ABSTRACT

Increasing number of periprosthetic joint infections (PJI) are seen in correlation with the frequency of the surgeries performed and acquired a systematic approach to diagnosis. PJI and aseptic prosthesis loosening remain the most common and serious complications of total hip arthroplasty and total knee arthroplasty. The differentiation of septic from aseptic prosthetic loosening is of great importance because the treatment of these two conditions are vastly different. Despite many tests available, diagnosis of PJI remains a challenge. A comprehensive medical history including risk factors for infection, physical examination, erythrocyte sedimentation rate and serum C-reactive protein levels, and also appropriate radiographs are the first line screening tests. Joint aspiration has a high value in the diagnosis of PJI. Aspirates which should be immediately transferred into pediatric blood culture bottles for cultures, should also be sent for synovial leukocyte count and polymorphonuclear percentage. Recently, it has been shown that some biomarkers in the synovial fluid exhibit a higher accuracy in diagnosis of PJI despite patients with the systemic inflammatory diseases and those receiving antibiotic treatment. These synovial fluid biomarkers are expected to overcome the challenges in diagnosis of PJI. On behalf of the radiological screening; anatomical imaging procedures such as conventional radiography, computed tomography (CT), or magnetic resonance imaging are unable to differentiate septic and aseptic loosening, mainly because of hardware-induced artifacts. Nuclear medicin imaging, however, reflects functional rather than anatomical changes and also is not hampered by the presence of a metallic prosthesis. The commonly used nuclear imaging techniques include triple-phase bone scintigraphy, Ga-67, leukocyte scintigraphy, leukocyte/bone marrow scintigraphy, monoclonal antibodies/antibody fragments, radiolabeled ciprofloxacin, antimicrobial peptides, etc. Besides infection detection, single-photon emission computed tomography (SPECT) and positron emission tomography (PET) with CT provide additional information on the location of the infection foci, which is clinically important for surgeons to select the most appropriate treatment and guide the intraoperative clearance of the infection foci. The current review will describe the working mechanism, clinical practice, and pros and cons of these techniques in the evaluation of periprosthetic infection.