Clinical and radiologic outcomes of stand-alone anterior lumbar interbody fusion at L4-L5

Objectives: To assess early clinical outcomes of stand-alone minimally invasive ALIF for patients with DDD at L4-L5 and determine whether the procedure affects spino-pelvic parameters. Methods: The authors reviewed the records of all patients with DDD that underwent stand-alone minimally invasive ALIF at L4-L5 using the self-locking SynFix cage (DePuy Synthes, PA, USA). Patients were evaluated using the Oswestry Disability Index (ODI), Short Form 12, and lower back and legs pain on Visual Analog Scale. Spino-pelvic parameters were measured from whole-spine standing radiographs. Results: From the initial cohort of 48 patients, 3 could not be reached, and 4 were reoperated due to pseudarthrosis using posterior instrumentation with bone graft, leaving 41 for clinical and radiologic evaluation. At a follow-up of 18.2 ± 7.3 months, all 5 clinical scores improved from pre-operative values. Multi-variable regressions revealed no significant associations between independent variables and ODI. Comparing pre- and post-operative radiographs: global lumbar lordosis increased by 3.6 ± 7.7° (p = 0.001), L4-L5 lordosis increased by 7.4 ± 6.1° (p < 0.001), and L5-S1 lordosis decreased by 1.6 ± 4.5° (p = 0.029). There was a small but significant increase in pelvic incidence (1.8 ± 3.1°, p = 0.001), as well as small and insignificant increases in pelvic tilt (0.9 ± 4.9°, p = 0.252) and sacral slope (1.2 ± 5.2°, p = 0.143). Conclusions: Minimally invasive stand-alone ALIF at L4-L5 grants satisfactory early clinical outcomes, and can improve segmental and global lordosis, with satisfactory fusion rates and minimal complications. The procedure resulted in a small but significant increase in pelvic incidence, as well as small and insignificant increases in pelvic tilt and sacral slope