SPINAL INSTABILITY - FACT OR FICTION

Spinal instability has long been a highly controversial concept. Altho ugh the significance of spinal instability in traumatology is fairly w ell understood, its role in degenerative spinal disease remains debate d. Treatment-related spinal instability has only recently become a foc us of attention. Few data are available on spinal instability due to t umors or infections. In a questionnaire study conducted by Fidler [1], 30 members of the International Society for the Study of the Lumbar S pine gave 30 different descriptions of the signs and symptoms of spina l instability. Pope and Panjabi [2] and Frymoyer and Selby [3,4] defin ed spinal instability as loss of normal spinal rigidity, whereas Graf [5] identified excessive joint space widening at the lumbar facet join ts as the main abnormality. The term ''spinal instability'' is open to more than one interpretation [6]. At the shoulder or knee, instabilit y is a functional symptom, as opposed to an objective finding. Thus, c onfusion exists between mechanical ''instability'', the risk of ''inst ability'', and clinical ''instability''. Spinal instability can be def ined as an alteration in one of the elements responsible for spinal st ability. Using this definition as our starting point, we will attempt to forge a general theory of spinal destabilization [7].