Significance of serum protein electrophoresis in the diagnosis of Tsukayama type IV periprosthetic joint infection

Abstract

ObjectivesTo investigate the efficacy of serum protein electrophoresis (SPE) in the diagnosis of periprosthetic joint infection (PJI) after hip and knee arthroplasty.MethodsThe medical records of patients undergoing hip and knee arthroplasty at a class A tertiary hospital between August 2013 and January 2021 were retrospectively investigated. A total of 179 patients were included and divided into two groups: 66 patients in the PJI group and 113 patients in the aseptic loosening (AL) group. Serum C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), D-dimer, Fibrinogen, Serum albumin and the proportion of serum protein in SPE were compared between the two groups. The diagnostic sensitivity and specificity were determined using the receiver operating characteristic (ROC) curve, and the diagnostic value was compared using the area under the ROC curve (AUC).ResultsThere was no significant difference in age, sex and body mass index (BMI) between PJI group and AL group (P>0.05), but there was significant difference in the ratio of hip to knee (X2 = 22.043, P<0.001). The CRP, ESR, D-dimer, Fibrinogen and the proportion of α1 globulin band in PJI group was 22.99(10.55,40.58) mg/L, 37.00(23.00,61.70) mm/h, 790.00(500.00,1500.00) ng/ml, 4.84(3.81,5.55) g/L and 5.80(5.00,7.73) % which was higher than that in AL group [1.89(0.50,4.12) mg/L, U=7.984, P<0.001; 10.10(7.00,16.90) mm/h, U=8.095, P<0.001; 570.00(372.50,780.00) ng/ml, U=3.448, P<0.001; 2.84(2.45,3.43) g/L, U=8.053, P<0.001 and 4.20(3.90,4.80) %, U=8.154, P<0.001]. The Serum albumin and the proportion of Albumin band in PJI group was 36.10(33.10,39.00) g/L and 49.00(44.95,52.20) % which was lower than that in AL group [38.10(34.00,41.10) g/L, U=-2.383, P=0.017 and 54.40(51.55,56.70) %, U=-6.162, P<0.001]. The proportion of In PJI group, the AUC of proportion of α1 globulin was 0.8654, which was equivalent to CRP (0.8698), ESR (0.8680) and outperformed that of fibrinogen (0.8025).ConclusionsElevated proportion of α1 globulin in SPE presented with good diagnostic value for Tsukayama type IV PJI, and its accuracy was comparable to those of ESR and CRP. And α1 globulin can assist with CRP and ESR to determining the timing of second-stage revision.