Sagittal clefting of the body and other vertebral developmental errors in Canadian Inuit skeletons.

The objective of this study was to determine the expression, distribution in the column, and overall frequency of sagittal clefting of the vertebral body in the skeletons of two Canadian Inuit groups. One group, referred to as Thule-Historic, lived along the coast northwest of Hudson Bay, while the other, known as the Sadlermiut, were limited to Southampton Island and Coats Island north of Hudson Bay. The Thule-Historic people are thought to be the ancestors of the present-day Inuit of this region, whereas the much smaller, relatively isolated Sadlermiut became extinct during the winter of 1902-1903. The sagittal clefting results were also compared with those obtained for two other vertebral developmental problems, segmentation error and spina bifida. Sagittal clefting was found to occur with high frequency in the two Inuit series, especially in the region T6-T10. Segmentation errors were found to occur in approximately the same region of the column, while spina bifida produced a completely different pattern, occurring primarily at T11 and S1. The T11 involvement is limited to females, while S1 involvement occurs primarily in males. Sagittal clefting and spina bifida occur in the same individual more frequently than sagittal clefting and segmentation error. Possibly reflecting the smaller population size and isolated location of the Sadlermiut, sagittal clefting was found with greater frequency and intensity in the skeletons of this group than in those of the Thule-Historic Inuit. Am J Phys Anthropol, 2003.

Asymmetrical spondylolysis.

The objective of this study was to examine examples of spondylolysis in which the pattern of separation was clearly asymmetrical, in order to learn more about the process of bone separation that produces this condition. Although the primary focus was on unilateral complete separation, examples of asymmetry represented by incomplete separation and by complete bilateral separation where the separation sites are in different locations on the two sides were included. Two collections were used, one consisting of Canadian Inuit skeletons curated at the Canadian Museum of Civilization, and the other of 48 individual examples of asymmetrical spondylolysis from sites in a variety of localities curated by several different institutions. The first collection was studied primarily to observe early manifestations of spondylolysis, particularly incomplete separation, while various patterns of asymmetrical complete separation were the focus of the second. The results indicate that asymmetry is part of the earliest osteological picture of spondylolysis, with right-sidedness predominating, a condition perhaps related in some way to handedness. The right-side predominance appears to decrease with age. The ratio of unilateral to bilateral separation ranges from 3-33% in different studies, and a significant number of the unilateral separations have spina bifida occurring in the same vertebra. Overall, the specimens examined here, considered along with clinical cases, nicely illustrate a progression of spondylolysis. A unilateral separation may heal, it may progress to bilateral separation, or it may remain as a permanent condition, producing a pattern of degenerative changes that can include spondylolisthesis. A unilateral healing of bilateral complete separation is likely a rare phenomenon, at least after the separations have reached a certain level of maturity.