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Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_17 | Pages 76 - 76
24 Nov 2023
TO SONICATE OR NOT TO SONICATE?
Hesselvig AB Bjarnsholt T Jørgensen A Gottlieb H
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Aim

To evaluate whether sonication of implant material and subsequent culturing add clinical relevance to culturing of tissue biopsies for improved antibiotic treatment in treatment of bone and joint infection.

Method

A retrospective examination of patients’ charts and microbiological analyses in patients who had explanted material (plates, screws, k-wires and prostheses) send for sonication between December 2020 and April 2022.

Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_17 | Pages 21 - 21
24 Nov 2023
RETHINKING THE INOCULUM USED IN ANIMAL MODELS OF IMPLANT-ASSOCIATED OSTEOMYELITIS: THE FORMATION AND APPLICATION OF BACTERIAL AGGREGATES
Hartmann KT Nielsen RL Mikkelsen F Ingmer H Kvich LA Aalbaek B Odgaard A Jensen HE Lichtenberg M Bjarnsholt T Jensen LK
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Aim

To make an inoculum for induction of Implant-Associated Osteomyelitis (IAO) in pigs based on bacterial aggregates resembling those found on the human skin, i.e. aggregates of 5–15 µm with low metabolic activity. The aggregates were evaluated and compared to a standard planktonic bacterial inoculum.

Method

The porcine Staphylococcus aureus strain S54F9 was cultured in Tryptone Soya Broth for seven days. Subsequently, the culture was filtered through cell strainers with pore sizes of 15 µm and 5 µm, respectively. The fraction of 5–15 µm aggregates in the top of the 5 µm filter was collected as the aggregate-inoculum. The separation of aggregates into different size fractions was evaluated by light microscopy. The metabolism of the aggregate-inoculum and a standard overnight planktonic inoculum was evaluated with isothermal microcalorimetry. In total, six female minipigs were allocated into three groups (n=2), receiving different inoculums. Group A: overnight planktonic inoculum; 104 CFU S. aureus (S54F9), Group B: seven days old 5–15 µm aggregate-inoculum; 104 CFU S. aureus (S54F9), Group C: saline. All inoculums were placed in a pre-drilled implant cavity in the right tibia of the pig and a sterile stainless-steel implant was inserted. The pigs were euthanized seven days after surgery. Postmortem macroscopic pathology, microbiology, computed tomography and histopathology were performed.

Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_10 | Pages 61 - 61
1 Oct 2022
TREATMENT OF IMPLANT-ASSOCIATED OSTEOMYELITIS WITH INJECTABLE IN SITU-FORMING DEPOT DRUG DELIVERY SYSTEM
Fuglsang-Madsen A Henriksen NL Kvich LA Birch JKM Hartmann KT Bjarnsholt T Andresen TL Jensen LK Henriksen JR Hansen AE
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Aim

Several local antibiotic-eluting drug delivery systems have been developed to treat bacterial bone infections. However, available systems have significant shortcomings, including suboptimal drug-release profiles with a burst followed by subtherapeutic release, which may lead to treatment failure and selection for drug resistance.

Here, we present a novel injectable, biocompatible, in situ-forming depot, termed CarboCells, which can be fine-tuned for the desired antibiotic-release profile. The CarboCell technology has flexible injection properties that allow surgeons to accurately place antibiotic-eluting depots within and surrounding infectious sites in soft tissue and bones. The CarboCell technology is furthermore compatible with clinical image-guided injection technologies.

These studies aimed to determine the therapeutic potential of CarboCell formulations for treatment of implant-associated osteomyelitis by mono- and dual antimicrobial therapy.

Methods

The solubility and stability of several antibiotics were determined in various CarboCell formulations, and in vitro drug release was characterized. Lead candidates for antimicrobial therapy were selected using a modified semi-solid biofilm model with 4-day-matured Staphylococcus aureus biofilm (osteomyelitis-isolate, strain S54F9). Efficacy was investigated in a rat implant-associated osteomyelitis model established in the femoral bone by intraosseous implantation of a stainless-steel pin with 4-day-old in vitro-matured S. aureus biofilm. CarboCells were injected subcutaneously at the femur, and antimicrobial efficacy was evaluated 7 days post-implantation. Lead formulations were subsequently tested in a well-established translational implant-associated tibial S. aureus osteomyelitis pig model. Infection was established for 7 days before revision surgery consisting of debridement, washing, implantation of a new stainless-steel pin, and injection of antibiotic-releasing CarboCells into the debrided cavity and in the surrounding bone- and soft-tissue. Seven days post-revision, pigs were euthanized, and samples were collected for microbial and histopathological evaluation.

