2020 Volume 11 Issue 10 Pages 1193-1201
Introduction: The utilization of extreme lateral interbody fusion (XLIF) coupled with percutaneous pedicle screw (PPS) instrumentation has revolutionized the methodology for surgical correction of sagittal plane deformity of the lumbar spine, which used to be treated with open closing osteotomies. Further advancement of the minimally invasive correction technique, proposed in 2012 as the anterior column realignment (ACR) procedure, comprised sectioning the anterior longitudinal ligament (ALL) via the lateral transpsoas approach followed by a hyperlordotic cage placement. At the present, however, few studies have provided confirmatory evidence to support the clinical utility of this technique. Therefore, we report our experience on the ACR applied to adult spinal deformity (ASD) as an additional technique to combined XLIF and PPS procedures, describing its effects on global and regional sagittal spinal balance and indirect neural decompression.
Methods: The ACR procedure consisted of ALL release and 30-degree hyperlordotic cage placement. Eighteen patients, who had ASD and [pelvic incidence (PI) -lumbar lordosis (LL) ] mismatch (i.e., [PI-LL] ≥ 10 degrees), underwent the ACR procedure at a single level except for one patient who had a two-level ACR. All but one patient had ACR either at L2-3 (6) or L3-4 level (10) or both. The remaining one patient had ACR at L4-5 level. We compared various imaging studies performed preoperatively with those obtained at 6 months postoperatively, and preoperative Oswestry Disability Index (ODI) results with those tested at 12 months postoperatively.
Results: The full-spine standing X-ray showed significant increases in LL (from 12.1° to 34.6°), segmental lordosis (from 3.8°to 22.5°), and thoracic kyphosis (from 20.7° to 26.7°) with significant decrease in sagittal vertical axis (from 96.1 mm to 42.3 mm), pelvic tilt (from 31.1°to 25.1°) and PI-LL (from 29.9°to 7.2°) postoperatively, resulting in an improvement in the global sagittal balance. The sagittal reformatted CT scans revealed significant increases in disc space height, and bilateral intervertebral foraminal height at the ACR level. Axial T2-weighted MRIs at the disc level that received ACR revealed a significant increase in cross-sectional area of the dural sac (from 107.9 mm2 to 156.3 mm2) postoperatively. The ODI scores significantly decreased from 45.8% preoperatively to 26.2% postoperatively.
Conclusions: The current results confirmed that the ACR could provide a useful addition to XLIF procedure in achieving not only better sagittal spinal alignment but also indirect neural decompression as a result of restoration of disc height as well as intervertebral foraminal height.
