Comparison of Adjacent Segment Degeneration After Minimally Invasive or Open Transforaminal Lumbar Interbody Fusion

Abstract

STUDY DESIGN: This was a retrospective case series. OBJECTIVE: The purpose of this study was to compare radiologic and clinical outcomes in patients with L4-L5 lumbar spinal stenosis (LSS) who had undergone either minimally invasive (MIS-) or open (O-) transforaminal lumbar interbody fusion (TLIF), especially with regard to the development of adjacent segment degeneration (ASDeg). SUMMARY OF BACKGROUND DATA: ASDeg is defined as the degenerative changes at adjacent segments of a fused segment, with no obvious clinical symptoms. MATERIALS AND METHODS: A total of 121 LSS patients with a minimum 5-year follow-up were included. Patients were divided into 2 groups according to the surgery performed (MIS-TLIF: 57 patients, O-TLIF: 64 patients). Preoperative and final follow-up radiologic parameters were determined. The incidence of ASDeg was evaluated and compared between the 2 groups. Visual Analog Scale score, Japanese Orthopaedic Association score, and Oswestry Disability Index were used to assess clinical outcomes. RESULTS: Before surgery, no significant difference was found between MIS-TLIF and O-TLIF groups regarding demographic, radiologic, and clinical data. After a 5-year follow-up, the incidence of ASDeg in LSS patients was 47.1% (57/121). ASDeg was mostly located at the cranial segment of the fused level in each group. The most common type of ASDeg in both groups was intervertebral space collapse. There was a lower chance of ASDeg in MIS-TLIF group than that in O-TLIF group (33.3% vs. 59.4%, P <0.01). Postoperatively, both groups had significant improvement in clinical outcomes, and there were no statistically significant intergroup differences assessed by Visual Analog Scale, Japanese Orthopaedic Association, and Oswestry Disability Index scores. CONCLUSION: The clinical effect of MIS-TLIF and O-TLIF were similar, but the incidence of ASDeg was significantly lower after MIS-TLIF at 5-year follow-up.