Intervertebral Subluxation, Lumbar Lordosis but not Cobb Angle, Correlate with Surgical Rates in Adult Thoracolumbar and Lumbar Scoliosis: A Multi-center Analysis

Summary: This study analyzed radiographic parameters shown to correlate with disability in adult scoliosis, and review associated surgical rates. This multi-center study included 870 adults with thoracolumbar/lumbar scoliosis. Treatment was surgical in 42%. Surgical rates and disability for patients with intervertebral subluxation >7mm vs. those with no subluxation were 52% vs. 37%, p<0 .001 (ODI/SRS scores, p<0.001), for patients with lumbar lordosis exceeding 400 vs. no lordosis, surgical rates were 36% 54%, p="0.038," scores p<0.003).

Purpose: Recent reports have focused on establishing a radiographic classification system for adult scoliotic deformities. The purpose of this study was to analyze radiographic parameters shown to correlate with disability in the setting of adult scoliosis, and study the surgical rates associated with these parameters.

Methods: This is a multi-center IRB-approved prospective study including 870 consecutive adults with thoracolumbar/lumbar scoliosis. Treatment modality was analyzed and correlated with radiographic parameters. Radiographic analysis included: frontal plane Cobb angle, apical level, lumbar lordosis (T12- S1), frontal/sagittal plane intervertebral subluxations. Health assessment questionnaires included: Oswestry Disability Index, Scoliosis Research Society instrument (SRS-29)). Surgical rates were analyzed by grouping patients into categories, based upon radiographic parameters (statistical comparison (t-test)).

Results: For the 870 patients, (avg. age 48 years, SD 18) mean frontal plane Cobb angle was 460 (SD 200). Lumbar lordosis (T12-S1) was: for 505 patients >400, for 249 patients 0-400, for 39 patients >00 (kyphotic). In 388 patients frontal or sagittal plane intervertebral subluxation was noted. Treatment reported was surgical in 42% of patients. Surgical rates and disability for patients with subluxation >7mm compared to those with no subluxation were 52% vs. 37%, p400 vs. subluxation >7mm and no lumbar lordosis had different surgical rates (34% vs. 61%, p=0.02, ODI/SRS scores <0 .002)).

Conclusion: This study is a unique analysis of scoliosis in adults. Previously established risk factors for greater "disability" (ODI, SRS-29) included loss of lumbar lordosis and intervertebral subluxation. This investigation has established that surgical rates were also significantly influenced by these factors. The data further supports that a clinically significant classification approach to adult scoliosis can be established.