56. Minimally invasive pedicle screws provide similar clinical outcomes to open posterior fusion in the management of adult isthmic spondylolisthesis

BACKGROUND CONTEXT In adult patients undergoing anterior lumbar interbody fusion (ALIF) for the treatment of isthmic spondylolisthesis, the literature shows that posterior percutaneous pedicle screw fixation leads to shorter hospital stays, less time under anesthesia, and less intraoperative blood loss compared to open posterior fusion. However, there is conflicting evidence on whether patients undergoing posterior percutaneous fixation experience similar clinical outcomes as those undergoing open posterior fusion. PURPOSE The purpose of this study was to determine the impact of minimally invasive posterior surgery on clinical outcomes following lumbar spinal fusion for isthmic spondylolisthesis. STUDY DESIGN/SETTING This study was a retrospective analysis of prospectively collected data from a single, high-volume academic medical center. PATIENT SAMPLE Analysis of patients who underwent lumbar fusion for isthmic spondylolisthesis from 2014 to 2019 was conducted. Surgery was indicated after failure of conservative treatment to address lumbar radiculopathy and/or neurogenic claudication. OUTCOME MEASURES Patient-reported outcome measures (PROMs) were recorded at preoperative and postoperative clinical visits, and included the Visual Analog Scale back pain (VAS back) and leg pain (VAS leg), the Short-Form 12 Mental Component Score (MCS-12) and Physical Component Score (PCS-12), and the Oswestry Disability Index (ODI). Secondary measures included estimated blood loss (EBL) and length of stay (LOS). METHODS Patient and surgical characteristics including age, gender, body mass index (BMI), Charlson Comorbidity Index (CCI), number of levels decompressed and number of levels fused were recorded. Preoperative and final PROMs were obtained from an institutional query. For analysis, patients were divided into two groups based on surgical approach: ALIF with percutaneous pedicle screws (Percutaneous) and ALIF with open posterior fusion (Open). Multivariate linear regression was performed to correlate surgical approach and outcomes. RESULTS A total of 61 patients were included, with 20 patients in the Percutaneous group and 41 patients in the Open group. Patients undergoing open surgery had greater intraoperative EBL (p=0.013) and longer LOS (p=0.034). Otherwise, there were no significant differences in patient characteristics. Patients in both the Percutaneous and the Open groups had significant improvement in VAS back scores (p=0.001, p CONCLUSIONS Our results suggest that patients undergoing minimally invasive posterior fusion and patients undergoing open posterior fusion for adult isthmic spondylolisthesis have similar improvement of PROMs from preoperative to final assessment. Additionally, open surgery is significantly correlated with less improvement in VAS leg scores than minimally invasive approaches and was associated with significantly higher intraoperative blood loss and hospital length of stay. This study underscores the importance of considering surgical approach as a prognostic factor. Furthermore, the results provide additional information that can be used by physicians in preoperative discussions with patients regarding expectations of postoperative improvements in pain. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.