[Spondylolisthesis of L5 and retrospondylolisthesis of L4]

A group of 106 cases of I. isthmic spondylolisthesis of L5 was divided into two subgroups: "A", without retrospondylolisthesis(n = 51) and "B", with retrospondylolisthesis of L4 (n = 55). A spondylometric analysis took into account the line of static loading, lumbar lordosis, the Fergusson's angle, the angles of the L4L5 and L5S1 intervertebral disks, and their heights. The measurements showed that a statistically significant difference occurs in the medium values of incidence of the line of static loading. It would confirm the thesis about the compensatory character of the position in retrospondylolisthesis of the L4 vertebra in consequence of disturbances of statics caused by isthmic spondylolisthesis of L5. Furthermore, this interdependence occurring in 52 per cent of the cases manifests possibility of complications caused by instability in the segment above spondylolisthesis.