A randomised controlled, prospective trial protocol comparing MID-MIS approaches for the treatment of discogenic low back pain: clinical outcomes, complication rates, and treatment costs in MIDLIF vs. MIS-TLIF.

backgroundDegenerative disc disease (DDD) is a major cause of low back pain and disability, with prevalence increasing with age. Surgical spinal fusion may be required when conservative treatment fails. Minimally invasive techniques such as midline lumbar interbody fusion (MIDLIF) and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) have demonstrated advantages over conventional open transforaminal lumbar interbody fusion, including reduced tissue trauma and faster recovery. However, evidence directly comparing these two minimally invasive techniques in patients with DDD remains limited and inconsistent.

methodsThis study is a prospective, randomised, partially blinded, two-arm clinical trial designed to compare the clinical outcomes, complication rates, 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 with or without radicular symptoms, unresponsive to conservative treatment for more than one year, will be enrolled. Participants will be randomised in a 1:1 ratio to undergo either MIS-TLIF (control group, n = 50) or MIDLIF (intervention group, n = 50), with a 12-month follow-up. Eligible patients will be ≥ 18 years of age and have one- or two-level lumbar discopathy requiring interbody stabilisation. Those with multilevel degenerative disease requiring surgery, spinal deformities, or pain caused by non-degenerative conditions will be excluded. The primary outcome is the change in pain intensity, measured using the Visual Analogue Scale (VAS) from baseline to 12 months postoperatively. Secondary outcomes include pain intensity (VAS and NRS), disability (COMI and ODI), and quality of life (EQ-5D-5 L) assessed at 1, 3, 6, and 12 months postoperatively. Additional outcomes include complication rates, treatment costs (hospitalisation and implants), length of hospital stay, procedure duration, blood loss, morphometric parameters such as intervertebral disc height, and adjacent segment disease assessed using MRI, CT, and X-ray imaging. Statistical analyses will be performed using parametric or non-parametric methods in R. The study follows the Declaration of Helsinki and has received ethics approval (no. 112/2024). DISCUSSION: Evidence comparing MIDLIF and MIS-TLIF for the treatment of DDD is scarce and sometimes contradictory. Although some studies have demonstrated shorter operative times, reduced blood loss, and shorter hospital stays with MIDLIF, others have indicated that MIS‑TLIF offers advantages. This randomised trial aims to provide high-quality evidence regarding clinical outcomes, safety, and cost-effectiveness of these two minimally invasive fusion techniques.

trial registrationClinicalTrials.gov NCT07127380. Date of registration in primary registry 11 August 2025.Unique Protocol ID 112/2024.