Evaluating Instability in Degenerative Lumbar Spondylolisthesis

• Published in: JBJS Open Access
• Main Authors: Mark A. MacLean, MD, MSc, Chris Bailey, MD, MS, FRCSC, Charles Fisher, MD, MHSc, FRCSC, Yoga Raja Rampersaud, MD, MSc, FRCSC, Ryan Greene, MSc, Edward Abraham, MD, FRCSC, Nicholas Dea, MD, MSc, FRCSC, Hamilton Hall, MD, FRCSC, Neil Manson, MD, FRCSC, Raymond Andrew Glennie, MD, MSc, FRCSC
• Format: Article
• Language: English
• Published: Wolters Kluwer 2022-12-01
• Online Access: http://journals.lww.com/jbjsoa/fulltext/10.2106/JBJS.OA.22.00052

Background:. The subjective degenerative spondylolisthesis instability classification (S-DSIC) system attempts to define preoperative instability associated with degenerative lumbar spondylolisthesis (DLS). The system guides surgical decision-making based on numerous indicators of instability that surgeons subjectively assess and incorporate. A more objective classification is warranted in order to decrease variation among surgeons. In this study, our objectives included (1) proposing an objective version of the DSIC system (O-DSIC) based on the best available clinical and biomechanical data and (2) comparing subjective surgeon perceptions (S-DSIC) with an objective measure (O-DSIC) of instability related to DLS. Methods:. In this multicenter cohort study, we prospectively enrolled 408 consecutive adult patients who received surgery for symptomatic DLS. Surgeons prospectively categorized preoperative instability using the existing S-DSIC system. Subsequently, an O-DSIC system was created. Variables selected for inclusion were assigned point values based on previously determined evidence quality. DSIC types were derived by point summation: 0 to 2 points was considered stable, Type I); 3 points, potentially unstable, Type II; and 4 to 5 points, unstable, Type III. Surgeons’ subjective perceptions of instability (S-DSIC) were retrospectively compared with O-DSIC types. Results:. The O-DSIC system includes 5 variables: presence of facet effusion, disc height preservation (≥6.5 mm), translation (≥4 mm), a kyphotic or neutral disc angle in flexion, and low back pain (≥5 of 10 intensity). Type I (n = 176, 57.0%) and Type II (n = 164, 53.0%) were the most common DSIC types according to the O-DSIC and S-DSIC systems, respectively. Surgeons categorized higher degrees of instability with the S-DSIC than the O-DSIC system in 130 patients (42%) (p < 0.001). The assignment of DSIC types was not influenced by demographic variables with either system. Conclusions:. The O-DSIC system facilitates objective assessment of preoperative instability related to DLS. Surgeons assigned higher degrees of instability with the S-DSIC than the O-DSIC system in 42% of cases. Level of Evidence:. Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.