一种基于数字影像数据的骨科压力模具设计

Design of orthopedic pressure mold based on digital image data

目的设计一种基于数字影像数据的骨科压力模具,以改变传统骨科钢板加工方式的同时提高钢板骨外形贴合度。方法设计一种骨科压力模具,主要由数据采集器、信息处理器、压力箱与压力泵四部分组成。以患者数字影像数据为依据,将其轮廓信息转换为压力棒行程,在压力泵、控制器、位移传感器的共同配合下,可对压力棒矩阵的精准操控,从而完成对钢板的精准加工。为验证骨科压力模具的可靠性,以1例21岁男性自愿者股骨部位为影像数据来源3D打印制作骨折部位模型,并以此数据定制骨折钢板。试验中用于测试钢板贴合度的股骨模型通过3D打印设备制造,成型原理为熔融层积方式。将钢板贴合于骨折部位,螺钉固定到位后,使用塞尺测量钢板4个相邻空洞部分检验钢板与骨面缝隙,以二者配合缝隙大小评价钢板贴合度。结果成功打印层片厚度0.15 mm、表面层3层、间隔8行、支撑密封侧3层、支撑材料表面使用面积大于3 mm^(2)的股骨。股骨远端内侧髁、外侧髁端面至股骨体打印总长度为25 cm。用螺钉固定远端股骨贴合钢板,拧入螺钉作用仅为固定钢板位置,旋拧过程中应尽量避免对钢板施压形成内应力改变钢板形状,固定到位后,测量第一孔与第二孔间至第四孔与第五孔间的缝隙大小分别为0.02 mm、0.03 mm、0.03 mm、0.01 mm。结论压力模具具有操作简便,易于掌握,可按患者骨外形个性化加工钢板的特点。定制钢板不仅有利于钢板与骨面贴合度的提升,同时也能减轻医生的劳动强度。

Objective To design an orthopedic pressure mold based on digital image data,and to change the traditional orthopedic plate processing method and improve the appearance of shape suitability of plate bone.Methods The design of orthopedic pressure mold mainly consisted of 4 parts:data collector,information processor,pressure box and pressure pump.Based on digital image data of patients,the profile information was converted into stroke of pressure rod.Under the joint action of pressure pump,controller and displacement sensor,pressure rod matrix was accurately controlled to complete precise machining of steel plate.The reliability of the orthopedic pressure mold was verified.The femoral part of a 21-year-old male volunteer was used as image data source to make the fracture site model by 3D printing,and fracture plate was customized according to the data.The femur model used to test the suitability of the steel plate was manufactured by 3D printing equipment,and the forming principle was molten stratification.After the plate was attached to fracture site and fixed with screws,the gap between plate and bone surface was tested by measuring 4 adjacent cavities of the plate with stopper,and plate suitability was evaluated by gap size.Results The femur with layer thickness of 0.15 mm,3 layers of surface,8 rows of interval,3 layers of support sealing sides and surface area of more than 3 mm2 of support material was successfully printed.The total printing length from the medial condyle and lateral condyle of the distal femur to the femoral body was 25 cm.The screws were used to fix distal femoral plate,and screws were only used to fix plate position.During screwing process,the internal stress caused by pressure on plate was avoided to change plate shape.After successful fixation,4 adjacent cavities of plate between the first hole and the second hole to the fourth hole and the fifth hole were measured to be 0.02 mm,0.03 mm,0.03 mm,and 0.01 mm,respectively.Conclusion It is demonstrated that pressure mold is easy to be operated and mastered,and could be personalized processed according to the patient’s bone shape.The customized steel plate is beneficial to improve the suitability of steel plate and bone surface,and can reduce the labor intensity of doctors.