Risk of progression of degenerative lumbar scoliosis.

OBJECT In this paper the authors' goal was to determine the factors associated with the progression of degenerative lumbar scoliosis (DLS). METHODS Twenty-seven patients (3 men and 24 women; mean age 64.9 years) with more than 10° of lumbar scoliosis at baseline were monitored for a mean period of 10 years. The radiological evaluation included measurement of the scoliosis angle using the Cobb method, the direction of the scoliosis, the relationship between the intercrest line and the L-5 vertebra, lateral listhesis, segmental angle, distance from the center of the sacral line to the apical vertebra, degenerative listhesis anteriorly or posteriorly or both, and lordosis angle. In addition, the lateral osteophyte difference, disc index, and severity of osteoporosis were measured. The pain and disability outcomes were assessed using the visual analog scale and the Oswestry Disability Index (ODI) relative to severity of the angle of scoliosis. RESULTS The mean initial and final scoliosis angles were 14° ± 5.4° and 25° ± 8.5°, respectively. The initial disc index at the L-3 vertebra (Spearman ρ = 0.7, p < 0.001), the sum of the segmental wedging angles above and below the L-3 vertebra (ρ = 0.6, p < 0.001), and the initial disc index at the apical vertebra (ρ = 0.6, p < 0.001) were correlated with the last follow-up angle of the scoliosis. By contrast, there was no statistically significant correlation between the initial segmental angles at L2-3 and L3-4 and the final follow-up scoliosis angle (ρ = 0.2, p = 0.67; and ρ = 0.1, p = 0.22; respectively). When the authors separated the patients into 3 groups according to the sum of the segmental angles above and below L-3 (< 5°, 5° to 10°, and > 10°), they found that 3 (42.9%) of 7, 8 (66.7%) of 12, and 6 (75.0%) of 8 patients in the 3 groups showed increases of greater than 10° in scoliosis angle. The mean distance from the center of the sacral line to the apical vertebra was 36.0 ± 9.7 mm, and the distance correlated with the measurement of the last follow-up angle of the scoliosis (ρ = 0.6, p < 0.001). The mean angle of the scoliosis was significantly greater when the intercrest line passed through the L-5 or L4-5 disc space than when the line passed through the L-4 vertebral body (31.4° ± 7.9° vs 21.8° ± 6.7°, p = 0.01). The ODI correlated with the measurement of the angle of the scoliosis (ρ = 0.6, p < 0.001). Age, sex, osteoporosis, the direction of the scoliosis, listhesis of coronal and sagittal planes, the lateral osteophyte difference, and the vertebral body index did not correlate with curve progression. CONCLUSIONS The findings of this study demonstrated that the progression of DLS was affected by the relationship between the intercrest line and the L-5 vertebra. When L-5 was deep seated, progression of DLS was found. Asymmetrical change in the disc space above and below the L-3 or apical vertebra may also be an important predictor of curve progression.