Minimally invasive transforaminal lumbar interbody fusion versus microscopic lumbar interbody fusion for the treatment of lumbar degenerative diseases: a radiological imaging-based retrospective study

Objective: To compare the radiographic efficacy of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and endoscopic lumbar interbody fusion (Endo-LIF) in the treatment of lumbar degenerative diseases, especially to evaluate the effects of the two procedures on spino-pelvic parameters and vertebral stability. Methods: A retrospective analysis was conducted on the clinical and radiological data of 178 patients who underwent single-level lumbar fusion surgery (75 cases in the endoscopic group and 103 cases in the channel group). Independent sample t-tests and chi-square tests were used to compare baseline characteristics. Paired t-tests were employed to analyze the changes in vertebral parameters (intervertebral inclination angle, height, slip distance, etc.) and sagittal parameters of the spine-pelvis (lumbar lordosis angle, Cobb angle, pelvic tilt angle, etc.) before and after surgery. The differences in improvement values between groups were evaluated by independent sample tests. The significance threshold was set at P < 0.05. Results: 1. Baseline characteristics: There were no statistically significant differences in age, gender, BMI, hospital stay, and distribution of fusion segments between the two groups (P > 0.05). 2. Implant parameters: The width of the fusion cage in the MIS-TLIF group was significantly greater than that in the Endo-LIF group (11.8 ± 1.6 mm vs. 10.7 ± 1.9 mm, P = 0.021). The usage rate of the L5/S1 segment was higher in the endoscopic group (10.3% vs. 3.5%, P = 0.115). 3. Improvement of vertebral parameters: The intervertebral inclination angle correction was significantly greater in the Endo-LIF group (7.2°→ 6.1°, Δ = -1.1°, P = 0.002), while there was no improvement in the MIS-TLIF group (6.5°→ 6.8°, Δ = 0.3°, P = 0.361); the difference in improvement between the groups was -1.4° (P = 0.007). There was no difference in intervertebral height recovery and slip correction between the groups (P > 0.05). 4. Sagittal balance parameters: The Cobb angle correction was more significant in the MIS-TLIF group (Δ = -1.82° vs. -0.43°, P = 0.003 between groups). The improvement of pelvic tilt angle in the MIS-TLIF group was better than that in the Endo-LIF group (Δ = -2.64° vs. +1.95°, P = 0.002 between groups). The stability of lumbar lordosis was better in the MIS-TLIF group (P = 0.021 between groups). Conclusion: Endo-LIF surgery has a significant advantage in correcting the intervertebral inclination angle, which may be attributed to the precise endoscopic operation. MIS-TLIF surgery is more effective in improving sagittal plane deformities (Cobb angle, pelvic tilt angle). The difference in fusion cage width suggests that endoscopic surgery tends to choose larger implants to enhance stability. The choice of clinical surgical methods should be combined with the type of deformity: Endo-LIF surgery is suitable for cases that require fine adjustment of intervertebral alignment, while MIS-TLIF surgery is more appropriate for patients with sagittal imbalance.