Saturday, September 29, 2018 10:30 am–12:00 pm Applying Deformity Concepts in Your Practice: 275. Does approach matter? A comparative radiographic analysis of spinopelvic parameters in single-level lumbar fusion

BACKGROUND CONTEXT Lumbar fusion is a popular and effective surgical option to provide stability and restore anatomy. Particular attention has recently been focused on sagittal balance and radiographic spinopelvic parameters that apply to lumbar fusion as well as spinal deformity cases. Current literature has demonstrated the effectiveness of various techniques of lumbar fusion; however, there is little data comparing these all together. PURPOSE To directly compare the impact of various lumbar fusion techniques (ALIF, LLIF, TLIF, PLF) based on radiographic parameters. STUDY DESIGN/SETTING A single-center retrospective study examining preoperative and postoperative radiographs. PATIENT SAMPLE A consecutive list of lumbar fusion surgeries performed by multiple spine surgeons at a single institution from 2013 to 2016 were identified. OUTCOME MEASURES Radiographic measurements utilized included segmental lordosis (SL), lumbar lordosis (LL), pelvic incidence (PI), pelvic incidence-lumbar lordosis mismatch (PI-LL), anterior and posterior disc height (DH-A, DH-P respectively) and foraminal height (FH). METHODS Radiographic measurements were performed on preoperative and postoperative lateral lumbar radiographs on all single-level lumbar fusion cases. Demographic data was collected including age, gender, approach, diagnosis, surgical level and implant lordosis. Paired sample t -test, one-way ANOVA, McNemar Test and independent sample t -test were used to establish significant differences in the outcome measures. Multiple linear regression was performed to determine a predictive model for lordosis from implant lordosis, fusion technique and surgical level. RESULTS There were 164 patients (78 males, 86 females) with a mean age of 60.1 years and average radiographic follow-up time of 9.3 months. These included 34 ALIF, 23 LLIF, 63 TLIF and 44 PLF surgeries. ALIF and LLIF significantly improved SL (7.9° & 4.4°), LL (5.5° & 7.7°), DH-A (8.8 mm & 5.8 mm), DH-P (3.4 mm & 2.3 mm) and FH (2.8 mm & 2.5 mm), respectively (p≤.003). TLIF significantly improved these parameters, albeit to a lesser extent: SL (1.7°), LL (2.7°), DH-A (1.1 mm), DH-P (0.8 mm) and FH (1.1 mm), p≤.02. PLF did not significantly alter any of these parameters while significantly reducing FH (−1.3, p=.01). One-way ANOVA showed no significant differences between ALIF and LLIF other than ALIF with greater ΔDH-A (3.0 mm, p=.02). Both ALIF and LLIF significantly outperformed PLF in preoperative to postoperative change in all parameters p≤.001. Additionally, ALIF and LLIF significantly outperformed TLIF in the change in SL (6.2°, p CONCLUSIONS This study demonstrated that these four lumbar fusion techniques yield divergent radiographic results. ALIF and LLIF produced greater improvements in radiographic measurements postoperatively as compared to TLIF and PLF. ALIF was the most successful in improving PI-LL mismatch, an important parameter relating to sagittal balance. Lordotic implants provided better sagittal correction and surgeons should be cognizant of the impact that these differing implants and techniques produce after surgery. Surgical technique is an important determinant of postoperative alignment and means for addressing sagittal balance in lumbar fusion surgery. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.