Guidelines for Complications of Cancer Treatment Vol VIII Part B

Diagnosis of InfectionThe diagnosis of infection after total joint arthroplastycontinues to pose a challenge, particularly when it presents asa subacute or low-grade infection. Currently, there is nouniversally accepted diagnostic test or modality that isabsolutely accurate or reliable for the determination ofinfection. The diagnosis of periprosthetic infection relies onclinical suspicion and a combined armamentarium ofserological and imaging modalities 33 , with isolation oforganisms from the intraoperative culture samples constitutingthe “gold standard” for ultimate diagnosis 34,35 .Serological tests, including the erythrocyte sedimentation rateand the C-reactive protein level, are frequently used to screenfor septic and aseptic failure of total joint arthroplasty andhave a relatively high sensitivity and specificity whencombined 36 . However, their specificity and sensitivity varydepending on the cutoff values chosen 34 . The role of analysisof synovial fluid for determination of the leukocyte count andneutrophil percentage, although frequently employed, remainsunclear. The indicators of periprosthetic infection based onjoint fluid analysis still remain unknown 34,36 .There are also numerous limitations related to the use ofradiographic or radioisotope imaging modalities. Plainradiographs can impart very important information regardingthe cause of failure of a total joint arthroplasty. Infection cancause radiographic changes at the bone-cement or boneprosthesisinterface, including periosteal and endostealreactions, osteopenia, and osteolysis 33,34 . Rapid andprogressive loosening of cemented and cementless implantsin the absence of any mechanical cause raises the possibilityof infection 36 . However, there is no marked difference betweeninfection and aseptic failure of total joint arthroplasty withregard to these radiographic parameters 3 . Therefore, plainradiography is neither sensitive nor specific for infection and114