples. These data suggest that subtle morphological variation in the hip influencing loading patterns are correlated with hip OA and indicate that modern humans may be more predisposed to OA than australopiths and Early Homo as result of increased joint reaction forces associated with the modern morphology.