个性定制人工半膝关节的快速设计制造与临床试用(英文)

Rapid design and fabrication of custom artificial semi-knee joint and its clinical application

背景:半膝关节置换中假体的设计与制造只有针对患者损伤的具体情况进行个体定制,才能实现假体关节面的良好匹配,这是传统的设计制造手段难以完成的。目的:建立以计算机辅助设计和快速成型技术为核心的人工半膝关节个体定制化设计方案和快速制造方法,通过临床试用评估假体设计制造技术和半膝关节置换的应用价值。设计、时间及地点:假体个体定制化设计及临床试用,于2002-01/2005-12在解放军第四军医大学附属西京医院,西安交通大学先进制造技术研究所,西安交通大学机械学院材料与力学国家重点实验室完成。对象:患者为男性,14岁,因右股骨下段骨肉瘤术后1年复发入院。经讨论及家属同意,拟行肿瘤切除、大段异体骨移植及定制化半膝关节面置换。方法:以患者CT扫描和三维重建等临床影像学资料为数据源,利用图像处理技术获取关节形状的数据,采用NURBS算法在Surface软件下重构出关节曲面,在计算机上完成半膝关节假体及其辅助装置的三维设计。采用快速成型技术制作出原型并通过精密铸造等手段完成实体制造。利用瞄准器将假体装入异体骨,锁定远端后置入患肢。主要观察指标:包括在Surfacer软件下对所构关节面的误差分析,关节假体及辅助装置加工后的组装情况,假体置换后患者膝关节X射线片检查结果、关节间隙情况及关节屈伸活动度。结果:全部设计和制造过程可在1周内完成。所设计的关节面计算机辅助设计模型与原始数据的最大误差﹤1mm,在屈、伸、旋转等状态下与胫骨关节面匹配良好,应力分布均匀。通过快速成型和精密铸造技术制作的假体及其辅助装置符合设计要求,可与大段异体骨装配。置入患膝后假体位置准确,能够实现与对侧胫骨关节面的良好匹配,关节间隙正常。置换后患者无不良反应,可早期功能锻炼。随访1年,患者膝关节功能恢复满意,未见关节脱位、慢性疼痛等。结论:通过计算机辅助设计和快速成型技术制造的个体定制化半膝关节在特定病例中具有一定的临床实用价值。

BACKGROUND： During semi-knee arthroplasty, only the design and fabrication performed according to patient＇s injury can implement the good matching between prosthesis and joint surface, which is difficult to perform by conventional design and fabrication. OBJECTIVE： To develop a custom design and rapid fabrication method for artificial semi-knee joint based on computer aided design （CAD） and rapid prototyping （RP） techniques, and to evaluate the clinical application value of semi-knee arthroplasty and the role of CAD/RP in the design and fabrication of prosthesis. DESIGN, TIME AND SETTING： A custom design and fabrication of prosthesis and its clinical application was performed in the Xijing Hospital Affiliated to Fourth Military Medical University of Chinese PLA ＆ Institute of Advanced Manufacturing Technology, Xi＇an Jiaotong University ＆ the State Key Laboratory of Materials and Mechanics, College of Mechanical Engineering, Xi＇ an Jiaotong University between January 2002 and December 2005. PARTICIPANTS： A 14-year-old male patient with osteosarcoma in the lower segment of the right femur was recruited into this study due to recurred osteosarcoma one year after surgery. Tumorectomy, large allogenic bone transplantation, and custom-made semi-knee arthroplasty were to be performed in this patient. A written informed consent was obtained from his relatives. METHODS： Clinical imageological data of the patient in terms of CT scanning and three-reconstruction were taken as data source. Data regarding joint shape were acquired by image processing technique. Joint contour was reconstructed by NRRBS algorithm using Surfacer software. Through the use of computer, the three-dimensional design of semi-knee joint prosthesis and its auxiliary devices was conducted. Subsequently, prosthetic prototype was fabricated by RP technique and prosthetic products were made by precise casting methods. Finally, the manufactured prosthesis was installed into the allogenic bone with the help of aiming device and was transplanted into the affected limb following distal locking. MAIN OUTCOME MEASURES： Error analysis of joint contour reconstructed using the Surfacer software; assembling of manufactured joint prosthesis and auxiliary devices; X-ray examination results, joint space status, and range of motion of joint in flexion and extension positions following prosthesis replacement. RESULTS： All procedures were conducted within 1 week. The maximum difference between CAD model-related data and original data was less than 1 ram. In the flexion, extension, and rotation positions, joint prosthesis well matched tibial joint surface, with evenly distributed stress. The prosthesis and auxiliary manufactured by RP and precise casting techniques met the requirements of design and could be installed into large segment of allogenic bone. Prosthesis was precisely placed into the affected knee and could well match contralateral tibial joint surface with normal joint space. No adverse reactions were found and the patient could implement functional exercise, One-year follow-up results revealed that the patient acquired satisfactory therapeutic effects without dislocation and chronic pain. CONCLUSION： Semi-knee joint individually fabricated by CAD and RP techniques provides some clinical application values in specific cases.