Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P162. Safety profile of lumbosacropelvic fixation in elderly patients: comparison between S2-Alar-Iliac screws and iliac screws.

BACKGROUND CONTEXT The surgical management of deformity, degenerative pathology, neoplasms, trauma and infection in the lumbosacropelvic spine remains a challenge due to high mechanical demand around this area, risks of pseudarthrosis, and invasive nature of the procedures. To date, two instrumentation techniques are primarily available: iliac screws (ISs) and S2-alar-iliac (S2AI) screws. Previous articles demonstrated lower rates of complications with S2AI screws as compared to ISs; however, none of them have focused on elderly patients who may harbor significant comorbidities, and as such, require more meticulous perioperative management, given these invasive and lengthy procedures. PURPOSE To report safety profile of S2AI in patients over 60 and address differences between S2AI screws and ISs. STUDY DESIGN/SETTING Single-center, retrospective, case-control study. PATIENT SAMPLE Single center, retrospective cohort who underwent lumbosacropelvic fixation with more than two-year follow-up. OUTCOME MEASURES Rates of complications such as mortality, unplanned reoperation, cardiorespiratory complications, transfusion-related complications and functional outcome measures such as visual analogue scale for back pain. METHODS Between October 2010, and December 2014, 171 sacropelvic fusion procedures with IS or S2AI screw instrumentation were performed in 161 patients. The inclusion criteria for this study were as follows: (1) patients over 60years old and (2) patients with more than two-year follow-up periods, which yielded 15 patients (IS) and 41 cases (S2AI), respectively. Rates of complications such as mortality, unplanned reoperation, pseudoarthrosis, cardiorespiratory complications, transfusion-related complications and functional outcome measures such as visual analogue scale for back pain and ambulatory status were collected and statistically analyzed. Intergroup comparison of binary variables was performed via Fisher's exact test. Intergroup comparison of continuous variables was achieved using unpaired t-tests. For the analyses on pain and functional outcomes, the perioperative comparisons for each group and intergroup comparisons were conducted using the Wilcoxon signed-rank test and the Mann–Whitney U test, respectively. All reported p values are 2-sided and p values <.05 were regarded as statistically significant. RESULTS Baseline characteristics such as age, sex, smoking history, diagnoses and comorbidities were similar in both groups. The S2AI group had lower rates of reoperation (19.5% vs 66.6%, p=.002), surgical site infection (0% vs. 16.0%, p<.001), wound dehiscence (0.0% vs. 20.0%, p<.001) and postoperative hyperkalemia (17.7% vs. 43.8%, p=.04) and had lower volume of estimated blood loss (EBL) [ml] (1817.5vs. 2775.6, p=.01) and transfused red blood cell units (4.6vs. 8.0, p=.001) than the IS group, while rates of mortality, L5-S1 pseudarthrosis, and other cardiorespiratory complications were similar in both groups. Pain relief and functional recovery were achieved in both groups without any significant intergroup differences. On multivariate analyses, use of S2AI screws over ISs, smoking, and operated levels were independent predictors of volume of transfusion. CONCLUSIONS Use of S2AI screws over ISs in the elderly was associated with lower rates of reoperation, surgical site infection, wound dehiscence and lower volume of EBL and RBC transfusion, while achieving similar clinical and functional outcomes. [ABSTRACT FROM AUTHOR]