Anatomical Characteristics Affecting the Surgical Approach of Oblique Lateral Lumbar Interbody Fusion: an MR-based Observational Study

Background: Oblique lateral lumbar interbody fusion (OLIF) is one of the most widely used lumbar interbody fusion procedures in clinical practice. The aim of this study was to minimize the incidence rate of surgical complications by measuring the anatomical parameters of structures surrounding the working channels of OLIF with 3D COSMIC sequence.

Methods: The MRI examination included conventional MRI sequence and 3D COSMIC sequence. Surgical window, psoas thickness, the transverse diameter of the endplate, and nerve distance were measured to evaluate the anatomical characteristics surrounding the OLIF working channels.

Results: The widths of the natural surgical window at the level of the L2-3, L3-4, and L4-5 intervertebral measured in this study were 16.25 ± 4.22, 15.46 ± 4.64 mm, and 11.71 ± 6.29 mm, respectively. The average thickness of the left psoas major muscle at the level of L2-3, L3-4, and L4-5 intervertebral space was 28.42 ± 5.08 mm, 30.76 ± 5.84 mm, and 31.16 ± 7.72 mm, respectively. The mean value of insertion angle (β) was 45.57° ± 6.19° in L2-3 intervertebral space, 49.90° ± 6.53° in L3-4 intervertebral space, and 43.34° ± 8.88° in L4-5 intervertebral space.

Conclusions: The 3D COSMIC sequences can be used for imaging anatomical assessment before OLIF surgery. In preoperative planning, the 3D COSMIC sequence can be used to measure the relevant parameters mentioned above to optimize the planned surgical approach.