title: Spondylolisthesis and posterior instability.
abstract: We present the case of a patient with a spondylolisthesis of L5 on S1 due to spondylolysis at the level L5/S1. The vertebral slip was fixed and no anterior instability was found. Using functional magnetic resonance imaging (MRI) in an upright MRI scanner, posterior instability at the level of the spondylolytic defect of L5 was demonstrated. A structure, probably the hypertrophic ligament flava, arising from the spondylolytic defect was displaced toward the L5 nerve root, and a bilateral contact of the displaced structure with the L5 nerve root was shown in extension of the spine. To our knowledge, this is the first case described of posterior instability in patients with spondylolisthesis. The clinical implications of posterior instability are unknown; however, it is thought that this disorder is common and that it can only be diagnosed using upright MRI.
authors.affiliation: Privatpraxis für Upright MRT, Köln, Germany. p.niggemann@mrt-koeln.de
authors.forename: P
authors.initials: P
authors.lastname: Niggemann
authors.forename: P
authors.initials: P
authors.lastname: Simons
authors.forename: J
authors.initials: J
authors.lastname: Kuchta
authors.forename: H K
authors.initials: HK
authors.lastname: Beyer
authors.forename: H
authors.initials: H
authors.lastname: Frey
authors.forename: D
authors.initials: D
authors.lastname: Grosskurth
mesh_terms: D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D007593:Joint Instability / Q000175:diagnosis*; D017116:Low Back Pain / Q000209:etiology; D008159:Lumbar Vertebrae / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology; D012447:Sacrum / Q000473:pathology; D012680:Sensitivity and Specificity; D013115:Spinal Canal / Q000473:pathology; D013126:Spinal Nerve Roots / Q000473:pathology; D013168:Spondylolisthesis / Q000175:diagnosis*; D013169:Spondylolysis / Q000175:diagnosis*