Modified Freehand Minimally Invasive Transforaminal Lumbar Interbody Fusion for Single‐Level Degenerative Lumbar Disease: 3‐Year Multicenter Retrospective Outcomes

ABSTRACT Objective This study introduces a modified minimally invasive transforaminal lumbar interbody fusion (MIS‐TLIF) technique to address the limitations of conventional MIS‐TLIF, including soft tissue injury, excessive reliance on intraoperative fluoroscopy, and a steep learning curve. We evaluated the clinical efficacy of this modified approach in the treatment of single‐level degenerative lumbar spine disease, with the aim of elucidating its advantages over the traditional technique and summarizing key technical considerations. Methods This retrospective study analyzed 286 patients who underwent surgery between January 2018 and July 2021 for single‐level degenerative lumbar disease. Patients were divided into modified MIS‐TLIF (n = 131) and traditional MIS‐TLIF (n = 155) groups. Clinical outcomes were evaluated using the Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and Japanese Orthopedic Association (JOA) scores. Surgical parameters included operation time, intraoperative blood loss, fluoroscopy time, hospital stay, and complication rates. Radiographic assessments used CT and dynamic lateral X‐rays to evaluate interbody fusion, while MRI was used to measure the fatty infiltration ratio of the multifidus (MF‐FI Ratio). Continuous variables were compared between groups using independent‐samples t tests, whereas categorical variables were analyzed using the chi‐square test or Fisher's exact test when expected cell counts were < 5. Paired t tests were employed to compare preoperative and postoperative measurements within each group. A two‐tailed p < 0.05 was considered statistically significant. Results Baseline characteristics showed no significant differences between groups (p > 0.05). Postoperative VAS, ODI, and JOA scores improved significantly in both groups (p < 0.05). All cases achieved successful fusion at the final follow‐up. Compared to the traditional group, the modified MIS‐TLIF group had shorter operation time (101.83 ± 26.23 vs. 117.81 ± 27.87 min), less blood loss (111.83 ± 26.22 vs. 147.68 ± 28.19 mL), shorter fluoroscopy time (12.35 ± 1.72 vs. 50.33 ± 6.36 s), fewer complications (5/131 vs. 16/155), and a lower MF‐FI ratio (36.67% ± 4.52% vs. 39.61% ± 4.58%). Conclusion The modified MIS‐TLIF technique better preserves paravertebral muscles, reduces radiation exposure, shortens operative time, and lowers complication rates, offering a more optimized treatment option for managing single‐segment lumbar degeneration.