When is compensation for lumbar spinal stenosis a clinical sagittal plane deformity?

BACKGROUND CONTEXT: Degenerative lumbar stenosis (DLS) patients have been reported to lean forward in an attempt to provide neural decompression. Spinal alignment in patients with DLS may resemble that of adult spinal deformity (ASD). No previous studies have compared and contrasted the compensatory mechanisms of DLS and ASD patients. PURPOSE: This study aimed to determine the differences in compensatory mechanisms between DLS and ASD patients with increasing severity of sagittal spinopelvic malalignment. Contrasting these compensatory mechanisms may help determine at what severity sagittal malalignment represents a clinical sagittal deformity rather than a compensation for neural compression. STUDY DESIGN/SETTING: This is a retrospective clinical and radiological review. PATIENT SAMPLE: Baseline x-rays in patients without spinal instrumentation, with the clinical radiological and diagnoses of DLS or ASD, were assessed for patterns of spinopelvic compensatory mechanisms. Patients were stratified by sagittal vertical axis (SVA) according to the Scoliosis Research Society-Schwab [SRS-Schwab] classification. OUTCOME MEASURES: Radiographic spinopelvic parameters were measured in the DLS and ASD groups, including SVA, pelvic incidence-lumbar lordosis mismatch (PI-LL), T1 spinopelvic inclination (T1SPi), T1 pelvic angle (TPA), and pelvic tilt (PT). METHODS: The two diagnosis cohorts were propensity-matched for PI and age. Each group contained 125 patients and was stratified according to the SRS-Schwab classification. Regional spinopelvic,lower limb, and global alignment parameters were assessed to identify differences in compensatory mechanisms between the two groups with differing degrees of deformity. No funding was provided by any third party in relation to carrying out this study or preparing the manuscript. RESULTS: With mild to moderate malalignment (SRS-Schwab groups "0," or "+" for PT, PI-LL, or SVA), DLS patients permit anterior truncal inclination and recruit posterior pelvic shift instead of pelvic tilt to maintain balance, while providing relief of neurologic symptoms. Adult spinal deformity patients with mild to moderate deformity recruit pelvic tilt earlier than DLS patients. With moderate to severe malalignment, no significant difference was found in compensatory mechanisms between DLS and ASD patients. CONCLUSIONS: Patients with DLS permit mild to moderate deformity without recruiting compensatory mechanisms of PT, reducing truncal inclination and thoracic hypokyphosis to achieve neural decompression. However, with moderate to severe deformity, their desire for upright posture overrides the desire for neural decompression, evident by the adaptation of compensatory mechanisms similar to that of ASD patients.

Investigating the Universality of Preoperative Health-Related Quality of Life (HRQoL) for Surgically Treated Spinal Deformity in Young Adults: A Propensity Score-Matched Comparison Between African and US Populations.

STUDY DESIGN: Retrospective analysis of propensity score-matched (PSM) observational cohorts. OBJECTIVES: To evaluate and compare preoperative health-related quality of life (HRQoL) scores and radiographic measurements of young African and US adults with spinal deformity (ASD). SUMMARY OF BACKGROUND DATA: Young ASD patients in the United States are motivated more to correct coronal and sagittal plane deformities than to alleviate pain. Motivations for surgical correction in young ASD patients in Africa have not been previously investigated. METHODS: Retrospective review of two large databases of African and US patients with ASD. African patients who underwent ASD surgery were PSM by age, gender, and pelvic tilt with US patients. Preoperative radiographic parameters and HRQoL scores (ODI, SRS-22r, back/leg pain) were compared between cohorts. Pearson correlations used to evaluate relationships between radiographic parameters and HRQoL scores. RESULTS: Fifty-four US patients (average age 22.9 ± 4.9 years; 0% African American) and 54 African patients (24.6 ± 7.2 years) met inclusion criteria. Compared to the United States, African patients had significantly lower body mass index (21.1 ± 3.3 vs. 24.6 ± 7.2) and more severe scoliosis, coronal malalignment, and sagittal malalignment (p < .05). Africans also had significantly better Oswestry Disability Index (12.8 vs. 17.7), worse Scoliosis Research Society questionnaire (SRS-22r)-Appearance (2.5 vs. 3.2), SRS-Function (3.3 vs. 3.9), and SRS-Total (3.2 vs. 3.5) scores than US patients (p < .05). SRS-Appearance scores correlated with Cobb angles of the upper thoracic (r = -0.321), thoracic (r = -0.277), and thoracolumbar (r = -0.300) curves for US patients. For African patients, global sagittal alignment and C7 inclination correlated with SRS-Appearance (r = -0.347, -0.346, respectively). CONCLUSIONS: Young African ASD patients have significantly more severe deformity, less disability, and worse SRS-22r scores preoperatively than a matched cohort of US patients. Spinal deformity and associated poor self-image appear to be the major drivers of surgical intervention in this cohort. Global malalignment in African patients is most closely correlated with appearance scores and should be surgically addressed accordingly. LEVEL OF EVIDENCE: Level III.