Vertebral Body Rotation in Patients with Lumbar Degenerative Scoliosis: Surgical Implication for Oblique Lumbar Interbody Fusion

Background To investigate changes of oblique corridor in patients with lumbar degenerative scoliosis and determine proper working angle with respect to the direction of vertebral axial rotation during the oblique lumbar interbody fusion procedure. Methods The distance of oblique corridor and the rotational angle of the left or right apex group were measured on axial T2 magnetic resonance images and then compared with those of the propensity score-matched control group. Results Fifty-five patients of the left apex group and 57 patients of the right apex group were compared with the equal number of patients of the propensity score-matched control group. The distance of oblique corridor in the left apex group was shorter than that in the control group at the levels of L1-2 and L2-3. In contrast, the distance of oblique corridor in the right apex group was longer than that of the control group at the level of L2-3. Patients of the left apex group showed the vertebral body rotating to the left side from L1-2 to L5-S1, whereas in the right apex group, the vertebral body rotated to the right side at the levels of L1-2, L2-3, and L3-4. Conclusions In the left apex group, the oblique corridor was decreased from psoas overlap, and coupled axial rotation to the left side might increase the risk of contralateral nerve root injury during orthogonally working. Thus, surgeons should pay attention to the state of coupled vertebral axial rotation of lumbar degenerative scoliosis for the oblique lumbar interbody fusion procedure.