title: A square to indicate the unstable zone in severe spondylolisthesis.
abstract: The reduction and stabilisation of high-grade dysplastic developmental spondylolisthesis by means of modern internal fixators can correct slip, but can leave the sagittal alignment unbalanced, causing instability, e.g. in the adjacent, non-fused lumbar segments. Through analysis of the modifications of imbalance in the spine and pelvic ring due to surgical correction, this study defines the unstable zone of high-grade dysplastic developmental spondylolisthesis and proposes a simple radiographic method to identify it.
authors.affiliation: II Sezione di Chirurgia Vertebrale, Istituto Ortopedico Galeazzi, Milan, Italy. c.lamartina@flashnet.it
authors.forename: C
authors.initials: C
authors.lastname: Lamartina
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000209:etiology*; D011859:Radiography; D012720:Severity of Illness Index; D013122:Spinal Diseases / Q000209:etiology*; D013123:Spinal Fusion; D013168:Spondylolisthesis / Q000150:complications* / Q000000981:diagnostic imaging* / Q000601:surgery