Background: Modular mega-endoprosthesis systems are used to bridge very large bone defects and have become a widespread method in orthopaedic surgery for the treatment of tumours and revision arthroplasty. However, the indications for the use of modular mega-endoprostheses must be carefully considered. Implanting modular endoprostheses requires major, complication-prone surgery in which the limited salvage procedures should always be borne in mind. The management of periprosthetic infection is particularly difficult and beset with problems. Given this, the present study was designed to gauge the significance of periprosthetic infections in connection with modular mega-implants in the lower extremities among our own patients. Methods: Patients who had been fitted with modular endoprosthesis on a lower extremity at our department between September 1994 and December 2011 were examined retrospectively. A total of 101 patients with 114 modular prostheses were identified. Comprising 30 men (29.7 %) and 71 women (70.3 %), their average age at the time of surgery was 67 years (18–92 years). Results: The average follow-up period was 27 months (5 months and 2 weeks to 14 years and 11 months) and the drop-out rate was about 8.8 %. Altogether, there were 19 (17.7 %) endoprosthesis infections: 3 early infections and 16 late or delayed infections. The pathogen spectrum was dominated by coagulase-negative staphylococci (36 %) and Staphylococcus aureus (16 %), including 26 % multi-resistant pathogens. Reinfection occurred in 37 % of cases of infection. Tumours were followed by significantly fewer infections than the other indications. Infections were twice as likely to occur after previous surgery. Conclusion: In our findings modular endoprostheses (18 %) are much more susceptible to infection than primary endoprostheses (0.5–2,5 %). Infection is the most common complication alongside the dislocation of proximal femur endoprostheses. Consistent, radical surgery is essential – although even with an adequate treatment strategy, the recurrence rate is very high. Unfortunately, the functional results are frequently unsatisfactory, with amputation often being the last resort. Therefore, the indication for implantation must be carefully considered and discussed in great detail, especially in the case of multimorbid patients with previous joint infections.

Background: Modular mega-endoprosthesis systems are used to bridge very large bone defects and have become a widespread method in orthopaedic surgery for the treatment of tumours and revision arthroplasty. However, the indications for the use of modular mega-endoprostheses must be carefully considered. Implanting modular endoprostheses requires major, complication-prone surgery in which the limited salvage procedures should always be borne in mind. The management of periprosthetic infection is particularly difficult and beset with problems. Given this, the present study was designed to gauge the significance of periprosthetic infections in connection with modular mega-implants in the lower extremities among our own patients. Methods: Patients who had been fitted with modular endoprosthesis on a lower extremity at our department between September 1994 and December 2011 were examined retrospectively. A total of 101 patients with 114 modular prostheses were identified. Comprising 30 men (29.7 %) and 71 women (70.3 %), their average age at the time of surgery was 67 years (18–92 years). Results: The average follow-up period was 27 months (5 months and 2 weeks to 14 years and 11 months) and the drop-out rate was about 8.8 %. Altogether, there were 19 (17.7 %) endoprosthesis infections: 3 early infections and 16 late or delayed infections. The pathogen spectrum was dominated by coagulase-negative staphylococci (36 %) and Staphylococcus aureus (16 %), including 26 % multi-resistant pathogens. Reinfection occurred in 37 % of cases of infection. Tumours were followed by significantly fewer infections than the other indications. Infections were twice as likely to occur after previous surgery. Conclusion: In our findings modular endoprostheses (18 %) are much more susceptible to infection than primary endoprostheses (0.5–2,5 %). Infection is the most common complication alongside the dislocation of proximal femur endoprostheses. Consistent, radical surgery is essential – although even with an adequate treatment strategy, the recurrence rate is very high. Unfortunately, the functional results are frequently unsatisfactory, with amputation often being the last resort. Therefore, the indication for implantation must be carefully considered and discussed in great detail, especially in the case of multimorbid patients with previous joint infections.

