Elution characteristics of tobramycin from polycaprolactone in a rabbit model

Results of Antibiotic-Impregnated Cement/Polymer-Coated Intramedullary Nails in the Management of Infected Nonunion and Open Fractures of Long Bones

Background Fractures of long bones can sometimes lead to complications such as infection or nonunion, resulting in significant patient morbidity. Surgical intervention and antibiotics are often necessary to treat these complications. Antibiotic-impregnated cement/polymer-coated intramedullary nails have emerged as an effective surgical treatment for infected nonunion and open fractures. These implants elude high concentrations of antibiotics at the infection site while stabilizing the fracture. Extensive research has shown promising results, with success rates ranging from 60% to 100%. Benefits of these implants include stable fracture fixation, early weight-bearing, and reduced need for prolonged antibiotic therapy. However, concerns remain regarding antibiotic resistance and potential toxicity. This study aims to evaluate the efficacy and safety of these implants in managing infected nonunion and open fractures of the femur and tibia. Methods This prospective hospital-based study aimed to assess the efficacy and safety of antibiotic-impregnated cement/polymer-coated intramedullary nails for managing infected nonunion and open fractures of the femur and tibia. The study included patients aged 18 or older who received treatment with these implants between January 1, 2021 and December 31, 2022. Patients allergic to vancomycin or teicoplanin, with gap nonunion >2 cm, or lost to follow-up were excluded. Data on demographics, fracture details, previous treatment, surgery, antibiotics, and outcomes were collected using a structured proforma. Surgeries involved implant removal, debridement, culture testing, reaming, fracture reduction, and stabilization with an antibiotic-impregnated cement/polymer-coated intramedullary nail. Postoperatively, patients received antibiotics, had wound inspections, and were gradually allowed weight-bearing. Follow-up appointments and radiographic/laboratory assessments were conducted at regular intervals. The primary outcome was successful bone union, and secondary outcomes included time to union, infection rate, nonunion rate, and revision surgery. Results The majority of participants were male, with a mean age of 39.76 years. Most fractures were Gustilo-Anderson grade 3 (46.7%) and involved the tibia (73.3%). The mean bone gap after debridement was 1.3 cm. The median follow-up period was 8.21 months. Infection was controlled in 93.3% of patients, with the tibia being the most common site (70.0%). Successful bone union was achieved in 90.0% of patients, with a mean union rate of 22.13 weeks for tibial fractures and 17.21 weeks for femoral fractures. Among patients with bone union, 60.0% did not require additional procedures. Most patients had excellent bony (76.7%) and functional (70.0%) outcomes. The most common complications were the persistence of bone nonunion, impingement of proximal nail, and debonding of nail cement, each occurring in 10.0% of patients. Conclusion The study concluded that antibiotic-impregnated cement/polymer-coated intramedullary nails are effective in managing infected nonunion and open fractures of the femur and tibia. The procedure demonstrated a high success rate in controlling infections (93.3%) and achieving bone union (90.0%). Paley's criteria showed excellent bony and functional outcomes in the majority of patients. These findings support the use of this treatment option for such fractures.

Identification of mesenchymal stromal cell survival responses to antimicrobial silver ion concentrations released from orthopaedic implants

Antimicrobial silver (Ag⁺) coatings on orthopaedic implants may reduce infection rates, but should not be to the detriment of regenerative cell populations, primarily mesenchymal stem/stromal cells (MSCs). We determined intramedullary silver release profiles in vivo, which were used to test relevant Ag⁺ concentrations on MSC function in vitro. We measured a rapid elution of Ag⁺ from intramedullary pins in a rat femoral implantation model, delivering a maximum potential concentration of 7.8 µM, which was below toxic levels determined for MSCs in vitro (EC₅₀, 33 µM). Additionally, we present in vitro data of the reduced colonisation of implants by Staphylococcus aureus. MSCs exposed to Ag⁺ prior to/during osteogenic differentiation were not statistically affected. Notably, at clonal density, the colony-forming capacity of MSCs was significantly reduced in the presence of 10 µM Ag⁺, suggesting that a subpopulation of clonal MSCs was sensitive to Ag⁺ exposure. At a molecular level, surviving colony-forming MSCs treated with Ag⁺ demonstrated a significant upregulation of components of the peroxiredoxin/thioredoxin pathway and processes involved in glutathione metabolism compared to untreated controls. Inhibition of glutathione synthesis using l-buthionine sulfoxamine eliminated MSC clonogenicity in the presence of Ag⁺, which was rescued by exogenous glutathione.

