Incidence rate of adjacent-segment disorder after oblique lateral interbody fusion at more than two levels: Data from the Chiba Spine Surgery Registry database Geundong Kim 1 Hiromitsu Takaoka 1 Kazuhide Inage 1 Sumihisa Orita 1 2 Yawara Eguchi 1 Yasuhiro Shiga 1 Takeo Furuya 1 Satoshi Maki 1 Yasuchika Aoki 3 Masahiro Inoue 3 Takayuki Fujiyoshi 4 Shinichiro Nakamura 5 Tomoaki Kinoshita 5 Takahito Kamada 5 Hiroshi Takahashi 6 Junya Saito 7 Toshiaki Kotani 8 Tsuyoshi Sakuma 8 Yasushi Iijima 8 Tetsuhiro Ishikawa 9 Mitsutoshi Ohta 10 Miyako Narita 1 Seiji Ohtori 1 1. Graduate school of Medicine, Chiba University, Chuo-ku, CHIBA, Japan 2. Chiba University Center for Frontier Medical Engineering, Chiba 3. Eastern Chiba Medical Center, Chiba 4. Kimitsu Chuo Hospital, Chiba 5. Narashino Dai-Ichi Hospital, Chiba 6. Department of Orthopaedic Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba 7. Department of Orthopaedic Surgery, Toho University Sakura Medical Center, Chiba 8. Department of Orthopedic Surgery, Seirei Sakura Citizen Hospital, Chiba 9. Department of Orthopedic Surgery, Sanmu Medical Center, Chiba 10. Department of Orthopedic Surgery, Seirei Yokohama Hospital, Yokohama The International Society for the Study of the Lumbar Spine 47th Annual Meeting Disclosure of Conflict of Interest We have nothing to declare for this study. Introduction • Adjacent-segment disorder (ASD) is an important complication of spinal fusion, but the detailed incidence of ASD has not been fully reported. • We investigated the incidence of ASD after oblique lateral interbody fusion (OLIF) at multiple levels that were performed in different centers and registered in the Chiba Spine Surgery Registry database. Methods • We collected cases of OLIF at >2 levels that were performed for lumbar degenerative disease and followed up for at least 1 year. • Defined radiological ASD ① >3mm decrease in intervertebral disc height from that before surgery, ② >5% spondylolisthesis in the lateral view of the whole spine on Xp, ③ worsening intervertebral disc degeneration as compared with that before surgery according to the Pfirrmann classification of adjacent intervertebral discs on MRI. • As symptomatic ASD : the occurrence of new-onset clinical symptoms at the radiological ASD. 1) S Orita, S Ohtori. MB Orthop. 2018 Results Total 42 patients 21 men, 21 women Age 69.6 ± 9.6 years The mean number of fused 4.2 ± 3.2 levels intervertebral levels The mean observation period 1.4 ± 0.9 years Average surgery time 335 ± 119 minutes Average bleeding volume 665 ± 1522 g Results Radiological ASD : Loss of adjacent intervertebral disc height • 10 cases (23.8%) showed showed loss 4 6 of adjacent intervertebral disc height. • None of the cases had 8 spondylolisthesis. Cranial side Caudal side Both sides Results Radiological ASD : Progression of the Pfirrmann classification 2 2 • 12 cases (28.6%) had progression of the Pfirrmann classification. 12 Cranial side Caudal side Both sides Results Symptomatic ASD • As for symptomatic ASD, we found 4 4 cases (9.5%). • All of which were at the caudal adjacent segments (L5/S). 38 • 3 cases (7.2%) needed follow-up surgery after 2 yrs (mean). No symptoms Caudal ASD Discussion The incidence rates of Posterior or Transforaminal Lumbar Interbody Fusion This study 3 years after surgery at multiple levels2-8) Radiological ASD 3.6 ~ 43.3% 28.6% Symptomatic ASD 1.3 ~ 19% 9.5% The reoperation rate 5.6 ~ 10% 7.2% Frequency of occurrence Cranial > Caudal Cranial < Caudal General risk factors of ASD ; Preoperative disc degeneration, multiple levels fusion, etc9-14) 2) Sun J, et al. World Neurosurg. 2018 3) Bae JS, et al. Neurosurgery. 2010 4) Yamasaki K, et al. Spine. 2017 5) Lee DY, et al. J Neurosurg Spine. 2008 Pressure on Pressure on 6) Yee TJ, et al. J Clin Neurosci. 2014 cranial caudal 7) Seng C, et al. Spine. 2013 adjacent intervertebral disc < adjacent intervertebral disc 8) Perez-Cruet MJ, et al. Spine. 2014 9) P.E. Moreau, et al. Orthopaedics & Traumatology: Surgery & Research 2016 10) Z.M. Zhong, et al. Clinical Neurology and Neurosurgery 2017 11) S R Bagheri, et al. J of Orthopaedic Surgery 2019 12) K Hashimoto, et al. International Orthopaedics 2019 More pressure to L5/S level 13) A A Ghasemi. Clinical Neurology and Neurosurgery 2016 14) Zhaoxin Ma, et al. J of Orthopaedic Surgery and Research 2019 by floating fusion 15,16) 15) S Orita et al. J of Orthopaedic Surgery and Research. 2015 16) M Bydon, et al. J Neurosurg Spine. 2014 Summary points • We found that the incidence of radiological and symtomatic ASD diagnosed using imaging modalities after multiple OLIF were similar to those of ASD after posterior lumbar spinal fusion. • In symtomatic ASD after OLIF, this result suggests that the caudal adjacent segment is more vulnerable..