Medical Faculty, Cancer and Translational Medicine Research Unit, University of Oulu and Medical Research Center, Oulu University Hospital, P.O. Box 5000, 90014, Oulu, Finland.
Division of Orthopaedic Surgery, Oulu University Hospital, Oulu, Finland.
BMC Musculoskelet Disord. 2020 Sep 12;21(1):610. doi: 10.1186/s12891-020-03636-0.
Modern metal-on-metal (MOM) arthroplasties were performed for over a decade before alarming reports of adverse metal reactions dramatically reduced their use. Failures are seen more often with high-wearing implants, but also well-positioned components with more favourable wear patterns can cause problems. There are no specific clinical indicators that could help us to predict the prognosis of these implants. For this reason, we still need more information on the effect of underlying factors that contribute to this process.
In this prospective cohort study, we investigated how cup orientation and type of pseudotumour determined by the Hart classification effect the distribution of metals in blood, synovial fluid and tissues surrounding the metal-on-metal hip prosthesis in revision surgery patients. One thousand two hundred twenty-nine metal-on-metal hip patients were screened and of those, 60 patients that had a revision surgery due to adverse metal reaction were included. Whole blood, synovial fluid and synovial/pseudotumour tissue samples were analysed for metal ion concentrations (Co, Cr, Mo and Ti).
The lowest metal concentrations were found when both cup anteversion and inclination were optimal, and the highest when both were suboptimal. Suboptimal anteversion alone raised Cr-ion concentrations more than suboptimal inclination. The concentrations of metals in blood, synovial fluid or synovial soft tissue were the same in patients with and without a pseudotumour, but the relative transfer percentage of cobalt from synovial fluid to blood was higher in patients with a pseudotumour.
The implant orientation alone does not explain the metal concentrations found in tissues or distribution of metals between different tissues. The accumulation of metals in periprosthetic soft tissues increase the total metal load, and in the presence of a pseudotumour this is reflected in the transfer ratio of Co from synovial fluid to the blood. The total metal load of the pseudotumour tissue should be defined in future studies to determine if this will provide new insights for clinical practice.
在令人震惊的不良金属反应报告大幅减少其使用之前，现代金属对金属（MOM）关节置换术已经进行了十多年。高磨损植入物更容易出现故障，但即使是位置良好、磨损模式更有利的部件也可能导致问题。目前还没有特定的临床指标可以帮助我们预测这些植入物的预后。因此，我们仍然需要更多关于导致这种情况的潜在因素的信息。
在这项前瞻性队列研究中，我们研究了 Hart 分类确定的杯倾斜度和假瘤类型如何影响金属对金属髋关节置换术后翻修手术患者血液、滑液和金属周围组织中金属的分布。筛选了 1229 例金属对金属髋关节患者，其中因不良金属反应行翻修手术的 60 例患者纳入研究。对全血、滑液和滑膜/假瘤组织样本进行金属离子浓度（Co、Cr、Mo 和 Ti）分析。
当杯前倾和倾斜都最佳时，金属浓度最低，当两者都不理想时，金属浓度最高。单独的杯前倾不理想比单独的杯倾斜不理想会导致 Cr 离子浓度升高。血液、滑液或滑膜软组织中金属的浓度在有或无假瘤的患者中相同，但有假瘤的患者中钴从滑液向血液的相对转移百分比更高。
单独的植入物方位并不能解释组织中发现的金属浓度或不同组织之间金属的分布。在假体周围软组织中金属的积累增加了总金属负荷，在存在假瘤的情况下，这反映在 Co 从滑液向血液的转移比上。未来的研究应确定假瘤组织的总金属负荷，以确定这是否会为临床实践提供新的见解。
