Biportal Endoscopic Transforaminal Lumbar Interbody Fusion Using Double Cages: Surgical Techniques and Treatment Outcomes

Objective: To describe the surgical techniques and the treatment outcomes of biportal endoscopic transforaminal lumbar interbody fusion (BETLIF) using double cages. Methods: This study included 89 patients with 114 fusion segments between July 2019 and May 2021. One pure polyetheretherketone (PEEK) cage and 1 composite titanium-PEEK cage were used for interbody fusion. Clinical outcomes measures included visual analogue scale (VAS) scores for lower back pain and leg pain, Oswestry Disability Index (ODI), and Japanese Orthopedic Association (JOA) scores. Computed tomography (CT) of the lumbar spine 1 year postoperatively was used to evaluate the Bridwell interbody fusion grades. Results: There were significant improvement in VAS for lower back pain from 5.2 +/- 3.1 to 1.7 +/- 2.1, VAS for leg pain from 6.3 +/- 2.5 to 1.7 +/- 2.0, ODI from 46.7 +/- 17.0 to 12.7 +/- 16.1, and JOA score from 15.6 +/- 6.3 to 26.4 +/- 3.2. The p-values were all < 0.001. The average hospital stay was 5.7 +/- 1.1 days. The CT studies available for 60 fusion segments showed successful fusion (Bridwell grade I or grade II) in 56 segments (93.3%). Significant cage subsidence of more than 2 mm was only noted in 3 segments (5.0%). Complications included 1 dural tear, 2 pedicle screws malposition, and 2 epidural hematomas, in which 2 patients required reoperations. Conclusion: BETLIF with double cages provided good neural decompression and a sound environment for interbody fusion with a big cage footprint, a large amount of bone graft, endplate preservation, and segmental stability.