For many years, joint replacement of damaged hips has been a standard treatment in orthopaedic surgery. There is currently no mechanism for early detection of implant failure following surgery. Early detection of total hip replacement (THR) failure could lead to more proactive surgical intervention and better patient outcomes. In this instance, the Acoustic Emission (AE) measuring approach may be a good fit as a diagnostic indication for joint health, implant failure modes, and gait analysis.

The previous study’s AE monitoring technique did not collect patient motion data, making it hard to make accurate comparisons between AE events and implant motions, or to determine whether specific AEs are caused by specific implant articulation angles, loads, or angular velocities. FitzPatrick et al. (2022) established a concurrent technique of AE monitoring to combine lower-limb motion and AE data to enable temporal interpretation of acoustic information for gait analysis to study this issue.

Three patients (two males and one female) between the ages of 50 and 70 were taken for a combined AE and gait analysis. They underwent a ceramic-on-ceramic implant bearing hip replacement. Four passive ultrasonic receivers set in a flexible array on the patient’s skin surface from the iliac crest to the upper femur were used to identify AEs. As the patient walked across the room in a straight line at a self-selected speed over a force plate, AE data were recorded. A motion analysis system with six infrared tracking cameras recorded the patient’s limb motions at the same time.

Their findings revealed that AEs are significantly linked to the stance phase of walking, when implant loads are high and the hip joint’s angular velocity is high. The key observation from the male patient was that all of the recorded squeaks happened between 30% and 50% of their individual gait cycle, which pertains to terminal stance, across all walking tests. Interestingly, the situation was significantly different for the female patient; total voltage magnitudes were lowered, and AEs of significant magnitude occurred consistently during the stance phase.

Based on current findings, the exact mechanism that causes implant squeaking is unknown. As a result, ongoing research aims to collect combined AE and gait data from more hip replacement patients in order to evaluate if the findings apply to a larger group of patients and to get greater insight into quantitative relationships between AE activity and hip joint dynamics.

Source: FitzPatrick, A. J., et al. “Synchronized acoustic emission and gait analysis of total hip replacement patients.” Biomedical Signal Processing and Control 74 (2022): 103488.

 

This article was written by MM Raihan as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

Raihan is researching In-situ Measurement of Nano-scale Wear Utilising Advanced Sensors at University of Leeds, UK.

PRG4 or lubricin is a protein with a bottle-brush shape that can be perfectly mimicked by polymer brush grafting to biomaterial surfaces. This imparts to biomaterials’ surfaces super lubricous properties and a coefficient of friction (µ) lower than 0.01.  In addition, polymer brushes grafted to material surfaces may impart tunable hydrophilicity, self-cleaning, catalysis, controlled cell, and bacteria adhesion [1]. They can be applied for response actuation and drug delivery. Lubrication polymer brushes can be charged (positive and negative charges), amphiphilic, or act via steric hindrances[1]. The end properties can be controlled by molecular weight, grafting density, and radius of gyration.

One of the mechanisms of lubrication is brush hydration. The thick water film would prevent the probe from contacting the surface[1]. In nature, this role is played by hyaluronic acid and other sugar molecules in articular cartilage, for example. The sugar molecules are conjugated to lubricin forming a mucinous domain. The protein is anchored by a somatomedin-B (SMB) domain to hyaluronic acid from the extracellular matrix of cartilage cells (chondrocytes) [2,3]. The glycosylated domains can trap water and establish electrostatic repulsion promoting lubricity of the tissue [4,5]

Several strategies have been developed to mimic this biochemical environment. Poly(l-lysine) (PLL) brushes were grafted onto poly(ethylene glycol) (PEG) surfaces to obtain good lubricity and biocompatibility[6]. Morgese et al. grafted to poly(glutamic acid) different polyoxazolines. These polymers are known for passivating surfaces and promoting now-fouling without eliciting immune responses. In samples with hydroxybutyrate (HBA), she obtained a biomimetic material that could bind to degraded cartilage and regenerate tissue[7]. This implies interesting solutions for people with early-onset arthritis.

To conclude, bottle-brush materials might be the future of cartilage tissue engineering, but more studies need to be conducted to show the in vivo feasibility of the concepts. We expect these new materials to influence scaffolds/gels potentially entering the market in the next decades.

REFERENCES

[1]          S. Ma, X. Zhang, B. Yu, F. Zhou, Brushing up functional materials, NPG Asia Mater. 11 (2019) 24. https://doi.org/10.1038/s41427-019-0121-2.

