Clinical and Radiological Outcomes Following Biportal Endoscopic Lumbar Interbody Fusion: A Comparative Study of Three Interbody Cage Strategies

Background While traditional open fusions yield high fusion rates, they can result in significant muscle damage. Biportal Endoscopic Lumbar Interbody Fusion (BELIF) has emerged. This study compares clinical and radiological outcomes of BELIF using three different interbody cage strategies. Methods This retrospective cohort study included 106 consecutive patients undergoing single-segment BELIF for lumbar degenerative disease. Patients were divided into three groups based on cage strategy: Group A (n=34, two 28x10 mm Titanium cages), Group B (n=32, single 40x15 mm PEEK cage), and Group C (n=40, single 32x10 mm PEEK cage). Clinical outcomes and radiological outcomes were assessed preoperatively and at final follow-up. Results All groups showed significant improvements in VAS and ODI scores, with no significant intergroup differences in final scores. Group B had the longest operative time (p<0.001). No major neurological complications occurred. While sagittal parameters improved within groups, there were no significant intergroup differences in the degree of correction. Fusion rates differed significantly at 6 and 12 months (Groups A & B > Group C) but were not significantly different at final follow-up (p=0.845). The incidence of subsidence was significantly higher in Group C (15.0%) compared to Group A (5.9%) and Group B (6.3%) (p=0.035) Conclusion BELIF provide satisfactory clinical outcomes regardless of the cage strategy. However, cage size and potentially material significantly influenced early fusion rates and subsidence. Cages with larger footprints demonstrated superior early fusion, whereas the smallest footprint cage was associated with a significantly higher subsidence rate.