In the present study, our results suggest that (1) FIB is significantly associated with reinfection after DAIR treatment compared with traditional inflammatory indicators CRP and ESR. (2) Fibrinogen may be a promising indicator for predicting acute and chronic PJI after DAIR treatment. The literature review confirms that this study appears to be the first to evaluate the use of fibrinogen in predicting reinfection after treatment with DAIR for acute and chronic PJI.
PJI is a catastrophic complication after total joint replacement, which is the main reason for failure after primary replacement . PJI can be classified into acute and chronic PJI according to MSIS criteria . PJI treatment is a huge challenge for orthopedic surgeons. Treatment options for PJI include DAIR, primary or secondary revision arthroplasty, joint fusion, and amputation [3, 4, 20]. When acute PJI occurs after joint replacement, it may be difficult for orthopedic surgeons and patients to choose the treatment, because the results of preserving the prosthesis or undergoing revision surgery phase I or II are different, and improper treatment choices will lead to increased burden on patients. The international Consensus recommended DAIR for acute PJI . If the implant can be retained without infection, the patient can avoid having to undergo the surgery again, avoiding the risk of complications. Our results showed that the success rate of DAIR treatment in acute PJI was 52.17%, which was relatively close to the previously reported results . CRP and ESR, as traditional inflammatory indicators, have been widely used to evaluate and predict post-replacement infection [15, 22, 23]. A study by Kuiper et al.  showed that when ESR was greater than 60 mm/h, the risk of DAIR treatment failure would increase. A multicentric retrospective study showed  that high CRP was associated with DAIR treatment failure. However, CRP is also elevated during the acute phase by the operation itself, and ESR is not recommended as a diagnostic indicator during the acute phase . This requires a new indicator as a supplement to predict the outcome of DAIR treatment. FIB, as a coagulation test indicator, has recently been favored in the diagnosis of PJI. Recent evidence shows that fibrinogen can be used in the diagnosis of PJI and is a practical and economic marker . Our previous studies have shown that FIB can be a good indicator for differentiating aseptic loosening and PJI . Therefore, FIB was designed in this study to evaluate and predict the risk of reinfection in PJI patients treated with DAIR. Our results showed that compared with CRP and ESR, FIB predicted the maximum AUC of reinfection in the acute stage by 0.75, and the sensitivity and specificity were different compared with CRP and ESR. The above results suggest that FIB appears to have some advantages in predicting acute PJI reinfection treated by DAIR.
The treatment failure rate of DAIR for chronic PJI is high , However, DAIR can be used as a treatment for patients with immune dysfunction, comorbidities, and reluctance to undergo revision surgery phase I or II . Studies have shown  that DAIR has been successfully applied to chronic PJI. Our results showed that the failure rate of DAIR in the treatment of chronic PJI was 71.43%, and the AUC of FIB in the prediction of chronic reinfection was 0.81, with sensitivity and specificity of 80.00% and 66.66%, respectively, which seemed to indicate that the increase of FIB may indicate an increased risk of reinfection. However, a recent study  showed that the AUC of ESR and CRP in predicting the reinfection of chronic PJI after DAIR treatment was 0.48 and 0.27 respectively, and the sensitivity and specificity were 67%, 47% and 50%, 26%, respectively. Their results also showed that CRP and ESR showed poor predictive efficacy of reinfection. However, this is related to the inconsistency of AUC, critical value, specificity and sensitivity of each indicator. In interpreting the above data and results, patient selection bias, sample size, study population, drug sensitivity test, treatment regimen, patient comorbidities, perioperative period, and PJI definition should also be taken into account.
There are some limitations to our study that should be taken into account in interpreting our findings. First of all, the study was a retrospective design, and it had some inherent biases. In addition, we chose serum FIB, and the results of plasma FIB may vary, and our sample size in each group is limited. Finally, there are many factors leading to the failure of DAIR treatment, such as the choice of surgical timing, bacterial culture results, drug sensitivity, comorbidities, etc. [30, 31], which need to be homogenized. Therefore, the design of a prospective, multicenter, large sample study is necessary to further confirm our findings.