A new method for establishing operative channels in unilateral biportal endoscopic surgery: Technical notes and preliminary results

The unilateral biportal endoscopic (UBE) technique has been widely used in spine surgery. At present, a traditional rigid working channel is available for the UBE system. A metal semicircular canal is located in the working channel. However, due to the metal material of the working channel, arthroscopy and instruments are constrained from moving in UBE surgery. Additionally, an assistant is needed during the procedure to hold the traditional working channel.For simplicity of operation and convenient movement of the arthroscopy and instrument, we describe a new method for establishing operative channels in UBE surgery.We retrospectively reviewed 50 patients who underwent unilateral biportal endoscopic discectomy (UBED) from February 2020 to August 2020 via our new method. The Oswestry Disability Index (ODI) and visual analogue scale (VAS) score were measured preoperatively and 1 month, 3 months, 6 months and 12 months postoperatively. Statistical comparisons were made using analysis of covariance and paired t tests.The VAS scores for back pain at the five time points were 5.20 ± 2.57, 1.96 ± 0.95, 1.50 ± 0.84, 1.64 ± 1.08 and 1.18 ± 0.39. The leg pain VAS scores were 7.02 ± 2.25, 2.02 ± 1.27, 1.48 ± 0.89, 1.32 ± 0.79 and 0.88 ± 0.52. The ODI values were 51.08 ± 19.97, 19.62 ± 15.51, 8.26 ± 7.40, and 7.54 ± 6.42 to 3.24 ± 1.10. The postoperative ODIs and VAS scores of low back pain and leg pain were significantly lower than those before surgery, and differences were statistically significant (all p< 0.05). The pressure of the closed outflow was significantly higher than that of the open outflow (37.35 ± 13.11 mm Hg vs. 24.55 ± 12.64 mm Hg p= 0.003). After we tightened the infusion strap to open the outflow, the pressure decreased significantly (26.4 ± 14.08 mm Hg vs. 37.35 ± 13.11 mm Hg p= 0.015). There were 2 cases of complications, including 1 case of postoperative recurrence and 1 case of dural tears.This study demonstrates the technical feasibility, safety, and efficacy of modified channel establishment in UBE surgery.