Study For Seasonal Risk Factors Of Periprosthetic Joint Infection After Total Knee Arthroplasty

Background:With the development of total knee arthroplasty(TKA), knee joint function of patients with end-stage diseases such as osteoarthritis, rheumatoid arthritis can be effectively improved, their pain symptoms also can be relieved.But complications such as periprosthetic joint infection(PJI) which is a complication occurs after total knee arthroplasty, will seriously affect the outcome of the operation, and bring huge economic burden and psychological stress to the patients and their family members.As people pay more and more attention to PJI and its related risk factors,a number of risk factors of PJI has been confirmd,such as aged patients, obesity, diabetes, hypoalbuminemia, etc.However, there are still a few patients develop PJI after TKA due to some uncertain factors. A seasonal variation of infectious diseases has been founded in several studies,which was significantly higher in summer seasons than the other seasons.PJI, as a kind of infectious disease, whether it is also affected by seasonal factors need to be further discussed. Objective:To analyze the differences in incidence of PJI after total knee arthroplasty in different seasons, and to further study the controllable seasonal risk factors related to PJI, in order to provide the basis for the effective preventive measures to reduce the incidence of PJI after total knee arthroplasty. Methods:This study was divided into two parts, the first part: 17 patients who developed PJI after TKA from December 2005 to December 2014 were involved in the study according to the patient selection and exclusion criteria.First,the patients were divided into different season groups according to the operation time, then the correlation between season and PJI rate was analyzed. Second, pathogenic bacteria distribution and their drug resistance in PJI patients in different season groups were discussed.Third, the prognosis and satisfaction degree of PJI patients were evaluated according to the follow-up results of patients.The second part: 869 patients who had undergone TKA from January 2014 to January 2016 were involved in the study according to the patient selection and exclusion criteria. Nasal swabs and urine samples were cultured in all these patients. First,the correlation between season and bacteria carriers was analyzed. Furthermore, bacteria distribution and their drug resistance in bacteria carriers were also analyzed.Second, different incidence of PJI between bacteria carriers group and noncarriers group was compared. Results:The first part was about the seasonal variation in PJI after TKA. The incidence of PJI in summer was significantly higher than in the other three seasons. A significant difference(P<0.05)was founded in the incidence of PJI between summer and autumn(P = 0.029), summer and spring(P = 0.038). The incidence of drug resistant bacteria infections such as MRSA was higher in summer group than the other three groups which contributed to the poor prognosis and satisfaction degree of PJI patients. At the time of last follow-up,there was no obvious difference in joint range of motion(ROM) and VAS score of PJI patients in summer group compared with other groups,while HSS score(50.18 + 4.57) of PJI patients in summer group was significantly lower than other groups.The second part was about the relationship between bacteria carriers and PJI after total knee arthroplasty. Results of bacterial culture showed that gram-positive bacteria such as staphylococcus aureus, staphylococcus epidermis were the most common bacteria survive in people's nasal mucosa,while gram-negative bacteria including e. coli, citric acid bacteria, lactic acid bacteria,etc. were popular in urine. In summer group, 25.77% of the patients were identified as bacteria carriers in nasal mucosa, and 6.7% were identified as methicillin-resistant Staphylococcus aureus carriers,which were significantly higher than that in the other three groups.The same was true in bacteria carriers in urine.A significantly higher rate of PJI was observed among staphylococcus aureus and staphylococcus epidermis carriers in nasal mucosa(2.04%) compared with noncarriers(0.14%). Significant difference was found between the two groups(P = 0.038).There is no significant difference in incidence of PJI was observed among bacteria carriers in urine compared with noncarriers(P = 0.538). Conclusions:1. PJI after total knee arthroplasty is affected by seasonal factors.Heat and humid environment in summer makes people vulnerable to the colonization of staphylococcus aureus and staphylococcus epidermis which leads to higher incidence of PJI in summer than in other seasons.2. The incidence of drug resistant bacteria infections such as MRSA is higher in summer group than in the other three groups which contributes to the poor prognosis and satisfaction degree of PJI patients.3. The colonization of staphylococcus aureus and staphylococcus epidermis in nasal mucosa increases the risk of PJI. Therefore,it is essential to eradicate staphylococcus aureus and staphylococcus epidermis carrier status among patients undergoing total knee arthroplasty. However,whether bacteria carriers in urine affect the incidence of PJI is unclear.