www.nature.com/scientificreports OPEN Comparison between intervertebral oblique lumbar interbody fusion and transforaminal lumbar interbody fusion: a multicenter study Hiromitsu Takaoka 1*, Kazuhide Inage1, Yawara Eguchi1, Yasuhiro Shiga1, Takeo Furuya1, Satoshi Maki1,2, Yasuchika Aoki3, Masahiro Inoue3, Takayuki Fujiyoshi4, Takuya Miyamoto4, Yuji Noguchi4, Shinichiro Nakamura5, Tomoaki Kinoshita5, Takahito Kamada5, Hiroshi Takahashi6, Junya Saito7, Masaki Norimoto7, Toshiaki Kotani8, Tsuyoshi Sakuma8, Yasushi Iijima8, Tetsuhiro Ishikawa9, Tomotaka Umimura9, Mitsutoshi Ohta10, Miyako Suzuki‑Narita1, Keigo Enomoto1, Takashi Sato1, Masashi Sato1, Masahiro Suzuki1, Takashi Hozumi1, Geundong Kim1, Norichika Mizuki1, Ryuto Tsuchiya1, Takuma Otagiri1, Tomohito Mukaihata1, Takahisa Hishiya1, Seiji Ohtori1 & Sumihisa Orita1,2 This study aimed to perform a comparative analysis of postoperative results between lumbar degenerative spondylolisthesis (LDS) treated with oblique lateral interbody fusion (OLIF) and transforaminal lumbar interbody fusion (TLIF) from the Chiba spine surgery registry database. Sixty‑fve patients who underwent single‑level OLIF (O group) for LDS with ≥ 3 years’ follow‑up were retrospectively reviewed. The control group comprised 78 patients who underwent single‑level TLIF (T group). The analyzed variables included global alignment, radiological parameters of fused segments, asymptomatic and symptomatic ASD incidence, clinical outcomes at 3 years postoperatively using the Japanese Orthopedic Association Back Pain Evaluation Questionnaire data, visual analogue scale scores for low back pain, lower extremity pain, and lower extremity numbness. There was no signifcant change in global alignment between the two groups. The rate of improvement in anterior intervertebral disc height was not signifcantly diferent between the groups at 1‑month postoperatively. However, at the fnal evaluation, the anterior intervertebral disc height and incidence of asymptomatic ASD were signifcantly higher in the O group. There was no signifcant diference in symptomatic ASD, reoperation cases, or clinical results between groups. Thus, single‑level OLIF can maintain the corrected disc height, but as it has no efect on global alignment, its beneft is limited. Te posterior approach of posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF) has been used for the treatment of spinal canal stenosis associated with lumbar degenerative spondylolisthesis (LDS)1–3. Oblique lateral interbody fusion (OLIF), in contrast, has recently been adopted by spine surgeons as a minimally invasive and rigid fxation procedure using a lateral approach to insert a large 1Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan. 2Center for Frontier Medical Engineering, Chiba University, Chiba, Japan. 3Department of Orthopaedic Surgery, Eastern Chiba Medical Center, Togane, Chiba, Japan. 4Department of Orthopedic Surgery, Kimitsu Chuo Hospital, Kisarazu, Chiba, Japan. 5Department of Orthopedic Surgery, Narashino Dai-Ichi Hospital, Narashino, Chiba, Japan. 6Department of Orthopedic Surgery, University of Tsukuba, Tsukuba, Ibaraki, Japan. 7Department of Orthopaedic Surgery, Toho University Sakura Medical Center, Sakura, Chiba, Japan. 8Department of Orthopedic Surgery, Seirei Sakura Citizen Hospital, Sakura, Chiba, Japan. 9Department of Orthopedic Surgery, Sanmu Medical Center, Sanmu, Chiba, Japan. 10Department of Orthopedic Surgery, Seirei Yokohama Hospital, Yokohama, Kanagawa, Japan. *email: [email protected] Scientifc Reports | (2021) 11:16673 | https://doi.org/10.1038/s41598-021-95774-1 1 Vol.:(0123456789) www.nature.com/scientificreports/ O group T group P value Age, y.o 66 ± 12 71 ± 9 0.122 Sex Male 28 Female 38 Male 37 Female 42 0.595 Fusion level L3/4 13 L3/4 8 0.109 (Cases) L4/5 53 L4/5 70 Follow up (months) 64.0 ± 16.2 53.0 ± 13.0 < 0.001 Preoperative parameter LL, ° 36 ± 14 40 ± 14 0.127 PT, ° 22 ± 10 22 ± 7 0.42 PI-LL, ° 15 ± 14 13 ± 13 0.347 SS, ° 29 ± 11 30 ± 8 0.501 Local parameter Anterior disc height, mm 8.2 ± 3 7.9 ± 2.5 0.483 Posterior disc height, mm 5.1 ± 2.1 4.6 ± 1.9 0.097 Segmental lordotic angle, ° 15.6 ± 6.5 13.7 ± 6.5 0.123 Table 1. Demographic characteristics. LL indicates lumbar lordosis; PT pelvic tilt, PI-LL pelvic incidence minus lumbar lordosis, SS sacral slope. cage between the vertebrae to improve spinal alignment. OLIF has been used in the treatment of LDS and its indirect decompression efect results in progressive widening of the dural canal, resulting in improvement of neurological symptoms in the lower extremities 4,5. However, this technique involves the insertion of a cage with a height larger than the preoperative disc height to achieve indirect