Value of D-Dimer as a Diagnostic Marker of Infection Associated with Orthopedic Implants

Recently, the D-dimer biomarker has gained the researchers' attention for predicting infections. We aimed to determine the relationship between this marker and other inflammatory markers involved in orthopedic implant-associated infections.

In this study, all patients diagnosed with an orthopedic implant-associated infection were investigated in 3 years. The serum level of D-dimer, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) was measured. Infection was diagnosed based on the clinical and culture results of biopsy samples.

The cultured microorganisms, detected in 26 patients with infections, included Staphylococcus aureus (n = 13, 50%), Staphylococcus epidermidis (n = 2, 7.7%), Klebsiella aerogenes (n = 8, 30.8%), and Pseudomonas aeruginosa (n = 3, 11. 5%). Based on laboratory findings, there was a significant difference in the CRP level and ESR (P = 0.001). Although the level of D-dimer was higher in infected patients, compared to the controls (992.6 ± 667.2 vs. 690.1 ± 250.2 ng/mL), the difference was not statistically significant. There was no significant correlation between the elevated D-dimer level and CRP level, whereas ESR had a positive correlation with the elevated D-dimer level (r = 0.6, P = 0.03). The sensitivity, specificity, and positive predictive value (PPV) of D-dimer in the prediction of infection were 65%, 57%, and 45%, respectively. Furthermore, the sensitivity, specificity, and PPV of CRP were 100%, 92.3%, and 95%, respectively, whereas the corresponding values for ESR were 85%, 69.2%, and 62%, respectively.

Measurement of the serum D-dimer level is not efficient for the diagnosis of orthopedic implant-associated infections due to its low predictive value. Furthermore, there was no significant correlation between the serum D-dimer level and CRP.