[2]          Y. Lee, J. Choi, N.S. Hwang, Regulation of lubricin for functional cartilage tissue regeneration: a review, Biomater Res. 22 (2018) 9. https://doi.org/10.1186/s40824-018-0118-x.

[3]          I. Bayer, Advances in Tribology of Lubricin and Lubricin-Like Synthetic Polymer Nanostructures, Lubricants. 6 (2018) 30. https://doi.org/10.3390/lubricants6020030.

[4]          S.M.T. Chan, C.P. Neu, G. DuRaine, K. Komvopoulos, A.H. Reddi, Atomic force microscope investigation of the boundary-lubricant layer in articular cartilage, Osteoarthritis and Cartilage. 18 (2010) 956–963. https://doi.org/10.1016/j.joca.2010.03.012.

[5]          I.M. Schwarz, B.A. Hills, Surface-active phospholipid as the lubricating component of lubricin, Rheumatology. 37 (1998) 21–26. https://doi.org/10.1093/rheumatology/37.1.21.

[6]          S. Lee, M. Müller, M. Ratoi-Salagean, J. Vörös, S. Pasche, S.M. De Paul, H.A. Spikes, M. Textor, N.D. Spencer, Boundary Lubrication of Oxide Surfaces by Poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) in Aqueous Media, Tribology Letters. 15 (2003) 231–239. https://doi.org/10.1023/A:1024861119372.

[7]          G. Morgese, E. Cavalli, J.-G. Rosenboom, M. Zenobi-Wong, E.M. Benetti, Cyclic Polymer Grafts That Lubricate and Protect Damaged Cartilage, Angew. Chem. 130 (2018) 1637–1642. https://doi.org/10.1002/ange.201712534.

 

This article was written by André Plath as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

André is researching Boundary Lubrication of Fibrous Scaffolds at ETH Zürich, Switzerland.

Reaching back over 2,000 years, an ancient network of trade routes called the ‘Silk Road’ connected the East and the West. Precious goods, splendid cultures and religions travelling along thousands of miles, stroke, exchanged and merged. The term ‘Silk Road’ was first used by German geographer Ferdinand von Richthofen in 1877, as silk is one of the favourite goods traded from China to Europe, also as a metaphor for the ideas travelled from different civilizations.²

Amazed by this picture (marks are the origins of all ESRs who joined BioTrib this year) and the idea of ‘BioTrib Silk Road’ presented by Prof Richard during our ESRs meeting, I started to think about the importance of international research collaboration in the modern world.

 

“Ideas transcend borders, no country controls the marketplace of ideas.”

— Alejandro Adem ³

Indeed, there isn’t a researcher who knows everything in the world, nor a university owns all of the state-of-the-art equipment and facilities. We have to collaborate, and we love to collaborate. When people from diverse backgrounds meet, idea sparks. When institutions collaborate, science thrives. While in BioTrib, deep international connections have formed between universities and industries from the UK, Sweden, Switzerland, Germany, China and Australia; researchers are not only from different academic backgrounds but also diverse cultural backgrounds. The diversity and inclusiveness are the treasures of BioTrib and I can’t wait to see our footprints of contribution to academic research on this ‘BioTrib Silk Road’.

Header Image: Marco Polo Geography and Map Division/Library of Congress, Washington, D.C. (gct00215-ca000005) ¹

 

References

(1) Marco Polo on the Silk Road https://www.britannica.com/topic/Silk-Road-trade-route

(2) The Silk Road https://www.nationalgeographic.org/encyclopedia/silk-road/

(3) The benefits and challenges of international research collaboration https://www.universityaffairs.ca/features/feature-article/the-benefits-and-challenges-of-international-research-collaboration/

 

This post was written by Esperanza Shi as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

Esperanza is researching the Optimisation of Scanning Strategies for 3D Printed Artificial Joints at Imperial College London, UK.

 

The ongoing 4th Industrial Revolution has shifted the traditional paradigm of producing medical devices. Additive Manufacturing (AM), a mould-less technology commonly referred to as 3D printing, plays an essential role in the shift taking place in this field.

Because of the high degree of geometrical freedom that can be achieved, AM is being used to conceive polymeric microneedles (MNs) with tailored design. For instance, Caudill and co-workers (2021) studied the benefits of microneedle vaccination over the traditional subcutaneous one. An AM process that relies on resin photopolymerization (i.e., continuous liquid interface production) was used to fabricate the MNs in two different shapes: square pyramidal and faceted (cf. image given in this post).

