Predicting factors of adjacent segment degeneration after long-segment spinal fusion: spinopelvic parameters analysis

Abstract

Background We investigated whether spinopelvic parameters are important prognostic factors causing adjacent segment degeneration (ASD) after long instrumented spinal fusion for degenerative spinal disease. Methods This uncontrolled, randomized, single arm retrospective study included patients who underwent long instrumented lumbar fusion (fusion levels≥ 4) in the past 5 years with follow-up for at least 2 years. The inclusion criteria included adult patients (≥40 years of age) with a diagnosis of spinal degeneration who underwent instrumented corrective surgery. The exclusion criteria included preexisting adjacent disc degeneration, combined anterior reconstructive surgery, and distal ASD. Clinical and operative characters were evaluated. Angle of lumbar lordosis (LLA), sacral slope (SSA), pelvic tilt (PTA) and pelvic incidence (PIA) were compared preoperatively, postoperatively and at the final follow-up. Results From 2009 to 2014, 60 patients (30 ASD and 30 non-ASD) were enrolled. The average age was 66.82 ± 7.48 years for the study group and 67.97 ± 7.81 years for the control group. There was no statistically significant difference in clinical and operative characteristics. Among all spinopelvic parameters, only pre-, post-operative and final follow-up PIA in ASD group (53.9±10.4ﾟ, 54.6±14.0ﾟ, 54.3±14.1ﾟ) and non-ASD group (60.3±13.0ﾟ, 61.8±11.3ﾟ, 62.5±11.2ﾟ) showed statistically significant differences ( p <0.05). Conclusion This study confirms that preoperative, postoperative and final follow-up PIA is a significant factor contributing to the development of ASD after long instrumented spinal fusion.