112. Degenerative disc disease and isthmic spondylolisthesis have similar outcomes after L5-S1 ALIF

BACKGROUND CONTEXT Anterior lumbar interbody fusion (ALIF) is a well-accepted surgical technique for lumbar spondylolisthesis and has been shown to have excellent radiographic and clinical outcomes. ALIF as a treatment for lumbar degenerative disc disease (DDD) is more controversial, with some authors reporting less reliable clinical improvement compared to other pathology. PURPOSE The purpose of this study is to compare the clinical outcomes of L5-S1 ALIF with posterior instrumentation in the setting of isthmic spondylolisthesis (IS) with L5-S1 ALIF for DDD. STUDY DESIGN/SETTING Retrospective cohort study. PATIENT SAMPLE The study included 93 consecutive patients who underwent L5-S1 ALIF without direct posterior decompression for either IS (n=37) or DDD (n=56) identified. All patients who underwent ALIF for IS underwent percutaneous posterior instrumentation, while DDD patients had a stand-alone construct. OUTCOME MEASURES Baseline characteristics including age, sex, body mass index (BMI), and American Society of Anesthesiologists (ASA) physical status classification were reviewed and compared between groups. Preoperative/baseline clinical outcome measures, including visual analog scale (VAS), Short Form 12 (SF-12), Oswestry Disability index (ODI), and Veterans RAND 12 (VR-12), were collected and compared to postoperative measures at a minimum of 6 months. METHODS Changes in outcome measures from preoperative to final postoperative visit were calculated and compared between IS and DDD groups. Proportions of patients who reached minimum clinically important differences (MCID) in VAS and ODI were compared between IS and DDD groups. Bivariate and multivariate logistic regression were used to control for baseline differences in patient characteristics. RESULTS There were no significant differences between IS and DDD groups in terms of age, sex, and ASA score (p>0.05). There was a small, but statistically significant, difference in BMI between IS and DDD groups (27.32 vs 29.99, respectively, p=0.012). There were no significant differences in preoperative VAS-back, VAS-leg, and ODI between IS and DDD groups (p>0.05, Table 2). DDD patients had a lower preoperative SF-12 and VR-12 compared to IS patients (p=0.011 and p=0.01, respectively). At final follow-up, IS patients had better VAS-back, ODI, SF-12, and VR-12 scores compared to DDD patients, with no significant difference in VAS-leg scores. When comparing change from preoperative scores to final follow-up, there were no significant differences in improvement in terms of VAS, ODI, SF-12, and VR-12 between IS and DDD groups. IS and DDD groups had similar proportions of patients who achieved MCID in terms of VAS-back, VAS-leg, and ODI. CONCLUSIONS Although DDD patients have worse preoperative and postoperative clinical measures compared to IS patients, patients with DDD achieve similar levels of clinical improvement after ALIF compared to patients with IS. Additionally, DDD patients were just as likely as IS patients to achieve MCID at final follow-up after ALIF. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.