A novel method for the prediction of the pedicle screw stability

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K10838
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Orthopaedic surgery
• Research Institution: Showa University
• Principal Investigator: Toyone Tomoaki 昭和大学, 医学部, 教授 (10407918)
• Co-Investigator(Kenkyū-buntansha): 稲垣 克記 昭和大学, 医学部, 教授 (50245833) ; 松岡 彰 昭和大学, 医学部, 助教 (60465119) ; 工藤 理史 昭和大学, 医学部, 講師 (60621985)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 脊椎固定術 / 脊柱変形 / 骨粗鬆症 / 手術 / 合併症 / スクリュートルク / CT

Outline of Final Research Achievements

Methods: Consecutive 50 patients were evaluated preoperatively for BMD measured by DXA and quantitative CT(QCT). Regional volumetric BMD around the pedicle screw (PS-vBMD) using the novel QCT technique was also evaluated. Among all patients, 190 screws (diameter, 7.5 to 8.5mm) were analyzed.
Results: Insertional torque was significantly correlated with each BMD measurement and strongest with PS-vBMD (r=0.61, P<0.001). Multiple regression analysis showed PS-vBMD was most strongly correlated with screw insertional torque (stdβ=0.494; P<0.001). A model containing the following 5 predictors was significantly associated with screw insertional torque: age, pedicle diameter, screw diameter, screw length, and PS-vBMD.
Conclusions: The preoperative measurement of PS-vBMD was technically feasible and reliably predictive of screw insertional torque during transpedicular fixation in a clinical setting.

Free Research Field

整形外科

Academic Significance and Societal Importance of the Research Achievements

椎弓根スクリュー最大挿入トルクは従来の骨密度測定法 (DXA・QCT)と比し、最も強くPS-BMDと相関していた(r=0.62, P＜0.01)。また、最大挿入トルクに寄与する独立した因子は[年齢, スクリュー径, スクリュー長, 椎弓根径, PS-BMD]であり、PS-BMD (標準β＝0.49, P＜0.01)が最も強く寄与していた (自由度調節寄与率R2=0.52, P＜0.01)。
椎弓根スクリュー軌道上骨密度（PS-BMD）により、椎弓根スクリューの固定性をより正確に予測し得た。PS-BMDを術前に測定することで、良好な長期成績の獲得、高齢者に対する脊椎固定術の合併症減少に寄与し得る。