Clinical Characters Of Culture-negative Periprosthetic Joint Infection

Objective: To explore clinical characters and possiblerisk factors of culturenegative periprosthetic joint infection patients.Materials and Methods:61patients during January2012to December2013wereenrolled in this retrospective study according to diagnostic criteria. All patientsunderwent both preoperative and intraoperative aspiration culture. Based on the cultureresult,45patients were divided into culture-positive group (CP) and16patients weredivided into culture-negative group (CN). Patients-related information including age,gender, BMI, prosthetic survival time and preoperative treatment were reviewed.Intraoperative frozen sections were performed to identify PJI. Paraffin sections wereobserved and differentiated by Morawietz’s histological typing method.All patientswent through two-stage revision. Patients in CN group were implantedvancomycin/gentamicin with or without meropenem impregnatedbone cement spacer.After surgery, CN patients were treated with combination of antibiotics. All patientswere followed at3month,6month and1year after revision surgery.Results: The HSS and HARRIS scorings were estemated,CN patients showed asignificant better joint function than CP groups(p=0.036， p=0.017). Significantdifferences were found in preoperative serum CRP (t=2.094, P=0.038) and ESR(t=7.761, P=0.001) between two groups. In CN group the prosthetic median survivaltime72months (8-504months), which has a significant longer survival span than CPgroup (prosthetic median survival time25months,15d-300months).Morawietz’shistological typing results identified that7cases as type II, and9cases as type III inCN group; meanwhile,6cases were rated as type I,25cases as type II,13cases as typeIII, and1case as type IV in CP group.45patients have found definite pathogenicbacterium among which Staphylococcus was at the leading role (68.89%). In our studythe culture positive rate was73.8%.After two-stage revision surgery, no patients with high-risk re-infection symptoms were observed amongboth CN and CP patientstill thelast follow-up. We found young patients (less than50years) and antibiotic use beforedifinite culture results were two risk factors for culture-negative phenomenon.Conclusion:PJI is very difficult to diagnosis and treat in patients with a negativeculture result. Young patients and antibiotic use are risk factors for negative cultureresults. Culture-negative PJI patients have a more mild inflammation response andslower onset.However, its diagnosis should be more prudent, which not only requiresmultiple tissue or aspiration culture, but also histological confirmation and laboratoryexamination.