Exploratory comparisons of unilateral and bilateral fixation in unilateral biportal endoscopic extreme transforaminal lumbar interbody fusion for lumbar degenerative diseases

The aim of this study was to explore and compare the clinical and radiographic outcomes of unilateral pedicle screw fixation (UPSF) and bilateral pedicle screw fixation (BPSF) in unilateral biportal endoscopic extreme transforaminal lumbar interbody fusion (UBE-eXTLIF) for the treatment of lumbar degenerative diseases. A total of 29 patients who underwent UBE-eXTLIF with either UPSF or BPSF were investigated retrospectively. The operation time, length of postoperative hospital stay, and complications were recorded. A visual analog scale (VAS) for low back pain and leg pain, the Oswestry Disability Index (ODI) and a modified Macnab scale were used to evaluate clinical efficacy. Radiographs and CT were utilized to assess radiological outcomes such as disc height (DH), lumbar lordosis (LL) and the interbody fusion rate. Both surgical techniques resulted in significant improvements in the VAS score and ODI. The VAS scores for low back pain and leg pain improved after the operation in both groups, and there were no statistically significant differences between the two groups at postoperative 1, 3, 6, 12, or 24 months (P > 0.05). The ODI scores improved after the operation in both groups, and there were no statistically significant differences between the two groups at postoperative 1, 3, 6, 12, or 24 months (P > 0.05). According to the modified Macnab scale at the final follow-up, 6 cases were excellent, 1 case was good, and 1 case was fair in the UBE-eXTLIF with UPSF group, while 16 cases were excellent, 2 cases were good, and 3 cases were fair in the UBE-eXTLIF with BPSF group, and the difference was not statistically significant between the two groups (P > 0.05). The fusion rate at 2 years post-surgery was similar: 100% for UBE-eXTLIF with UPSF and 90.5% for UBE-eXTLIF with BPSF. Both lumbar lordosis and disc height were restored 2 years postoperatively in both groups, and the changes in LL and DH from preoperative to postoperative 2 years were not significantly different between the two groups (P > 0.05). The incidence of complications did not significantly differ between the two groups (P > 0.05). However, compared with that of UBE-eXTLIF with BPSF, the operation time of UBE-eXTLIF with UPSF was shorter (P < 0.05), but there was no statistically significant difference between the two groups in terms of postoperative hospital stay (P > 0.05). In carefully selected patients, UBE-eXTLIF with unilateral posterior fixation may yield short-to-mid-term outcomes comparable to those of bilateral posterior fixation within a shorter operative time. However, owing to the small sample size, lack of biomechanical confirmation, and limited follow-up, the generalizability of these conclusions remains limited.