Hart A J, Sabah S A, Sampson B, Skinner J A, Powell J J, Palla L, Pajamäki K J J, Puolakka T, Reito A, Eskelinen A
Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, London HA7 4LP, United Kingdom. E-mail address for A.J. Hart:
Department of Clinical Biochemistry, Charing Cross Hospital, Imperial College Healthcare NHS Trust, London, W6 8RF, United Kingdom. E-mail address:
J Bone Joint Surg Am. 2014 Jul 2;96(13):1091-1099. doi: 10.2106/JBJS.M.00957.
We designed a prospective, single-center study to assess whether blood metal ion levels could predict implant failure in patients managed with unilateral metal-on-metal hip resurfacing or total hip arthroplasty.
Five hundred and ninety-seven patients who had received unilateral Articular Surface Replacement prostheses at least twelve months earlier were recruited. Blood metal ion levels were compared between the group of patients with failed implants and the group with non-failed implants. Implant failure was defined as prostheses associated with revision, an intention to revise, or poor patient-reported hip function (Oxford Hip Score, <31 of 48). Specificity, sensitivity, area under the curve, positive and negative predictive values, and odds ratios were calculated. Logistic regression analysis was used to identify other risk factors for implant failure.
Patients with failed arthroplasty had significantly higher blood cobalt and chromium ion levels than did patients with non-failed arthroplasty (p < 0.01). Blood cobalt ion levels were disproportionately raised in patients with failed total hip arthroplasty (8.2 μg/L) compared with patients with failed hip resurfacing (2.5 μg/L) (p = 0.018). Blood chromium ion levels were not significantly different in patients with failed total hip arthroplasty and failed hip resurfacing (p = 0.058). The maximum value of either metal ion had good discriminant ability to predict implant failure (area under the curve, 0.76). A 7-μg/L cutoff had a positive predictive value of 0.75 (95% confidence interval, 0.66 to 0.82) and a negative predictive value of 0.82 (95% confidence interval, 0.78 to 0.86). In patients managed with total hip arthroplasty, for each increase of 1 μg/L there was a 23% (p < 0.001) increase in the odds of them being in the failed group. For patients managed with hip resurfacing, the increase in odds was 5% (p < 0.001).
Raised levels of blood metal ions were associated with failed metal-on-metal hip resurfacings and total hip arthroplasties. A threshold level of 7 μg/L had inadequate sensitivity to be used in isolation as a screening test for implant failure, but it provided nearly optimal misclassification rates. No level had a perfect positive predictive value, and so we discourage surgeons from performing revision surgery based on blood metal ion levels alone. Levels of cobalt ions were raised out of proportion to levels of chromium ions in failed total hip arthroplasty and may reflect a different mechanism for metal ion generation.
Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
我们设计了一项前瞻性单中心研究，以评估血金属离子水平是否能预测接受单侧金属对金属髋关节表面置换术或全髋关节置换术患者的植入物失败情况。
招募了至少在12个月前接受单侧关节表面置换假体的597例患者。比较植入物失败患者组和未失败患者组的血金属离子水平。植入物失败定义为与翻修相关的假体、翻修意向或患者报告的髋关节功能较差（牛津髋关节评分，48分中<31分）。计算特异性、敏感性、曲线下面积、阳性和阴性预测值以及比值比。采用逻辑回归分析确定植入物失败的其他危险因素。
关节置换失败患者的血钴和铬离子水平显著高于未失败的关节置换患者（p<0.01）。与髋关节表面置换失败患者（2.5μg/L）相比，全髋关节置换失败患者的血钴离子水平升高不成比例（8.2μg/L）（p = 0.018）。全髋关节置换失败患者和髋关节表面置换失败患者的血铬离子水平无显著差异（p = 0.058）。任一金属离子的最大值对预测植入物失败具有良好的判别能力（曲线下面积，0.76）。7μg/L的临界值阳性预测值为0.75（95%置信区间，0.66至0.82），阴性预测值为0.82（95%置信区间，0.78至0.86）。在接受全髋关节置换术的患者中，每增加1μg/L，其在失败组中的几率增加23%（p<0.001）。对于接受髋关节表面置换术的患者，几率增加为5%（p<0.001）。
血金属离子水平升高与金属对金属髋关节表面置换术和全髋关节置换术失败相关。7μg/L的阈值单独用作植入物失败筛查试验时敏感性不足，但它提供了近乎最佳的错误分类率。没有一个水平具有完美的阳性预测值，因此我们不鼓励外科医生仅根据血金属离子水平进行翻修手术。在失败的全髋关节置换术中，钴离子水平升高的比例超过铬离子水平，这可能反映了金属离子产生的不同机制。
治疗性III级。有关证据水平的完整描述，请参阅作者指南。
