Effects of Lordotic Angle of a Cage on Sagittal Alignment and Clinical Outcome in One Level Posterior Lumbar Interbody Fusion with Pedicle Screw Fixation

This study aims to assess the differences in the radiological and clinical results depending on the lordotic angles of the cage in posterior lumbar interbody fusion (PLIF). We reviewed 185 segments which underwent PLIF using two different lordotic angles of 4° and 8° of a polyetheretherketone (PEEK) cage. The segmental lordosis and total lumbar lordosis of the 4° and 8° cage groups were compared preoperatively, as well as on the first postoperative day, 6th and 12th months postoperatively. Clinical assessment was performed using the ODI and the VAS of low back pain. The pre- and immediate postoperative segmental lordosis angles were 12.9° and 12.6° in the 4° group and 12° and 12.0° in the 8° group. Both groups exhibited no significant different segmental lordosis angle and total lumbar lordosis over period and time. However, the total lumbar lordosis significantly increased from six months postoperatively compared with the immediate postoperative day in the 8° group. The ODI and the VAS in both groups had no differences. Cages with different lordotic angles of 4° and 8° showed insignificant results clinically and radiologically in short-level PLIF surgery. Clinical improvements and sagittal alignment recovery were significantly observed in both groups.