Park Sang-Hyun, Lu Zhen, Hastings Robert S, Campbell Patricia A, Ebramzadeh Edward
S.-H. Park, Z. Lu, P. A. Campbell, E. Ebramzadeh, The J. Vernon Luck, Sr, MD Orthopaedic Research Center, Orthopaedic Institute for Children and UCLA Department of Orthopaedic Surgery, Los Angeles, CA, USA R. S. Hastings, DePuy, Inc, Warsaw, IN, USA.
Clin Orthop Relat Res. 2018 Feb;476(2):261-278. doi: 10.1007/s11999.0000000000000044.
In 2010, a widely used metal-on-metal hip implant design was voluntarily recalled by the manufacturer because of higher than anticipated failure rates at 5 years. Although there was a large published range of revision rates, numerous studies had reported a higher risk of revision for excessive wear and associated adverse tissue reactions when compared with other metal-on-metal total hips. The reasons for this were suggested by some to be related to cup design features.
QUESTIONS/PURPOSES: From retrievals of ASR metal-on-metal implants and tissue samples obtained at revision surgery, we asked the following questions: (1) What were the common and uncommon surface features? (2) What were the common and uncommon linear and volumetric wear characteristics? (3) Were there common taper corrosion characteristics? (4) What aseptic lymphocytic vasculitis-associated lesion (ALVAL) features were present in the tissues?
Five hundred fifty-five ASRs, including 23 resurfacings, were studied at one academic research center. Features of wear (eg, light and moderate scratching), damage (eg, deposits, gouges), and bone attachment on the porous coating were semiquantitatively ranked from 0 (none) to 3 (> 75%) based on the amount of a feature in each region of interest by the same experienced observer throughout the study. Visible features of head taper corrosion were ranked (Goldberg score) from 1 (none) to 4 (severe) by the same observer using a previously published scoring method. An experienced tribologist measured component wear depth using a coordinate measuring machine and quantified wear volume using previously validated methods. All available tissues were sampled and examined for features of ALVAL and scored from 0 to 10 by a single observer using a method they previously developed and published. A score from 0 to 4 is considered low, 5 to 8 is considered moderate, and 9 or 10 is considered high with regard to the risk of metal hypersensitivity features in the tissues.
The most common bearing surface features were light and moderate scratches and removal or postremoval damage. Discoloration and deposits were commonly observed on femoral heads (55% [305 of 553]) and less commonly on cups (30% [165 of 546]). There was no evidence of impingement or dislocation damage. There was typically a small amount of bone attachment in at least one of eight designated regions of interest (84% [460 of 546]); extensive or no bone attachment was uncommon. Edge wear was highly prevalent. The maximum wear of 469 cups (88%) occurred near the edge, whereas the maximum wear of 508 femoral heads (94%) occurred between the pole and 45° from the pole. The median combined head-cup wear volume was 14 mm (range, 1-636 mm). One hundred sixty-nine pairs (32%) had a combined wear volume of < 10 mm, 42 pairs (8%) had volumetric wear of > 100 mm, and 319 pairs (60%) had wear volume between 10 and 100 mm³. Seventy-four percent of tapers (390 of 530) received a Goldberg score of 4, 22% (116 of 530) a score of 3, < 5% (24 of 530) a score of 2, and none received a score of 1. The most frequent ALVAL score was 5 out of 10 (35 of 144 hips [24%]) and ranged from 2 (one hip) to 10 (nine hips); 92 of 144 (64%) had a moderate score, 17 of 144 (12%) had a high score, and 35 (24%) had a low score.
Although edge wear was prevalent, in most cases, this was not associated with high wear. The increased diameter and decreased coverage angle of the ASR design may have resulted in the observed high incidence of edge wear while perhaps decreasing the risk for impingement and dislocation.
