Lumbar Fusion including Sacroiliac Joint Fixation Increases the Stress and Angular Motion at the Hip Joint: A Finite Element Study

Takuhei Kozaki; Hiroshi Hashizume; Hiroyuki Oka; Satoru Ohashi; Yoh Kumano; Ei Yamamoto; Akihito Minamide; Yasutsugu Yukawa; Hiroshi Iwasaki; Shunji Tsutsui; Masanari Takami; Keiji Nakata; Takaya Taniguchi; Daisuke Fukui; Daisuke Nishiyama; Manabu Yamanaka; Hidenobu Tamai; Ryo Taiji; Shizumasa Murata; Akimasa Murata; Hiroshi Yamada

doi:10.22603/ssrr.2021-0231

Lumbar Fusion including Sacroiliac Joint Fixation Increases the Stress and Angular Motion at the Hip Joint: A Finite Element Study

Spine Surg Relat Res. 2022 Apr 12;6(6):681-688. doi: 10.22603/ssrr.2021-0231. eCollection 2022 Nov 27.

Authors

Takuhei Kozaki¹, Hiroshi Hashizume¹, Hiroyuki Oka², Satoru Ohashi³, Yoh Kumano⁴, Ei Yamamoto⁵, Akihito Minamide¹, Yasutsugu Yukawa¹, Hiroshi Iwasaki¹, Shunji Tsutsui¹, Masanari Takami¹, Keiji Nakata¹, Takaya Taniguchi¹, Daisuke Fukui¹, Daisuke Nishiyama¹, Manabu Yamanaka¹, Hidenobu Tamai¹, Ryo Taiji¹, Shizumasa Murata¹, Akimasa Murata¹, Hiroshi Yamada¹

Affiliations

¹ Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Wakayama, Japan.
² Department of Medical Research and Management for Musculoskeletal Pain, Faculty of Medicine, 22nd Century Medical and Research Center, The University of Tokyo, Tokyo, Japan.
³ Department of Orthopaedic Surgery, Sagamihara Hospital, National Hospital Organization, Sagamihara, Kanagawa, Japan.
⁴ Department of Spine Surgery, Tokyo Yamate Medical Center, Japan Community Healthcare Organization, Tokyo, Japan.
⁵ Department of Biomedical Engineering, Faculty of Biology-Oriented Science and Technology, KinDai University, Kinokawa, Wakayama, Japan.

Abstract

Introduction: Adult spinal fusion surgery improves lumbar alignment and patient satisfaction. Adult spinal deformity surgery improves saggital balance not only lumbar lesion, but also at hip joint coverage. It was expected that hip joint coverage rate was improved and joint stress decreased. However, it was reported that adjacent joint disease at hip joint was induced by adult spinal fusion surgery including sacroiliac joint fixation on an X-ray study. The mechanism is still unclear. We aimed to investigate the association between lumbosacral fusion including sacroiliac joint fixation and contact stress of the hip joint.

Methods: A 40-year-old woman with intact lumbar vertebrae underwent computed tomography. A three-dimensional nonlinear finite element model was constructed from the L4 vertebra to the femoral bone with triangular shell elements (thickness, 2 mm; size, 3 mm) for the cortical bone's outer surface and 2-mm (lumbar spine) or 3-mm (femoral bone) tetrahedral solid elements for the remaining bone. We constructed the following four models: a non-fusion model (NF), a L4-5 fusion model (L5F), a L4-S1 fusion model (S1F), and a L4-S2 alar iliac screw fixation model (S2F). A compressive load of 400 N was applied vertically to the L4 vertebra and a 10-Nm bending moment was additionally applied to the L4 vertebra to stimulate flexion, extension, left lateral bending, and axial rotation. Each model's hip joint's von Mises stress and angular motion were analyzed.

Results: The hip joint's angular motion in NF, L5F, S1F, and S2F gradually increased; the S2F model presented the greatest angular motion.

Conclusions: The average and maximum contact stress of the hip joint was the highest in the S2F model. Thus, lumbosacral fusion surgery with sacroiliac joint fixation placed added stress on the hip joint. We propose that this was a consequence of adjacent joint spinopelvic fixation. Lumbar-to-pelvic fixation increases the angular motion and stress at the hip joint.

Keywords: adjacent joint disease; adjacent segment disease on hip joint; adult spinal deformity surgery; finite element analysis; hip pathology; sacroiliac joint fixation.