In a collection of Eskimo and Indian skeletons, three specimens were found with first-degree or second-degree spondylolisthesis without separate neural arch. This type of vertebral displacement is shown to be due to arthritic erosion of the articular facets and, therefore, idenitical with the so called "pseudospondylolisthesis" of Junghanns. Because of the infrequency of this condition, a large series of adult spines of these racial groups has been studied with the aim of detecting possible etiological factors.
On the basis of the usual distribution of lipping of the vertebral bodies, it is pointed out that displacement is apparently not responsible for the lipping in the present cases. A study of the distribution of arthritic facets shows that other regions of the column may be more frequently involved than the lumbar. Within the lumbar region the frequency favors the fourth and fifth lumbar joint and the female sex. The locations of arthritic facets suggest that trauma connected with spinal mobility may be a predisposing factor. Clinical data will be required to determine immediate factors.