INTRODUÇÃO: O diagnóstico microbiológico das infecções em artroplastias é de fundamental importância para a definição da estratégia de uso dos antimicrobianos. As culturas microbiológicas convencionais apresentam elevados índices de falso-negativos, em especial, nas infecções crônicas, em que é frequente a presença do biofilme aderido ao implante. A utilização de amostras deste biofilme, viáveis à cultura, a partir de seu descolamento do implante pela técnica de sonicação, tem mostrado aumento da sensibilidade em publicações recentes. O objetivo deste estudo foi comparar os resultados das culturas microbiológicas de fragmentos de tecido periprotético, realizadas em meio sólido, àquelas obtidas pelo cultivo do líquido oriundo da sonicação do implante removido, semeado, inicialmente, em frascos de hemocultura e, posteriormente, em meio sólido. MÉTODOS: Neste estudo de análise descritiva, prospectivo e comparativo, 30 pacientes com diagnóstico de infecção em artroplastias de joelho ou quadril, com mais de 90 dias de história, tiveram seus implantes cirurgicamente removidos e foram coletadas seis amostras do tecido periprotético, de locais previamente determinados, para a realização de cultura microbiológica em meios sólidos. Simultaneamente, os implantes foram submetidos ao processo de sonicação e o material resultante foi injetado em frascos de hemocultura BD Bactec e submetidos ao processo de cultura automatizada. Todas as amostras foram pesquisadas quanto à presença de bactérias aeróbias, anaeróbias, micobactérias e fungos, e os resultados comparados por meio de análise estatística, em busca da superioridade de um método sobre o outro. Como objetivo secundário, buscou-se analisar quais os pontos de coleta do tecido periprotético teriam maior sensibilidade em suas culturas. RESULTADOS: Não houve diferenças estatisticamente significantes da amostra em relação ao gênero, patologia articular primária, tipo de artroplastia, localização do implante ou lateralidade. Em 17 casos (56,7%), houve uso de antimicrobianos no período de 15 dias que antecederam a retirada do implante. O método de cultura do fluido de sonicação mostrou sensibilidade de 86,7% e foi superior, de modo estatisticamente significante (P < 0,001), em relação à cultura dos fragmentos periprotéticos, cujos resultados tiveram sensibilidades entre 26,7 e 53,3%. O uso de antibioticoterapia recente não interferiu de modo estatisticamente significante na sensibilidade da cultura do líquido oriundo da sonicação. (P = 0,113). Quanto ao objetivo secundário, a coleta de fragmentos da membrana periprotética mostrou maior sensibilidade, estatisticamente significante, na comparação com três dos demais cinco pontos de coleta (P < 0,05). CONCLUSÕES: A cultura microbiológica do líquido obtido por sonicação dos implantes removidos de pacientes com diagnóstico de infecção periprotética e semeado inicialmente em frascos de hemocultura mostrou ter sensibilidade superior, estatisticamente significante, à cultura convencional de fragmentos do tecido periprotético semeados em meios sólidos. A cultura microbiológica da membrana periprotética mostrou ter maior sensibilidade em relação à maioria dos outros sítios que tiveram fragmentos de tecido periprotético pesquisados. / INTRODUCTION: Microbiological diagnosis in periprosthetic infection is of fundamental importance to define the most appropriate antimicrobial strategies. Conventional microbiological cultures have high rates of false negatives, especially in chronic infections, in which there is often the presence of biofilm attached to the implant. The use of samples of viable culturable biofilm taken from the detachment of the implant by sonication technique has been shown to increase the sensitivity in recent studies. The objective of this study was to compare the results of microbiological cultures of periprosthetic tissue fragments, made in a solid medium, to those obtained through the cultivation of the liquid coming from the sonication of the removed implant initially seeded in blood culture bottles and later in solid medium. METHODS: Using descriptive, prospective and comparative analysis, thirty patients with a diagnosis of infected knee or hip arthroplasty, with more than ninety days of history, had their implants surgically removed. Six periprosthetic tissue samples, collected at predetermined places, were used for microbiological culture on solid media. Simultaneously, the implants were subjected to the sonication process, and the resulting material was injected into vials of BD Bactec blood cultures and subjected to an automated culture process. All samples were screened for the presence of aerobic bacteria, anaerobes, mycobacteria and fungi and the results compared by statistical analysis to find the superiority of one method over the other. As a secondary objective, this study sought to analyze which of the periprosthetic tissue collecting points would have greater sensitivity in their cultures. RESULTS: There were no statistically significant differences in the sample as related to gender, primary joint pathology, type of arthroplasty, implant location or laterality. In seventeen cases (56.7%), antimicrobials were used within the 15-day period leading up to the removal of the implant. The sonication culture fluid showed a sensitivity of 86.7% and was higher, statistically significant (P < 0.001) in relation to the culture of periprosthetic fragments, where results displayed sensitivities between 26.7 and 53.3%. The use of recent antibiotic therapy did not affect the sensitivity of the liquid coming from the sonication culture, which was not statistically significant (P = 0.113). As for the secondary objective, the collection of periprosthetic membrane fragments showed higher sensitivity, statistically significant (P < 0.05), as compared to three of the remaining five collecting points. CONCLUSIONS: The microbiological culture liquid obtained by sonication of the implants removed from patients with diagnosis of periprosthetic infection and initially seeded in blood culture bottles was shown to have superior sensitivity, statistically significancy, as compared to conventional culture of the periprosthetic tissue fragments seeded on solid media. The microbiological culture of the periprosthetic membrane seems to be more sensitive compared to most other sites that had periprosthetic tissue fragments surveyed

