My Experience with Implants

What’s every teenager’s worst nightmare? To me, it was being told at the young age of 13 that I was missing 2 adult teeth! But why was this such a bad thing? Because the corresponding milk teeth would eventually become too weak, fall out, and nothing would grow back. 9 years later brings us to now, and unfortunately, that dreaded day came. Luckily for me, the medical world has advanced, and dental implants exist, meaning I don’t have to be ‘toothless forever’, or so I thought. 

Recently, 1 out of my 2 implant screws decided it was going to fail and fall out causing a delay in receiving my new teeth. I felt this massively inconvenienced me as I now must remain ‘toothless’ for a little longer. However, this experience had me thinking about the bigger picture of implant failure and I realised that my implants were only for cosmetic purposes. What if my implant was for my knee or hip and that was to fail? How much of an inconvenience would that be? Intrigued, I decided to dive deeper into the topic.

Implant Failure in Joint Replacements

From reading this article by Steven Richard Knight et al, I’ve learnt that, amazingly, hip replacements date back to over 100 years ago when the first surgery took place in 1891 in Germany. Ever since then total joint replacement has advanced in the materials being used, the surgical techniques and technology. This has helped with the life expectancy of the implants which ultimately has reduced the percentage of failure seen today. Although it’s not foolproof yet. 

Joint replacements are mostly seen in people over 60 due to factors such as osteoarthritis. However, they aren’t uncommon in the younger generation.  In a study by Lee E Bayliss et al, I found it interesting that you are more likely to experience implant failure if you’re younger. After further reading, I started to understand why this is the case. Imagine living a day in the life of a 20-year-old and then a day as an 80-year-old. I’m sure you will agree that these days are substantially different. At 20, you’re going to be more active which causes the implant to be put under more strain. This causes the bone to wear down causing it to loosen and fail. However, aseptic loosening isn’t the only reason for implant failure. Other factors such as infection can also be a cause which you can find out more about here.

The Complications of Major Implant Failure and How it is Resolved

When my implant was failing it was obvious to detect as it started to rise out of my gum until it eventually fell out. However, I began to wonder how you would be able to tell if an implant placed inside your bone was failing.  I did some research on the symptoms and it explained how you would experience severe pain and instability in that joint. Imagining what that would be like I decided that although I felt very inconvenienced, it was minor compared to this. These patients would have to endure 1-2 more surgeries to receive joint revision and I only have to wait for the bone to heal before replacing my dental screw. However, even though implants come with a risk of failure, I think it’s incredible that doctors can fix these problems and I think it’s a risk worth taking.  

Stem cells represent a groundbreaking frontier in medicine, offering a revolutionary approach to treating a myriad of diseases and injuries. At the core of their promise lies the remarkable plasticity and self-renewal capacity of stem cells. Unlike specialised cells in the body, which have limited regenerative capabilities, stem cells retain the ability to proliferate and differentiate into specialised cell types, such as neurons, muscle cells, or blood cells. This remarkable versatility makes them invaluable tools for repairing damaged tissues, replacing dysfunctional cells, and restoring organ function in a wide range of conditions.

One of the most compelling applications of stem cells lies in regenerative medicine, where they offer hope for individuals suffering from degenerative diseases and injuries such as MS. Multiple sclerosis is a chronic autoimmune disease of the central nervous system (CNS) characterised by inflammation, demyelination, and damage to nerve fibers. It is believed to result from a combination of genetic predisposition and environmental factors triggering an abnormal immune response. MS typically presents with a variety of symptoms, including fatigue, weakness, numbness, vision problems, and difficulties with coordination and balance. The course of the disease varies widely among individuals, with periods of relapse (exacerbations) followed by partial or complete recovery, and periods of remission. Over time, however, MS can lead to cumulative neurological damage, resulting in permanent disability. Treatment aims to manage symptoms, reduce the frequency and severity of relapses, and slow disease progression through medications, rehabilitation therapies, and lifestyle modifications.

