Correspondence (letter to the editor): Amendment Necessary

In their successful overview of the complicated topic of periprosthetic joint infections (PJI), I believe that procalcitonin is also worth mentioning along with the laboratory tests (1). As correctly pointed out, no single laboratory test can unambiguously be used to diagnose PJI; nonetheless, procalcitonin is of particular value, especially for people with inflammatory rheumatic diseases. This group, which is overrepresented in patients who receive joint replacements, often presents disease-specific increases in humoral inflammatory activity (C-reactive protein [CRP] and blood-lowering rate); furthermore, the immunomodulatory therapy given to this group makes them more susceptible to infections than the “classical” arthrosis patient. Especially in these patients, procalcitonin helps to distinguish between disorder-related and infection-related inflammatory activity.

Additionally, within the framework of PJI functional diagnostics, the rapid alpha-defensin test should be mentioned. Regardless of antibiotic pre-treatment, the alpha-defensin test diagnoses PJI with a sensitivity of 69%, and a specificity of 94%, according to current literature (2)—and does so within 10 minutes. Obviously, this rapid test does not replace microbiological pathogen detection, but it has become indispensable as a preoperative screening method before a total endoprosthetic replacement with presumed aseptic loosening, as well as during the operative care of periprosthetic fractures. In our department, it is now an obligatory part of the diagnostic algorithm in suspected cases of PJI.