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- Title
Clinical and Radiographic Results after Posterior Wedge Osteotomy for Thoracolumbar Kyphosis Secondary to Ankylosing Spondylitis: Comparison of Long and Short Segment Instrumentation.
- Authors
Mu Qiao; Bangping Qian; Yong Qiu
- Abstract
Introduction: Although lumbar PSO with posterior instrumentation was widely used to correct thoracolumbar kyphosis secondary to AS, studies designed to investigate the selection of long or short segment instrumentation are rather scarce. The current study aims at comparing the efficacy of long and short segmental fusion following lumbar pedicle subtraction osteotomy (PSO) in the correction of thoracolumbar kyphosis caused by ankylosing spondylitis (AS). Materials and methods: Radiographic data of 64 consecutive AS patients who were surgically treated through lumbar PSO combined with posterior segment fusion were analyzed retrospectively. Patients were divided into two groups according to location of the uppermost instrumented vertebra (UIV): SSF group (n = 20) treated by short segment instrumentation (UIV below T10) and LSF group (n = 44) underwent long segment fusion (UIV at or above T10). Radiological parameters included global kyphosis (GK), lumbar lordosis (LL), sagittal vertical axis (SVA), angle of fused segments (AFS), osteotomized vertebral angle (OVA) and proximal junctional angle. The degree of ossification in the thoracolumbar region is assessed by the modified stoke ankylosing spondylitis spine score (mSASSS). Clinical assessment involved oswestry disability index (ODI) and visual analogue scale (VAS). Results: LSF group had significantly larger deformity correction in GK and LL than SSF group while both groups had similar magnitude of correction for SVA. No significantly different loss of correction in GK and LL was identified in LSF group when compared to SSF group (GK correction loss: 2.63° vs 3.84°; LL correction loss: 2.89° vs 4.30°). In terms of OVA and AFS, no significant difference was noted in both groups. Notably, significant higher mSASSS in the thoracolumbar region was noticed in the SSF group in comparison with LSF group. The Pearson correlation analysis demonstrated that mSASSS for thoracic and lumbar spine was significantly associated with sagittal alignment changes at the final follow-up, which explained 34.5% and 53.0% of the variability of correction loss in GK and LL, respectively. Improved ODI and VAS were found in both groups at the final follow-up (P < 0.05). Intraoperative vertebral subluxation at the osteotomy site was detected in 3 patients with long constructs. There were 2 patients developed with a proximal junctional kyphosis (PJK) and 1 patient with rod fracture in LSF group. Conclusion: Both long and short segment instrumentations could maintain sustained surgical outcomes for thoracolumbar kyphosis caused by AS. Short segment instrumentation is recommended for AS patients with bridging syndesmophytes in the thoracolumbar region. Long segment fixation is better indicated for patients without fully ossified anterior longitudinal ligaments. Nevertheless, extension for length of instrumentation might not prevent the complications such as PJK or rod fracture in patients without fully ossified spine.
- Publication
Global Spine Journal, 2018, Vol 8, p5S
- ISSN
2192-5682
- Publication type
Article
- DOI
10.1177/2192568218771030