183. Patient outcomes following short-segment lumbar fusion are not affected by PI-LL mismatch

Abstract

BACKGROUND CONTEXT Mismatch between pelvic incidence (PI) and lumbar lordosis (LL) has been emphasized as a reason for poor outcomes in deformity surgery and long-segment spinal fusions. However, literature assessing the importance of this spinopelvic relationship on patient outcomes in short segment lumbar fusions for degenerative lumbar disease is scarce. PURPOSE To determine whether patient reported outcomes are affected based on degree of postoperative PI-LL mismatch after 1- and 2-level lumbar fusion for degenerative pathology. STUDY DESIGN/SETTING Retrospective cohort study. PATIENT SAMPLE Three hundred and forty-eight patients who underwent a 1-2-level lumbar spine fusion procedure at a high-volume academic center were retrospectively identified. Patients were divided into two groups based on the presence of postoperative PI-LL mismatch ≤ 10° (NM) vs PI-LL mismatch >10° (M). OUTCOME MEASURES Patient reported outcome measures: SF-12 PCS and MCS, ODI, VAS Back, VAS Leg. Spinopelvic measurements: pelvic tilt (PT), sacral slope (SS), pelvic incidence (PI), lumbar lordosis (LL). METHODS Preoperative and postoperative radiographic measurements were obtained for all patients. Those with less than one-year follow-up were excluded. Univariate analysis with an independent t-test or Mann-Whitney U test was used to compare differences between groups. Multiple linear regression was used to determine if postoperative PI-LL mismatch was an independent predictor of change in each patient outcome. RESULTS Sixty-seven patients were included in the NM group compared to 281 patients in the M group. There were no baseline differences (p > 0.05) in age, sex, BMI, CCI, smoking status, follow-up, preoperative diagnosis, number of levels decompressed and fused, or number of cases with TLIF or ALIF. On univariate analysis, there was a significant difference pre- and postoperatively in PT, PI, LL and PI-LL between the two groups at baseline and postoperatively (p 0.05). In addition, having a postoperative PI-LL mismatch was not found to be an independent predictor of any health-related outcome score on multiple linear regression analysis. CONCLUSIONS Pelvic incidence minus lumbar lordosis is recognized as an important spinopelvic parameter to normalize in deformity surgery; however, this importance is less clear in short-segment lumbar fusion for degenerative pathology. The results of this study show that even though the M group had a higher degree of mismatch pre- and postoperatively, there was no difference in patient-reported outcomes before or after surgery. This is one of the first studies to report on short-term patient outcomes based on spinopelvic parameters in routine lumbar degenerative cases. Further research is needed to elucidate this important relationship. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.