The Clinical Study On Seronegative Periprosthetic Joint Infection

Objective:1.To identify clinical and pathogenic characteristics of seronegative periprosthetic joint infection.2.To discuss the treatment and results of seronegative periprosthetic joint infection.Methods:All patients of periprosthetic joint infection from November 2000 to December 2014 were retrospectively evaluated.The inflammation marks as CRP and ESR were assessed to identify seronegative infection(CRP<10mg/l,ESR<30mm/h).An age-and gender-matched cohort were identified from remaining patients for comparison.The mean ages of two cohorts were 65±12 years,8 males and 13 females in each cohort.To compare clinical features including symptoms,laboratory test results and image results,to compare pathogens and treatment methods,and to compare the outcomes by evaluating knee society pain and function score and Harris hip score.Results:Overall 9% of PJI patients were confirmed seronegativity,the sepsis score(SS)of them was 8.2±4.4 and seropositive patients’ SS was 12.6±6.1.Companied with positive cohort,patients in seronegative cohort were more often presented with simply pain and lack of sinus or purulence(p<0.05);The commonest pathogens of seronegative patients were coagulase negative staphylococci(53%),while,more virulent pathogens like Staphylococcus aureus were frequently isolated from seropositive cohort(31% VS 12%).The cure rate of seronegative cohort was 86%,seropositive cohort was 91%,the postoperative joint functions of the two groups were significantly improved(p<0.05).Seronegative PJI without antibacterial therapy were treated with one-stage surgery and achieved 100% cure rate,the postoperative KSS was 92.5±4.9,ROM was 101.3°±6.3°,HSS was 91.8±4.5,the joint function was surprisingly improved(p<0.01).Conclusion:The seronegative patients were rare and mostly infected with low virulent pathogens,and clinical symptoms were mainly pain,as to the patients who were not received antibacterial therapy,one-stage surgery was a good choice for them.