Indication for lumbosacral fusion and reduction in spondylolisthesis.

The indication for operative treatment in spondylolisthesis results from pain, progressive sliding and, in up to 60 % of the patients with progressive dislocation, from radicular malfunction. The posterolateral fusion in situ is a safe procedure, but the deformation remains and in spondyloptosis plastic deformation of the fusion mass can lead to further dislocation. With the external fixator as an instrument for reduction and the internal fixator for stabilization the reduction of even serious spondyloptosis and the recovery of a normal spine alignement and posture is possible, with an acceptable neurological risk. Therefore a concept of treatment is suggested, which as a rule is aiming at the anatomical reduction of the dislocated vertrebra beside stabilization and nerveroot decompression. Depending on the extent of the slip, reduction and stabilization is to be performed in one, two or three stages. An anterior or posterior fusion is sufficient in grade I dislocation. In grade II-V a combined posterior and anterior surgical proceedure is recommended.