1580. Fusion and Quality of Life using Interspinous Process Clamp for the Treatment of Delayed Lumbar Fusion: a Retrospective Cohort Study

Authors: Richard Floyd Cook, DO; Doris Tong, MD; Matthew Bahoura, BA; Teck-Mun Soo, MD; Peter Bono, DO (Farmington Hills, MI)

Introduction: Spacer-devices have been used as stand-alone devices and to augment lumbar decompression. We sought to demonstrate that interspinous process clamps (ISP) are effective in rescuing delayed fusions in order to avoid lumbar pseudarthrosis. Methods: We retrospectively analyzed prospectively collected data of consecutive patients who underwent revision lumbar surgery using ISP for 1-2 levels delayed lumbar fusion by a single surgeon at two hospitals between February 2014 and December 2017. Patients were included if delayed fusion was diagnosed within 18 months of their prior surgery. Patients were followed by XR/CT for at least 3 months and by clinic visit/phone interview for at least 6 months after the ISP surgery. We collected data for patient demographics and surgical characteristics. The primary outcomes are interbody fusion as evaluated by the Suk criteria and posterior interlaminar fusion as evaluated by the modified Christensen criteria. Our secondary outcomes were Quality-of-life (QoL) outcomes as evaluated by VAS and SF-12. Descriptive statistics were used. Results: Twenty-two patients were included in the study. All 22 patients underwent XR and 18 patients underwent CT evaluation. QoL outcomes were evaluated in all 22 patients. The mean age of the delayed fusion before ISP surgery was 0.71±0.24 year. Patient demographics were presented in table 1. Surgical characteristics were presented in table 2. The mean postoperative imaging interval was 10±8.5 months. Among the 25 interspaces, the rate for solid interbody fusion was 68%, probable interbody fusion was 32%. Among the 22 patients, the rate for solid posterior fusion was 100% (table 3). QoL data collected with at least 6 months’ followup showed satisfactory results (table 4). Conclusion: ISP achieved satisfactory interbody and posterior fusion as a rescue technique in patients suffering from delayed fusion. The study is limited by the retrospective design and low incidence of delayed fusion.