(I-620) Is the Spinopelvic Alignment Achieved in a Short Segment Lumbar Fusion at 3 Months After Surgery Maintained at 24 months?

Introduction: 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 undetermined. We sought to examine the fate of postop 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.

Methods: Spinopelvic parameters were measured on preop and postop (3- and 24- months postop) 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-LL < 10°) or malaligned (MAL)(PI-LL >10°) at all timepoints. Alignment was categorized postop as preserved (AL to AL), restored (MAL to AL), not corrected (MAL to MAL), or worsened (AL to MAL). Oswestry Disability Index (ODI) scores were collected at both time points.

Results: 3 months postop, PI-LL matching was preserved in 61%, restored in 9%, not corrected in 28%, and worsened in 3% of patients. PI-LL matching at 24 months was preserved in 58%, restored in 8%, not corrected in 29%, and worsened in 5% of patients. Preop malalignment was predictive of postop malalignment. Preop ODI was not affected by preop alignment status (AL:40, MAL:43). All 4 categories of postop alignment had improved ODI at 3- and 24-months (p < 0.0001). At 3-months, ODI did not statistically differ regarding alignment. However, at 24-months aligned patients had significantly lower ODI than malaligned patients (p=0.02, AL:17, MAL:27).

Conclusion : 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 are significantly more improved than the malaligned group. Surgeons may consider longer follow-up in patients in which “proper” alignment was not initially achieved.

How to Improve Patient Care: Surgeons should consider longer follow-up in patients in which proper alignment was not initially achieved.