Efficacy of rib anchor to prevent Proximal Junctional Kyphosis (PJK) after posterior spinal fusion -Analysis using finite element method

• Published in: Journal of Spine Research Vol. 15; no. 7; pp. 988 - 993
• Main Authors: Kono, Hitoshi, Takamizawa, Yuhei, Kataoka, Tsugikazu, Tachibana, Atsuko, Hosogane, Naobumi, Akaike, Yuki, Takeuchi, Takumi, Nakamichi, Kiyohiro, Watanabe, Hironobu
• Format: Journal Article
• Language: Japanese
• Published: The Japanese Society for Spine Surgery and Related Research 20.07.2024; 一般社団法人 日本脊椎脊髄病学会
• Subjects: posterior spinal fusion; proximal junctional kyphosis; rib anchor; 肋骨フック; 脊椎後方固定術; 近位隣接椎間後弯変形
• ISSN: 1884-7137; 2435-1563
• DOI: 10.34371/jspineres.2024-0703

Background: An effective method for preventing proximal junctional kyphosis (PJK), a major complication of posterior spinal surgery, has not yet been established. We developed a new device called a rib anchor, and this study aimed to investigate whether it can be used to prevent PJK using the finite element method.Methods: A three-dimensional model from the T6 to T10 vertebral bodies and ribs was created, and axial loads and forward bending moments were applied to the T6 vertebral body. The equivalent stress on each vertebral body was evaluated under three conditions: no hook, transverse process hook (placed on T8), and rib anchor (placed on the seventh rib).Results: The average value of the vertebral equivalent stress applied to Uppermost Instrumented Vertebra (UIV) +1 was 0.723 MPa without the hook, 0.715 MPa with the transverse process hook, and 0.625 MPa with the rib anchor when an axial load (200 N) and forward bending moment (5 Nm) were applied. When rib anchors were used, the average equivalent stress applied to UIV+1 was lowest.Conclusions: This study suggests that the use of a rib anchor reduces the equivalent stress involving UIV+1.