Long-Term Outcome After Midline Lumbar Fusion for the Treatment of Lumbar Spine Instability Due to Degenerative Disease

Background: Midline lumbar fusion (MIDLF) is one promising new surgical technique that has been developed to minimize perioperative damage to the paravertebral stabilizing musculotendinous system. The aim of this study was to assess long-term clinical and radiological effects of MIDLF.

Methods: This prospective cohort study evaluated patients who underwent MIDLF for degenerative spinal instability. Clinical and radiological examinations were performed before and after surgery. Perioperative and postoperative complications were recorded. Follow-up was 2 years. P ≤ 0.05 was considered statistically significant.

Results: The study included 64 patients (mean age 58.9 ± 10.7 years; 41 women [64.1%]). The most frequent indication for MIDLF was degenerative spondylolisthesis grade I (28 cases [43.8%]); the prevalent spinal segment to be fused was L4-L5 (35 cases [54.7%]). Mean duration of surgery was 148.2 ± 28.9 minutes. Relief of low back pain and leg pain was significant and stable in the postoperative period as assessed by visual analog scale (P < 0.001). Of patients, 86.9% reported fair, good, or excellent outcomes in terms of pain relief based on MacNab score 2 years after surgery. Patients' level of function in activities of daily living improved significantly based on Oswestry Disability Index score: from 66.8 ± 9.8 before surgery to 33.9 ± 16.5 2 years after surgery (P < 0.001). X-rays and computed tomography at 12 months showed interbody fusion in 46 cases (73.4%), inconclusive results in 13 cases (20.3%), and no fusion in 4 cases (6.3%). No damage to neural or vascular structures and no failure of hardware or screw loosening were recorded.

Conclusions: MIDLF is a safe, efficient method for surgical treatment of lumbar spine instability. Its limited invasiveness contributes to better preservation of paravertebral muscles and enhanced postoperative spinal stability.