Over 2 million people worldwide suffer from MS and before now treatment has focused mainly on symptom management and not the initial problem. A person develops MS when their body’s own immune system attacks the myelin, an insulating and protective sheath, that surrounds nerve fibres. This causes the disruption of messages sent around the central nervous system. The central nervous system consists of the brain and spinal cord. The particular section of the immune system that initiates the attack are cells called macrophages that eat harmful cells or pathogens that have made their way into the body. The macrophages found in the brain are called microglial cells and in progressive forms of MS they cause chronic inflammation and damage to nerve cells.

Now, in research published in the Cell Stem Cell, scientists have completed a first-in-human, early-stage clinical trial that involved injecting neural stem cells directly into the brains of 15 patients with secondary MS recruited from two hospitals in Italy. The trial was conducted by teams at the University of Cambridge, Milan Bicocca and the Hospitals Casa Sollievo della Sofferenza and S. Maria Terni  (IT) and Ente Ospedaliero Cantonale (Lugano, Switzerland) and the University of Colorado (USA).

The stem cells utilized in the study were derived from brain tissue sourced from a single miscarried foetus, these stem cells would be classed as adult stem cells. This method offers a solution to the practical hurdles associated with sourcing foetal tissue from multiple donors. Over a span of 12 months, the Italian research team closely monitored the patients and observed no treatment-related fatalities or severe adverse effects. While temporary or reversible side effects were noted, none of the patients experienced a deterioration in disability or symptoms throughout the study duration. Moreover, there were no indications of relapse symptoms reported, and cognitive function remained relatively stable. As a result, the researchers concluded that the patients demonstrated considerable stability in their disease progression, showing no signs of deterioration. However, the initial high levels of disability among participants present challenges in conclusively affirming the findings.

There are some ethical implications of using stem cells from a miscarried foetus (need to do more research on harvesting stem cells in this instance and not just from embryos)

Need to reduce word count / sum up sections more

A 3D printed prosthetic arm example design

Prosthetics are substitutes for missing limbs in the body, in particular arms and legs, but also bones, heart and arteries. There are 30 million people in need of replacement limbs, but the main challenge that people face is that prosthetics are very expensive.

According to this report, the average cost for a single prosthetic limb is around $4,500 USD and can go as high as $50,000 USD. For people in low income countries, this can be unattainable and for people in high income countries, this can be expensive. As a result, I started to think about what solutions are out there that could potentially help this cause. After some research, I came across the field of 3D printed prosthetics, which caught my eye.

What exactly are 3D printed prosthetics?

Essentially, 3D printed prosthetics involves using additive manufacturing methods such as 3D printing to create artificial limbs instead of manually manufacturing them. 3D printed prosthetics are composed mainly of plastic, just like traditional prosthetics, but can also use materials such as acrylonitrile butadiene styrene, or simply ABS, plastics, as well as bridge nylon for a stronger material.

There are 4 main types of prosthetics: transradial, transhumeral, transtibial, and transfemoral. The first 2 types are implants above and below the arm, whilst the last 2 types are implants above and below the knee. Additive manufacturing enables the fast production of these implants.

How do 3D printed prosthetics work?

3D printed prosthetics offer a more streamlined approach to the manufacturing process of prosthetics in comparison to the traditional method. There are 4 steps to this approach, with the first step being 3D scanning. This involves using medical imaging methods such as X-rays and Computerised Tomography (CT) scans to collect images of the patients broken limb.

The next step involves the images being modelled by prosthetists to create and design the required device. This is heavily influenced by the level of detail the computer software provide. The third step is the 3D printing itself, which print layers of the material to create a bonded object. This method prints lots of complex structures in a short period of time. Finally, the device made is fitted onto the patient, where the device made is designed to match the patients anatomy.

This video details the company Unlimited Tomorrow, who create prosthetic arms using 3D printing which has led to the production of their True Limb device.

Benefits and Challenges of 3D printed prosthetics

The benefits that 3D printed prosthetics provide are the reductions in the manufacturing time and costs of the prosthetics. Prosthetics produced by traditional methods often involve stringent procedures, whereas, 3D printed prosthetics offer a more step by step method which is more streamlined.

