探讨金对金髋关节表面置换术(HRA)后金属离子水平的变化趋势。

回顾性分析2006年9月至2016年8月接受金对金HRA并有完整随访资料的患者72例81髋，男30例31髋，女42例50髋；年龄24~66岁。术前诊断髋臼发育不良29髋(35.8%)；股骨头坏死34髋(42.0%)；骨关节炎3髋(3.7%)；类风湿关节炎5髋(6.2%)；强直性脊柱炎10髋(12.3%)，排除金属离子过敏、使用含金属药物等患者。采用美国Wright公司Conserve Plus假体22髋，英国Smith & Nephew公司的伯明翰表面髋置换系统(BHR或BMHR)假体59髋。术前随机选取20例患者检测血清金属离子水平，作为对照组。使用电感耦合等离子体质谱仪检测术前及术后3、6个月以及术后每年血清样本中钴(Co)、铬(Cr)、钼(Mo)离子水平，使用t检验比较术前术后金属离子水平差异，同时间点Co、Cr、Mo离子水平采用单因素重复测量资料的方差分析。

平均随访(7.9 ± 0.3)年，Co、Cr、Mo三种离子术前水平分别为(1.13±0.24)μg/L、(2.22±0.54)μg/L、(2.62±1.00)μg/L。术后三种金属离子水平均升高，其中Co离子和Cr离子与术前比较差异有统计学意义(F＝51.93、61.00，均为P<0.05)。Co离子在术后6个月达到高峰，为术前3.2倍，然后开始逐渐下降，至术后7年基本恢复到术前水平，术后8年及10年Co离子水平再次升高，分别为术前2.0倍和2.5倍，差异有统计学意义(均为P<0.05)，此后Co离子水平逐渐下降，术后13年，Co离子基本恢复术前水平，为(1.28± 0.79)μg/L。术后1年，Cr离子水平达到高峰，是术前2.2倍，较术前差异有统计学意义(P<0.05)，术后7年，Cr离子升高到与顶峰时离子水平相似，是术前水平2.0倍，差异有统计学意义(P<0.05)。此后Cr离子水平始终处于下降趋势，至术后13年，Cr离子水平低于术前，差异没有统计学意义(P>0.05)。Mo离子水平术后升高，但与术前相比差异没有统计学意义(F＝35.93，P>0.05)；Mo离子术后3个月达到随访期的高峰，是术前的2.23倍；术后4年，Mo离子水平出现明显下降过程，术后8年Mo离子水平最低，为(2.62±1.43)μg/L，较术前差异没有统计学意义(P>0.05)，术后9年至10年，离子水平再次升高，为(5.29±2.07)μg/L，是术前2.0倍，术后13年下降至术前水平(P>0.05)。

金对金HRA术后早期金属离子水平均升高并达到高峰，中长期金属离子水平存在波动，但总体呈下降趋势。对于金属离子水平的变化情况需继续密切监测及观察。

To investigate the mid-and long-term trend of metal ion levels after metal-on-metal hip resurfacing arthroplasty.

A retrospective analysis was performed on 72 patients with 81 hips, including 30 males (31 hips)and 42 females(50 hips)who underwent metal-on-metal hip resurfacing arthroplasty in Tianjin First Central Hospital from September 2006 to August 2016. The age range was 24-66 years. Twenty-nine hips(35.8%)were diagnosed as acetabular dysplasia before the operation, 34 hips (42.0%) were diagnosed femoral head necrosis, three hips were diagnosed osteoarthritis (3.7%), five hips were diagnosed rheumatoid arthritis (6.2%), 10 hips were diagnosed ankylosing spondylitis (12.3%). The patients who were allergic to metal ions and using metal-containing drugs were excluded. Twenty-two hips used Conserve Plus prosthesis from Wright Company(USA), and 59 hips used Birmingham Hip Resurfacing or Birmingham Mid Head Resection System (BHR or BMHR) from Smith & Nephew Company (United Kingdom). Serum samples from 20 patients were randomly selected before surgery to detect metal ion levels, and served as control groups. Inductively coupled plasma mass spectrometer was used to detect the levels of Co, Cr and Mo ions in serum samples before and after surgery, three months, six months, and every year after surgery, and analyze their changes. The t-test was used to compare the differences in metal ion levels before and after surgery, and the Co, Cr, and Mo ion levels at the same time point were analyzed by single-factor repeated measurement data analysis of variance.

The mean follow-up time was (7.85±0.34)years. The preoperative levels of Co, Cr and Mo were (1.13±0.24)μg/L, (2.22±0.54)μg/L, and(2.62±1.00)μg/L. The levels of the three metal ions increased after the operation, among which the differences of Co and Cr ion levels were statistically significant (F=51.93, 61.00, both P<0.05). Co ions reached a peak six months after the operation, 3.2 times to that before the operation, and then gradually decreased. Seven years after the operation, the levels of Co ions returned to the levels before the operation. The levels of metal ions increased again at eight years and 10 years after surgery, 2.0 times and 2.5 times to that before surgery respectively, and the differences were statistically significant (both P<0.05). After 10 years, the levels of metal ions gradually decreased to 13 years after surgery. Co ion level basically recovered to the preoperative level, (1.28±0.79)μg/L. One years after Cr ion, the metal ion level reached a peak, which was 2.2 times to that before the operation, and the difference was statistically significant (P<0.05) At seven years after operation, the metal ion level increased significantly, compared with the metal ion level at the peak. Similarly, it was 2.0 times to the metal ion level before surgery, and the difference was statistically significant (P<0.05). The level of metal ions was in a downward trend. By 13 years after operation, the level of metal ions was lower than before surgery, and the difference was not statistically significant (P>0.05). Although Mo ion level increased following the surgery, the difference was not statistically significant(F=35.93, P>0.05). Mo ion level reached the peak of the follow-up period at three months after the operation, which was 2.2 times to the preoperative level. Four years after the operation, Mo ion level showed a significant decline process, and Mo ion was the lowest eight years after the operation. The lowest level was (2.62±1.43) μg/L, which was not statistically significant compared with preoperative difference (P>0.05). From nine to 10 years after operation, the ion level increased again, which was (5.29±2.07) μg/L, which was 2.02 times preoperatively, and reached a plateau, dropped to the preoperative level 13 years after operation, yet the difference was not statistically significant (P>0.05).

After metal-on-metal hip resurfacing arthroplasty, in the early stage increased and reached a peak, and the metal ion level in the medium and long term shows a downward trend. The fluctuation of metal ion level needs to be continuously monitored and closely observed.