Explant analysis can provide key insights to understanding failures of artificial joints and thus how they might be improved for the ultimate benefit of patients. There are no previous reports of explant analysis of an artificial wrist joint. In this study, an explanted metal-on-polymer Maestro wrist was analysed both in macro and nanoscales to estimate its biotribological performance. The articulation was formed between a cobalt chromium carpal head and an ultrahigh molecular weight polyethylene bearing. The surface roughness values of its articulating surfaces and the backside of the articulation were measured. On average, the articulating surface roughness values were calculated as 0.06 ± 0.02 μm and 1.29 ± 0.63 μm for the cobalt chromium carpal head and ultrahigh molecular weight polyethylene bearing, respectively. Both surfaces had negative skewness, indicating a preponderance of valleys. On the articulating surface of the carpal head, light scratches were observed, and no impingement was observed throughout the component. The polymeric surface had a polished appearance. It had unidirectional scratches at the centre of the articulation, pits of different sizes on its articulating surface, and matt white subsurface regions. The backside of the UHMWPE bearing and the convex surface of the radial body that it was sitting on, were found to have average surface roughness values of 4.23 ± 0.69 μm and 5.57 ± 1.05 μm, respectively. The difference in the means was not significant (p > 0.05). Taking the articulating surface roughness values, the lubrication regime that the explanted Maestro wrist operated under in vivo was estimated for varying physiological conditions, i.e. varying loads, entraining velocities and lubricant viscosities. In every case considered, the explant was found to operate under boundary lubrication.

外植体分析可以提供关键见解，以了解人造关节的衰竭，从而可以为患者的最终利益而进行改善。以前没有关于人工腕关节的外植体分析的报道。在这项研究中，从宏观和纳米两个层面分析了外植聚合物金属化Maestro手腕，以评估其生物摩擦学性能。关节在钴铬腕骨头和超高分子量聚乙烯轴承之间形成。测量其铰接表面的表面粗糙度值和铰接的背面。平均而言，钴铬腕带头和超高分子量聚乙烯轴承的铰接表面粗糙度值分别计算为0.06±0.02μm和1.29±0.63μm。两个表面都具有负偏斜度，表明有许多山谷。在腕头的关节表面上，观察到轻微的划痕，并且在整个组件中均未观察到撞击。聚合物表面具有抛光的外观。它在关节中央有单向刮擦，在关节表面有不同大小的凹坑，表面有无光泽的白色亚表面。发现UHMWPE轴承的背面和所坐径向物体的凸面的平均表面粗糙度分别为4.23±0.69μm和5.57±1.05μm。均值差异不显着（p> 0.05）。取清晰的表面粗糙度值，根据不同的生理条件（即变化的负荷，夹带速度和润滑剂粘度）估算了Maestro外植腕在体内操作的润滑方式。在每种情况下，都发现外植体在边界润滑下运行。