Instability of the lumbar spine after surgery of a prolapse of an intervertebral disc was treated in 58 patients in the course of the last 5 years, i.e. in 4.7% of all operated patients. In 38 for stabilization of the spine Cloward’s PLIF method was used, in the remaining 20 it was supplemented by metal hook fixation using ISOLA. This simple device proved suitable for fixation of unstable vertebrae above the level of L5. Fusion of vertebrae without pseudoarthrosis was achieved on average within one year.

        Key words: Cloward’s method, discopathy