Background: The search for potential markers for a timely and accurate diagnosis of periprosthetic joint infection (PJI) is ongoing. Previous studies have focused on inflammatory markers and have rarely examined coagulation-related indicators. The purpose of this study was to evaluate the values of plasma fibrinogen, D-dimer, and other blood markers for the diagnosis of PJI through a multicenter retrospective study. Methods: A total of 565 revision total hip and knee arthroplasty cases were enrolled in this study from January 2016 through December 2017, 126 of which had coagulation-related comorbidities and were analyzed separately. The remaining 439 cases included 76 PJI and 363 non-PJI patients. The definition of PJI was based on the International Consensus Meeting (ICM) on Periprosthetic Infection criteria. The diagnostic values of D-dimer, plasma fibrinogen, the erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) level, and white blood-cell (WBC) count were analyzed using receiver operating characteristic (ROC) curves. Results: ROC curves showed that plasma fibrinogen had the highest area under the curve (AUC), 0.852, followed by 2 classical markers, the CRP level and ESR, which had an AUC of 0.810 and 0.808, respectively. D-dimer had an AUC of 0.657, which was the second lowest value and only slightly higher than that of the WBC count, 0.590. The optimal threshold for plasma D-dimer was 1.25 μg/mL, with a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 0.645, 0.650, 0.278, and 0.897, respectively. The optimal threshold for plasma fibrinogen was 4.01 g/L, which showed good sensitivity, specificity, PPV, and NPV, with values of 0.763, 0.862, 0.537, and 0.946, respectively. Conclusions: Plasma D-dimer may have a very limited diagnostic value for PJI, while plasma fibrinogen, another coagulation-related indicator, exhibits promising performance. Plasma fibrinogen has good sensitivity and specificity for diagnosing PJI, with values similar to those of classical markers, including CRP level and ESR. Level of Evidence: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Background Periprosthetic joint infection (PJI) is a catastrophic complication after total knee or hip arthroplasty. The diagnosis of PJI is very difficult, especially in the early postoperative period. The value of the neutrophil to lymphocyte ratio (NLR) is useful for diagnosing infectious diseases. The objective of this study was to investigate the accuracy of the NLR for the diagnosis of early PJI after total knee or hip arthroplasty. Methods We retrospectively evaluated consecutive primary total knee or hip arthroplasty and identified the patients who readmitted within the first 90 days postoperatively between January 2011 and October 2018.There were 20 cases diagnosed early PJI and 101 uninfected cases on the basis of the modified Musculoskeletal Infection Society (MSIS) criteria. The serum parameters including C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), white blood-cell (WBC) count, NLR and interleukin-6 (IL-6) were compared between the two groups. Receiver operating characteristic curves were generated to estimate the optimal cutoff values for each parameter. The sensitivity, specificity, positive predictive value and negative predictive value for each parameter were calculated. Results The CRP, ESR, WBC, NLR and IL-6 values were all significally higher in the infected group than the uninfected group. The median of CRP was 66.6 mg/l in the infected group and 8.6 mg/l in the uninfected group (p < 0.001). The median of ESR was 34.8 mm/hr. in the infected group and 17.4 mm/hr. in the uninfected group (p < 0.001). In the infected group and uninfected group, the median of WBC was 8.2X109 /L and 6.1 X109 /L (p = 0.002), respectively; while the median of NLR was 5.2 and 2.1 (p < 0.001). The median of IL-6 was 46 pg/ml and 6.4 pg/ml (p < 0.001),respectively. The best parameter for the diagnosis of early PJI was IL-6 (AUC = 0.814) followed by the NLR (AUC =0.802), CRP (AUC =0.793), ESR (AUC =0.744) and WBC (AUC = 0.632). Conclusions This study is the first to show that NLR values are more accurate than CRP and may be considered as useful parameters for the diagnosis of early PJI because it is a cheap and convenient parameter to be calculated in daily practice without extra costs.

Numerous advances have been made in prosthesis design, instrumentation and postoperative rehabilitation for unicompartmental knee arthroplasty; however, only 70-86% of patients are satisfied with the functional outcome and revision rates range between 10% and 20%. The primary outcome for this meta-analysis was implantation accuracy of component positioning and tibiofemoral component safe zone. A total of three randomized controlled trials (RCT), three quasi-RCTs and one prospective trial were included in this review. It was found that the use of robotic-assisted systems reduces implantation errors without an increase in adverse events. There are only a few reports about clinical outcome and long-term follow-up and whether the more accurate component positioning results in a better clinical effect or a better long-term survival of the implants is unknown.

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