General Session: Adult Spinal Deformity-2

Presented by: D. Crandall - View Audio/Video Presentation (Members Only)

Author(s):

D. Crandall(1), J. Revella(2), M. Chang(1), L. Young(1), A. Chung(3), L. Taylor(1), M. Immediato(1), R. Mclemore(2)

(1) Sonoran Spine, Tempe, AZ, United States
(2) Sonoran Spine Research and Education Foundation, Tempe, AZ, United States
(3) Banner University Medical Center Phoenix, Orthopedic Residency Program, Phoenix, AZ, United States

Abstract

Purpose: In the surgical treatment of degenerative lumbar scoliosis (DLS), improvement of sagittal alignment is often required. Posterior-only approaches frequently rely on transforaminal lumbar interbody fusion (TLIF) with cage support to assist in improving sagittal alignment. This study, done without industry support, evaluates the clinical and radiographic differences between patients treated using new expandable TLIF cages (EC) compared to commonly used static height cages (SC) in patients with DLS.

Methods: Prospective data was retrospectively reviewed from consecutive DLS patients who underwent posterior spinal fusion (PSF), and TLIF at 1-3 levels. Excluded:adult idiopathic scoliosis, 3-column osteotomies. The cohort was divided: SC vs. EC, with SC patients consecutively treated earliest in the study. Radiograph measurements pre-op, 1year, and 2years for disc height, disc angle, lumbar lordosis (T12-S1) and sagittal balance (C7-S1). Clinical data: Visual Analog pain scores (VAS), Oswestry Disability Index (ODI), and pain medication use pre-op, 1year, 2years, and latest follow-up. Mann Whitney, Wilcoxon signed rank test, t-test, and multivariate linear regression were used in statistical analysis. Differences in anterior, middle, and posterior disc height were determined by t-test after subsetting by level to prevent confounding from multiple measurements in the same patient.

Results: Forty-three patients met inclusion criteria: SC group- 25 patients (57 TLIF levels), EC group- 18 patents (37 TLIF levels). There was no difference SC vs EC for age (68years), smoking, prior spine surgery, or anatomic levels of TLIF. Preop disc height at TLIF level (average 7mm), pre-op sagittal imbalance (average 8cm), lumbar lordosis (average 35°) had expected wide variations patient to patient. Pre-op, SC discs were average 3° more lordotic than EC discs. Posterior fusion length was similar for both groups (6.3 levels, range 3-8 levels); All had Ponte osteotomies for curve correction. SC group had more 3-level TLIFs (14 vs 4) and 1-level TLIFs (7 vs 3) than EC group. Follow-up averaged 47months (range 26-68 months). Two year results by level: L2-3 EC had higher anterior disc height (9.8mm vs 12.6mm, p=0.05); L3-4 EC had higher anterior disc height (13.6mm vs 10.0mm, p=0.03) and mid-disc height (9.75mm vs 4.0mm, p=0.04); L4-5 EC had greater anterior disc height (13.5mm vs. 10.8mm, p=0.004) and mid-disc height(10.4mm vs 8.4mm, p-0.001); L5-S1 EC had greater anterior disc height (16.9mm vs 12.9mm, p=0.008). Two-year posterior disc heights were similar EC vs SC(p>0.05). Considering all levels, EC produced better 2-year disc angulation (13.7° vs 9.7°) though SC averaged 3° more preop lordosis. EC tended to produce better lumbar lordosis(52° vs 47°) and better sagittal balance (4.0cm vs 6.0cm) through a wide range in the initial deformity. Complications were similar SC vs EC: Adjacent fracture-9, symptomatic sagittal imbalance-6 (SC-3, EC-3), revision surgery-3. Both groups improved clinically (p< 0.01): VAS(preop-6.5, 2 year-3.4), and ODI (preop-49.3, 2 year- 27.2). Pain medication use showed similar trend without difference SC vs EC.

Conclusions: EC was more effective at increasing disc height, segmental lordosis, lumbar lordosis, and sagittal balance than SC in patients with DLS augmented with TLIF. These results were achieved despite the SC group having 3 times as many 3-level TLIF's as the EC group. These results reflect a single center's early experience, and a larger study is needed to confirm these findings.