Impact of shift to the concave side of the C7-center sacral vertical line on de novo degenerative lumbar scoliosis progression in elderly volunteers.

Abstract

Degenerative lumbar scoliosis (DLS) is one of the most frequent spinal deformities of the aging spine. The purpose of our study was to clarify the independent predictors of pre-existing DLS progression and their influence on the health related quality of life (HRQOL). This study included 356 volunteers (127 men and 229 women; mean age, 72.2 years; follow-up period, 4 years) who underwent musculoskeletal screening. Standing whole-spine radiographic measurements included the Cobb angle of DLS and C7-center sacral vertical line (C7-CSVL; shift to the concave side of the DLS curve indicated a positive value). A baseline Cobb angle ≥10° indicated pre-existing DLS, and Cobb angle deterioration of ≥4° was considered DLS progression. For HRQOL assessment, the Oswestry Disability Index (ODI) was used. Pre-existing DLS cases were divided into progression and non-progression groups. Among 93 cases (26.1%) with pre-existing DLS at baseline, 23 cases (pre-existing DLS progression group) showed DLS progression. The mean C7-CSVLs were 10.5 and -3.1 mm in the pre-existing progression and non-progression groups, respectively (p < 0.01). The optimal cutoff C7-CSVL length was 5 mm, with high sensitivity and specificity. Multivariate logistic regression analysis showed that a C7-CSVL ≥5 mm (odds ratio, 3.8; 95% CI: 1.42-10.34; p < 0.01) was independently associated with pre-existing DLS progression. ODI scores deteriorated significantly more in the pre-existing progression group than the non-progression group (+9.8% versus +3.9%; p < 0.05). Pre-existing DLS progression is associated with a shift to the concave side of C7-CSVL and influences HRQOL deterioration. It is important to assess coronal global alignment for prediction of a DLS progression.