Fate of Untreated Adjacent Spondylolysis in Selectively Surgically Treated Patients with Multi-Level Spondylolysis: Should All Segments Always be Fused?

Abstract

The purpose of this study was to observe the natural course of remained untreated spondylolysis adjacent to previous fusion segments in patients with multi-level lysis and its clinical outcome. Methods: Nineteen patients who underwent selective fusion of multi-level spondylolysis (MLS) at a single institute were enrolled. As a matched cohort for comparison, 19 patients who had single-level spondylolysis (SLS) and undergone singlelevel fusion with similar demographics and preoperative radiologic measurements as the MLS group were included. We evaluated the preoperative, postoperative, and last followup angular displacement and sagittal translation on dynamogram radiographs, and axial and radial pain using the visual analogue scale in both groups. We then compared the increment in radiological instability and clinical outcome between the MLS and SLS groups. Results: There were no significant differences in patient demographics and preoperative radiological measurements, including disc degeneration, facet degeneration, lumbar lordosis, pelvic incidence, and sacral table angle between both groups. Both groups showed an increase in the average angular displacement and slippage during the final follow-up as compared to preoperative findings, but no significant difference was noticed between them. Both the MLS and SLS groups showed improvement in lower back pain and leg pain from before surgery, but with no statistical significance. Conclusion: Selective fusion in patients with multiple spondylolysis can be an alternative surgical option without increasing the risk of adjacent segment degeneration under strict narrow indications. However, a thorough preoperative evaluation is needed to prevent early surgical failure.