Clinical and histomorphometrical study on titanium dioxide-coated external fixation pins

Preoperative antibiotics reduce early surgical site infections after orthopaedic implant removal: a propensity-matched cohort study

BACKGROUND

Implant removal in orthopaedics after fracture consolidation is a very common procedure but is still associated with a high rate of surgical site infection (SSI). Antibiotic prophylaxis is not recommended but advocated by some.

AIM

To assess the efficacy of antibiotic prophylaxis in the prevention of early SSI following orthopaedic implant removal.

METHODS

A monocentric retrospective cohort study was conducted. Patients who underwent orthopaedic implant removal procedures performed from 2016 to 2021 were included. A 1:1 propensity score matching function was used to create a cohort with matched baseline characteristics and associated risk factors for SSI. Inter-cohort comparison of the occurrence of SSI (superficial or deep) and revision surgery for SSI, after propensity score matching, was performed using the odds ratio to determine the effect of preoperative antibiotic prophylaxis.

FINDINGS

In total, 965 distinct surgical procedures were included. Of these, 69 (7.15%) had an SSI, 24 (35.7%) of which required surgical revision; 214 procedures (22.18%) were performed under preoperative antibiotic prophylaxis. The propensity-matched cohort consisted of 396 procedures (198 with and without antibiotic prophylaxis). The SSI rates were 11.11% and 3.03%, respectively, in the control and antibiotic prophylaxis groups (odds ratio: 0.25; 95% confidence interval: 0.099; 0.63; P = 0.011). No difference was found for revision surgery.

CONCLUSION

Preoperative administration of antibiotic prophylaxis considerably reduces the risk of SSI during the removal of an orthopaedic implant without increasing the risk of side-effects.

Coating Technologies for Copper Based Antimicrobial Active Surfaces: A Perspective Review

Microbial contamination of medical devices and treatment rooms leads to several detrimental hospital and device-associated infections. Antimicrobial copper coatings are a new approach to control healthcare-associated infections (HAI’s). This review paper focuses on the efficient methods for depositing highly adherent copper-based antimicrobial coatings onto a variety of metal surfaces. Antimicrobial properties of the copper coatings produced by various deposition methods including thermal spray technique, electrodeposition, electroless plating, chemical vapor deposition (CVD), physical vapor deposition (PVD), and sputtering techniques are compared. The coating produced using different processes did not produce similar properties. Also, process parameters often could be varied for any given coating process to impart a change in structure, topography, wettability, hardness, surface roughness, and adhesion strength. In turn, all of them affect antimicrobial activity. Fundamental concepts of the coating process are described in detail by highlighting the influence of process parameters to increase antimicrobial activity. The strategies for developing antimicrobial surfaces could help in understanding the mechanism of killing the microbes.

Polyetheretherketone and Its Composites for Bone Replacement and Regeneration

In this article, recent advances in the development, preparation, biocompatibility and mechanical properties of polyetheretherketone (PEEK) and its composites for hard and soft tissue engineering are reviewed. PEEK has been widely employed for fabricating spinal fusions due to its radiolucency, chemical stability and superior sterilization resistance at high temperatures. PEEK can also be tailored into patient-specific implants for treating orbital and craniofacial defects in combination with additive manufacturing process. However, PEEK is bioinert, lacking osseointegration after implantation. Accordingly, several approaches including surface roughening, thin film coating technology, and addition of bioactive hydroxyapatite (HA) micro-/nanofillers have been adopted to improve osseointegration performance. The elastic modulus of PEEK is 3.7-4.0 GPa, being considerably lower than that of human cortical bone ranging from 7-30 GPa. Thus, PEEK is not stiff enough to sustain applied stress in load-bearing orthopedic implants. Therefore, HA micro-/nanofillers, continuous and discontinuous carbon fibers are incorporated into PEEK for enhancing its stiffness for load-bearing applications. Among these, carbon fibers are more effective than HA micro-/nanofillers in providing additional stiffness and load-bearing capabilities. In particular, the tensile properties of PEEK composite with 30wt% short carbon fibers resemble those of cortical bone. Hydrophobic PEEK shows no degradation behavior, thus hampering its use for making porous bone scaffolds. PEEK can be blended with hydrophilic polymers such as polyglycolic acid and polyvinyl alcohol to produce biodegradable scaffolds for bone tissue engineering applications.

