The Experimental Research Of The Serological Markers And Timing Of The Two-stage Revision ForProsthetic Knee Joint Infection

Objective:Through the establishment of the the rabbit prosthetic knee joint infection model,we will explore the potential serological markers for the diagnosis of the PJI on the one hand, and study the timing of the two-stage revision on the other hand.Methods:(1) Design and customize artificial knee prosthesis for rabbit; (2) Modeling: 42 healthy male adult New Zealand rabbits.weighing 3kg on average were choosed and divided into seven groups,named ABCDEFG. All were conducted with left total knee arthroplasty. Group A was the control group, giving an intra-articular injection of 0.5ml 0.9% saline intraoperatively. Group BCDEFG were the experimental group, giving an intra-articular injection of 0.5ml of Staphylococcus aureus named ATCC25923 at a concentration of 2 X 106 CFU/ml intraoperatively. (3) One-stage Debridement:4 weeks later, all the experimental groups were infectef. An one-stage debridement was conducted and a cement spacer infused with vancomycin was placed for experimental experimental rabbit;(4) Sacrificing animals:All rabbits were sacrificed according to the group at correspondent intervals of,2,4,6,8,10, and 12 weeks after debridement.(5) Laboratory tests:1. Serological tests:Concentrations of serum CRP、ESR、IL6、PCT、TLR2、NOD2、TNFR1 were measured after replacements and debridements.2. Bacteriological examination:Debridements and sacrifices samples around the prosthesis from experimental group were taken for bacterial cultures.3. Pathology observation:Debridements and sacrifices samples around the prosthesis from experimental group were taken for pathology observation by HE staining.4.PCR:Debridements and sacrifices samples around the prosthesis from experimental group were taken for 16srRNA PCR detection.Results:1. Serological tests (1) After modeling, The concentrations of serum TLR2x NOD2、TNFR1 from the experimental group were significantly elevated when compared with control group(P<0.05).(2) After debridement, The concentrations of serum TLR2、NOD2、TNFR1 from the experimental group decreased rapidly within 2 weeks, restoring to a normal level about 4-6 weeks,and shared a consistent trend with CRP, IL6, PCT.(3) Pearson correlation coefficient:the correlation coefficients for TLR2 with CPR and IL6 were r=0.892, r=0.947 respectively; the correlation coefficients for NOD2 with CPR and IL6 were r=0.998, r=0.755 respectively; the correlation coefficients for TNFR1 with CPR and IL6 were r=0.981, r=0.863 respectively.2.Bacteriological examination:(1)The results of debridements samples around the prosthesis from experimental group taken for bacterial cultures were positive, the infection rate was 100%.(2)The infection rate of tissue samples taken from sacrificed experimental group animals were:Group B 33.3%(2/6), group C 16.7%(1/6), D group,0%(0/6), E group 0%(0/6), F group,0%(0/6), G group 0%(6/6).3. Pathology observation(1) The results of debridements samples around the prosthesis from experimental group taken for pathology observation all showed an inflammatory state.(2) The results of tissue samples from sacrificed animals:group B (2 weeks),and C (4 weeks) showed a poor infection control; group D (6 week), E (8 week), F (10 week),and G (12 week) showed a good infection control.4.16srRNA PCR detection(1) The results of debridements samples around the prosthesis from experimental group taken for 16srRNA PCR detection were positive, the infection rate was 100%.(2) The infection rate of tissue samples taken from sacrificed experimental group animals were were:group B 50%(3/6), group C 33% (1/6), group D,0%(0/6), group E 0%(0/6), group F 0%(0/6), group G 0%(6/6).Conclusion:(1) TLR2, NOD2 and TNFR1 have a good sensitivity for the diagnosis of PJI and showed a good correlation with CRP, ESR, IL6 and other indicators.(2) Integrated results of CRP, ESR, as well as tissue culture, pathology, PCR and other laboratory tests, we recommended for two-stage revision surgery 6-8 weeks after debridements.