The average cost of a prosthetic arm costs around $2,000 USD, and the patient may have to wait for the prosthetic to come. Prosthetics 3D printing is more affordable in comparison, with the cost of a 3D printed prosthetic costing around $395 USD.

One challenge that 3D printed prosthetics face is in regards to material strength and durability. 3D printed prosthetics can be created by thin layers of hot plastic, which can be broken easily. Some prosthetics also incorporate materials like silicone, which can be challenging due to the limited availability of printers that can handle these materials.

The rise of 3D printing can potentially create a bright future for prosthetics thanks to the technological advances made in prosthetics design, as well as the cost efficiency, rapid production times and flexible design.

Prosthetic hands are used to support people that are missing their hands due to a congenital condition, an illness or from an injury. They can help with mobility, strength, and everyday tasks. Some children will wear a prosthetic hand throughout their life whereas other children may never wear one. Prosthetic hands encourage children to use both their hands which improves their brain and motor development. They also help with their appearance and self-confidence.

Development of the prosthetic hand

  In the late 15^th century, France and Switzerland were making artificial hands. These were made from wood, glue, metal, and leather. In the 16^th century, Götz Von Berlichingen wore 2 iron prosthetic hands due to losing his right arm from the war. The second hand was able to hold objects. In the 19^th century, William Robert Grossmith created a left prosthetic arm from wood and aluminium.  In the 20^th century, plastic was used for prostheses. Today, prosthetic hands are made from silicone, titanium, aluminium, and plastic.

Cosmetic devices

  For children under 18 months an ideal prosthetic hand is a passive prosthetic device which is a cosmetic device. These do not move by themselves; they are made from silicone and are lightweight. The earlier a child starts wearing a hand prosthesis, the more they become accustomed to it. The Greek Series, Infant 2 Hand, L’il E-Z Hand and Lite Touch Biomechanical hands are examples of prosthetic devices that can be used for children.

The Greek Series are suitable from 4 months to 3 years old. They have realistic hand features so they can be used to hold light objects such as small plastic toys.

The Infant 2 Hand can be used from 6-18 months. This hand can be used for pushing and pulling objects as the hand is a cup shape.

The L’il E-Z Hand is suitable from 6-24 months. This hand has a mechanical thumb which helps infants to grasp objects easily.

The Lite Touch Biomechanical hands are recommended from 2-9 years old. This hand has moulded fingers which can voluntarily open and close.

Myoelectric prosthesis for children

  Myoelectric prosthetics are suitable for older children, over 10 years old. These use more advance technology and can benefit children as it develops their muscle memory and helps them perform activities that involve 2 hands.

3D printing for prosthesis

  3D-printing technology can make prostheses more affordable for the public. It also reduces the manufacturing time which can take up to 6 weeks. Instead, a prosthetic limb can be created within a day. The aim is to make 3D printing more accessible so people can make their own hands. In 2011, Ivan Owen created the first prosthetic hand using 3D printing. These prostheses are made with plastic, carbon fibre, aluminium or titanium therefore making them lightweight.

Overall, prosthetic hands have developed significantly over the years. They are very important for both children and adults as they can positively impact their lives by developing their everyday skills. There is an amazing foundation called the Douglas Bader Foundation which works with charities in the UK involved in Project Limitless. Project Limitless aims to give all children (that need) a prosthetic arm. Over 300 children have already been provided with one.

Links

https://www.steepergroup.com/prosthetics/upper-limb-prosthetics/hands/trs-paediatric-hands/

https://www.yourkoalaa.com/projectlimitless

Medical 3D-printing using stem cells sounds like a dream but recent advances in printing technologies has paved the way for new possibilities in artificial organ printing and regenerative medicine.

Across the globe many individuals who need organ transplants are suffering due to the lack of available donors. The NHS states that in the last 10 years, 1/4 of patients waiting for a lung transplant have died. Utilising 3D-printing to make organs accessible can play a crucial role in removing the issue of waiting years for a donor.

