Implementation of an Algorithm for Prosthetic Joint Infection: Deviations and Problems

Diagnostic algorithm in septic total knee arthroplasty failure - What is evidence-based?

Prosthetic joint infection (PJI) is among the most common differential diagnoses of total knee arthroplasty failure. It is a challenging complication, not least because of the difficulty of establishing the correct diagnosis. The fact that no single diagnostic parameter or test has been identified that can accurately rule in or out PJI has led to an evolution of similar but competing definitions of PJI on the grounds of an array of criteria. This development has had very positive effects on the scientific evaluation of various methods of PJI diagnostics and treatment because of an increased comparability. However, it can be challenging to stay abreast of the evidence these definitions are based on. Also, the definitions alone do not necessarily entail an algorithm to aid in evaluating the right criteria in a sound order to be able to use the definitions as a sensible tool. The aim of this overview is to state the most recent evidence on the diagnostic parameters included in the most established PJI definitions and to exhibit and compare the few algorithmic approaches published. Clinical symptoms of PJI are very rarely reported on in the literature, hence the evidence on their diagnostic value is poor. The only symptom that is part of the established PJI definitions is the presence of a fistula. Concerning serological markers, CRP and ESR are still the common denominator in the literature, most recently accompanied by D-Dimer as a potentially suitable marker that has been included in the most recent update of the International Consensus Meeting (ICM) criteria. Imaging plays a minor role in the diagnostic cascade because of inconsistent evidence, and no role whatsoever in the established definitions. The most important preoperative diagnostic measure is arthrocentesis and cultural and cytological analysis of the synovial fluid. The much acclaimed α-Defensin test has so far not been included in the established criteria due to inconsistent reports on its diagnostic accuracy, it is, however, in wide use and considered an optional diagnostic tool for inconclusive cases. The most diagnostic accuracy lies in the cultural and histological analysis of periprosthetic tissue biopsies, whether they are gathered in a small procedure or during arthroplasty revision. Published algorithmic approaches to PJI diagnosis are much rarer than the well-established definitions by various associations. With their PJI definition, the American Academy of Orthopedic Surgeons (AAOS) published a consensus based flowchart for PJI diagnosis. Another algorithm was proposed as part of the endeavor of the MSIS and the first consensus meeting, also based on a consensus among experts. There have been two more recent publications of flowcharts based on the current evidence, one introduced at our institution in 2013, one established in 2020 by the German Society for Arthroplasty (AE).

Improved pre-operative diagnostic accuracy for low-grade prosthetic joint infections using second-generation multiplex Polymerase chain reaction on joint fluid aspirate

BACKGROUND

A major obstacle for the treatment of prosthetic joint infection (PJI) is the identification of the underlying causative organism. While the diagnostic criteria ruling PJI in or out have become ever more accurate, the detection of the causative pathogen(s) still relies mostly on conventional and time-consuming microbial culture. The aim of this study was to evaluate the diagnostic potential of a second-generation multiplex PCR assay (Unyvero ITI G2, Curetis AG, Holzgerlingen, Germany) used on synovial fluid specimens. Our hypothesis was that the method would yield a higher diagnostic accuracy in the pre-operative workup than synovial fluid culture. Thus, a more precise classification of septic and aseptic prosthesis failure could be achieved before revision surgery.

METHODS

Prospectively collected frozen joint fluid specimens from 26 patients undergoing arthroplasty revision surgery of the hip or knee were tested as per the manufacturer's protocol. Sensitivities, specificities, positive and negative predictive values as well as positive and negative likelihood ratios with corresponding confidence intervals were estimated using the statistical software R. A combination of the serum C-reactive protein (CRP) level, leukocyte count, erythrocyte sedimentation rate, joint fluid culture, tissue biopsy culture, and tissue biopsy histology served as the gold standard.

RESULTS

Of the 26 patients included in the study, 15 were infected and 11 were aseptic. Conventional joint fluid culture showed a sensitivity of 0.67 and a specificity of 0.91. Joint fluid multiplex PCR yielded a sensitivity of 0.8 and a specificity of 1.0.

CONCLUSIONS

Using the second-generation Unyvero ITI cartridge on joint fluid aspirate for the detection of prosthetic joint infection, we were able to achieve a higher diagnostic accuracy than with conventional culture. We conclude that to improve pathogen detection before revision surgery, this method represents a valuable and practicable tool.

Integrated IT Platform for Coordination of Diagnosis, Treatment, and Aftercare of Prosthetic Joint Infections

BACKGROUND/AIM

Prosthetic joint infections (PJI) are difficult to diagnose and treat. For a correct diagnosis, an array of information has to be processed and weighted. Successful treatment depends on the diagnosis, timing, and surgical strategy paired with treatment of the infectious agent. The complexity and interdisciplinarity needed cause difficulties concerning decision-making, the communication between disciplines, and the execution of a treatment strategy. The aim of this study was to develop a software platform to enhance the collection of information for the diagnosis of PJI, the interdisciplinary decision-making process, the communication between team members, and continuous evaluation of treatment.

PATIENTS AND METHODS

In regular planning sessions with an information technology (IT) specialist, a concept for an IT solution was chosen and the tool was designed in an interdisciplinary approach.

RESULTS

The tool has been used as a trial version since June 2017. It consists of 14 user interfaces with 431 items. A total of 117 patients with 118 infections have been entered and the strategy decided upon and communicated using 298 infection board documents outlining the treatment. The tool is now being used to organize the infections board agenda, schedule patient case discussions, document the relevant data and treatment plan, as well as communicate with the other teams involved in the treatment.

CONCLUSION

Using the developed tool enables the infections team to work collaboratively and under division of labor on each case, rendering the work flow more efficient for each team member.