Key points are not available for this paper at this time.
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.
Alf Nachemson (1985) studied this question.