MID-MIS: MIDLIF versus MIS-TLIF in the treatment of discogenic low back pain, comparison of clinical outcomes, complications rate, and treatment costs: a randomized controlled, prospective trial protocol

Background Degenerative disc disease (DDD) is the leading cause of lower back pain and disability, whose prevalence increases with age. When conservative treatment fails, surgical methods of spinal fusion are employed. Minimally invasive techniques, including minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and midline lumbar interbody fusion (MIDLIF), have well-documented advantages over traditional open transforaminal interbody fusion. However, data comparing these two minimally invasive methods in treating DDD are limited and sometimes contradictory. Methods This is a prospective, randomized, partially masked, two-arm trial comparing the outcomes, complications, and treatment costs of MIS-TLIF and MIDLIF in patients with discogenic low back pain. A total of 100 adult patients with lumbosacral spine pain and radicular symptoms, unresponsive to conservative treatment for over one year, will be enrolled. Patients will be randomized (1:1) into two arms: MIS-TLIF (control, n = 50) and MIDLIF (intervention, n = 50), with a 12-month follow-up period. Inclusion criteria include age ≥ 18 years and discopathy at one or two levels requiring interbody stabilization. Exclusion criteria include multilevel pathology, spinal deformities, and pain causes other than degenerative disease. Primary endpoints assess pain (VAS, NRS scales), disability (COMI, ODI questionnaires), and quality of life (EQ-5D-5L questionnaire) at 1, 3, 6, and 12 months post-surgery. Secondary endpoints include complication rates, costs (hospitalization, implants), length of hospital stay, procedure duration, blood loss, morphometric parameters (intervertebral space height), and adjacent segment disease, as determined by imaging studies (MRI, CT, X-ray). Data analysis uses parametric/non-parametric tests in the R software. The trial adheres to the Helsinki Declaration, with ethics approval (no. 112/2024). Discussion Data on the comparison of MIDLIF and MIS-TLIF in treating DDD are minimal and inconsistent. Some reports favor MIDLIF for shorter operative time, decreased intraoperative blood loss, and reduced hospital stays, while others prefer MIS-TLIF. This trial addresses these gaps by providing high-quality evidence on clinical superiority, cost-effectiveness, and long-term outcomes comparing MIDLIF and MIS-TLIF. There is a high need for high-quality, prospective studies to examine this problem. Trail registration The study had been retrospectively registered on ClinicalTrials.gov with the number NCT07127380. Registered 11 August 2025.