INTRODUÇÃO: O diagnóstico microbiológico das infecções em artroplastias é de fundamental importância para a definição da estratégia de uso dos antimicrobianos. As culturas microbiológicas convencionais apresentam elevados índices de falso-negativos, em especial, nas infecções crônicas, em que é frequente a presença do biofilme aderido ao implante. A utilização de amostras deste biofilme, viáveis à cultura, a partir de seu descolamento do implante pela técnica de sonicação, tem mostrado aumento da sensibilidade em publicações recentes. O objetivo deste estudo foi comparar os resultados das culturas microbiológicas de fragmentos de tecido periprotético, realizadas em meio sólido, àquelas obtidas pelo cultivo do líquido oriundo da sonicação do implante removido, semeado, inicialmente, em frascos de hemocultura e, posteriormente, em meio sólido. MÉTODOS: Neste estudo de análise descritiva, prospectivo e comparativo, 30 pacientes com diagnóstico de infecção em artroplastias de joelho ou quadril, com mais de 90 dias de história, tiveram seus implantes cirurgicamente removidos e foram coletadas seis amostras do tecido periprotético, de locais previamente determinados, para a realização de cultura microbiológica em meios sólidos. Simultaneamente, os implantes foram submetidos ao processo de sonicação e o material resultante foi injetado em frascos de hemocultura BD Bactec e submetidos ao processo de cultura automatizada. Todas as amostras foram pesquisadas quanto à presença de bactérias aeróbias, anaeróbias, micobactérias e fungos, e os resultados comparados por meio de análise estatística, em busca da superioridade de um método sobre o outro. Como objetivo secundário, buscou-se analisar quais os pontos de coleta do tecido periprotético teriam maior sensibilidade em suas culturas. RESULTADOS: Não houve diferenças estatisticamente significantes da amostra em relação ao gênero, patologia articular primária, tipo de artroplastia, localização do implante ou lateralidade. Em 17 casos (56,7%), houve uso de antimicrobianos no período de 15 dias que antecederam a retirada do implante. O método de cultura do fluido de sonicação mostrou sensibilidade de 86,7% e foi superior, de modo estatisticamente significante (P < 0,001), em relação à cultura dos fragmentos periprotéticos, cujos resultados tiveram sensibilidades entre 26,7 e 53,3%. O uso de antibioticoterapia recente não interferiu de modo estatisticamente significante na sensibilidade da cultura do líquido oriundo da sonicação. (P = 0,113). Quanto ao objetivo secundário, a coleta de fragmentos da membrana periprotética mostrou maior sensibilidade, estatisticamente significante, na comparação com três dos demais cinco pontos de coleta (P < 0,05). CONCLUSÕES: A cultura microbiológica do líquido obtido por sonicação dos implantes removidos de pacientes com diagnóstico de infecção periprotética e semeado inicialmente em frascos de hemocultura mostrou ter sensibilidade superior, estatisticamente significante, à cultura convencional de fragmentos do tecido periprotético semeados em meios sólidos. A cultura microbiológica da membrana periprotética mostrou ter maior sensibilidade em relação à maioria dos outros sítios que tiveram fragmentos de tecido periprotético pesquisados. / INTRODUCTION: Microbiological diagnosis in periprosthetic infection is of fundamental importance to define the most appropriate antimicrobial strategies. Conventional microbiological cultures have high rates of false negatives, especially in chronic infections, in which there is often the presence of biofilm attached to the implant. The use of samples of viable culturable biofilm taken from the detachment of the implant by sonication technique has been shown to increase the sensitivity in recent studies. The objective of this study was to compare the results of microbiological cultures of periprosthetic tissue fragments, made in a solid medium, to those obtained through the cultivation of the liquid coming from the sonication of the removed implant initially seeded in blood culture bottles and later in solid medium. METHODS: Using descriptive, prospective and comparative analysis, thirty patients with a diagnosis of infected knee or hip arthroplasty, with more than ninety days of history, had their implants surgically removed. Six periprosthetic tissue samples, collected at predetermined places, were used for microbiological culture on solid media. Simultaneously, the implants were subjected to the sonication process, and the resulting material was injected into vials of BD Bactec blood cultures and subjected to an automated culture process. All samples were screened for the presence of aerobic bacteria, anaerobes, mycobacteria and fungi and the results compared by statistical analysis to find the superiority of one method over the other. As a secondary objective, this study sought to analyze which of the periprosthetic tissue collecting points would have greater sensitivity in their cultures. RESULTS: There were no statistically significant differences in the sample as related to gender, primary joint pathology, type of arthroplasty, implant location or laterality. In seventeen cases (56.7%), antimicrobials were used within the 15-day period leading up to the removal of the implant. The sonication culture fluid showed a sensitivity of 86.7% and was higher, statistically significant (P < 0.001) in relation to the culture of periprosthetic fragments, where results displayed sensitivities between 26.7 and 53.3%. The use of recent antibiotic therapy did not affect the sensitivity of the liquid coming from the sonication culture, which was not statistically significant (P = 0.113). As for the secondary objective, the collection of periprosthetic membrane fragments showed higher sensitivity, statistically significant (P < 0.05), as compared to three of the remaining five collecting points. CONCLUSIONS: The microbiological culture liquid obtained by sonication of the implants removed from patients with diagnosis of periprosthetic infection and initially seeded in blood culture bottles was shown to have superior sensitivity, statistically significancy, as compared to conventional culture of the periprosthetic tissue fragments seeded on solid media. The microbiological culture of the periprosthetic membrane seems to be more sensitive compared to most other sites that had periprosthetic tissue fragments surveyed