Objective: To evaluate retrospectively the relationship between low back pain and changes of lumbar spine sagittal alignment after lumbar spine fusion.
Methods: During January-December 2008, a total of 182 consecutive patients with degenerative lumbar spine diseases underwent posterior lumbar interbody fusion (PLIF) and the follow-up period was over 24 months. Standing lumbar spine anteroposterior and lateral radiography were taken during the follow-up and the lumbar lordosis Cobb angles were measured on radiography. Pain degrees were assessed by visual analog scale (VAS) and Oswestry disability index (ODI). The relationship between the changes of Cobb angle and lumbar sagittal plane curve was analyzed by the SPSS software. Also the relationship between back pain degree and Cobb angle was examined.
Results: Among them, 42 cases with postoperative back pain were followed up for 24 months. There were 19 males and 23 females with a mean age of 59.6 years (range: 40 - 77). Lumbar spine sagittal Cobb angles were measured from radiographic images:lumbar lordosis angle: (1) mean angle at 12-month follow-up: 40.1° ± 10.6°, range: 20° - 60°; (2) mean angle at 24-month follow-up: 40.8° ± 10°, range: 24° - 60°. Back pain of 42 patients: VAS: (1) mean at 12-month follow-up: 29.4 ± 11.5, range: 5 - 50; (2) mean at 24-month follow-up: 27.6 ± 11.7, range: 25 - 48. Lumbar spine function of 42 patients: ODI: (1) mean at 12-month follow-up: 15.1 ± 5.4, range: 0 - 25; (2) mean at 24-month follow-up: 13.9 ± 5.2, range: 0 - 24. Difference between lumbar lordosis angle and standard score: (1) mean angle at 12-month follow-up: 19.9° ± 10.6°, range:0°-40°; (2) mean angle at 24-month follow-up:19.2° ± 10.0°, range:0°-36°. Angle difference versus back pain VAS: (1) at 12-month follow-up:P < 0.001, positive correlation; (2) 24-month follow-up: P < 0.001, positive correlation; angle difference versus back pain ODI: (1) 12-month follow-up:P < 0.001, positive correlation; (2) 24-month follow-up: P < 0.001, positive correlation.
Conclusion: There is a close relationship between back pain after fusion and loss of lumbar sagittal lordosis. And reconstruction of lumbar lordosis should be one important goal for lumbar fusion.