Abstract: Objective To investigate the changes of serum procalcitonin levels in patients with early infection after rheumatoid arthritis replacement. Methods a retrospective analysis of 20 cases of rheumatoid arthritis after replacement of early infection patients as research group A，200 cases of replacement rheumatoid arthritis without postoperative infection in patients with as the study group B，40 healthy subjects served as study group C were carried out in our hospital from February 2016 to February 2017 were. The erythrocyte sedimentation rate，C-reactive protein，procalcitonin，WBC count，specificity，sensitivity，negative predictive value and positive predictive value of the three groups were compared and analyzed. Results 1.Sedimentation rate，C-reactive protein and procalcitonin，replacement of rheumatoid arthritis patients the level of white blood cell count and study group B after infection were compared in patients with early infection of red blood cell group A rheumatoid arthritis after arthroplasty is significantly higher，P<0.05 was statistically significant in patients with red; cells not infected with rheumatoid arthritis with replacement of group B after sedimentation rate，C-reactive protein and procalcitonin，white blood cell count and the level of C subjects，significantly higher，P<0.05 was statistically significant. 2.The sensitivity of the level of PCT and ESR and the sensitivity of WBC，CRP and PCT in patients with early infection after rheumatoid arthritis replacement were significantly higher，and the positive rate of PCT positive was the highest. 3.The AUC of PCT is 0.752，the truncation value is 15.70ng/mL，the standard error is 0.061，and the 95%CI range is from 0.633 to 0.982. Conclusion Serum procalcitonin levels in patients with early infection after rheumatoid arthritis replacement can be used as diagnostic criteria. The cut-off value is 10.50ng/ml，which can be used as a reference for clinical diagnosis.

Key words: Rheumatoid arthritis, Early infection , Serum procalcitonin levels , Artificial joint replacement