INTRODUCTION: The spinal endoscopic technique has been extensively documented in decompression procedures for treating lumbar degenerative diseases. However, there is limited literature on the spinal endoscopic in lumbar fusion techniques. This study evaluates the outcomes and safety of full-endoscopic posterior lumbar interbody fusion (Endo-PLIF) for the treatment of lumbar degenerative diseases. METHODS: A retrospective case series was conducted at Beijing Chaoyang Hospital, Capital Medical University, involving 43 patients who underwent Endo-PLIF between February 2020 and March 2021, with a minimum follow-up period of two years. Clinical outcomes were evaluated using the Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and modified MacNab criteria. VAS and ODI scores were analyzed using one-way analysis of variance (ANOVA) at preoperative, 3-month, 12-month, 24-month, and final follow-up time points. Paired t-tests were employed to compare imaging parameters, including lumbar lordosis, disc height, segmental lordosis, and foraminal area, between the preoperative and final follow-up assessments. RESULTS: This study included 43 consecutive patients with a mean age of 60.7 years and an average symptom duration of 4.6 years. All surgical procedures were successfully completed, with a mean operation duration of 233.8 ± 38.6 min. Mean VAS and ODI scores showed significant improvements postoperatively, decreasing from 7.05 ± 3.05, 7.44 ± 2.95, and 67.52 ± 9.31 points preoperatively to 1.22 ± 0.54, 1.50 ± 0.42, and 20.42 ± 3.57 at the latest follow-up (p <
0.001). Disc height (p = 0.012) and foraminal area (p = 0.013) increased significantly. MacNab evaluation indicated 90.6% of patients had good to excellent outcomes. Three patients experienced symptomatic nerve root irritation. CONCLUSION: Endo-PLIF is safe and effective in the treatment of patients with lumbar degenerative disease in early follow-up. However, further extensive, long-term, multicenter studies are necessary to validate these findings.