新型“髌股关节友好”人工全膝关节假体的设计和研究

Total knee arthroplasty (TKA) is the most effective treatment for the advanced knee diseases. However, the postoperative patellofemoral complications, such as anterior knee pain, patellar fracture and polyethylene wear, have become the major reasons for the TKA revisions. The traditional patellar polyethylene prostheses require the excision of approximately one third of the patellar bone volume, which dramatically decreases the patellar strength, and has been considered to be the critical reason for the patellofemoral complications. In addition, the current TKA prostheses have been generally designed according to the knee geometry of the Western people, and often cause the mismatch between the prostheses and the knees of the Chinese population, compromising the knee function after TKA. Targeting at the above clinical problems and challenges, the current research is to design the "patellofemoral joint- friendly" TKA prosthesis based on the knee gemoetry of the Chinese population...In the design of the "patellofemoral joint- friendly" TKA prosthesis, the patellar component will be made of CoCrMo alloy, which will allow the patellar component to be as thin as 3.5 mm, compared to the 8-10 mm thickness of the traditional polyethylene components. The main advantage of the 3.5 mm metal patellar component is that it needs the least bone resection of patella and can soundly keep the bone volume and strength, thus avoiding paftellar fracture, reducing the anterior knee pain and facilitating patellar revision. On the femoral side, the trochlear area of the femoral component will consist of a metal-backed polyethylene surface, which articulates with the metal patellar component. The research will also investigate the 3D geometry of the articular surface of the knees of Chinese population, and the data will be used for the design of the "patellofemoral joint- friendly" TKA prostheses. The polyethylene wear of the "patellofemoral joint- friendly" TKA prostheses will be assayed on knee motion simulator. And after TKA surgery, the patellar strength, force distribution, and patellofemoral tracking will be evaluated. The traditional TKA prostheses and normal human knees will serve as control groups. ..In conclusion, the new design of "patellofemoral joint- friendly" TKA prostheses will significantly reduce postoperative patellofemoral complications and improve knee function, possessing broad prospects of clinical application.

人工全膝关节置换术是目前治疗晚期膝关节病损最有效的方法。但术中对髌骨的处理仍存在争议：置换髌骨需切除约1/3的髌骨骨量，骨强度显著受损，易造成术后髌骨骨折、膝前疼痛，翻修困难等；不置换髌骨虽可保留骨量，但髌前疼痛率及翻修率显著增高。以上髌股关节问题已成为膝关节翻修的主要原因。设计一种即可置换髌骨病变表面，又可有效保留髌骨骨量的假体是解决以上问题的新思路。本研究拟设计新型"髌股关节友好"人工全膝关节假体，髌骨假体厚度仅3.5mm，由钴铬钼合金制成，能够极大程度地保留髌骨骨量和强度，降低骨折风险；患者不再因髌骨过薄而无法置换髌骨；改善髌骨应力分布，减少膝前疼痛。股骨假体滑车部分设计为一体化成型的带金属背衬的聚乙烯关节面，可减少髌股关节聚乙烯总磨损量。研究还将对国人髌股关节软骨面三维形态进行系统分析，作为新型假体形态设计的依据。本研究将为研发适合国人解剖特点的高性能人工膝关节假体提供科学依据。

通过定量测量了解自然股骨滑车沟形态特点，探讨滑车沟轨迹形态与股骨髁尺寸、几何形状和解剖对线的关系；分析进口假体滑车沟设计是否符合生理特点。纳入健康中国成年人男性和女性各50名，通过三维软件对股骨模型滑车沟形态进行分析。首先，从滑车沟近端向远端，绕滑车沟轴并间隔 15°建立同轴切平面，在每个横截面处标记滑车沟最低点，根据点数据分析滑车沟轨迹形状、位置和偏转方向。其次，测量并分析轨迹形态与股骨髁尺寸（前后径AP和内外侧径ML，滑车沟半径R)、几何形状（AP/ML比值，滑车沟延伸角度）和解剖对线（膝关节生理外翻角 KVPA、内侧远端股骨角 mMDFA、外科上髁轴角sTEAA）的关系。最后，通过虚拟全膝关节置换术，分析42例股骨模型和5种不同进口假体滑车沟轨迹形态差异。弧形滑车沟轨迹可以分为向外侧偏转的近段和向内侧偏转的远段部分，两部分间由一转点连接，且位于机械力线外侧。根据转点位置不同，轨迹可分为以下四种类型（外侧-内侧）：type 45°，60°，75° 和 90° ；但是四种轨迹类型的远段部分延伸路径相似。不同类型的偏转方向相对一致，从近端向远端逐渐内偏，每个滑车沟点处约1°，转点处约10°。假体滑车沟呈现由近端外侧至远端内侧的单向偏转，与自然轨迹的近段存在交叉且偏转方向相反；远段虽然两者偏转方向相似，但假体轨迹位置更偏向内侧；而且假体与不同的自然轨迹类型在交叉区域、内-外侧位置方面均有不同。滑车沟轨迹自然形态存在个体变异，根据轨迹转点位置可以分为不同类型。现代假体滑车设计不符合生理形态， TKA 术后自然滑车沟形态不能得到理想恢复。本研究有助于更好的了解自然和假体滑车沟轨迹形态特点及 TKA 假体设计改进。

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