# Assessment of serum diagnostic biomarkers for periprosthetic joint infection in hip and knee arthroplasty: a retrospective study

## TL;DR

This study evaluates blood markers to diagnose joint infections after hip and knee replacement surgeries, finding that CRP and fibrinogen are most effective.

## Contribution

The study validates CRP and fibrinogen as superior serological biomarkers for diagnosing periprosthetic joint infection.

## Key findings

- CRP and fibrinogen showed the best diagnostic performance with high area under the ROC curve values.
- PC/MPV had moderate diagnostic accuracy but was less effective than CRP and fibrinogen.
- Combining CRP with fibrinogen or PC/MPV improved diagnostic accuracy for periprosthetic joint infection.

## Abstract

Periprosthetic joint infection (PJI) after total hip and knee arthroplasty is challenging to differentiate from similar afflictions. Platelet count-to-mean platelet volume (PC/MPV) ratio has been proposed, but requires validation. This study evaluated PC/MPV and other potential serological biomarkers for diagnosing PJI prior to reimplantation arthroplasty of the hip and knee.

Medical records were retrospectively reviewed of patients who received hip and knee revision, and there were 88 PJI patients and 156 non-PJI patients met the modified 2018 criteria for inclusion. Receiver operating characteristic curves (ROCs) were used to analyze and compare the diagnostic performances of PC/MPV, fibrinogen (FIB), C-reactive protein (CRP), platelet count (PLT), erythrocyte sedimentation rate (ESR), and serum white blood cell (WBC) count.

Compared with the control group, the patients with PJI had significantly higher PC/MPV, FIB, ESR, CRP, serum WBC, and PLT, respectively, and the areas under the ROC curve were 0.787, 0.917, 0.832, 0.934, 0.685, and 0.778; that of FIB and CRP were similar. Regarding PC/MPV, the optimal cutoff was 27.81, and the sensitivity, specificity, and positive and negative predictive values were 0.807, 0.673, 0.582, and 0.861.

The best diagnostic performance was achieved by CRP and FIB, and we recommend that these tests should be prioritized. Serum WBC, PC/MPV and PLT were insufficient to predict PJI prior to reimplantation arthroplasty of the hip and knee; however, CRP combined with FIB or PC/MPV best serves to obtain the most accurate prediction of PJI in our study.