Clinical and Radiographic Outcomes of Degenerative Scoliosis using Lateral Lumbar Interbody Fusion (LLIF) with Lateral Rod Fixation in Patients with PI-LL ≥ 20° at Average 18 Months Post-op

Presented at SMISS Annual Forum 2016
By William Smith MD
With Libby Bergmann BS,

Disclosures: William Smith MD A; NuVasive, Providence Medical Technologies, Inc. B; NuVasive, SI Bone, Providence Medical Technologies, Inc, SpineGuard, Celling Biosciences. C; NuVasive, SI Bone. D; NuVasive. F; NuVasive. Libby Bergmann BS A; NuVasive, Providence Medical Technologies, Inc, Celling Biosciences.,

Introduction

The minimally invasive lateral approach for lumbar interbody fusion (LLIF) is increasingly being applied to more complex indications, including sagittal plane deformities. Using this novel MIS technique with LLIF, an early series of patients with PI-LL ≥ 20° were treated and obtained similar results as open surgery with less morbidity. 

Aims/Objectives

This study reviews clinical and radiographic outcomes of patients with significant sagittal deformity who underwent minimally invasive LLIF with segmental lateral fixation for treatment of adult scoliotic deformity. 

Methods

Twelve consecutive adult degenerative scoliosis patients with significant sagittal malalignment (PI-LL ≥ 20°) treated with multi-level LLIF and lateral rod fixation were identified retrospectively and included for review. Average age was 62.8 years, gender 7F/5M, with average BMI of 27.1. Three patients had notable comorbidities; 1 diabetes, 2 CAD. Four patients had undergone previous lumbar surgeries, two with pre-existing hardware. Patients were treated in the lateral decubitus position without repositioning for posterior work in all cases, except one. No procedures were staged. Full anterior longitudinal ligament (ALL) release was performed in the majority of cases (67%). Treatment variables, complications, clinical outcomes and radiographs were evaluated. Radiographic measurements were taken preoperatively, immediately postop and at 6+ months postop (range 6-57) for evaluation of initial surgical correction and maintenance of this correction, over time.

Results

An average of 6 levels were treated, per patient (range 3-8). Intraoperative ORT, EBL and LOS averaged 4.6 hours, 430 cc and 5.6 days, respectively. No intraoperative or postoperative complications were observed. Low back pain (VAS) declined from 7.5 preoperatively to 3.4 at last follow-up, with 67% of patients reporting more than a 4 point improvement in VAS score. Clinical follow-up averaged 18.8 months, with an average radiographic follow-up of 19.6 months. Preoperative radiographic measures averaged; LL=-28.1°, PI=57.2°, PT=29.6°, SS=28.6°, PI-LL=29.1, coronal Cobb=28.4°. Immediate postoperative measures averaged; LL=-37.8°, PI=53.9°, PT=24.3°, SS=32.5°, PI-LL=12.2°, coronal Cobb=5.1°. Last postoperative measures average; LL=-41.1°, PI=57.6°, PT=22.3°, SS=35.3°, PI-LL=11.3°, coronal Cobb=4.5°. Of primary focus, the latest radiographic evaluation of PI-LL mismatch exhibited a 64.4% correction of sagittal alignment from pre to postop. No instances of proximal junctional kyphosis have yet been observed and no reoperations have occurred. 

Conclusions

The radiographic correction seen is encouraging, with mean PI-LL proportionality improving from 29° preoperatively to 11° at last follow-up. These results suggest the feasibility of lateral approach MIS surgery for more advanced deformity using LLIF and lateral rod fixation through the same MIS incision.