How does 3D-bioprinting organs work?

In short, 3D printed organs are made from a mixture of biopolymer hydrogels and cultured stem cells forming a bio-ink. Hydrogels like alginate or gelatin, are used as ‘scaffolds’ in the printing process of the organ. The process sounds simple but researchers must take into account factors like cell/ tissue type and the bio-ink needed for the specific organ.

Mark Skylar-Scott, an assistant professor at the Stanford University department of bioengineering stated the bio-ink is loaded into “syringes and is squeezed out of the nozzle like icing on a cake”. This process is repeated with different cell types, and once complete is provided with oxygen and nutrients. Over time developing to perform its intended function.

Skylar-Scott’s team developed a method to speed up the printing process, it involves printing in clusters called organoids which he describes as a “human stem cell mayonnaise” which is then printed. The video below describes the process in full :

What role do stem cells have?

Stem cells are old news in the medicinal world, the first successful Hematopoietic stem cell transplant was in 1959! Stem cells have the ability to turn into other cell types and for that reason they are still extremely relevant to this day.

Stem cells are still used to innovate treatments. For example, induced pluripotent stem cells (iPSCs) obtained from de-differentiating skin cells, can turn into any type of cell, making the possibilities for new treatments endless, as stem cells can be acquired without the controversial use of embryos.

The video below shows Dr. Brenda Ogle’s team at the University of Minnesota using iPSCs to create a 3D printed functional human heart pump :

The future of 3D-bioprinting organs ?

In 2022/2023, 281 people died while waiting for a kidney transplant in the UK, 3D printed organs can reduce the waiting time for in-demand organs. Wake Forest scientists have been able to grow mini-kidneys and livers, demonstrating the promise that printed organs have for the future .The cost of a liver transplant in the USA is approximately $812,500, 3D-bioprinters that can make printed organs can be as cheap as $45,000, providing a cost effective alternative for patients.

The actual use of these organs is still 20 to 30 years away. Better hardware with the ability to replicate the complex nature of organs, and mitigating issues like biomaterial degradation and tissue integration is crucial if we want to use these organs in the future. I believe that the use of 3D-printed organs can revolutionise medicine and give hope to those in need of transplants.

Hearing is a sense that I, and likely many others worldwide, take for granted. That said, around 1 in every 6 adults in the UK live with at least partial hearing loss. The technology behind cochlear implants piqued my interest after listening to the insights from users in the lecture, leading me to begin reading parts of Dr Yoder’s cochlear implant journey.

What is a Cochlear Implant?

Cochlear implants are made up of both internal and external parts and require a relatively short surgery to fit. The external parts are made up of a microphone to pick up the sound waves, a language processor to convert the sound waves into electrical signals, and a transmitter to transfer these to the internal components. The language processor and microphone usually rest on the ear, while the transmitter is placed further back on the head. The transmitter is held on via a magnet fitted under the skin during surgery. This allows for the previously converted electrical signals to reach the string of electrodes inserted into the cochlear, which stimulates the auditory nerve directly.

Tuning

One aspect of cochlear implants that I found fascinating was tuning and the period over which it takes place; initial tuning usually takes place one month after the surgery, with periodic sessions after this to slowly ease users into the new sounds. This initially shocked me; “Why does this process take so long?”, I found myself thinking. However, after reading Dr Yoder’s experience with tuning as well as others (seen in the video below), I realised that hearing is not restored with the surgery, but with the practice users do to re-understand how everyday noises and speech sounds. The video below by Cochlear Americas documents four users and their experiences with training themselves to understand how to hear through their new implants, which I found very insightful.

Current and Future Research

A recent publication in Ear and Hearing in 2023 discussed advancements in tuning of cochlear implants, and how artificial intelligence can be used to outperform traditional tuning methods. The traditional method, despite performing less effectively, was preferred by participants, owing to it feeling more comfortable for them. I believe that this aspect of optimising implants should not be neglected; how the users think or feel about such methods, be it tuning or any other aspect of the implants, is of utmost importance.

