The Significance Of Fibrinogen,D-Dimer,and Platelet In The Diagnosis Of Chronic Phase Infection After Fracture Fixation

BackgroundOrthopedic device Related Infection（ODRI）is one of the most serious complications after Orthopedic surgery.ODRI mainly includes periprosthetic joint infection（PJI）and infection after fracture fixation（IAFF）,in which chronic low-virulence infections are increasingly common.At present,there are many studies on the diagnosis of PJI,but the research on IAFF is insufficient.The diagnostic efficacy of classical C-reactive protein（CRP）and erythrocyte sedimentation rate（ESR）cannot fully meet the needs of clinical diagnosis of chronic phase IAFF.New diagnostic markers need to be explored to supplement the reliability of the diagnosis.ObjectiveTo analyze the relationship between fibrinogen（FBG）,D-Dimer,platelet（PLT）and its ratio to mean platelet volume（PLT/MPV）in peripheral venous blood with pathogenic bacteria,and compare their significance in the diagnosis of chronic phase IAFF.MethodsThis study retrospectively analyzed the clinical data of 1214 patients admitted to the Department of Orthopedics of our hospital from January 2016 to January 2020.113 patients meeting the inclusion and exclusion criteria were obtained,including 41 patients with chronic phase IAFF after limb closed fracture（IAFF group）,and 72 patients with closed fractures of limbs without infection after the operation（IAFF control group）.CRP and ESR were used as a reference to compare the blood FBG,D-Dimer,PLT,and PLT/MPV data of patients before surgery,analyze the relationship between the above indicators and infected bacteria,draw the corresponding ROC curve,and compare their diagnostic efficacy for chronic phase IAFF.Result1、There were no significant differences in CRP,ESR,FBG,D-Dimer,and PLT levels in peripheral venous blood between patients infected with different Gram-stained pathogens and different virulence pathogens（P>0.05）.The level of PLT/MPV in patients with chronic phase IAFF of high virulence pathogens was significantly lower than that of low virulence pathogens（P<0.05）,but there was no statistical difference among different Gram-stained pathogens（P>0.05）.2、CRP,ESR,FBG,D-Dimer,PLT,and PLT/MPV in peripheral blood of IAFF group were higher than those of IAFF control group（P<0.05）.3、When chronic phase IAFF was diagnosed,the Area under curve（AUC）of CRP,ESR,FBG,D-Dimer,PLT and PLT/MPV were 0.858,0.787,0.812,0.877,0.646 and 0.721,respectively.The sensitivity was 0.875,0.750,0.903,0.750,0.875,0.806,and the specificity was 0.829,0.732,0.610,0.878,0.439,0.634,respectively.CRP,ESR,FBG and D-Dimer had no significant difference in AUC in diagnosis of chronic phase IAFF（P>0.05）.The AUC of PLT/MPV in diagnosing chronic phase IAFF was lower than that of CRP（P<0.05）,but higher than that of PLT（P<0.05）.4、The AUC of FBG combined with D-Dimer,PLT,and PLT/MPV for diagnosis of chronic phase IAFF was 0.900,0.810,and 0.825,respectively.The AUC of FBG,D-Dimer,and PLT combined diagnosis of chronic phase IAFF was 0.901.The AUC of FBG,D-Dimer,and PLT/MPV combined in the diagnosis of chronic phase IAFF was 0.902.5、The AUC of ESR in diagnosing chronic phase IAFF of upper and lower limbs was 0.552 and 0.827,respectively,with statistical significance（P<0.05）,while the AUC of CRP,FBG,D-Dimer,PLT and PLT/MPV in diagnosing upper limb IAFF and lower limb IAFF was not statistically significant（P>0.05）.ConclusionWhen we consider that patients after fracture internal fixation may be chronic phase IAFF of low virulence bacteria,but the clinical hematological indicators commonly used to diagnose infections such as white blood cell count,CRP or ESR are not enough to assist diagnosis,we can consider FBG,D-Dimer,and PLT/MPV are used to assist in the diagnosis of chronic phase IAFF:1、FBG and D-Dimer may be excellent indicators for the diagnosis of chronic phase IAFF,and their efficacy is comparable to CRP and ESR.PLT/MPV may be a valid indicator for the diagnosis of chronic phase IAFF.However,the effect of PLT diagnosis may not be suitable for the clinical diagnosis of chronic phase IAFF.2、The combination of FBG,D-Dimer,PLT,and PLT/MPV may obtain better diagnostic efficacy but does not always improve the diagnostic efficacy of chronic phase IAFF.3、ESR may be more suitable for the diagnosis of chronic phase IAFF in lower limbs than in upper limbs;PLT/MPV may have potential in differentiating the virulence of bacteria with chronic phase IAFF.