Holleyman Richard J, Scholes Susan C, Weir David, Jameson Simon S, Holland Jim, Joyce Tom J, Deehan David J
Newcastle Upon Tyne Hospitals Trust, Royal Victoria Infirmary & Freeman Hospital, Newcastle upon Tyne, NE1 4LP, UK.
Newcastle University, Newcastle upon Tyne, UK.
Knee Surg Sports Traumatol Arthrosc. 2015 Dec;23(12):3523-31. doi: 10.1007/s00167-014-3197-9. Epub 2014 Aug 7.
With the advent of modular total knee arthroplasty (TKA) systems, backside wear at the articulation between the ultra-high-molecular-weight-polyethylene (UHMWPE) component undersurface and the tibial baseplate has received increasing attention as a source of clinically significant polyethylene wear debris. The aim of this study was to investigate the reciprocating interface at the TKA undersurface articulation using profilometry after in vivo service. Our null hypothesis was that there would be no discernible pattern or relationship between the metal tibial baseplate and UHMWPE surface profile.
A nanoscale analysis of thirty retrieved fixed-bearing TKA explants was performed. Surface roughness (Sa) and skewness (Ssk) were measured on both the UHMWPE component undersurface and the tibial baseplate of explants using a non-contacting profilometer (1 nm resolution). Four pristine unimplanted components of two different designs (Stryker Kinemax and DePuy PFC) were examined for control purposes.
Mean explant baseplate surface roughness was 1.24 μm (0.04-3.01 μm). Mean explant UHMWPE undersurface roughness was 1.16 μm (0.23-2.44 μm). Each explant had an individual roughness pattern with unique baseplate and undersurface UHMWPE surface roughness that was different from, but closely related to, surface topography observed in control implants of the same manufacturer and design. Following in vivo service, UHMWPE undersurface showed changes towards a negative skewness, demonstrating that wear is occurring at the backside interface.
In vivo loading of the TKA prosthesis leads to measurable changes in surface profile at the backside articulation, which appear to be dependent on several factors including implant design and in vivo duration. These findings are consistent with wear occurring at this surface. Findings of this study would support the use of a polished tibial tray over an unpolished design in total knee arthroplasty with the goal of reducing PE wear by means of providing a smoother backside countersurface for the UHMWPE component.
随着模块化全膝关节置换术（TKA）系统的出现，超高分子量聚乙烯（UHMWPE）部件下表面与胫骨基板之间关节处的背面磨损作为临床上重要的聚乙烯磨损碎屑来源受到了越来越多的关注。本研究的目的是在体内使用后，通过轮廓测定法研究TKA下表面关节处的往复界面。我们的零假设是金属胫骨基板与UHMWPE表面轮廓之间不存在可辨别的模式或关系。
对30个回收的固定平台TKA外植体进行了纳米级分析。使用非接触式轮廓仪（分辨率为1nm）测量外植体的UHMWPE部件下表面和胫骨基板的表面粗糙度（Sa）和偏度（Ssk）。为作对照，检查了两种不同设计（史赛克Kinemax和捷迈PFC）的四个未植入的原始部件。
外植体基板的平均表面粗糙度为1.24μm（0.04 - 3.01μm）。外植体UHMWPE下表面的平均粗糙度为1.16μm（0.23 - 2.44μm）。每个外植体都有独特的粗糙度模式，其基板和UHMWPE下表面粗糙度与同一制造商和设计的对照植入物中观察到的表面形貌不同，但密切相关。在体内使用后，UHMWPE下表面显示出向负偏度的变化，表明背面界面处正在发生磨损。
TKA假体的体内负荷导致背面关节处表面轮廓发生可测量的变化，这似乎取决于包括植入物设计和体内使用时间在内的几个因素。这些发现与该表面发生磨损一致。本研究结果将支持在全膝关节置换术中使用抛光的胫骨托而非未抛光设计，目的是通过为UHMWPE部件提供更光滑的背面相对表面来减少聚乙烯磨损。