Recent developments in drug eluting devices with tailored interfacial properties

Drug eluting devices have greatly evolved during past years to become fundamental products of great marketing importance in the biomedical field. There is currently a large diversity of highly specialized devices for specific applications, making the development of these devices an exciting field of research. The replacement of the former bare metal devices by devices loaded with drugs allowed the sustained and controlled release of drugs, to achieve the desired local therapeutic concentration of drug. The newer devices have been "engineered" with surfaces containing micro- and nanoscale features in a well-controlled manner, that have shown to significantly affect cellular and subcellular function of various biological systems. For example, the topography can be structured to form an antifouling surface mimicking the defense mechanisms found in nature, like the skin of the shark. In the case of bone implants, well-controlled nanostructured interfaces can promote osteoblast differentiation and matrix production, and enhance short-term and long-term osteointegration. In any case, the goal of current research is to design implants that induce controlled, guided, and rapid healing. This article reviews recent trends in the development of drug eluting devices, as well as recent developments on the micro/nanotechnology scales, and their future challenges. For this purpose medical devices have been divided according to the different systems of the body they are focused to: orthopedic devices, breathing stents, gastrointestinal and urinary systems, devices for cardiovascular diseases, neuronal implants, and wound dressings.

Gentamicin coating of nanotubular anodized titanium implant reduces implant-related osteomyelitis and enhances bone biocompatibility in rabbits

Titanium and titanium alloy are widely used as orthopedic implants for their favorable mechanical properties and satisfactory biocompatibility. The aim of the present study was to investigate the antibacterial effect and bone cell biocompatibility of a novel implant made with nanotubular anodized titanium coated with gentamicin (NTATi-G) through in vivo study in rabbits. The animals were divided into four groups, each receiving different kinds of implants, that is, NTATi-G, titanium coated with gentamicin (Ti-G), nanotubular anodized titanium uncoated with gentamicin (NTATi) and titanium uncoated with gentamicin (Ti). The results showed that NTATi-G implant prevented implant-related osteomyelitis and enhanced bone biocompatibility in vivo. Moreover, the body temperature of rabbits in NTATi-G and Ti-G groups was lower than those in Ti groups, while the weight of rabbits in NTATi-G and Ti-G groups was heavier than those in NTATi and Ti groups, respectively. White blood cell counts in NTATi-G group were lower than NTATi and Ti groups. Features of myelitis were observed by X-ray films in the NTATi and Ti groups, but not in the NTATi-G and Ti-G groups. The radiographic scores, which assessed pathology and histopathology in bone tissues, were significantly lower in the NTATi-G and Ti-G groups than those in the NTATi and Ti groups, respectively (P<0.05). Meanwhile, explants and bone tissue culture demonstrated significantly less bacterial growth in the NTATi-G and Ti-G groups than in the NTATi and Ti groups, respectively (P<0.01). The bone volume in NTATi-G group was greater than Ti-G group, and little bone formation was seen in NTATi and Ti groups.

Osteomyelitis: Recent advances in pathophysiology and therapeutic strategies

This review article summarizes the recent advances in pathogenic mechanisms and novel therapeutic strategies for osteomyelitis, covering both periprosthetic joint infections and fracture-associated bone infections. A better understanding of the pathophysiology including the mechanisms for biofilm formation has led to new therapeutic strategies for this devastating disease. Research on novel local delivery materials with appropriate mechanical properties, lower exothermicity, controlled release of antibiotics, and absorbable scaffolding for bone regeneration is progressing rapidly. Emerging strategies for prevention, early diagnosis of low-grade infections, and innovative treatments of osteomyelitis such as biofilm disruptors and immunotherapy are highlighted in this review.

A resorbable antibiotic eluting bone void filler for periprosthetic joint infection prevention

