Center for Orthopedics, Trauma Surgery and Spinal Cord Injury, Heidelberg University Hospital, Heidelberg, Germany.
Laboratory of Biomechanics and Implant Research, Center for Orthopedics, Trauma Surgery and Spinal Cord Injury, Heidelberg University Hospital, Heidelberg, Germany.
Orthop Surg. 2020 Apr;12(2):396-403. doi: 10.1111/os.12591. Epub 2020 Feb 5.
To investigate the course of in vivo blood metal ion levels in patients undergoing primary total knee arthroplasty (TKA) and to investigate potential risk factors associated with metal ion release in these patients.
Twenty-five patients with indication for TKA were included in this prospective study. Whole blood metal ion analysis was performed pre-operatively and at 1 week, 6 weeks, 3 months, 6 months, and 12 months postoperatively. Clinical scores were obtained using the American Knee Society Score (AKSS) and the Oxford Knee Score (OKS) at each follow-up and patients' activity levels were assessed by measuring the mean annual walking cycles at 12 months follow-up. Anteroposterior and lateral radiographs of the operated knee were evaluated postoperatively and at 12-month follow-up with regard to implant position and radiological signs of implant loosening. Correlation analysis using multivariate linear regression was performed to investigate the influence of different variables (age, gender, functional scores, number of walking cycles, and body mass index [BMI]) on blood cobalt ion concentrations.
Mean metal ion levels of cobalt, chromium, molybdenum, and titanium were 0.28 μg/L (SD, 0.14), 0.43 μg/L (SD, 0.49), 0.62 μg/L (SD, 0.45), and 1.96 μg/L (SD, 0.98), respectively at 12-month follow-up. Mean cobalt ion levels significantly increased 1-year after surgery compared to preoperative measurements. There was no statistically significant increase of mean metal ion levels of chromium, titanium, and molybdenum at 1-year follow-up. Overall, metal ion levels were low and no patient demonstrated cobalt ion levels above 1 μg/L. Postoperative radiographs demonstrated well-aligned TKAs in all patients and no signs of osteolysis or implant loosening were detected at 1-year follow-up. Both the AKSS and OKS significantly improved during the course of the study up to the final follow-up. Multivariate regression analysis did not show a statistically significant correlation between the tested variables and blood cobalt ion concentrations.
A statistically significant increase of mean cobalt ion concentration at 1-year follow-up was found in this cohort of patients with well-functioning TKA, although overall blood metal ion levels were relatively low. Despite low systemic metal ion concentrations seen in this cohort, the local effects of increased metal ion concentrations in the periprosthetic environment on the long-term outcome of TKA should be further investigated.
研究初次全膝关节置换术（TKA）患者体内血液金属离子水平的变化过程，并探讨与这些患者金属离子释放相关的潜在危险因素。
本前瞻性研究纳入了 25 例有 TKA 适应证的患者。在术前和术后 1 周、6 周、3 个月、6 个月和 12 个月时进行全血金属离子分析。在每次随访时使用美国膝关节协会评分（AKSS）和牛津膝关节评分（OKS）获得临床评分，并在 12 个月随访时通过测量平均年度步行周期评估患者的活动水平。术后和 12 个月随访时对患侧膝关节进行正侧位 X 线片检查，评估假体位置和假体松动的影像学征象。采用多元线性回归分析对不同变量（年龄、性别、功能评分、步行周期数和体重指数[BMI]）对钴离子浓度的影响进行相关性分析。
术后 12 个月时钴、铬、钼和钛的平均金属离子浓度分别为 0.28μg/L（标准差[SD]，0.14）、0.43μg/L（SD，0.49）、0.62μg/L（SD，0.45）和 1.96μg/L（SD，0.98）。与术前测量值相比，术后 1 年钴离子水平显著升高。术后 1 年时，铬、钛和钼的平均金属离子水平无统计学意义的升高。总体而言，金属离子水平较低，无患者钴离子水平超过 1μg/L。术后 X 线片显示所有患者的 TKA 均对线良好，1 年随访时未发现骨溶解或假体松动的迹象。在研究过程中，AKSS 和 OKS 评分均显著改善，直至最终随访。多元回归分析显示，所测试的变量与血钴离子浓度之间无统计学显著相关性。
在功能良好的 TKA 患者中，我们发现术后 1 年钴离子平均浓度有统计学意义的升高，尽管总体血液金属离子水平相对较低。尽管在本队列中观察到系统性金属离子浓度较低，但应进一步研究假体周围环境中金属离子浓度增加对 TKA 长期结果的局部影响。
