镁合金中空螺钉内固定齿状突ⅡA型骨折生物力学研究

Biomechanical study of magnesium alloy hollow screws in fixation of typeⅡA odontoid process fracture

目的研制应用于齿状突ⅡA型骨折前路内固定的新型镁合金中空螺钉,并进行生物力学研究。方法将30个新鲜人体枢椎标本,根据年龄、性别、齿状突大小配对分为2组:镁合金螺钉组、钛合金螺钉组。将2组枢椎按齿状突ⅡA型骨折锯断,造成统一齿状突骨折模型,分别用镁合金螺钉、钛合金螺钉固定,在生物力学机上测量不同垂直负荷下齿状突载荷-位移关系、扭矩-位移关系及最大拔出力。结果分别加载不同垂直负荷作用于齿状突矢状面,当加载负荷<400 N时,两组的位移差异无统计学意义(P>0.05),当载荷>500 N时骨折端产生的位移差异有统计学意义(P<0.05)。当颈部受到<100 N/mm扭矩时两种材料螺钉固定的齿状突位移差异无统计学意义(P>0.05),但当扭矩>200 N/mm时两者的位移差异有统计学意义(P<0.05)。结论镁合金中空螺钉在固定齿状突ⅡA型骨折端时足以防止前后移位的发生,但抗扭转能力较差,建议术后予以颈托制动。

Objective To develop a new magnesium alloy hollow screw for anterior fixation of the type Ⅱ Aodontoid process fracture and perfor a biomechanical study. Methods Thirty fresh human arias specimens, according to age, gender, dentate size pairs were divided into 2 groups： magnesium alloy, titanium alloy screws screws group. Two： groups of axis odontoid fractures typeⅡA were cut by sawing, causing uniform odontoid fracture model. Magnesium alloy titanium alloy screws were used for fixation. On the biomechanics machine the load-displacement relationship of odontoid process, torque and pullout force-displacement relationship in different vertical load were measured. Results Loaded with different vertical loads acting on the odontoid sagittal plane, when the load was 〈400 N, no significant displacement difference between the. two groups （P 〉 0.05）, when the displacement difference load 〉500 N fracture had statistical significance （P 〈0.05）. No statistical significance when the neck by 〈100 N/mm torque of two materials screw fixation of odontoid displacement difference （P 〉0.05）, but the difference was statistically significant when the torque of the 〉200 N/mm （P 〈0.05）. Conclusion Magnesium alloy hollow screw fixation of odontoid process fracture of type ⅡA in the end is enough to prevent a before and after the shift occurred, but the anti-torsion ability is poor, suggest that postoperative neck support brake.