Periprosthetic joint infection (PJI) following total knee arthroplasty is a globally increasing procedural complication. These infections are difficult to treat and typically require revision surgery. Antibiotic-loaded bone cement is frequently utilized to deliver antibiotics to the site of infection; however, bone cement is a nondegrading foreign body and known to leach its antibiotic load, after an initial burst release, at subtherapeutic concentrations for months. This work characterized a resorbable, antibiotic-eluting bone void filler designed to restore bone volume and prevent PJI. Three device formulations were fabricated, consisting of different combinations of synthetic inorganic bone graft material, degradable polymer matrices, salt porogens, and antibiotic tobramycin. These formulations were examined to determine the antibiotic's elution kinetics and bactericidal potential, the device's degradation in vitro, as well as osteoconductivity and device resorption in vivo using a pilot rabbit bone implant model. Kirby-Bauer antibiotic susceptibility tests assessed bactericidal activity. Liquid chromatography with tandem mass spectrometry measured antibiotic elution kinetics, and scanning electron microscopy was used to qualitatively assess degradation. Results indicated sustained antibiotic release from all three formulations above the Staphylococcus aureus minimum inhibitory concentration for a period of 5 to 8 weeks. Extensive degradation was observed with the Group 3 formulation after 90 days in phosphate-buffered saline, with a lesser degree of degradation observed in the other two formulations. Results from the pilot rabbit study showed the Group 3 device to be biocompatible, with minimal inflammatory response and no fibrous encapsulation in bone. The device was also highly osteoconductive-exhibiting an accelerated mineral apposition rate. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1632-1642, 2016.

Development of intra-vaginal matrices from polycaprolactone for sustained release of antimicrobial agents

Microporous poly(ɛ-caprolactone) matrices were loaded with an antibacterial agent, ciprofloxacin and an antifungal agent, miconazole nitrate, respectively, for investigations of their potential as controlled vaginal delivery devices. Ciprofloxacin loadings up to 15% w/w could be obtained by increasing the drug content of the poly(ɛ-caprolactone) solution, while the actual loadings of miconazole were much lower (1–3% w/w) due to drug partition into methanol during the solvent extraction. The kinetics of ciprofloxacin release in simulated vaginal fluid at 37℃ were characterised by a small burst release phase in the first 24 h, low drug release up to 7 days (10%) and gradual release of up to 80% of the drug content by day 30. Meanwhile, the release kinetics of miconazole-loaded matrices could be effectively described by the Higuchi model with 100% drug release from the highest loaded matrices (3.2% w/w) in 13 days. Ciprofloxacin or miconazole released over 30 and 13 days, respectively, from poly(ɛ-caprolactone) matrices into simulated vaginal fluid retained high levels of antimicrobial activity in excess of 80% of the activity of the free drug. This study confirms the potential of poly(ɛ-caprolactone) matrices for delivering antimicrobial agents in the form of an intra-vaginal device.

Bone tissue engineering therapeutics: controlled drug delivery in three-dimensional scaffolds

This paper provides an extensive overview of published studies on the development and applications of three-dimensional bone tissue engineering (TE) scaffolds with potential capability for the controlled delivery of therapeutic drugs. Typical drugs considered include gentamicin and other antibiotics generally used to combat osteomyelitis, as well as anti-inflammatory drugs and bisphosphonates, but delivery of growth factors is not covered in this review. In each case reviewed, special attention has been given to the technology used for controlling the release of the loaded drugs. The possibility of designing multifunctional three-dimensional bone TE scaffolds for the emerging field of bone TE therapeutics is discussed. A detailed summary of drugs included in three-dimensional scaffolds and the several approaches developed to combine bioceramics with various polymeric biomaterials in composites for drug-delivery systems is included. The main results presented in the literature are discussed and the remaining challenges in the field are summarized with suggestions for future research directions.

Preliminary investigations on a new gentamicin and vancomycin-coated PMMA nail for the treatment of bone and intramedullary infections: An experimental study in the rabbit

To evaluate a new gentamicin-vancomycin- impregnated (2:1) PMMA coating nail as a drug delivery device to treat bone and intramedullary infections, methicillin-resistant Staphylococcus aureus (MRSA) was used to induce femoral osteomyelitis in 20 New Zealand male rabbits. Four weeks after inoculum, the animals were submitted to debridement of infected femur canal, divided into four groups of five animals each and treated according to the following protocols: Group 1, insertion of a steel AISI316 intramedullary nail; Group 2, insertion of a gentamicin-vancomycin-impregnated PMMA nail; Group 3, no therapy; and Group 4 no fixation device and 1-week systemic antibiotic therapy with teicoplanin i.m. At 7 weeks after inoculum, the femurs were explanted sterilely. The radiological score showed that the lowest and best radiological score was observed in Group 2 that was significantly different from the other groups. The highest bacterial load in the femoral canal was found in Group 1, which was significantly different from Group 2 and Group 4 (p < 0.05). Histology showed that Group 2 produced a marked improvement (p < 0.005) of the bone injuries induced by the osteomyelitis in comparison with the other groups (Smeltzer score). The current findings showed that tested device might effectively lead to MRSA infection healing after surgical debridement and immediate implantation.