The role of bearing wear in the revisions of metal-on-metal implants is controversial, because it is known that there is a large range of in vivo wear rates even within the same implant type and that patient variability affects local tissue responses to wear debris. The observations from our study of 555 retrieved ASR implant sets indicate that there was a wide range of wear including a subset with very high wear. The results suggested that the failure of the ASR and ASR XL was multifactorial, and the failure of different subgroups such as those with low wear may be the result of mechanisms other than reaction to wear debris.
2010年，一种广泛使用的金属对金属髋关节植入物设计被制造商主动召回，原因是5年时的故障率高于预期。尽管已发表的翻修率范围很广，但许多研究报告称，与其他金属对金属全髋关节相比，过度磨损及相关不良组织反应导致的翻修风险更高。一些人认为其原因与髋臼杯设计特点有关。
问题/目的：通过对翻修手术中获取的ASR金属对金属植入物及组织样本进行检索，我们提出了以下问题：（1）常见和不常见的表面特征有哪些？（2）常见和不常见的线性及体积磨损特征有哪些？（3）是否存在常见的锥度腐蚀特征？（4）组织中存在哪些无菌性淋巴细胞性血管炎相关病变（ALVAL）特征？
在一个学术研究中心对555个ASR进行了研究，其中包括23个表面置换。在整个研究过程中，由同一位经验丰富的观察者根据每个感兴趣区域内磨损（如轻度和中度划痕）、损伤（如沉积物、 gouges）以及多孔涂层上骨附着的特征量，将其从0（无）到3（>75%）进行半定量分级。由同一位观察者使用先前发表的评分方法，对头部锥度腐蚀的可见特征进行分级（戈德堡评分），从1（无）到4（严重）。一位经验丰富的摩擦学家使用坐标测量机测量部件磨损深度，并使用先前验证的方法对磨损体积进行量化。对所有可用组织进行采样，并检查ALVAL特征，由一名观察者使用他们先前开发并发表的方法从0到10进行评分。就组织中金属超敏反应特征的风险而言，0至4分被认为是低风险，5至8分被认为是中度风险，9或10分被认为是高风险。
最常见的承重表面特征是轻度和中度划痕以及移除或移除后损伤。在股骨头（55%[553个中的305个]）上常见变色和沉积物，而在髋臼杯（30%[546个中的165个]）上较少见。没有撞击或脱位损伤的证据。在八个指定的感兴趣区域中至少有一个区域通常有少量骨附着（84%[546个中的460个]）；广泛或无骨附着并不常见。边缘磨损非常普遍。469个髋臼杯（88%）的最大磨损发生在边缘附近，而508个股骨头（94%）的最大磨损发生在极点与极点45°之间。头杯组合磨损体积的中位数为14mm（范围为1 - 636mm）。169对（32%）的组合磨损体积<10mm，42对（8%）的体积磨损>100mm，319对（60%）的磨损体积在10至100mm³之间。74%的锥度（530个中的390个）戈德堡评分为4分，22%（530个中的116个）评分为3分，<5%（530个中的24个）评分为2分，无评分为1分的。最常见的ALVAL评分为10分中的5分（144个髋关节中的35个[24%]），范围从2分（1个髋关节）到10分（9个髋关节）；144个中的92个（64%）评分为中度，144个中的17个（12%）评分为高，35个（24%）评分为低。
尽管边缘磨损很普遍，但在大多数情况下，这与高磨损无关。ASR设计中直径增加和覆盖角度减小可能导致了观察到的边缘磨损高发生率，同时可能降低了撞击和脱位的风险。
承重磨损在金属对金属植入物翻修中的作用存在争议，因为已知即使在同一植入物类型中，体内磨损率也有很大范围，而且患者个体差异会影响局部组织对磨损碎屑的反应。我们对555套回收的ASR植入物的研究观察结果表明，磨损范围很广，包括一部分磨损非常高的情况。结果表明，ASR和ASR XL的失败是多因素的，不同亚组（如低磨损组）的失败可能是除对磨损碎屑反应之外的其他机制导致的。