Bone & Joint Research
Vol. 9, Issue 7 | Pages 394 - 401
1 Jul 2020
Pathological and microbiological impact of a gentamicin-loaded biocomposite following limited or extensive debridement in a porcine model of osteomyelitis
Blirup-Plum SA Bjarnsholt T Jensen HE Kragh KN Aalbæk B Gottlieb H Bue M Jensen LK
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Aims

CERAMENT|G is an absorbable gentamicin-loaded biocomposite used as an on-site vehicle of antimicrobials for the treatment of chronic osteomyelitis. The purpose of the present study was to investigate the sole effect of CERAMENT|G, i.e. without additional systemic antimicrobial therapy, in relation to a limited or extensive debridement of osteomyelitis lesions in a porcine model.

Methods

Osteomyelitis was induced in nine pigs by inoculation of 104 colony-forming units (CFUs) of Staphylococcus aureus into a drill hole in the right tibia. After one week, the pigs were allocated into three groups. Group A (n = 3) received no treatment during the study period (19 days). Groups B (n = 3) and C (n = 3) received limited or extensive debridement seven days postinoculation, respectively, followed by injection of CERAMENT|G into the bone voids. The pigs were euthanized ten (Group C) and 12 (Group B) days after the intervention.

Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_14 | Pages 82 - 82
1 Dec 2019
IODINE-IMPREGNATED INCISION DRAPE DOES NOT PREVENT INFECTION IN KNEE ARTHROPLASTY SURGERY: 12 MONTHS' FOLLOW-UP IN A COHORT OF 1187 PATIENTS
Hesselvig AB Odgaard A Arpi M Bjarnsholt T Madsen F
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Aim

The primary aim of this study was to examine whether the use of iodine impregnated incision drape (IIID) decreased the risk of periprosthetic joint infections (PJIs). The secondary aim was to investigate whether intraoperative contamination could predict postoperative infection.

PJI is a devastating incident for the patients and in a population that is getting older and the incidence of arthroplasty surgery is rising it is vital to keep the infection rate as low as possible. Despite prophylactic measures as pre-operative decontamination, antisepsis and prophylactic antibiotics the infection rate has been constant at 1–2%.

Method

We performed a transregional, prospective, randomized two arm study (IIID vs control group) of 1187 patients undergoing primary knee arthroplasty surgery. A database with patient demographics and surgical observations was established with the purpose of following the patients for ten years. Patients, who developed an infection within the first year of surgery were analyzed for correlation with the intraoperative bacterial findings and the use of IIID.

Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_14 | Pages 77 - 77
1 Dec 2019
EXTENSIVE DEBRIDEMENT IS FUNDAMENTAL FOR THE SUCCESS OF AN ABSORBABLE GENTAMICIN-LOADED BIO-COMPOSITE
Jensen LK Blirup SA Aalbæk B Bjarnsholt T Kragh KN Gottlieb H Bue M Jensen HE
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Aim

To study the antimicrobial effect of a gentamicin loaded bio-composite bone void filler in relation to a limited or extensive debridement of osteomyelitis lesions, respectively.

Methods

Nine pigs were inoculated into the right proximal tibial bone with a high virulent gentamicin sensitive strain of Staphylococcus aureus (104 CFU). Seven days after inoculation, Group A pigs (n=3) were exposed to a limited debridement of the bone lesion, whereas Group B pigs (n=3) were exposed to an extensive debridement. The bone defects of Groups A and B were filled with (2–5 ml) of an absorbable gentamicin (175 mg/10 mL) loaded bio-composite. The animals of Group A and B were euthanized 12 days after revision surgery. Group C animals did not undergo revision surgery and were euthanized seven (n=1) or nineteen (n=2) days post inoculation in order to follow the development of the untreated infection. None of the animals were treated with systemic antimicrobials. All bones were exposed to a post mortem CT scan and rigours pathological examinations. The surrounding bone tissue and the bio-composite were sampled for microbiology.

Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_17 | Pages 64 - 64
1 Dec 2018
EXTREME HIGH LOCAL INTRAOPERATIVE GENTAMICIN CONCENTRATIONS ARE NEEDED TO PREVENT BIOFILM FORMATION IN VIVO
Jensen LK Bjarnsholt T Henriksen NL Kragh KN Jensen HE
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Aim

To investigate the local intra-operative concentration of gentamicin needed to prevent biofilm formation in a porcine model of implant-associated osteomyelitis.

Method

In total 24 pigs were allocated to six groups. Group A (n=6) was inoculated with saline. Groups B (n=6), C (n=3), D (n=3), E (n=3) and F (n=4) were inoculated with 10 μL saline containing 104 CFU of Staphylococcus aureus, however, different minimal inhibitory concentrations (MIC) of gentamicin were added to the inoculum of Groups C(160xMIC), D(1600xMIC), E(16000xMIC) and F(160000xMIC). The inoculums were injected into a pre-drilled implant cavity proximally in the right tibial bone. Following inoculation, a steel implant (2 × 15 mm) was placed in the cavity. The pigs were euthanized after five days. The implants were sonicated and swabs were taken from the implant cavity for microbiological evaluation. The peri-implant tissue was analyzed by histopathology including estimation of neutrophil infiltration.

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