Antibiotic cement-coated interlocking nail for the treatment of infected nonunions and segmental bone defects

Chronic infection of bone with nonunion and/or bone defects is traditionally treated by a 2-stage procedure involving initial debridement and antibiotic delivery and then definitive internal fixation. Alternatively, external fixators are used to provide stability. A technique with which antibiotic cement-coated interlocking intramedullary nails are prepared in the operating room with the use of nails and materials that generally are available is herein described. Although useful for all infected nonunions and/or segmental bone defects, this technique is particularly useful for patients who are not ideal candidates for external fixation and for those who do not want to have an external fixator applied. This technique was used in a series of 20 patients. In 17 patients, the goal of bony union was achieved (85%). In the remaining 3 patients (15%), the goal of control of infection was achieved with stable nonunion (1 patient) and stable nonunion with cement spacer (2 patients). In 95% of the patients (19 of 20 patients) control of infection was achieved except for in 1 patient, who had a bony union with intermittent wound discharge and subsequently underwent an above-the-knee amputation. Three patients (15%) needed exchange nailing to another antibiotic cement-coated nail (for continued infection) before complete control of infection could be achieved. Four patients (20%) experienced cement-nail debonding during removal of the antibiotic cement-coated nail (3 during exchange to an uncoated intramedullary nail, 1 during removal at the request of patient). One patient experienced partial debonding at insertion, coinciding with the site of segmental defect, which was treated with an antibiotic cement spacer. In summary, control of infection and stability to promote union has traditionally been provided by 2 separate procedures, which have proved to be efficacious in the past. However, both these goals can be achieved in half the patients with 1 surgical procedure in a variety of scenarios using the technique of an antibiotic cement-coated intramedullary nail.

In vitro and in vivo testing of bioabsorbable antibiotic containing bone filler for osteomyelitis treatment

The use of local antibiotics from a biodegradable implant is appealing concept for treatment of chronic osteomyelitis. Our aim was to develop a new drug delivery system based on controlled ciprofloxacin release from poly(D/L-lactide). Cylindrical composite pellets (1.0 x 0.9 mm) were manufactured from bioabsorbable poly(D/L-lactide) matrix and ciprofloxacin (7.4 wt %). In vitro studies were carried out to delineate the release profile of the antibiotic and to verify its antimicrobial activity by means of MIC testing. A long-term study in rabbits was performed to validate the release of ciprofloxacin from the composite in vivo. Therapeutic level of ciprofloxacin (>2 microg/mL) was maintained between 60 and 300 days and the concentration remained below the potentially detrimental level of 20 microg/mL in vitro. The released ciprofloxacin had retained its antimicrobial properties against common pathogens. In an exploratory long-term in vivo study with three rabbits, ciprofloxacin could not be detected from the serum after moderate filling (160 mg) of the tibia (follow-up 168 days), whereas after high dosing (a total dose of 1,000 mg in both tibias) ciprofloxacin was found temporarily at low serum concentrations (14-34 ng/mL) during the follow-up of 300 days. The bone concentrations of ciprofloxacin could be measured in all samples at 168 and 300 days. The tested copolylactide matrix seems to be a promising option in selection of resorbable carriers for sustained release of antibiotics, but the composite needs modifications to promote ciprofloxacin release during the first 60 days of implantation.

The preparation of ciprofloxacin hydrochloride-loaded chitosan and pectin microspheres: their evaluation in an animal osteomyelitis model

Ciprofloxacin hydrochloride-loaded microspheres were prepared by a spray-drying method using pectin and chitosan. The effects of different polymers and drug ratios were investigated. The most appropriate carriers were selected by in vitro testing. A rat methicillin-resistant Staphylococcus aureus osteomyelitis model was used to evaluate the effects of the loaded microspheres. The drug was released rapidly from the pectin carrier but this was more sustained in the chitosan formulation.Chitosan microspheres loaded with ciprofloxacin hydrochloride were more effective for the treatment of osteomyelitis than equivalent intramuscular antibiotics.

