[Diagnostic value of D-dimer for chronic periprosthetic infection after hip and knee joint replacement].

Objective: To investigate the diagnose value of D-dimer for chronic periprosthetic infection (PJI) after hip and knee arthroplasty. Methods: A retrospective analyze was conducted on 168 patients underwent revision arthroplasty and primary arthroplasty at the First Affiliated Hospital of Xinjiang Medical University from November 2017 to December 2018.There were 58 males and 110 females, aged(58.6±14.5)years.There were 48 cases of chronic PJI (21 cases of knee joint, 27 cases of hip joint), 57 cases of aseptic loosening (16 cases of knee joint, 41 cases of hip joint), and 63 cases of normal follow-up patients after hip (35 cases) or knee (28 cases) arthroplasty.The levels of D-dimer, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were collected.The levels of D-dimer in patients with chronic PJI of hip and knee joints were compared by Mann-Whitney U test.The diagnostic efficacy of D-dimer, ESR and CRP in chronic PJI of hip and knee joints was analyzed by receiver operator curve (ROC). Results: The D-dimer level was significantly higher in knee chronic PJI patients than hip chronic PJI patients(M (Q(R)) ) (1 040 (1 140.5) μg/L vs.435 (605) μg/L, Z=3.169, P=0.002) . ROC analysis showed that the optimum cutoff value of D-dimer in the diagnosis of chronic PJI was 370.5 μg/L, the sensitivity was 90.5%, the specificity was 84.1%; the optimum cutoff value of CRP was 9.3 mg/L, the sensitivity was 95.2%, the specificity was 90.9%, the optimum cutoff value of ESR was 33 mm/h, the sensitivity was 90.5%, and the specificity was 88.6%.The optimum cutoff value of D-dimer in the diagnosis of chronic PJI of hip joint is 294 μg/L, the sensitivity of diagnosis is 66.7%, the specificity is 77.6%; the optimum cutoff value of ESR is 45 mm/h, the sensitivity of diagnosis is 55.6% , the specificity is 97.4%; the optimum cutoff value of CRP is 8.1 mg/L, the sensitivity of diagnosis is 74.1%, the specificity is 84.2%. Conclusion: The value of D-dimer in the diagnosis of chronic PJI of knee joint is higher than that of hip joint, but the value of D-dimer in the diagnosis of chronic PJI is not better than ESR and CRP.