Objectives: To find out the radiologic factors predicting the outcomes of reduction of lumbar spondylolisthesis.
Methods: Forty two patients were treated with pedicle screw fixation with posterolateral fusion because of lumbar spondylolisthesis, with the average age of 56.0 years. There were 11 males and 31 females; 20 degenerative spondylolisthesis cases, and 22 isthmic spondylolisthesis cases; 1 L(3,4) case, 26 L(4,5) cases and 25 L(5)S(1) cases; 23 grade I patients and 19 grade II ones. All patients were taken the X-ray examination before operation and one week after operation. Measurements of slip ratio, percentage disc height, slip angle, lumbar lordosis angle and sacral slope angle were based on pre-operation X-rays. Measurements of the post-operation slip ratio were based on post-operation X-rays. Multivariate regression analysis was used to analysis the correlation between reduction ratio and pre-operation slip ratio, slip angle, percentage of disc height, lumbar lordosis angle and sacral slope angle.
Results: The average pre-operation slip ratio was (22.5 +/- 10.6)%. The pre-operation percentage disc height was 0.23 +/- 0.10, the slip angle was 4.4 degrees +/- 5.4 degrees , the lumbar lordosis angle was 43 degrees +/- 13 degrees and the sacral slope angle was 34 degrees +/- 10 degrees . The reduction ratio was (63.2 +/- 27.9)%. No correlation was found among reduction ratio with pre-operation slip ratio, slip angle and sacral slope angle, but a positive correlation between reduction ratio and the pre-operation percentage of disc height (P < 0.05), a positive correlation between reduction ratio and the pre-operation lumbar lordosis angle (P < 0.05) was found.
Conclusion: The percentage disc height and the lumbar lordosis angle can predict the outcomes of reduction of lumbar spondylolisthesis.