Effect of sagittal spinal balance, levels of posterior instrumentation, and length of follow-up on low back pain in patients undergoing posterior decompression and instrumented fusion for degenerative lumbar spine disease: a multifactorial analysis.

STUDY DESIGN: Prospective controlled clinical study on low back pain (LBP).

OBJECTIVE: To investigate the possible effects of radiographic and other related parameters on LBP in patients underwent decompression and posterolateral instrumented fusion for degenerative lumbar spine disease.

SUMMARY OF BACKGROUND DATA: Sagittal balance of the spine after spine surgery has gained increasing interest regarding its correlation with LBP and fusion rate. To our knowledge, no advanced statistical analysis on the effects of sagittal roentgenographic and other parameters on LBP after lumbar surgery has been published.

METHODS: Forty-five patients with an average age of 63 years, who underwent pedicle-screw fixation in 2, 3, and 4 vertebrae for degenerative lumbar spine disease were selected to be included in this study. Radiographic and self-assessment (bodily pain, short form-36) data were evaluated using advanced statistics (multifactorial analysis) to investigate all possible correlations between a dependent parameter (LBP) and independent parameters (sex, extension of instrumentation, sagittal spinal balance, and angular motion at the adjacent free level above instrumentation).

RESULTS: All patients were observed for an average of 5.5 years (range, 5-7 years). Male patients showed significantly more improvement of LBP than female counterparts (P = 0.024). LBP improved after surgery by the first year (P < 0.000) and thereafter decreased (P < 0.000) at the final evaluation, but remained at levels significantly higher than before surgery (P < 0.000). The deviation of the apical lumbar vertebra from C7-plumbline was correlated with LBP (P < 0.000). Patients, who received third- and fourth- level instrumentation had less LBP (P = 0.0245) than their counterparts, who received second-level instrumentation.

CONCLUSION: Improvement of sagittal deviation of apical lumbar vertebra, instrumentation of third or fourth vertebrae, male gender, and fusion success were correlated with postoperative improvement of LBP after posterior decompression and pedicle screw fixation for symptomatic degenerative lumbar spine disease.This research suggests that the methods directed at the improvement in sagittal spinal balance of the lumbar spine, careful selection of fusion levels, and improvement of fusion rate might be beneficial for decreasing LBP after surgery in degenerative lumbar spine disease.