RESUMO
In recent years, metal-on-metal (MoM) orthopaedic implants have been associated with significant adverse tissue reactions, prompting revision surgeries and recalls by manufacturers. Adverse tissue reactions consist of a wide range of pathologic findings but are generally characterized by a histiocytic reaction to metal debris, with or without an inflammatory response. Inflammation is generally that of a lymphocytic infiltration that prompts concern of an immune reaction. Only occasionally have eosinophils been documented-never as a marked infiltrate. In this article, we present the first histologic description of a dominant eosinophilic infiltrate associated with MoM arthroplasty. In our case report, the patient is a 53-year-old woman who presented with recurrent fluid collections surrounding the hip after a MoM total hip arthroplasty. At the time of surgical revision, tissue samples were taken and found to consist of lymphocytes and a prominent infiltrating eosinophilia. To our knowledge, no factors predictive of this type of tissue response have been identified, and its significance remains unclear despite ongoing research about the nature of the immune response to metal. Future work may help to elucidate whether the type and significance of this response can be predicted preoperatively and modulated, if necessary, postoperatively.
RESUMO
BACKGROUND: Our study sought to identify independent risk factors predisposing patients with necrotizing soft tissue infections (NSTIs) to mortality from among laboratory values, demographic data, and microbiologic findings in a small population. To this end, a retrospective review was conducted of the medical records of all patients with NSTI who had been treated at our institution from 2003 to 2012 (n=134). METHODS: Baseline demographics and comorbidities, clinical and laboratory values, hospital course, and the microbiologic characteristics of surgical incision cultures were recorded. Each variable was tested for association with survival status and all associated variables with p<0.15 were included in a logistic regression model to seek factors associated independently with mortality. RESULTS: Surprisingly, no demographic or pre-existing condition proved to be a predictor of mortality. Two laboratory values had an inverse correlation to mortality: High C-reactive protein (CRP) and highest recorded CRP. Of surgical incisions that grew bacteria in culture, 33.6% were polymicrobial. Mortality rates were highest with Enterococcus-containing polymicrobial infections (50%), followed by those containing Pseudomonas (40%), and Streptococcus spp. (27%). Understanding why so many studies across the literature, now including our own, find such disparate results for correlation of NSTI mortality with patient data may lie in the fundamentally dynamic nature of the organisms involved. CONCLUSIONS: This study suggests that no single factor present on admission is a robust predictor of outcome; it is likely that survival in NSTI is predicated upon a complex interaction of multiple host and microbial factors that do not lend themselves to reduction into a simple formula. It is also abundantly clear that the well-established principles of NSTI surgery should continue to be followed in all cases, with an emphasis on early debridement, irrespective of apparent severity of initial presentation.
