[Reinterventions in postoperative instability of the lumbar spine]

Among the many reasons for reinterventions in the lumbar spine, postoperative instability was chosen as the subject for investigation. Abnormal mobility can be described more precisely in terms of pathological, segmental movement than in terms of instability, as such movement not only represents a greater range of motion of one vertebra towards the adjacent one, but also movement with a restricted (or normal) amplitude of a pathological pattern. Three conditions create pathological postoperative movement: (1) nonunion after attempted fusion; (2) pathologically increased movement because of removal of important weight-bearing structures; (3) compensatory movement of the segment next to a fusion. At the Wilhelm Schulthess Clinic in Zürich, 26 patients underwent one or more operations on the lumbar spine because of persisting pain as a result of postoperative pathological movement. In accordance with the results reported in the literature, good results were rare in reoperations on the lumbar spine (only 8 patients were completely free of pain); 14 patients had intermittent or continuous lumbar pain and 4 patients became worse. The indications for several interventions are carefully analyzed. Better results could probably have been obtained by more stable fixation techniques (transpedicular fixation, combined ventral and dorsal fusions), but the best means of avoiding reoperation is to observe the following guidelines: first, in disectomy cases, the osseous, weight-bearing structures (lamina, facet joint) should remain untouched. If even partial removal seems to be inevitable, fusion should be added done as well.(ABSTRACT TRUNCATED AT 250 WORDS)