[Progressive slipping in severe spondylolisthesis-long-term observation (author's transl)].

In total consolidated dorsal fusion it is possible that the decreased intervertebral distance as well as the displacement can increase. 50 patients treated in the period from 1925 till 1977 with a spondylolisthesis of more than 50% have been reviewed. 36 of them were treated by a dorsal fusion, the 14 other patients without operation. Increased displacement was found in 43 cases. This phenomen will be brought about the deflective deformation of the dorsal fusion. Depending on the elasticity bone rebuilding under substinent biomechanical conditions is possible. In the course of time, total intercorporal consolidation leads to a difinitive stability and relief of pain.