A Precautionary Approach to Guide the Use of Transition Metal-Based Nanotechnology to Prevent Orthopedic Infections

The increase of multidrug-resistant bacteria remains a global concern. Among the proposed strategies, the use of nanoparticles (NPs) alone or associated with orthopedic implants represents a promising solution. NPs are well-known for their antimicrobial effects, induced by their size, shape, charge, concentration and reactive oxygen species (ROS) generation. However, this non-specific cytotoxic potential is a powerful weapon effective against almost all microorganisms, but also against eukaryotic cells, raising concerns related to their safe use. Among the analyzed transition metals, silver is the most investigated element due to its antimicrobial properties per se or as NPs; however, its toxicity raises questions about its biosafety. Even though it has milder antimicrobial and cytotoxic activity, TiO₂ needs to be exposed to UV light to be activated, thus limiting its use conjugated to orthopedic devices. By contrast, gold has a good balance between antimicrobial activity as an NP and cytocompatibility because of its inability to generate ROS. Nevertheless, although the toxicity and persistence of NPs within filter organs are not well verified, nowadays, several basic research on NP development and potential uses as antimicrobial weapons is reported, overemphasizing NPs potentialities, but without any existing potential of translation in clinics. This analysis cautions readers with respect to regulation in advancing the development and use of NPs. Hopefully, future works in vivo and clinical trials will support and regulate the use of nano-coatings to guarantee safer use of this promising approach against antibiotic-resistant microorganisms.

From prevention of pin-tract infection to treatment of osteomyelitis during paediatric external fixation

Pin-tract infection (PTI) is the most commonly expected problem, or even an almost inevitable complication, when using external fixation. Left unteated, PTI will progress unavoidably, lead to mechanical pin loosening, and ultimately cause instability of the external fixator pin-bone construct. Thus, PTI remains a clinical challenge, specifically in cases of limb lengthening or deformity correction. Standardised pin site protocols which encompass an understanding of external fixator biomechanics and meticulous surgical technique during pin and wire insertion, postoperative pin site care and pin removal could limit the incidence of major infections and treatment failures. Here we discuss concepts regarding the epidemiology, physiopathology and microbiology of PTI in paediatric populations, as well as the clinical presentations, diagnosis, classification and treatment of these infections.

Silver Nanocoating Technology in the Prevention of Prosthetic Joint Infection

Prosthetic joint infection (PJI) is a feared complication of total joint arthroplasty associated with increased morbidity and mortality. There is a growing body of evidence that bacterial colonization and biofilm formation are critical pathogenic events in PJI. Thus, the choice of biomaterials for implanted prostheses and their surface modifications may significantly influence the development of PJI. Currently, silver nanoparticle (AgNP) technology is receiving much interest in the field of orthopaedics for its antimicrobial properties and a strong anti-biofilm potential. The great advantage of AgNP surface modification is a minimal release of active substances into the surrounding tissue and a long period of effectiveness. As a result, a controlled release of AgNPs could ensure antibacterial protection throughout the life of the implant. Moreover, the antibacterial effect of AgNPs may be strengthened in combination with conventional antibiotics and other antimicrobial agents. Here, our main attention is devoted to general guidelines for the design of antibacterial biomaterials protected by AgNPs, its benefits, side effects and future perspectives in PJI prevention.