Examination of a novel, specified local antibiotic therapy through polymethylmethacrylate capsules in a rabbit osteomyelitis model

Chronic bone and soft tissue suppurations have become more frequent recently due to the increasing number of high-energy injuries. There are certain antibiotic beads available for local administration, but they cannot always be applied specifically against the pyogenic microorganisms. In the present study, a new technique of local antibiotic therapy for the treatment of infections is described. Polymethylmethacrylate (PMMA) capsules were produced and filled with 0.1 ml Tazocin (0.02 g piperacillin sodium + 0.005 g tazobactam). The efficacy of these Tazocin-filled capsules was examined in vivo using a rabbit osteomyelitis model. Chronic osteomyelitis was induced in rabbit tibia by local injection of Staphylococcus aureus. The treatment included surgical debridement and implantation of Tazocin-containing PMMA capsules into the medullar cavity (n = 12). Simple surgical debridement with no antibiotic implantation was performed in control animals (n = 7). Results were evaluated using microbiological, radiological and histological methods 14 weeks after induction of osteomyelitis. Eight weeks after the implantation of PMMA capsules, complete physical, radiological and histological healing was achieved in 7 animals, initiation of the reparative phase was observed histologically in 3 cases and no reparative signs were detected in 2 rabbits. In the control group, no significant sign of reparation could be seen in any of the cases.

Delivery of the antibiotic gentamicin sulphate from precipitation cast matrices of polycaprolactone

Microporous, poly(epsilon-caprolactone) (PCL) matrices were loaded with the aminoglycoside antibiotic, gentamicin sulphate (GS) using the precipitation casting technique by suspension of powder in the PCL solution prior to casting. Improvements in drug loading from 1.8% to 6.7% w/w and distribution in the matrices were obtained by pre-cooling the suspension to 4 degrees C. Gradual release of approximately 80% of the GS content occurred over 11 weeks in PBS at 37 degrees C and low amounts of antibiotic were measured up to 20 weeks. The kinetics of release could be described effectively by the Higuchi model with the diffusion rate constant (D) increasing from of 1.7 to 5.1 microg/mg matrix/day(0.5) as the drug loading increased from 1.4% to 8.3% w/w. GS-loaded PCL matrices retained anti-bacterial activity after immersion in PBS at 37 degrees C over 14 days as demonstrated by inhibition of growth of S. epidermidis in culture. These findings recommend further investigation of precipitation-cast PCL matrices for delivery of hydrophilic molecules such as anti-bacterial agents from implanted, inserted or topical devices.

Comparative Study of Antibiotic-Containing Polymethylmetacrylate Capsules and Beads

BACKGROUND

This study aimed at making local antibiotic therapy wider in cases of chronic suppurations by administering antibiotics which previously could not be given in this way through the conventional polymethylmetacrylate (PMMA) carrier techniques. Capsules from this material were produced with a pressing machine designed and laid out by us. The characteristics of antibiotic penetration from this novel carrier were compared to those of PMMA beads.

METHODS

The time-dependent outflow of amikacin, clindamycin, pefloxacin, piperacillin + tazobactam, amoxicillin + clavulanic acid and cefotaxime was examined from the capsules and the beads with standard microbiological techniques using the Micrococcus luteus ATCC9341 test strain. The diameter of the inhibitory zones was measured after 24 h incubation at 37 degrees C and converted to mug/ml antibiotic concentrations.

RESULTS AND CONCLUSIONS

Our results revealed that all antibiotics showed longer-lasting and higher concentration outflow from the PMMA capsules than from the beads. Therefore, these capsules can provide a more promising new opportunity for specific local antimicrobial treatment in cases of chronic suppurative bone and soft tissue injuries. In these cases the polymerization has already been completed and the heat does not influence the structure of the antibiotics; therefore, it can be inserted into the capsules in powder or solution form.

Local antibiotic delivery vehicles in the treatment of musculoskeletal infection

The primary benefit achieved with local antibiotic delivery vehicles is the ability to obtain extremely high levels of local antibiotics without increasing systemic toxicity. Antibiotic-loaded bone cement represents the current standard as an antibiotic delivery vehicle in orthopaedic surgery. Biodegradable alternatives to antibiotic-loaded bone cement also are being used clinically and there are many new products in the active stages of development. These alternatives can be categorized as bone graft, bone graft substitutes or extenders, natural polymers (protein-based products), and synthetic polymers. Composite biomaterials that simultaneously provide the functions of variable antibiotic delivery patterns and also contribute to the process of bone regeneration represent the most ideal class of local antibiotic delivery vehicles. High concentrations of certain antibiotics have been shown to affect the process of normal bone regeneration adversely in a dose dependent response. Considerable investigation still is required to determine the proper use of locally administered antibiotics to negotiate the balance between eradicating infection without excessively inhibiting the processes of bone regeneration.

