Summary of Background Data: Biportal endoscopic techniques for transforaminal lumbar interbody fusion (BE-TLIF) has been shown to have similar clinical and fusion outcomes with potentially faster clinical recovery in comparison to tubular TLIF surgery. Subsidence of the interbody, however, could be a potential complication. This study compared the fusion and subsidence rate and clinical outcomes when using different sized static PEEK cages in BE-TLIF.
Methods: Patients who underwent 1 or 2 level BE-TLIF for degenerative and isthmic spondylolisthesis between January 2019 and January 2022, were included in this study. A 32x10 mm cage (Group A) or 40x15 mm cage (Group B) were compared. The Visual Analog Scale (VAS) for back and leg symptoms, and Oswestry Disability Index (ODI) were collected. Plain radiographs and computed tomography assessed fusion and subsidence at a minimum of 12 months.
Results: Of the sixty-nine enrolled patients, 39 Group A patients (51 levels) and 30 Group B patients (32 levels) were compared. The operation time per level was 123 ± 15.8 and 138 ± 10.5 minutes per fusion level in Group A and B, respectively (p < 0.05). ODI improved from 64.8 ± 6.2 to 15.7 ± 7.1 in Group A and from 65.3 ± 5.6 to 15.1 ± 6.3 in Group B at final follow-up (p<0.05). VAS leg and back score improvement between the groups did not differ; however, the three-month postoperative VAS back improvement was significantly higher in Group B. The final fusion rate at final follow-up did not significantly differ; however, the fusion ratio at 1 year was higher in Group B (p<0.05). Subsidence occurred in 5 cases (9.8%) in Group A and none in Group B (p<0.05).
Conclusion: BE-TLIF using a larger cage can be performed safely with similar clinical patient reported outcome measures with a faster fusion rate with less subsidence risk.