Facet Joint Orientation in Spondylolysis and Isthmic Spondylolisthesis

Abstract

Relative coronal FJO in the lumbar spine may be the phenotypic expression of the familial etiology of IS. This may result in increased stress concentration in the pars between or below coronally oriented FJs. These more coronal FJOs in IS may also explain the common observation of retrolisthesis at L4/5 above IS when the L4/5 disc degenerates, lateral overhang of the L4/5 FJ to the L5 pedicle entry point above an IS, and the rare combination of DS at L4/5 and IS at L5/S1 when both disorders are separately common. This latter observation can be explained by the observation that DS occurs in those individual with sagittal lumbar facets, and that IS occurs in those with more coronal FJs.