Abstract
The diagnosis of prosthetic-joint infection (PJI) is challenging, as bacteria adhere on implant and form biofilm. Therefore, current diagnostic methods, such as preoperative culture of joint aspirate have limited sensitivity with false-negative results.
Aim
To evaluate the performance of measurement synovial fluid (SF) D-lactate (as a pathogen-specific marker) for the diagnosis of PJI and estimate of treatment success.
Method
224 patients undergoing removal knee or hip prosthesis were included in the study between January 2015 and March 2017. 173 patients of this group had aseptic loosening of prosthesis and 87 were diagnosed with PJI. Prior to surgery, synovial fluid routine culture, D-lactate test, leukocyte count and neutrophils (%) were performed for each patient. In order to evaluate a treatment success, the measurement of SF D-lactate before second two-stage exchange procedure (after treatment) was implemented in 30 patients. Diagnosis of PJI was established according to modified Zimmerli criteria.
Results
Of 87 patients with infection of prosthetic joints, 61 (70%) had positive synovial fluid cultures, including Staphylococcus spp. (70%), Streptococcus spp. (10%), Enterococcus spp. (6%), Anaerobes (6%), Enterobacteriacae (4%), P. aeruginosa (2%), C. parapsilosis (2%). There was no significant difference in SF D-lactate levels due to different bacterial strains. The optimal D-lactate cut off was 1,2 mmol/l (sensitivity = 98%, specificity = 84%, PPV = 79%, NPV = 98%, AUC 0,99). Concentration of SF D-lactate was significantly higher in patients with PJI compared to aseptic loosening of prosthesis (median (range)) 2.33 (0.99–3.36) vs 0.77 (0.01–2.4), p<0.0001.D-lactate has better sensitivity for diagnosis of PJI (98%), compared to leukocytes (80%) and neutrophils % (89%), p<0.0001).
The concentration of D-lactate decreased below cut off within four weeks after revision surgery (after treatment) in all patients except of three, showing relapse of infection (p<0.0001).
Conclusions
The measurement of synovial fluid D-lactate demonstrated high analytical performance in the diagnosis of PJI, it is a reliable pathogen specific marker. D-lactate has the best sensitivity as independent diagnostic method and could be implemented for the evaluation of treatment success.
