Mika Aleksander P, Baker Courtney E, Wilson Jacob M, Pennings Jaquelyn S, Engstrom Stephen M, Polkowski Gregory G, Martin J Ryan
Department of Orthopedic Surgery, Vanderbilt University Medical Center, Nashville, Tennessee.
J Arthroplasty. 2025 Sep;40(9S1):S13-S17. doi: 10.1016/j.arth.2025.04.067. Epub 2025 May 6.
Implant loosening following primary total knee arthroplasty (TKA) remains the most common aseptic indication for revision. Aseptic loosening can be difficult to diagnose, as radiographic findings may be absent or difficult to detect or interpret. Commercially available bone cement contains either barium or zirconium to allow for radiographic detection. We hypothesized that implant loosening leads to abrasion-related release of detectable amounts of metal ions from the implant or bone cement, which may serve as biomarkers of aseptic loosening.
We prospectively enrolled 50 patients (mean age: 65 years, 52% were women) undergoing revision of a cemented TKA requiring component explantation. Synovial fluid was obtained prior to arthrotomy during revision surgery and analyzed for concentrations of barium, zirconium, titanium, cobalt, and chromium in parts per billion (ppb). The diagnostic utility of each ion for detecting loosening was assessed. The operative surgeon determined whether the femoral and tibial components were well-fixed or loose at the time of removal.
There were 25 (50%) patients who had intraoperatively confirmed component loosening. Patients who had confirmed component loosening had elevated levels of zirconium (median levels: 27 versus 6 ppb, P = 0.016) and cobalt (median levels: 16 versus 1.5 ppb, P = 0.002) compared to patients who did not have loosening. The most accurate synovial metal ion levels for diagnosing aseptic loosening were cobalt (area under the curve: 0.76 (95% confidence interval = 0.611 to 0.92); P = 0.001) and zirconium (area under the curve: 0.79 (95% confidence interval = 0.6 to 0.99); P = 0.003). In this series, barium, titanium, and chromium levels were not predictive of component loosening.
Aseptic loosening remains a challenging diagnosis without an available confirmatory test. Although the current sample size is limited, our results indicate that synovial fluid cobalt and zirconium levels are valuable indicators of component loosening. In the absence of definitive X-ray findings, synovial fluid analysis offers a promising diagnostic modality. This test can potentially improve patient outcomes by enabling earlier and more accurate detection of aseptic loosening following primary cemented TKA.
初次全膝关节置换术（TKA）后植入物松动仍是最常见的无菌性翻修指征。无菌性松动可能难以诊断，因为影像学表现可能不存在、难以检测或难以解读。市售骨水泥含有钡或锆，以便进行影像学检测。我们推测植入物松动会导致与磨损相关的可检测量金属离子从植入物或骨水泥中释放出来，这些金属离子可能作为无菌性松动的生物标志物。
我们前瞻性纳入了50例（平均年龄：65岁，52%为女性）因需要取出假体组件而进行骨水泥型TKA翻修的患者。在翻修手术关节切开术前获取滑液，并分析其中钡、锆、钛、钴和铬的浓度（以十亿分比计）。评估每种离子检测松动的诊断效用。手术医生在取出时确定股骨和胫骨组件是固定良好还是松动。
有25例（50%）患者术中证实组件松动。与未松动的患者相比，已证实组件松动的患者锆水平升高（中位数水平：27对6 ppb，P = 0.016），钴水平升高（中位数水平：16对1.5 ppb，P = 0.002）。诊断无菌性松动最准确的滑液金属离子水平是钴（曲线下面积：0.76（95%置信区间 = 0.611至0.92）；P = 0.001）和锆（曲线下面积：0.79（95%置信区间 = 0.6至0.99）；P = 0.003）。在本系列中，钡、钛和铬水平不能预测组件松动。
在没有可用确诊试验的情况下，无菌性松动仍然是一个具有挑战性的诊断。尽管目前样本量有限，但我们的结果表明滑液钴和锆水平是组件松动的有价值指标。在没有明确X线表现的情况下，滑液分析提供了一种有前景的诊断方式。该检测有可能通过更早、更准确地检测初次骨水泥型TKA后的无菌性松动来改善患者预后。