Cargo loading was performed via surface coating and assessed for the different MN designs. Whilst surface area increased 21.3%, cargo loading augmented 36% from square pyramidal to faceted with horizontal grooves, which pinpoints the importance of geometry design to loading biologics on MNs. Furthermore, transdermal delivery through MN vaccination was more effective in triggering primary antigen-specific IgG as well response duration when compared to subcutaneously or intradermally delivering paths.

Caudill et al. (2021) findings represent a major step towards a simpler, effective, and pain-free vaccination process that can potentially increase global vaccination. Furthermore, this self-administered vaccination path may aid in prompt responses during epidemic and pandemic scenarios. In that sense, AM has proved to be a feasible manufacturing route for improving drug delivery systems via tailored shapes and geometries.

Read more of this fascinating paper here: Transdermal vaccination via 3D-printed microneedles induces potent humoral and cellular immunity

This post was written by Pedro Luiz Lima dos Santos as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

Pedro is researching the Functional Biotribology of the Surface Engineering of 3D Printed Components at the University of Leeds, UK.

A £7 million research project has been launched to develop a new imaging and keyhole surgery approach to the treatment for secondary bone tumours of the spine. 

Known as metastatic bone disease, the tumours spread from a primary cancer located elsewhere in the body. The condition is particularly associated with breast cancer.  

The bone tumours cause vertebrae to weaken and eventually fracture, leaving people in severe pain, immobility and requiring surgery. In some cases, the fracture may damage the spinal cord and cause paralysis. For these patients, however, quality of life is a key issue and complex surgery may be inappropriate. 

A research collaboration between the University of Leeds, Imperial College London and UCL has received funding to develop an alternative approach based on developing new imaging and modelling techniques that will enable clinicians to predict which patients are at a high-risk of a vertebra fracturing.  

They would then be fitted – using minimally invasive surgery – with a tailor-made implant to strengthen the spine and prevent the fracture. 

The project – Oncological Engineering: A new concept in the treatment of bone metastases – has attracted £7 million in research funding, including £5.6 million grant from the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation, the Government-funded body set up to support research and innovation. 

According to Cancer Research UK, 150 people every day are diagnosed with breast cancer. Although more than 76% of people with the disease survive for more than ten years, some patients do develop stage 4 cancers, of which it is estimated about 50% to 60% get bone tumours.  

In stage 4 cancers, the disease has spread to other organs. 

Within five years, the research team hope to have developed new techniques and materials that will revolutionise the treatment of bone metastases.  

The approach is based on personalised medicine, assessing an individual’s risk that the spine has weakened so much that a vertebra will fracture. In those cases where surgeons intervene to strengthen the spine, the implant will be tailor-made.  

Predicting the risk of a vertebrae fracturing 

Researchers will develop news approaches to patient imaging and computer modelling, enabling them to track tumour development in the spine over time and how it might be weakening individual vertebrae. The information would be compared with the loading on the spine, enabling clinicians to predict which of the vertebrae is at risk of fracturing. 

Implant made of advanced materials 

Those vertebra at a high-risk of collapse would be supported by an implant inserted into the spine using minimally invasive techniques.  

The implant would be made from what is called a metamaterial, a material that has uncommon properties that can be fine-tuned to the needs of the patient, for example the material could harden when under stress. 

Metamaterials are currently used in the aerospace industry but with advances in 3-D computer printing, the research team believe they could be adapted to provide tailor-made structural integrity to vertebrae at high risk of fracturing. 

The advanced manufacturing group from the Dyson School of Design Engineering at Imperial College, London, will be developing a novel 3D printer capable of fabricating the intricate implant designs. Their machine will utilise smart optical systems to print photopolymers at extremely fine resolution. 

By using minimally-invasive techniques to implant the material, the recovery period for patients will be days – rather than weeks or months with the surgery that is required if one of the spinal bones fractures. 

The NHS long-term plan for cancer treatment had called on researchers to develop new interventions that would improve the quality of life of patients living with advanced cancers. 

It is hoped the new techniques will be applied to other areas of the healthcare sector.  

A year on since the start of BioTrib we have now completed recruitment of all 15 Early Stage Reseachers and achieved a milestone 500 followers on LinkedIn!

Thanks to everyone in the BioTrib community!