Abstract
BackgroundThis study aims to determine if (1) loss of lumbar lordosis (LL), often associated with degenerative scoliosis (DS), is structural or rather largely due to positional factors secondary to spinal stenosis; (2) only addressing the symptomatic levels with a decompression and posterolateral fusion in carefully selected patients will result in improvement of sagittal malalignment; and (3) degree of sagittal plane correction achieved with such a local fusion could be predicted by routine pre-operative imaging.MethodsA retrospective study design with prospectively collected imaging data of a consecutive series of surgically treated DS patients who underwent decompression and instrumented fusion at only symptomatic levels was performed. Pre- and post-operative plain radiographs and pre-operative magnetic resonance imaging (MRIs) of the spinopelvic region were analyzed. LL, pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS) were assessed in all patients. As a requirement for the surgical strategy, all patients presented with a pre-operative PI-LL mismatch greater than 10°. Post-operative complications were assessed.ResultsPre-operative MRIs and lumbar extension radiographs revealed a mean LL of 42° (range 10–66°) and 48° (range 20–74°), respectively, in 68 patients (mean follow-up 29 months). LL post-operatively was corrected to a mean PI-LL of 10°. Of patients who achieved PI-LL mismatch within 10o on their pre-operative extension lateral lumbar radiographs, 62.5% were able to maintain a PI-LL mismatch within 10° on their initial post-operative films. Only 37.5% were not able to achieve that mismatch on extension radiographs (p = 0.001, OR = 9.58). Similarly, 54.2% were able to achieve a PI-LL < 10° on initial post-operative radiographs, when pre-operative MRI revealed a PI-LL mismatch within 10°. In contrast, only 20.5% achieved that goal post-operatively if their mismatch was greater than 10o on their MRI (p = 0.003, OR = 4.25).ConclusionWith a decompression and instrumented fusion of only the symptomatic levels in symptomatic DS patients, we were able to achieve a PI-LL mismatch to within 10°. The loss of LL observed pre-operatively may be largely positional rather than structural. The amount of LL correction observed immediately after surgery can be predicted from pre-operative lumbar extension radiographs and supine sagittal MRI.
Highlights
With an aging population and the growing ability to manage difficult health problems in later years, the effective management of adult degenerative scoliosis (DS) is more critical than ever
We will focus our prospective research on evaluating these patients in the context of their age, specific symptoms, and etiology of presentation. This is the first study to demonstrate that when DS patients have sagittal deformities that are flexible on pre-operative imaging, a targeted instrumented arthrodesis and decompression of only the neurologically symptomatic levels can achieve a pelvic incidence (PI)-lumbar lordosis (LL) mismatch to within 10o
We demonstrate for the first time that the magnitude of pre-operative spinal flexibility is correlated with the amount of post-operative radiographic correction of sagittal plane parameters after fusion, giving the surgeon a simple tool to predict who this targeted surgical technique may be the most beneficial for
Summary
With an aging population and the growing ability to manage difficult health problems in later years, the effective management of adult degenerative scoliosis (DS) is more critical than ever. The prevalence of DS ranges widely in the literature from 8.3 to 68% of the adult population, with a higher prevalence in older patients [1, 2]. DS is a complex spine presentation that commonly involves a combination of both degenerative spinal stenosis and deformity. This study aims to determine if (1) loss of lumbar lordosis (LL), often associated with degenerative scoliosis (DS), is structural or rather largely due to positional factors secondary to spinal stenosis; (2) only addressing the symptomatic levels with a decompression and posterolateral fusion in carefully selected patients will result in improvement of sagittal malalignment; and (3) degree of sagittal plane correction achieved with such a local fusion could be predicted by routine pre-operative imaging
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