53. Spinopelvic mismatch after short segment lumbar fusions results in increased disability at 2 years following surgery

Although the relationship between pelvic incidence (PI), lumbar lordosis (LL), and patient outcomes are well established in spinal deformity surgery, this relationship in short-segment lumbar fusions for degenerative pathology is still unclear. We sought to examine the fate of postoperative spinopelvic parameters at early (3-month) and late (24-month) timepoints as well as clinical outcomes after 1-2 level lumbar fusions for degenerative pathology. Understanding the long-term relationship between spinopelvic parameters and disability. Retrospective cohort study from a prospectively-collected, institutional review board approved database. Patients were eligible if they had undergone a one- or two-level lumbar fusion for degenerative pathology using any surgical technique. Patients required standing lateral radiographs as well as Oswestry Disability Index (ODI) collected preoperatively and postoperatively at 3- and 24-month timepoints. Patients were placed in categories based on overall spinal alignment at each timepoint and comparisons were made between proper alignment and patient's overall reported disability. Spinopelvic parameters were measured on pre- and postoperative (3- and 24-months) neutral standing lateral lumbar radiographs prospectively acquired from 76 patients who underwent 1-2 level lumbar fusion for degenerative pathology. Patients were categorized based on the PI-LL mismatch as aligned (AL)(PI-LL10°) at all timepoints. Alignment was categorized postoperatively as preserved (AL to AL), restored (MAL to AL), not corrected (MAL to MAL), or worsened (AL to MAL). ODI scores were recorded at all time points. At 3 months, PI-LL matching was 61% preserved, 9% restored, 28% not corrected, and 3% worsened. PI-LL matching at 24 months was 58% preserved, 8% restored, 29% not corrected, and 5% worsened. Preoperatively patients reported equal amounts of disability regardless of alignment (aligned M=40.00, SD=15.85 and malaligned M=42.96, SD=16.03, p=.44). ODI scores improved in all patients from surgical intervention but did not significantly differ between aligned (M=20.85, SD=15.89) and malaligned (M=29.61, SD=21.89) patients at 3-months postop, p=.05. However, at 24-months postop, aligned patients reported significantly lower ODI scores (M=17.27, SD=16.46) compared to malaligned patients (M=27.19, SD=19.05), p=.02. The spinopelvic alignment achieved at 3-months for 1-2 level lumbar fusions for degenerative pathology remains stable at 24-months. Patients report significant improvement in level of disability at 3 months after surgery regardless of alignment, however at 24 months, those who are appropriately aligned have significant improvement in their disability compared to the malaligned group. Surgeons may consider longer follow-up in patients in which “proper” alignment was not initially achieved. Nuvasive Modulus (Approved for this indication)