Long-Term Outcomes of In Situ Fusion for Treating Dysplastic Spondylolisthesis

STUDY DESIGN: Retrospective, observational, single-center study. PURPOSE: To investigate the long-term outcomes of in situ fusion procedures for treating dysplastic spondylolisthesis. OVERVIEW OF LITERATURE: In situ fusion performed in patients with dysplastic spondylolisthesis avoids the development of nerve complications. METHODS: In total, 12 of 28 patients who underwent in situ fusion for treating dysplastic spondylolisthesis at Chiba University Hospital from 1974 to 2004 were followed up in August 2013. Surgical complications were evaluated. Low back pain and leg pain were assessed using a visual analog scale (VAS). Vertebral alignment, including the lumbosacral angle and lumbar lordosis angle measurement on radiographic images (profile view in the neutral standing position), was evaluated during preoperative, postoperative, and final examinations. RESULTS: The mean follow-up duration, patient age at the final examination, and patient age at operation were 20.0±7.2, 42.3±13.3, and 22.3±11.4 years, respectively. No complications were reported. Mean VAS scores for low back pain and leg pain were significantly lower at the final examination than at the preoperative examination (p<0.05). At the preoperative, postoperative, and final examinations, the mean lumbosacral angle was 32.3°±14.2°, 33.7°±11.8°, and 36.5°±16.4°, while the mean lumbar lordosis angle was 51.0°±14.8°, 48.6°±18.8°, and 49.6°±15.5°, respectively. No significant differences were noted among these values across the different time periods (p<0.05). CONCLUSIONS: In situ fusion performed in patients with dysplastic spondylolisthesis avoids the development of nerve complications such as nerve paralysis that may occur after repositioning operation and maintains appropriate long-term sagittal alignment, even 20 years after operation.