[Intra-articular Sampling with Novel Biopsy Forceps: a Simple and Reliable Diagnostic Procedure for Patients with Periprosthetic Infections of the Knee Joint]. / Intraartikuläre Probenentnahme mit einer neuartigen Biopsiezange: ein leichtes und sicheres diagnostisches Verfahren bei Patienten mit periprothetischen Infektionen des Kniegelenks.

Introduction: Rapid and reliable differentiation between septic and aseptic presentations can be challenging in patients with painful total knee arthroplasties. Clinical symptoms, serum tests, as well as the analysis of synovial fluid, are important parameters. Nevertheless, deep intra-articular tissue samples exhibit greater sensitivity and specificity regarding the diagnosis of a suspected periprosthetic joint infection. In 2014, Hügle et al. introduced novel retrograde forceps to acquire tissue samples and synovial fluid simultaneously in an outpatient setting. In this article, we present the first use of their device in patients with total knee arthroplasty. Methods: After approval by a local ethics board, retrograde forceps were used via the standard lateral suprapatellar approach. The technique was comparable to conventional aspiration of a total knee arthroplasty. Beside joint aspiration, tissue samples were gathered for further microbiological and histopathological examination. Results and Discussion: It is easy to collect synovial fluid and tissue samples using the retrograde forceps in patients with suspected periprosthetic infections of the knee joint. This is a safe and feasible method and can be performed in an outpatient setting. We have not yet observed any complications and consider that the risks are comparable to those with conventional joint aspiration. In our opinion, this technique may be useful in detecting infections in patients with painful total knee arthroplasty.