Evaluation of the location of intervertebral cages during oblique lateral interbody fusion surgery to achieve sagittal correction
Yasuhiro Shiga1), Sumihisa Orita1), Kazuhide Inage1), Jun Sato1), Kazuki Fujimoto1), Hirohito Kanamoto1), Koki Abe1), Go Kubota2), Kazuyo Yamauchi1), Yawara Eguchi3), Masahiro Inoue1), Hideyuki Kinoshita1), Yasuchika Aoki2), Junichi Nakamura1), Yusuke Matsuura1), Richard Hynes4), Takeo Furuya1), Masao Koda1), Kazuhisa Takahashi1), Seiji Ohtori1)
1) Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan 2) Department of Orthopaedic Surgery, Eastern Chiba Medical Center, Togane, Chiba, Japan 3) Department of Orthopaedic Surgery, Shimoshizu National Hospital, Yotsukaido, Chiba, Japan 4) Department of Orthopaedic Surgery, The Back Center Back Pain Spine Surgery Melbourne Florida, FL, USA
Introduction: Oblique lateral interbody fusion (OLIF) can achieve recovery of lumbar lordosis (LL) in minimally invasive manner. The current study aimed to evaluate the location of lateral intervertebral cages during OLIF in terms of LL correction. Methods: The subjects were patients who underwent OLIF for lumbar degenerative diseases, including lumbar spinal stenosis, spondylolisthesis, and discogenic low back pain. Their clinical outcome was evaluated using visual analogue scale on lower back pain (LBP), leg pain and numbness. The following parameters were retrospectively evaluated on plain radiographic images and computed tomography scans before and at 1 year after OLIF: the intervertebral height, vertebral translation, and sagittal angle. The cage position was defined by equally dividing the caudal endplate into five zones (I to V), and its association with segmental lordosis restoration was analyzed. Subjects were also evaluated for a postoperative endplate injury. Results: Eighty patients (121 fused levels) with lumbar degeneration who underwent OLIF were included. There were no significant specific distribution in preoperative disc pathology such as disc angle, height, and translation. After OLIF, sagittal alignment was improved with an average correction angle of 3.8º at the instrumented segments in a level-independent fashion. All cases showed significant improvement in clinical outcomes, and had improvement in the radiological parameters (P<0.05). A detailed analysis of the cage position showed that the most significant sagittal correction and the most postoperative endplate injuries occurred in the farthest anterior zone (I). Cages with a 12-mm height were associated with more endplate injuries compared with shorter cages (8 or 10 mm). Conclusions: OLIF improves sagittal alignment with an average correction angle of 3.8º at the instrumented segments. We suggest that the optimal cage position for better lordosis correction and the fewest endplate injuries is zone II with a cage height of up to 10 mm.