A sustainable, “smart plaster” for orthopaedic treatments

February 14, 2022 at 4:35 PM

By Chaminda Dissanayake

The World Health Organisation (WHO) recently reported approximately 1.71 billion people suffer from musculoskeletal injuries, among that 24% are related to bone fractures. Most fractures are non-fatal but need immediate medical intervention to mitigate the risk of permanent disability. Plaster of Parise (POP) and fibreglass are commonly used to immobilise fractured bones until they are fully cured. However, POP and fibreglass casts are uncomfortable, cumbersome, disintegrate in water, decrease X-ray transparency, and the process effectiveness depends on the cast technician’s competence and experience.

To address such issues, after three-year trials by a PhD researcher at the Centre for Future Material (CFM) Janitha Jeewantha has synthesised a novel hybrid shape memory polymer nanocomposite smart plaster that can be used in orthopaedic bone fracture Immobilisation. This alternative approach offers much more precise control over other Immobilisation methods. The researchers successfully demonstrated their new strategy on a mannequin, and the results encouraged them to explore more opportunities. Jeewantha believes that the medical community will accept this novel concept and make it available in accident and emergency (A&E) units in the next few years.

About shape memory polymers (SMPs)

SMPs are smart materials that can deform into a temporary shape and regain permanent shape upon external stimuli such as heat, light, magnetic field, electricity etc.; They have shown superior processability, recoverability, low density and cost compared to other polymers. Therefore, SMPs are good candidates for biomedical applications; besides, self-tightening sutures and staples, clot removals, control drug release, cardiac valves, stents and tissue engineering prototypes have already been developed. To date, USA Food and Drug Administration cleared anchors and soft tissue fasteners, now commercially available for minimum invasive surgeries.

Although the SMP technology is still not widespread, Jeewantha explained how he has struggled to find required raw materials and optimise the fabrication technique. However, after three years of hard work, he added that world-leading journals and conferences highly appreciated my work. 

Synthesis SMP smart plaster

First, the SMP glass transition temperature was tailored to 40oC since human skin is extremely sensitive to high temperatures. The next step was delicate shape memory properties improvement over 20% by introducing a custom curing schedule. Researchers reinforced resin with E-glass fibres to achieve the required structural strength at body temperature. Also, the research team added biocompatible TiO2 nanoparticles to improve further antimicrobial effects, self-cleaning and UV protection of the wound through smart plaster. As they moved further, the fabrication parameters were statistically optimised and that helped them to assure smart plaster functionality as well as optimise thermomechanical and viscoelastic properties for orthopaedic applications.

Smart plaster demonstration

With smart plaster, Jeewantha successfully demonstrated key steps and admitted the challenges he faced at the initial stages. The process is unlike other fractured bone immobilisation methods, he explains, the smart plater can cut to the required block or shapes by simply using a scissor at elevated temperature. After that, 100% unbleached elasticised radial and longitudinal stretchable cotton stockinette was applied and avoid wrinkles. Followed by with 50% overlap, unroll the webril cotton circumferentially. Then smart plaster was kept at 50oC for approximately 5 minutes before wrapping around the fractured limb. He kept constraining forces for around 3 minutes; this could minimise the self-recovery of the plaster. Jeewantha introduced a secondary locking mechanism to lock the bandage as the final step. Alternatively, a pressure bandage or Velcro tapes can be wrapped around the plaster to avoid the smart plaster spring back effect that may occur on hot days. The researchers have measured the overall time to complete plastering, which was less than 10 minutes. Interestingly, it was less than the POP and fibreglass casting processes.

The plastering process was cleaner, uniform thickness and strength, texture provided optimal air circulation resulting in less bacterial, fungal itchy infections as well as being comfortable and simple to remove. The major advantage of smart plaster is it allows multiple alterations observations of while it was on the fractured limb, unlike other methods. This may permit the orthopaedic specialist to reform and further adjust without wasting time and additional resources. Jeewantha explicitly states underneath pressure can be adjusted even after smart plaster has been applied; thus, preventing irreversible damage to muscles and nerves and reducing the severe threatening effect on the patients’ limbs. Also, Jeewantha recalled in 2013, Sri Lankan law student Achala Priyadarshani’s most dextrous arm was amputated due to medical negligence. This could have been saved if we had smart plasters; Jeewantha anxiously mentioned that.

Jayantha Epaarachchi, Professor at the University of Southern Queensland, supervises the fabrication and material characterisation process and strongly believes this is most likely the next-generation orthopaedic treatment method.

“I believe this was a successful initiation, and I don’t see this project as being finished yet.” Further, Dr Epaarachchi confirmed, “now the team wanted to conduct clinical trials and excitedly wait to receive approval from the governing bodies to things move forward”. This is one of the critical steps in Epaarachchis’ mind. At last, Professor Epaarachchi invited leading orthopaedic devise fabricators and researchers to collaborate with his research team and be a part of this great invention since this is not just a research project.

Finally, Jeewantha expresses his gratitude to the experts involved in this research for around three years, the University of Southern Queensland for granting an international fees research scholarship, and the Australian commonwealth government covering living expenses during his stay in Australia. At last, he said, “I am very proud to be present this as my PhD research”.

Research profiles:

Janitha Jeewantha: https://www.researchgate.net/profile/Janitha-Jeewantha/research

Jayantha Epaarachchi: https://www.researchgate.net/profile/Jayantha-Epaarachchi/research

Eng. Janitha Jeewantha

Jeewantha obtained his BSc Eng. degree from the University of Ruhuna, Sri Lanka, followed by a postgraduate diploma in “Manufacturing Systems Engineering” from the University of Moratuwa, Sri Lanka. He worked in ACECAM Pty Ltd. as an Applications Engineer, followed by AeroSense Pty Ltd. and LMI Aerospace Asia Pacific. After four years of research at Sultan Qaboos University, Oman, in 2019, Jeewantha accepted an offer by the University of Southern Queensland, Australia, for a PhD programme to develop “Shape Memory Polymer Composite for adaptive components for orthosis and lower limb fracture fixators”. He is a member of the Institution of Mechanical Engineers and the American Society of Mechanical Engineers.