Lumbar Spine Instability: A Critical Update and Symposium SummaryNACHEMSON, ALF, MDSpine: April 1985 - Volume 10 - Issue 3 - p 290–291 Article: PDF Only Abstract Author InformationAuthors Conflicting views exist on the definition of motion segment instability, from a clinical as well as from an experimental point. Enough data are at hand, however, on normal and abnormal motion to test their validity in clinical patient material, using refined radiographic techniques. It is likely that such testing must include motion in three planes, as well as correlation to relevant measures obtained by computed tomography. From the Department of Orthopaedic Surgery 1, University of Göteborg, Sweden. © Lippincott-Raven Publishers.