New polymers for drug delivery systems in orthopaedics: in vivo biocompatibility evaluation

The use of biodegradable polymers for drug delivery systems excluded the need for a second operation to remove the carrier. However, the development of an avascular fibrous capsule, reducing drug release, has raised concern about these polymers in terms of tissue-implant reaction. Five novel polymers were evaluated in vivo after implantation in the rat dorsal subcutis and compared to the reference polycaprolactone (PCL). Poly(cyclohexyl-sebacate) (PCS), poly(L-lactide-b-1,5-dioxepan-2-one-b-L-lactide) (PLLA-PDXO-PLLA), two 3-hydroxybutyrate-co-3-hydroxyvalerate copolymers (D400G and D600G), and a poly(organo)phosphazene (POS-PheOEt:Imidazole) specimens were histologically evaluated in terms of the inflammatory tissue thickness and vascular density at 4 and 12 weeks from surgery. The highest values of inflammatory tissue thickness were observed in D600G (P < 0.01), PCS (P < 0.001) and PLLA-PDXO-PLLA (P < 0.001) at 4 weeks, while POP-PheOEt:Imidazole showed the lowest value of inflammatory tissue thickness (P < 0.05) at 12 weeks. D400G, D600G, PLLA-PDXO-PPLA and POP-PheOEt:Imidazole showed higher (P < 0.001) values of vascular density near the implants in comparison to PCL at 4 weeks. Finally, D400G and D600G increased their vessel densities while POP-PheOEt:Imidazole and the synthetic polyester PLLA-PDXO-PLLA presented similar vessel density values during experimental times. These different behaviours to improve neoangiogenesis without severe inflammatory tissue-responses could be further investigated with drugs in order to obtain time-programmable drug delivery systems for musculoskeletal therapy.

Management of osteomyelitis

Osteomyelitis is an infection of the medullary or cortical bone that is becoming more difficult to cure with the increasing prevalence of methicillin- and vancomycin-resistant organisms. This article discusses the etiology of osteomyelitis and the effectiveness of various treatment options.

A bioresorbable calcium phosphate delivery system with teicoplanin for treating MRSA osteomyelitis

To assess the effectiveness of calcium phosphate as a delivery system of teicoplanin, methicillin-resistant Staphylococcus aureus osteomyelitis was induced in 36 rabbits. Osteomyelitis was induced by inoculating 10 cfu of methicillin-resistant Staphylococcus aureus isolate into a 2-mm hole at the upper 1/3 of the femur for 3 weeks, when all animals had reoperations, and calcium phosphate cement with 3% teicoplanin was implanted. Animals were divided into six groups of six animals each, sacrificed at Weeks 1, 2, 3, 4, 5, and 6, respectively, after implantation. One rabbit in each group was used as a control. Substantial clinical improvement of the rabbits was observed after implantation, accompanied with sterile cultures of bone after the second week of treatment. Throughout the same period, 10 to 10 cfu/g of methicillin-resistant Staphylococcus aureus isolate was cultured from the control samples. Bacterial eradication signified a considerable decrease of the total histologic scores of osteomyelitis compared with controls, accompanied with newly growing host bone. The calcium phosphate with teicoplanin delivery system seems promising for treatment of bone infection attributable to methicillin-resistant Staphylococcus aureus. In addition, this mixture allows filling of bone defects by new host bone.

Treatment of osteomyelitis with local antibiotics delivered via bioabsorbable polymer

The purpose of the current study was to show the efficacy and safety of an absorbable polymer (polycaprolactone) as an antibiotic delivery vehicle for treatment of osteomyelitis. An intramedullary osteomyelitis was induced in the femur of adult rabbits by Staphylococcus aureus inoculation after use of a sclerosing agent, and then treatment was done with intramedullary irrigation and implantation of a rod made of polycaprolactone, polycaprolactone plus 6% tobramycin, or polymethylmethacrylate plus 6% tobramycin. A control group received irrigation only. At defined intervals, the animals were euthanized and culture of the inoculated site was done. In addition, histologic sections of body tissues were made to look for signs of systemic toxicity of the implant. After 4 weeks of treatment, a statistically significant difference was found between the animals that were treated with irrigation alone and the animals that were treated with antibiotic-laden rods of polycaprolactone or polymethylmethacrylate. There was no difference between the antibiotic rod types. No histologic evidence of toxicity was found. Bioabsorbable rods of polycaprolactone are a safe and effective means of antibiotic delivery for treatment of osteomyelitis.