Preservation of the Posterior Interspinous Ligamentary Complex in Posterior and Transforaminal Lumbar Interbody Fusion

Posterior and transforaminal lumbar interbody fusion (PLIF and TLIF) allow some variation between surgeons, particularly regarding the extent of resection of the posterior interspinous ligamentary complex (PILC) with uncertain implications for outcome. The aim of this study was to assess the importance of preserving the PILC when performing PLIF or TLIF. Systematic review of clinical outcomes (adjacent segment degeneration (ASDG), fusion rate, reoperation rate, and visual analog scale (VAS) scores for back and leg pain) after PLIF/TLIF matched for integrity of PILC, Oswestry Disability Index (ODI) score, and radiological parameters. A total of 191 patients from 2 studies (1 prospective randomized control trial (RCT) and 1 retrospective observational cohort study) were identified. 102 (53.4%) had fusion (PLIF/TLIF) with preserved PILC. All 120 patients in the RCT underwent a L4-L5 single-level fusion, while the 71 patients in the retrospective cohort underwent surgery between T11 and S1. In the retrospective cohort study, significant differences between groups in mean number of fixed levels (4.8 +/- 1.0 vs. 4.2 +/- 0.5), decompressed levels (2.4 +/- 0.7 vs. 3.0 +/- 0.7), and interbody fusions (1.2 +/- 0.9 vs. 2.0 +/- 1.0) were reported. In each of the studies, all groups reported an improved ODI score at 3 months after surgery and at last follow-up. In each of the studies, the incidence of radiographic ASDG was significantly higher for the PILC resection group in both studies (9.0% vs. 43.0%, p < 0.01 and 23.0% vs. 49.0%, p = 0.042). Lumbar lordosis (which decreased after PILC resection in the RCT, p < 0.05) also differed between groups. Taken as a whole, these results suggest that preservation of the PILC during PLIF/TLIF surgery prevents future ASDG and loss of lumbar lordosis as well as the potential clinical consequences of these changes. Further prospective studies are needed.