Abstract
BACKGROUND: Anterior lumbar interbody fusion (ALIF) is an effective treatment for lumbar degenerative diseases, but it usually requires combined posterior fixation. Currently, Currently, there is no high-strength fixation technique for single-position anterior approach. This study aimed to introduce L5 vertebral body screws combined with S1 vertebral body-pedicle screw fixation (BPSF) as a novel single-position anterior fixation technique for ALIF, and to evaluate its clinical and biomechanical outcomes. METHODS: Sixty-three patients with L5/S1 degenerative disease undergoing ALIF were divided into BPSF (n = 22) and posterior pedicle screw fixation (PPSF, n = 41) groups. Clinical outcomes, radiographic parameters, and complications were collected and compared between groups. Biomechanically, an adult lumbar spine model was used to simulate two ALIF fixation configurations under normal and osteoporotic conditions. Each construct was loaded with 500N compression and 10N·m torque to simulate flexion/extension, lateral bending, and axial rotation. Kinematic analyses included ROM, interbody cage stress, and fixation device strain. RESULTS: The BPSF group showed significantly shorter operative duration (152.5 min (127.5, 173.1) vs. 165.0 min (140.0, 262.5), less intraoperative blood loss (115.0 ± 56.9 ml vs. 160.0 ml (110.0, 222.5) mL), and lower postoperative low back pain scores (1.6 ± 0.8 vs. 2.2 ± 0.7) compared to the PPSF group. And there were no statistically significant differences between the two groups in JOA improvement rate (49.9 ± 14.2% vs. 54.7 ± 18.1%), lumbar lordosis correction (6.9 ± 7.3° vs. 7.6 ± 7.1°), fusion rate (90.9% vs. 92.7%), or complication rate (27.3% vs. 19.5%). Biomechanically, BPSF reduced ROM during flexion (12% reduction) and axial rotation (63% reduction) compared to PPSF, with higher interbody cage stress but lower posterior fixation device stress under most loading conditions. CONCLUSION: BPSF provides safe anterior fixation for ALIF, reducing operative time and early postoperative pain. Its biomechanical stability, especially in rotational resistance, supports it as an alternative to PPSF for L5/S1 fusion.