Bori Guillem, Soriano Alex, García Sebastián, Mallofré Carme, Riba Josep, Mensa Josep
Department of Orthopaedics and Traumatology, Hospital Clinic, University of Barcelona, C/Villarroel 170, 08036 Barcelona, Spain.
J Bone Joint Surg Am. 2007 Jun;89(6):1232-7. doi: 10.2106/JBJS.F.00741.
Appropriate interpretation of a frozen section has a relatively high specificity and sensitivity for the diagnosis of infection when septic loosening of a prosthesis is suspected. However, its usefulness for predicting the presence of microorganisms at the time of reimplantation after hip resection arthroplasty for the treatment of infection is not well defined. The aim of the present study was to evaluate the usefulness of histological analysis in this situation.
From January 2002 to February 2006, a total of twenty-one patients underwent reimplantation after hip resection arthroplasty for the treatment of infection. Histological studies and cultures of specimens of periprosthetic tissue that had been obtained at the time of reimplantation were retrospectively reviewed. The results of culture were considered positive when the same microorganism was isolated in at least two samples. Two histological criteria were used to diagnose infection: (1) Criterion A (the Feldman criterion), defined as the presence of at least five neutrophils per high-power field (x400) in at least five separate microscopic fields and (2) Criterion B (the Athanasou criterion), defined as the presence of at least one neutrophil per high-power field (x400), on average, after examination of ten microscopic fields. The sensitivity, specificity, positive predictive value, and negative predictive value of each of these criteria were calculated with use of microbiological results as the gold standard for defining infection.
Seven of the twenty-one patients had a positive result on culture, and the most common microorganism was coagulase-negative staphylococcus. The sensitivity, specificity, positive predictive value, and negative predictive value of frozen-section analysis were 28.5%, 100%, 100%, and 73.6%, respectively, according to the Feldman criterion and 71.4%, 64.2%, 50%, and 81.8%, respectively, according to the Athanasou criterion. The numbers of lymphocytes and plasma cells did not help in the diagnosis of infection. Fibrosis was more common in patients without an infection.
The probability of infection is high when at least five neutrophils per high-power field are found in the periprosthetic tissue, but it is not possible to rule out infection when the number of neutrophils is less than five.
Diagnostic Level I.
当怀疑假体发生脓毒性松动时，冰冻切片的恰当解读对感染诊断具有较高的特异性和敏感性。然而，其对于预测髋关节切除关节成形术后再植入时微生物的存在情况的作用尚不明确。本研究的目的是评估在这种情况下组织学分析的作用。
从2002年1月至2006年2月，共有21例患者在髋关节切除关节成形术后因感染接受再植入手术。对再植入时获取的假体周围组织标本进行回顾性组织学研究和培养。当在至少两个样本中分离出相同微生物时，培养结果被视为阳性。使用两个组织学标准诊断感染：（1）标准A（费尔德曼标准），定义为在至少五个独立显微镜视野中每个高倍视野（×400）至少有五个中性粒细胞；（2）标准B（阿萨纳索标准），定义为在检查十个显微镜视野后平均每个高倍视野（×400）至少有一个中性粒细胞。以微生物学结果作为定义感染的金标准，计算每个标准的敏感性、特异性、阳性预测值和阴性预测值。
21例患者中有7例培养结果为阳性，最常见的微生物是凝固酶阴性葡萄球菌。根据费尔德曼标准，冰冻切片分析的敏感性、特异性、阳性预测值和阴性预测值分别为28.5%、100%、100%和73.6%；根据阿萨纳索标准，分别为71.4%､64.2%､50%和81.8%。淋巴细胞和浆细胞的数量无助于感染的诊断。纤维化在未感染患者中更常见。
当在假体周围组织中每个高倍视野发现至少五个中性粒细胞时，感染的可能性很高，但当中性粒细胞数量少于五个时不能排除感染。
诊断性I级。
