Abstract
Introduction
Prosthetic joint infections (PJIs) generate significant clinical and socio-economic pressures on the health service. Recent advances in the diagnosis of PJIs, with biomarkers and sonification have aided delineation of PJIs from aseptic processes. However these investigations are not widely available and expensive. Interface membrane histology has been shown to be superior to pseudocapsule histology; we therefore sought to ascertain the diagnostic benefit of deep canal sample microbiology in conjunction with standard pseudocapsule sampling.
Patients/Materials & Methods
We performed a prospective study over a 20-month period as part of new multi-disciplinary approach to the management of suspected PJIs. 22 patients underwent 26 procedures at our institution where intra-operative deep canal samples were obtained concurrent to conventional pseudocapsule samples. These samples were cultured and analysed following our standardised microbiological methodology.
Results
In 5 of 26 (19%) of cases deep canal microbiology yielded divergent results to those obtained from the pseudocapsule. There were 2 (8%) cases with negative capsule samples but positive deep canal samples, additionally different organisms were identified in the deep canal samples compared to conventional samples in 2 (8%) cases.
Discussion
Our study has shown the additional diagnostic value that deep canal sampling microbiology adds to the diagnosis of PJIs, with this benefit being multifaceted; (a) the confirmation of the absence/presence of PJI, (b) confirmation of causative organisms and most importantly (c) the identification of patients with PJIs where conventional biopsy techniques would have produced a false negative result.
Conclusion
Conventional pseudocapsule microbiology has good negative predictive value, however devastating complications of missing a PJI combined with the ease and accessibility to deep canal sampling, indicate the addition of this technique to a surgeon's armoury.
