Pediatric orthopedic implant devices are intended to restore the function of load-bearing joints which are subjected to high levels of mechanical stresses, wear and fatigue in the course of normal activity. These devices include prostheses for hip, knee, ankle, shoulder and elbow joints. They also include the fracture fixation devices such as wires, pins, plates, and screws. They must possess both structural and surface compatibility with the host tissue. With particular reference to bone implants, mechanical and physico-chemical compatibility is required. Children in particular are prone to bone fractures and trauma that require fixation with the help of titanium plates. This is an excellent way to prevent anatomical deformities. However, once the healing process is over, most of these implants must be removed from their place of fixation. Because if they remain fixed at their place for long, they might cause other issues like arrested bone growth, problems with bone remodeling, implant migration, and even bone resorption. In some, they might even dislodge, causing significant trouble. Moreover, their short-term safety is proven, but they might cause unexpected adverse effects in the long run, like carcinogenesis. All this means that removing the implants once they have served their purpose is the best strategy.
However, there are specific issues when removing these implants. Due to bone cell overgrowth, surgeons have to face a considerable problem. These implants get well fixed into the bone, and bone tissue grows over it, covering it and thus posing a challenge during its removal. Therefore, temporary implants, ideally, should be easy to remove and should not integrate well into the bone. It would also be good if these implants had some anti-bacterial properties to help prevent postoperative infections. It appears that modulating the surface of these implants may discourage bone overgrowth; however, there has been limited research into the subject.
Thus, Australian researchers: Dr Shaheer Maher, Dr. Denver Linklater, Dr. Hadi Rastin, Dr. Pei Le Yap, Professor Elena Ivanova, and led by Professor Dusan Losic from University of Adelaide created and tested the new kind of titanium implant that will help overcome the deficiencies of traditionally used titanium implants for temporary use. Researchers reported the novel 3d printed implant in peer-review Journal ChemMedChem. Their study found that specificly structured surface of the implant is the critical factor in cell adhesion, proliferation, and differentiation. They hypothesize that changing the implant surface may be an effective way of inhibiting bone overgrowth, making implant removal simpler. They found that titania nanotubes (TNTs) with diameters ~100 nm created on their surface by anodization process could be a perfect choice for it.
Apart from bone overgrowth, they decided to resolve the postoperative infection risk by pathogens like methicillin-resistant Staphylococcus aureus (MRSA). Indeed colonization by bacteria is a common issue and the focus of implant-related infection. Preventing these infections that may cause severe bone infection in some is challenging as systemic antibiotics fail to reach bone tissues in significant amounts. It means that a titanium implant with an anti-bacterial coating may be a better approach to preventing these infections. They found that coating these titanium nanotubes with gallium is a perfect way to prevent postoperative infections.
To support their finding, they carried out in-vitro testing of their implants. First, they tested whether these nanotubes can prevent bone overgrowth using MG-63 cells. The research team used titanium nanotubes (TNTs) with a diameter of ~100 nm without gallium coating, as it is anyway meant to be dissolved in about five days. When compared to traditionally used titanium implants, in the in-vitro study, they found that there wasn’t substantial cells growth at 4 and 7 days in this new kind of TNTs, thus confirming them to be superior to traditional titanium implants. Further, studies also showed that gallium coating on these implants could last for five days. In the in-vitro study, they found that gallium-coated and 3d printed titanium implants could eradicate infections like S. aureus and P. aeruginosa in five hours. Thus, the newly designed implant using 3d printing technology will not only be easier to remove, but it will also be excellent candidate to prevent bone infections caused by multi-antibiotic resistant strains of bacteria, as five days are enough to provide optimal benefit.
The Australian study by Professor Dusan Losic and his colleagues demonstrated that changing the surface of temporary titanium implants could be an excellent method to reduce bone cell attachment to temporary implants so that they are easier to remove at later dates. The work represents the future of orthodepic implants by providing a coating that transforms the implant from a hotspot for infection to a safer implant that prevent subsequent infection. The newly designed nano-coating has not yet been tested on humans still the researchers are confident that their innovation is up to the task and plan to pursue the steps needed to commercialize the product.
Maher, S., Linklater, D., Rastin, H., Le Yap, P., Ivanova, E. P., & Losic, D. (2022). Tailoring Additively Manufactured Titanium Implants for Short-Time Pediatric Implantations with Enhanced Bactericidal Activity. ChemMedChem, 17(2), e202100580. https://doi.org/10.1002/cmdc.202100580