OBJECTIVETo investigate degenerative changes of the intervertebral disc and their impact on spinal flexibility in patients with degenerative lumbar scoliosis (DLS).

METHODSRetrospective analysis of 66 patients (average age 58.4 years, 10 males and 56 females) with DLS was conducted from May 2008 to February 2014. For all patients, pre-operative standing X-ray film, Bending X-ray films and thoracolumbar MRI were taken. Cobb's angle was measured in each X-ray film and intervertebral angle was measured in both standing and Bending X-ray films. All discs were graded according to Pfirrmann degeneration grades on T2 weighted saggital MRI imaging. Statistical analyses were performed to determine the correlation between intervertebral disc degeneration with the whole spine flexibility and segmental flexibility.

RESULTSFor all 66 subjects, the average Cobb's angle of pre-operative and bending X-ray film was 36° ± 13°, 21° ± 11°, respectively. The average flexibility was 45% ± 15% in our study. Totally 268 discs were graded, including gradeI8, II 68, III 83, IV 91, V 18. In the main curve, there was significant correlation between the average degree of disc degeneration and the whole spine flexibility(r = -0.727, P < 0.01). There was significant correlation between the grade of segmental disc degeneration and segmental flexibility (P < 0.01) . The apical intervertebral disc had the most degeneration (P < 0.01) and worst flexibility (P < 0.01) , compared with other discs in the main curve.

CONCLUSIONSThe degree of intervertebral disc degeneration is closely correlated with spinal flexibility in DLS. The more the disc degeneration is, the worse the spinal flexibility becomes.