decompression, which may have an impact on the adjacent vertebrae. Few reports on the incidence of adjacent segment disorder (ASD) in OLIF have been published or compared with other interbody fusion procedures. Te purpose of this study was to extract cases from the Chiba spine surgery registry (CSSR) database in which single-level OLIF and conventional single-level TLIF were performed for LDS and perform a comparative analysis of changes in global alignment, incidence of ASD, and clinical outcome 3 years afer surgery. Patients and methods Tis was a multicenter, retrospective, observational study conducted with the approval of the Ethics Committee at our institution. Te study protocol was approved by the ethics review committee of School of Medicine, Chiba University (IRB approval code: 2030). Te opt-out method was adopted to obtain informed consent from the patients. Among 14,267 patients enrolled in the CSSR database since 2012, patients with lumbar spinal canal stenosis associated with LDS and neurological symptoms in the lower extremities who received single-level OLIF (group O) and single-level TLIF (group T) were included in this study. Exclusion criteria were: patients who underwent fusion of ≥ 2 vertebrae and combined surgery with other fusions. Patients followed up for 3 years afer surgery were selected for this retrospective study. Te O group consisted of 65 patients (27 men and 38 women, mean age 66 ± 12 years), and the T group of 78 patients (36 men and 42 women, mean age 71 ± 9 years), with a mean follow-up period of 53 ± 13.0 months (Table 1). Evaluation items. Image assessment. Global alignment. All patients underwent upright lumbar digital radiography in the frontal, lateral, and anterior fexion positions preoperatively, 1 month postoperatively, and 3 years postoperatively. Lumbar lordosis (LL), pelvic tilt (PT), sacral slope (SS), and pelvic incidence (PI) were measured on lateral digital radiographic images. Changes in LL, PT, and PI-LL were investigated preoperatively to 1 month and 3 years postoperatively. Radiological parameters of fused segments. Te anterior and posterior intervertebral heights and local angles of the fxed intervertebral space were measured and compared with those of the O and T groups. Te local angle was defned as the angle between the caudal endplate of the cephalad vertebral body and the cephalad endplate of the caudal vertebral body. Asymptomatic ASD incidence. Asymptomatic ASD was defned as (1) a decrease in disc height > 3 mm, (2) slippage progression > 5%, and (3) a posterior widening > 5° according to Okuda et al.6. Te incidence of ASD in the upper fxed vertebrae 3 years afer surgery was investigated. Te change from the preoperative period to 3 years afer surgery was assessed in each group, and the rate of change between the two groups compared. Symptomatic ASD incidence. Symptomatic ASD was defned as the presence of clinical symptoms of ASD at the time of the fnal assessment. Te incidence of symptomatic ASD and reoperation rate during follow-up were investigated and compared between both groups. Scientifc Reports | (2021) 11:16673 | https://doi.org/10.1038/s41598-021-95774-1 2 Vol:.(1234567890) www.nature.com/scientificreports/ Figure 1. When inserting the cage, the inserter enters it obliquely and then turns it orthogonally to allow the surgeon to place the cage orthogonally across the disc space. Clinical results. Visual analog scale (VAS). Low back pain VAS (LBP-VAS), lower extremity pain VAS (BLP- VAS), and lower extremity numbness VAS (BLN-VAS) were evaluated preoperatively and at 3 years postopera- tively as postoperative clinical outcome assessment. JOABPEQ. Te efcacy rates of each domain in the Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ)7 were used to compare the preoperative and 3-year postoperative surveys. Statistical analysis. For statistical analysis, the Mann–Whitney U test was used for each preoperative assessment in the O and T groups; the Student’s t-test for pre- and postoperative imaging and spinal-pelvic parameters, and the Chi-squared test for the ASD and the JOABPEQ efcacy rate comparison between the O and T groups in each domain. In each domain, if more than one of the following conditions was met, it was judged as "efective”: when the post-operative score obtained increased by ≥ 20 points compared to the pre- operative score, when the value of the preoperative score was < 90 points, and when the post-treatment reached a value ≥ 90 points. Te percentage of patients where the treatment was judged to be "efective" was then defned as the efective rate, and calculated for each domain. Surgical technique: single-level OLIF. All patients initially underwent OLIF surgery.