Anatomic reduction and monosegmental fusion in high-grade developmental spondylolisthesis

Study Design. A retrospective review of the clinical and radiographic outcomes of reduction by temporary instrumentation of L4 and monosegmental fusion of L5/S1 in patients with high-grade developmental spondylolisthesis. Objective. To assess the efficacy of this technique in the reduction of local deformity and correction of overall sagittal profile. Summary of Background Data. In situ fusions as well as partial reduction with fusion L4-S1 via various approaches have been described previously. To date and to our knowledge, there have been no reports describing complete reduction and monosegmental fusion for high-grade developmental spondylolisthesis. Methods. A total of 27 consecutive patients with severe developmental spondylolisthesis of L5/S1 were treated with operative reduction via temporary instrumentation of L4 and monosegmental fusion of L5/S1. The clinical and radiographic outcomes were retrospectively reviewed for each case at a minimum of 2 years (mean follow-up of 45 months; range 24-80). Mean age at surgery was 16.7 years (range 9-29). Results. At most recent follow-up, 23 patients were pain free. There were 4 patients who had moderate pain. All radiographic parameters improved. Mean slippage improved from 74.0% before surgery to 11.0% after surgery and 10.0% at latest follow-up. Slip angle improved from 36.6 degrees before surgery to 8.1 degrees after surgery and 7.6 degrees at latest follow-up. Sacral inclination improved from 34.6 before surgery to 43.4 degrees after surgery and 47.2 degrees at latest follow-up. The overall sagittal profile improved dramatically. There was 1 superficial infection, 6 patients had L5 root symptoms (5 of these resolved, 1 patient had a persistent sensory deficit). Four patients had decompensation at L4/5 (2 reoperations). Conclusions. Reduction of L5/S1 with temporary instrumentation of L4 and monosegmental fusion of L5/S1 is an effective technique for the treatment of high-grade developmental spondylolisthesis. A complete reduction of local deformity and excellent correction of overall sagittal profile can be achieved. Fusion of the primarily healthy segment L4/5 can be avoided.