Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Comparison Study Based on End Plate Subsidence and Cystic Change in Individuals Older and Younger than 65 Years.

Objective: To compare the outcomes between patients older and younger than 65 years who underwent single-level minimally invasive transforaminal interbody fusion (MI-TLIF) surgery.

Methods: This study is a retrospective analysis of 76 patients who underwent MI-TLIF between April 2012 and June 2016. Group A consisted of 35 patients (<65 years) and group B consisted of 41 patients (≥65 years). Intraoperative data were recorded. The evaluation of clinical outcomes was based on the visual analog scale for back and leg pain and the Oswestry Disability Index. Radiologic outcomes including cage subsidence, end plate cyst formation, and fusion rate were assessed.

Results: The mean age of the study subjects was 65.3 years, and the mean duration of follow-up was 18.98 months. Group B had a higher rate of comorbidities compared with group A (90.24% vs. 57.14%, respectively; P < 0.05). There was no statistically significant difference in the rate of complications between the groups (group A, 14.29%; group B, 17.07%). Clinical outcomes significantly improved in both groups postoperatively (P < 0.05). Although bony fusion in group A was slightly higher than that in group B, the fusion rate was not statistically different according to age. There were no statistically significant differences in the rates of cage subsidence or positive cyst sign between the groups.

Conclusions: MI-TLIF presented similar safeness and acceptable outcomes and complication rate in both groups. Cyst formation may be aggravated by cage subsidence, because cage subsidence was a useful potential predictor of cyst formation.