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Introduction: The pathogenesis of prosthesis loosening is not well understood. The aim of our study was to sonicate components of joint prostheses removed due to aseptic loosening, culture the sonicate fluid, and to correlate these results with the degree of radiological osteolysis. Methods: From January 2008 to June 2009 all consecutive patients who underwent a revision of hip or knee prosthesis due to aseptic loosening were included in the study. Aseptic loosening was established when the patient had radiological signs of loosening without symptoms or signs of infection. The diagnosis was confirmed when histology was negative, and ≥5 out of 6 standard cultures of periprosthetic tissue were negative. Bone lysis was measured according to the Paprosky or Engh classifications without knowing the result of sonication cultures. Removed components were placed in sterile bags and immediately transported to the microbiology laboratory and sonicated. Sonicate fluid was cultured and the results were correlated with the degree of bone lysis. The proportion of components with positive sonication culture according to the bone lysis classification was compared using χ test. Results: A total of 52 patients were included and 123 components were sonicated. In 30 patients at least 1 sonicated component was positive (57.7%) and 44 out of 123 (35.8%) components were positive. The proportion of positive sonication cultures was significantly higher in the group of components with a higher degree of bone lysis of 3 (76.5%) than in those with lower degrees (33.9% for 1 and 24% for 2) (χ test, p = 0.0004). Conclusions: Sonication cultures were positive in 57% of patients who underwent revision arthroplasty for aseptic loosening. The percentage of positive sonication cultures was significantly higher in patients with severe osteolysis. Level of evidence: level I of Prognostic Studies-Investigating the Effect of a Patient Characteristic on the Outcome of Disease. [ABSTRACT FROM AUTHOR]

The histology of periprosthetic tissue is a gold standard for the diagnosis of periprosthetic joint infection. However, the specificity and sensitivity of histology has never been 100%. In the present study we hypothesized that the type of microorganism could be related to the effectiveness of histology in the detection of infection. Frozen sections and cultures from periprosthetic tissue of 38 revision arthroplasties taken at the time of resection arthroplasty for the treatment of infection were retrospectively reviewed. Frozen sections were evaluated following Feldman’s criteria. A culture was considered positive when the same microorganism was isolated in at least two samples or when pus was present around the prosthesis. The literature providing information on histology and microbiology of arthroplasty-associated infection was reviewed. Coagulase-negative staphylococcus (CNS) was the etiology in 13 cases, Gram-negative bacilli in 8, Staphylococcus aureus in 7 , Candida sp in 2, Peptococcus sp in 2, Enterococcus sp in 1 and S. pneumoniae in 1. No microorganism was isolated in four cases. Almost all the frozen sections in the 38 cases were positive except in 2 of the 13 that were caused by CNS (15.3%). The articles reviewed supported our findings. Frozen section is a useful test to intraoperatively confirm an infection when preoperative septic loosening is suspected. However, histology has false-negative results when the infection is due to low-virulence microorganisms. [ABSTRACT FROM AUTHOR]

Tuberculous arthritis of the elbow joint is not commonly seen by orthopaedic physicians. In the past 20 years, with the pandemic of the human immunodeficiency virus and the increase in immunocompromised people, we have observed a resurgence of tuberculosis. Osteoarticular involvement has increased, too. Spinal and monoarthritis of weight-bearing joints such as the hip or knee are most frequently involved. The elbow joint is an uncommon location of osteoarticular tuberculosis. The aim of this case report is to describe a case of tuberculous arthritis of the elbow and the diagnostic problems that may arise and lead to a delay in treatment. [ABSTRACT FROM AUTHOR]