Method

First, we standardized the animal model to simulate implant contamination during the surgical procedure. We then implanted cobalt-chrome prostheses adapted to both knees of two New Zealand White rabbits, under standard aseptic measures and antibiotic prophylaxis with cefazolin. Prior to implantation, we immersed the prostheses in a 0.3 McFarland inoculum of S. aureus (ATCC 25923) for 30 seconds. In the first animal (control), the joint was directly closed after washing with saline. In the second animal (case), both prostheses were treated with electric current pulses for 30 seconds, washed with saline, and the joint was closed. After 72 hours, both animals were reoperated for the collection of periprosthetic tissue and bone samples, and prosthesis removal. In all samples, we performed quantitative cultures prior to vortexing and sonication, as well as prolonged cultures of the sonication broth. We confirmed the absence of contamination by identification with MALDI-TOF (VITEK-MS) and automated antibiotic susceptibility testing of the isolated colonies (VITEK-2).

Method

Using a 12-well culture plate designed for the application of electrical fields, strains of S. epidermidis were incubated at each well for 24 hours at 37ºC. After incubation, supernatant culture medium was removed, and each well was filled with 3ml of normal saline. Six different models were compared: a) control, b) low-pressure pulse lavage, c) high-pressure pulse lavage, d) pulsed electrical fields, e) low-pressure pulse lavage in combination with pulsed electrical fields, and f) high-pressure pulse lavage in combination with pulsed electrical fields. In all cases, exposure time was set to 25 seconds. In the electrical field models, 50 pulses were applied.

After exposure, each bottom electrode was scraped carefully to release adhered bacteria. Subsequently, different dilutions of biofilm removed were spread onto Müller Hinton agar plates and incubated for 24h at 37 ºC, and colony-forming units (CFU) per milliliters were counted. Bacterial counts were then compared to the control model.

Methods

Our retrospective analysis included patients 65 years of age or older with an acute fracture-related infection treated with implant retention from 2012 to 2020 in 6 Spanish hospitals with a minimum 1-year follow-up. Patients that required open reduction during the initial fracture surgery were excluded. Variables included in our analysis were patient demographics, type of fracture, date of FRI diagnosis, causative microorganism, and outcome. Treatment success was defined as fracture healing with infection eradication without the need for further hospitalization.

Methods

Experimental in vitro study to evaluate quantitative bacterial adherence to different cerclage wire materials. Two types of cerclage wires were compared: a metallic versus a polymer based wire (SuperCable®).

A two-centimeter cerclage wire piece of each material was included in 2 mL of tryptic soy broth (TSB) culture media, inoculated with 10 microliters of a 0.5 McFarland of a Staphylococcus epidermidis strain and cultivated at 37°C during 2h for adhesion and 48h for biofilm formation. After this time, the cerclages were washed using a 1% phosphate buffered saline (PBS) and sonicated in new culture medium. After sonication, dilutions of each culture were spread in TSB agar and incubated 37°C during 24h. The number of colonies were counted and the cfu/cm2 was calculated.

Method

A retrospective observational study was conducted, assessing51 patients that underwent a two stage septic hip or knee revision from 2010 to 2017.

According to the results of intraoperative cultures, after the first stage revision each patient was treated with an antibiotic protocol for 6–8 weeks. Following two weeks without antibiotics, a culture of synovial fluid was obtained. Synovial fluid was obtained by direct joint aspiration in cases of knee spacers by and by joint aspiration guided by fluoroscopy in the theatre room in cases of hip spacers. Synovial fluid was transferred into a Vacutainer ACD^® flask. Samples were processed and analysed in the microbiology laboratory. Gram stains were performed and the sample was subsequently transferred into a BacALERT bottle (bioMérieux, France) and incubated in a BacALERT instrument for seven days.

Results of these cultures were recorded and compared with cultures obtained during re-implantation surgery.

Method

A retrospective observational study was conducted in which 56 hip or knee spacers implanted at our center from 2010 to 2017 were analysed. Patients were grouped into three categories:

Patients with positive spacer sonication fluid culture, with or without positive cultures from the rest of the samples.

Patients with negative spacer sonication culture and negative second-stage intraoperative cultures.

Patients with negative spacer sonication culture but positive cultures of the rest of intraoperative samples.