Analysis of frozen sections of intraoperative specimens obtained at the time of reoperation after hip or knee resection arthroplasty for the treatment of infection

Background: Despite the effectiveness of a two-stage exchange protocol for the treatment of deep periprosthetic infection, infection can persist after resection arthroplasty and treatment,vith antibiotics, leading to a failed second-stage reconstruction. Intraoperative analysis of frozen sections ha s been shown to have a high sensitivity and specificity for the identificat ion of infection at the time of revision arthroplasty; however, the usefuln ess of this test at the time of reoperation after resection arthroplasty an d treatment with antibiotics is, to our knowledge, unknown. Methods: The medical records of sixty-four consecutive patients who had had a resection arthroplasty of either the knee (thirty-three patients) or the hip (thirty-one patients) and had had intraoperative analysis of frozen se ctions of periprosthetic tissue obtained at the time of a second-stage oper ation were reviewed. The mean interval between the resection arthroplasty a nd the attempted reimplantation was nineteen weeks. The results of the intr aoperative analysis of the frozen sections were compared with those of anal ysis of permanent histological sections of the same tissues and with those of intraoperative cultures of specimens obtained from within the joint. The findings of the analyses of the frozen sections and the permanent histolog ical sections were considered to be consistent with acute inflammation and infection if a mean of ten polymorphonuclear leukocytes or more per high-po wer field (forty times magnification) were seen in the five most cellular a reas. Results: The intraoperative frozen sections of the specimens from two patie nts (one of whom was considered to have a persistent infection) met the cri teria for acute inflammation. Four patients were considered to have a persi stent infection on the basis of positive intraoperative cultures or permane nt histological sections. Overall, intraoperative analysis of frozen sectio ns at the time of reimplantation after resection arthroplasty had a sensiti vity of 25 percent (detection of one of four persistent infections), a spec ificity of 98 percent, a positive predictive value of 50 percent (one of tw o), a negative predictive value of 95 percent, and an accuracy of 94 percen t. Conclusions: A negative finding on intraoperative analysis of frozen sectio ns has a high predictive value with regard to ruling out the presence of in fection; however, the sensitivity of the test for the detection of persiste nt infection is poor.