Objective: To perform a comparative analysis of outcomes in patients with lumbar spine segmental instability who underwent surgical treatment using transforaminal lumbar interbody fusion (TLIF) and direct lateral interbody fusion (DLIF) techniques.

Methods: The multicenter study involved 209 patients who underwent surgery for lumbar spine segmental instability. Long-term outcomes (up to 2 years) were studied in 134 patients: patients of the first group (98 patients) underwent traditional transforaminal lumbar interbody fusion (TLIF) and transpedicular stabilization of vertebral segments; patients of the second group (36 patients) underwent direct lateral interbody fusion (DLIF) in combination with transpedicular stabilization of the lumbar vertebral segments. We used standard checkpoints for monitoring the patients' condition: before surgery, at discharge, at 3, 6 and, 9 months, and at 1 and 2 years after surgery. To follow-up the patients, we used the Visual Analogue Scale, Oswestry Disability Index, and Goal Attainment Scaling.

Results: A comparative analysis of the two interbody fusion techniques was enabled by the developed Vertebrologic Registry profile (http://spineregistry.ru/Register_treatment.php) that was designed for entering data of Russian and foreign experts to analyze clinical characteristics, evaluate outcomes, and follow-up patients with degenerative lumbosacral spine diseases. In both groups of patients, a significant decrease in the pain intensity in the lumbar spine and lower extremities (VAS) occurred in the immediate postoperative period, which persisted in the long-term period. There were no differences in the disability level (Oswestry index) in both groups of patients (p<0.05). An analysis of treatment goal attainments one year after surgery revealed the best result in patients of the second group who underwent DLIF.

Conclusions: 1. Indirect decompression using direct lateral interbody fusion (DLIF) minimizes the risks of intraoperative injury to the dura mater and neural structures. Kawabata class I outcomes (good) were achieved in 89% of patients who underwent direct lateral spinal fusion (DLIF) and in 81% of patients who underwent transforaminal interbody stabilization in combination with transpedicular fixation.