Correlation between radiographic parameters and functional scores in degenerative lumbar and thoracolumbar scoliosis

Introduction: Adult scoliosis is a condition in which the spinal deformity occurs because of degeneration. Although various studies have agreed on the importance of restoring the sagittal balance, few have evaluated the relationship between functional scores and radiological parameters. The primary objective of this retrospective study was to demonstrate the correlation between radiographic parameters and functional outcomes in adult patients with lumbar or thoracolumbar degenerative scoliosis. The secondary objective was to assess the long-term effects of posterolateral fusion for treating this deformity.

Study outline: This single-centre retrospective study included 47 patients over 50years of age who had degenerative lumbar scoliosis treated with an instrumented posterolateral fusion; the mean follow-up was 6.4years (range 2 to 20).

Methods: Radiographic analysis of A/P and lateral full spine standing radiographs was carried out with the KEOPS software. Three pelvic parameters (pelvic tilt, pelvic incidence, sacral slope), two spinal parameters (lumbar lordosis and thoracic kyphosis) and three sagittal balance parameters (C7 sagittal tilt, C7 Barrey's ratio and spinosacral angle) were calculated. The functional outcomes were evaluated through three self-assessment questionnaires: Oswestry Disability Index, SRS-30 and SF-36. The correlation between clinical and radiographic parameters was calculated with Spearman's correlation test.

Results: There was a significant correlation between the SF-36 (PCS) and the following three sagittal parameters: sacral slope (r=-0.31453; P=0.04), lumbar lordosis (r=-0.30198; P=0.0491) and spinosacral angle (r=-0.311967; P=0.0366). The mean ODI score was 33.61, which corresponds to minimal to moderate disability. The mean physical (PCS) and mental (MCS) component summary scores of the SF-36 were 37.70 and 38.40, respectively. The mean SRS-30 score was 3.07.

Conclusion: It is essential that the sagittal balance be restored when treating degenerative lumbar scoliosis to generate better functional outcomes and better quality of life. To achieve this correction, instrumented posterolateral fusion appears to be a very reliable technique that leads to lasting improvement.

Level of evidence: IV.