Introduction Several studies have attempted to define etiological fac- t ors for the development of degenerative spondylolisthesis ( DS), and the orientation of lumbar facet angles relative to the transverse plane has been a major focus of interest. The facet joints play a critical role in maintaining stability of the lumbar spine by sharing load in compression and extension, and protecting the disc from excessive shear and rotational forces [1, 13, 24]. Determined by their spa- tial orientation, they also guide motion between two adja- cent vertebrae. Their oblique orientation in the lumbar spine allows flexion, extension, and lateral bending, but only a small amount of axial rotation [27]. It has been shown that in patients with DS, the facet joints are significantly more sagittally oriented, thus al- lowing the superior vertebra to glide anteriorly. Individu- als with sagittally oriented facet joints have therefore been regarded as candidates for DS [23]. However, it is clear whether this more pronounced sagittal orientatio the facet joint represents a pre-existing morphology whether it has to be considered a result of secondary re modeling. Facet joint asymmetry (tropism) has been claime be related to disc herniation and degenerative disc dise due to rotational instability of the spinal segment 20]. Whether facet joint tropism plays a role in the deve opment of DS, however, has not been investigated. The present study analyzed facet joint orientation the transverse plane in patients with DS and comp this to patients with no evidence of ventrolisthesis from three different age groups. The working hypothesis that if the more sagittal orientation in DS was a pre-exi ing anatomical feature, it then should be possible to ide tify a younger patient group being “at risk” for the deve opment of DS later in life. The incidence of facet joint t pism in the different groups was also investigated. Abstract This study analyzed trans- verse facet joint angulations at the three lower lumbar levels in 132 pa- tients assigned to one of four groups. Group A comprised 23 patients with degenerative spondylolisthesis (DS) at the level L4-5, group B comprised 40 patients above the age of 50 years, group C comprised 38 patients aged between 35 and 50 years, and group D comprised 31 patients under the age of 35 years. Groups B, C, and D had no evidence of DS. Measure- ments were taken from hard copies of axial MR or CT images. The transverse plane of facet joints was more sagittally oriented in group A than in any other group. This differ- ence was highly significant at the L4-5 level. The incidence of more sagittally oriented L4-5 facet joints was also significantly higher only in group A. The incidence of facet joint tropism, however, was not different in group A. These results support the view that the pronounced sagittal alignment of facet joints in patients with DS represents a secondary re- modeling rather than a pre-existing morphology. Facet joint asymmetry does not seem to play a major role in the development of DS. Key words Lumbar spine · Facet joint · Remodeling · Degeneration · Ventrolisthesis ORIGINAL ARTICLE Eur Spine J (1998) 7: 376–380 © Springer-Verlag 1998 U. Berlemann D. J. Jeszenszky D. W. Bühler J. Harms Facet joint remodeling in degenerative spondylolisthesis: an investigation of joint orientation and tropism Received: 12 January 1998 Revised: 6 June 1998 Accepted: 16 June 1998 U. Berlemann (Y) Department of Orthopaedic Surgery, Inselspital, University of Bern, Freiburgstrasse, CH-3010 Bern, Switzerland Tel.: +41-31-632 2222, Fax: +41-31-632 3600 D. J. Jeszenszky · J. Harms Department of Orthopaedic and Trauma Surgery, Center for Spinal Surgery, Karlsbad-Langensteinbach, Germany D. W. Bühler M. E. Müller Institute for Biomechanics, University of Bern, Switzerland