As a result of a radiological prospective study carried out in 121 cases in 19 years on the average, degenerative spondylolisthesis was found in 22 cases.
The type of the zygapophysial joint in a group of the spondylolisthesis in 22 cases was M type or W type, but was not X type.
In a group of the spondylolisthesis in 22 cases, the pedicle-facet angle and the zygapophysal joint angle had enlarged before spondylolisthesis.
We think that the cause of spondylolisthesis was associated with the type of the zygapophyseal joint, the pedicle-facet angle and the zygapophyseal angle.
