Adequate Restoration of Disc Height and Segmental Lordosis by Lumbar Interbody Fusion Decreases Adjacent Segment Degeneration

• Published in: World neurosurgery Vol. 118; pp. e856 - e864
• Main Authors: Tian, Haijun, Wu, Aimin, Guo, Mingke, Zhang, Kai, Chen, Chen, Li, Xunlin, Cheng, Xiaofei, Zhou, Tangjun, Murray, Samuel S., Sun, Xiaojiang, Zhao, Jie
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-10-2018
• Subjects: Adjacent segment degeneration; Degenerative lumbar disorder; Disc height; Lumbar interbody fusion; Segmental lordosis; LL; FH; Disc height; DH; ADH; VAS; Adjacent segment degeneration; AP; Degenerative lumbar disorder; MDH; ASD; TLIF; ODI; PDH; RFH; ALIF; Lumbar interbody fusion; RDH; SL; PLIF; Segmental lordosis; adjacent segment degeneration; degenerative lumbar disorder; segmental lordosis; lumbar interbody fusion; disc height
• ISSN: 1878-8750; 1878-8769
• DOI: 10.1016/j.wneu.2018.07.075

This study aimed to investigate the effects of lumbar interbody fusion–induced biomechanical changes on the adjacent segments, especially disc height and segmental lordosis restoration, and to provide more information for proper surgical strategy selection.
The medical records of 528 patients who underwent posterior lumbar interbody fusion were retrospectively reviewed, and a total of 89 patients were included. Surgical indications included degenerative spondylolisthesis (nonspondylolytic), marked disc herniation, or lumbar spinal stenosis requiring extensive decompression at L4/5. Postoperative adjacent segment degeneration (ASD) was assessed based on X-rays and functional status. Disc height, foraminal height, segmental lordosis, lumbar lordosis, and cage geometry were compared between the ASD and non-ASD patients. To identify the possible risk factors for radiographic ASD, univariate analysis was performed first, followed by multivariate logistic regression using variables with P < 0.20.
Univariate analysis revealed that the postoperative disc height in the non-ASD group were significantly greater than in the ASD group. The postoperative segmental lordosis in the non-ASD group was significantly greater than that in the ASD group, and the lumbar lordosis in the non-ASD group was also significantly greater than that in the ASD group at the final follow-up visit. Four variables were identified as independent risk factors for ASD by subsequent multivariate logistic regression: postoperative relative disc height of L4/5 (P = 0.011), postoperative segmental lordosis (P = 0.046), lumbar lordosis at the final follow-up visit (P = 0.007), and cage height (P = 0.038).
Improved lumbar lordosis is correlated with a lower incidence of ASD, and adequate disc height and segmental lordosis restoration are essential for ASD prevention.
•Spinal sagittal alignment is important for the development of adjacent segment degeneration (ASD).•Better segmental lordosis is correlated with a lower incidence of ASD.•Adequate disc height restoration is essential for ASD prevention.•Relatively large size and anterior position of the interbody cage can achieve greater disc height and segmental lordosis.•Excessive distraction of the disc space may still be unfavorable.