A less recent article from the engineering department in Cambridge highlights how 3D printing can be utilised to improve cochlear implants. The fluids inside the cochlear ducts are highly conductive to electrical signals and implant users often, due to this conductivity, experience distorted sounds through their implants; this is known as current spread. The use of 3D-printed cochleae, paired with machine learning, allowed researchers to analyse and predict how current spread was impacted by the cochlea’s shape and conductivity. Dr Shery Huang, an associate professor in Bioengineering at Cambridge, suggested that this is an extremely useful application of 3D printing since data regarding patients must be kept private; Dr Huang was quoted in the article, stating that to solve this, “3D printing is a powerful tool to create physical models which might provide a well-characterised training dataset as a purpose-built surrogate to clinical data for machine learning”.

During the lectures on sensors and sensing, we were shown a video of a ‘bionic arm powered by AI’. The video showed a man controlling a prosthetic hand using his mind, and got me thinking about the extent to which a prosthetic hand might be able to replicate the function of a biological hand, in particular if prosthetic hands could ever ‘feel’.

A touchy subject

So much of what we do and how we interact with the world relies on touch. Primarily, touch is important for perceiving pressure allowing you to interact with objects at just the right force. If you pick an egg up with too much force it will break, but not enough force and you’ll drop it. Either way you’ll break a few eggs, but won’t end up with an omelette. There are a range of receptors in the skin which give us our sense of touch. The mechanoreceptors act to convey tactile information from our fingertips to our nerves. Whereas the nociceptors are free nerve endings which conduct stimuli which we perceive as painful. In the past, prosthetic hands could replicate some of the hand functionality, but have not been able to sense tactile information. However, recent technological advances are paving the way for feeling with a prosthetic hand.

E-dermis: the prosthetic skin

John Hopkins have developed an engineered material skin, made with fabric and rubber, and implanted with sensors to act as pain and touch receptors. The sensors of the e-dermis can then stimulate the nerves in the residual limb or the amputee through the skin, to allow the perception of both painful and non painful tactile stimuli.

Brandon Preston’s story

After an industrial accident at his work in 2012, Brandon Prestwood lost his lower left arm and hand. After battling with depression after the accident, Prestwood volunteered for experimental research with Cleveland State Western University, leading to the insertion of electrical conductors to the remaining nerves in his residual left upper arm, with four wires then guided up through his residual left arm and out of his shoulder. As the nerves and their link to the brain remain in the residual limb, by incorporating sensors into the prosthetic hand, the signalling can be restored. The sensors in each prosthetic finger convert contact with a surface into an electrical signal, the signal is sent to a computer, then the computer stimulates the correct nerves through the implanted electrodes. By doing this, Prestwood could touch an object with a prosthetic finger and know which finger is touching it.

More than a feeling

You may wonder why the sense of touch is so important. Would it not be easier to shorten the loop, with the sensory receptors of the prosthetic feeding back to an internalised system to modulate the force used by the hand, and forget about transmitting signals to the brain all together? However, the need to perceive touch is for more than just to pick up an egg; touch is also a vital part of being human. From handshakes, to high-fives, to hugs, touching is integral to being human. It’s even engrained in our language, if someone buys you flowers you feel ‘touched’ by the kind gesture. Even Shakespeare alludes to the importance of hands and touch, ‘now join your hands, and with your hands your hearts’. For Brandon Prestwood it was as simple as being able to hold his wife’s hand again with his missing left hand:  “It’s the emotion that goes with any kind of touch. It is … it’s being complete.”

Reference links

Prosthesis with neuromorphic multilayered e-dermis perceives touch and pain | Science Robotics

From Research to Reward: Something Lost, Something Gained: High-Tech Prosthetics Build on New Understandings of the Human Body (nationalacademies.org)

New ‘E-Dermis’ Brings Sense of Touch, Pain to Prosthetic Hands – Johns Hopkins Biomedical Engineering (jhu.edu)

The audacious science pushing the boundaries of human touch | National Geographic

Advancements in prosthetics limb technology allow feeling, control | 60 Minutes – CBS News