Sustained release of VH and rhBMP-2 from nanoporous magnesium-zinc-silicon xerogels for osteomyelitis treatment and bone repair

Nanoporous magnesium-zinc-silicon (n-MZS) xerogels with a pore size ∼4 nm, a surface area of 718 cm(2)/g, and a pore volume of 1.24 cm(3)/g were synthesized by a sol-gel method. The n-MZS xerogels had high capacity to load vancomycin hydrochloride (VH) and human bone morphogenetic protein-2 (rhBMP-2), after soaking in phosphate buffered saline (PBS) for 24 hours (1.5 and 0.8 mg/g, respectively). Moreover, the n-MZS xerogels exhibited the sustained release of VH and rhBMP-2 as compared with magnesium-zinc-silicon (MZS) xerogels without nanopores (showing a burst release). The VH/rhBMP-2/n-MZS system not only exhibited a good antibacterial property but also promoted the MG63 cell proliferation and differentiation demonstrating good bactericidal activity and cytocompatibility. The results suggested that n-MZS with larger surface area and high pore volume might be a promising carrier for loading and sustained release of VH and rhBMP-2. Hence, the VH/rhBMP-2/n-MZS system might be one of the promising biomaterials for osteomyelitis treatment and bone repair.

Photoactive TiO₂ antibacterial coating on surgical external fixation pins for clinical application

External fixation is a method of osteosynthesis currently used in traumatology and orthopedic surgery. Pin tract infection is a common problem in clinical practice. Infection occurs after bacterial colonization of the pin due to its contact with skin and the local environment. One way to prevent such local contamination is to create a specific coating that could be applied in the medical field. In this work, we developed a surface coating for external fixator pins based on the photocatalytic properties of titanium dioxide, producing a bactericidal effect with sufficient mechanical strength to be compatible with surgical use. The morphology and structure of the sol-gel coating layers were characterized using, respectively, scanning electron microscopy and X-ray diffraction. The resistance properties of the coating were investigated by mechanical testing. Photodegradation of acid orange 7 in aqueous solution was used as a probe to assess the photocatalytic activity of the titanium dioxide layers under ultraviolet irradiation. The bactericidal effect induced by the process was evaluated against two strains, ie, Staphylococcus aureus and multiresistant Staphylococcus epidermidis. The coated pins showed good mechanical strength and an efficient antibacterial effect after 1 hour of ultraviolet irradiation.

Surface treatment of silica nanoparticles for stable and charge-controlled colloidal silica

An attempt was made to control the surface charge of colloidal silica nanoparticles with 20 nm and 100 nm diameters. Untreated silica nanoparticles were determined to be highly negatively charged and have stable hydrodynamic sizes in a wide pH range. To change the surface to a positively charged form, various coating agents, such as amine containing molecules, multivalent metal cation, or amino acids, were used to treat the colloidal silica nanoparticles. Molecules with chelating amine sites were determined to have high affinity with the silica surface to make agglomerations or gel-like networks. Amino acid coatings resulted in relatively stable silica colloids with a modified surface charge. Three amino acid moiety coatings (L-serine, L-histidine, and L-arginine) exhibited surface charge modifying efficacy of L-histidine > L-arginine > L-serine and hydrodynamic size preservation efficacy of L-serine > L-arginine > L-histidine. The time dependent change in L-arginine coated colloidal silica was investigated by measuring the pattern of the backscattered light in a Turbiscan™. The results indicated that both the 20 nm and 100 nm L-arginine coated silica samples were fairly stable in terms of colloidal homogeneity, showing only slight coalescence and sedimentation.

Antibacterial surface treatment for orthopaedic implants

It is expected that the projected increased usage of implantable devices in medicine will result in a natural rise in the number of infections related to these cases. Some patients are unable to autonomously prevent formation of biofilm on implant surfaces. Suppression of the local peri-implant immune response is an important contributory factor. Substantial avascular scar tissue encountered during revision joint replacement surgery places these cases at an especially high risk of periprosthetic joint infection. A critical pathogenic event in the process of biofilm formation is bacterial adhesion. Prevention of biomaterial-associated infections should be concurrently focused on at least two targets: inhibition of biofilm formation and minimizing local immune response suppression. Current knowledge of antimicrobial surface treatments suitable for prevention of prosthetic joint infection is reviewed. Several surface treatment modalities have been proposed. Minimizing bacterial adhesion, biofilm formation inhibition, and bactericidal approaches are discussed. The ultimate anti-infective surface should be “smart” and responsive to even the lowest bacterial load. While research in this field is promising, there appears to be a great discrepancy between proposed and clinically implemented strategies, and there is urgent need for translational science focusing on this topic.