The University of Southampton

Tag: Prosthesis

How can prosthetics be adapted for different lifestyles?

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During a lecture and workshop focusing on prosthetics, I was intrigued by the design and functions of prosthetic limbs. Whilst watching the lecture, I spent some time wondering how the body communicates and works with the prosthetic to provide a function so similar to those of a natural limb in different everyday activities. Going into this research I didn’t have much prior knowledge and I perceived prosthetics to be limb replacements, but didn’t know their wider use. Upon seeing and interacting with a lower limb prosthetic in the workshop, I decided to further research this concept. 

Types of prosthetics

At the start of my search, I found there were many ways a prosthetic limb could work. Firstly, it can be powered by the body moving itself, e.g. where a cable may be placed on the shoulder and extend to a prosthetic hand. As the shoulder moves, the prosthetic moves. Secondly, it may have buttons, e.g. pressing a button on a prosthetic hand will cause the hand to grip an object. More recently, myoelectric powered prosthetics have been developed. This links muscles in pre-existing limbs to generate electrical signals and pulses via electrodes placed on the skin.

Example of myoelectric prosthesis.

Prosthetics for different lifestyles

I then wondered how a prosthetic like these could be used in different scenarios and lifestyles, e.g with different hobbies. During my research I found the website Arm Dynamics which discusses the creation and execution of many prosthetic attachments for those with varied everyday lives.

Ways prosthetics have been adapted for different activities.

Being an active gym goer I wondered how prosthetics could be used efficiently at the gym to complete exercises with correct form and came across Max Okun. Max is a personal trainer who was born without a left arm and forearm, but living with this through his life wasn’t going to stop him in his passions. It did however cause him injury as he was overusing his right arm, to counteract this pain, instead of surgery, he decided to use exercise to build up his muscles. It was therefore important for the engineers creating his prosthetics to ensure whilst Max was doing the exercises he was not causing further injury. 

Max Okun Patient Profile from Arm Dynamics on Vimeo – This video shows Max using his prosthesis.

My reflections.

Researching this stream of engineering made me very grateful to be in a generation of such intelligent creators. As someone with fully functioning limbs, I think it is easy to take for granted how our brains are able to seamlessly communicate with our body parts. Even with tasks such as writing this blog, I require little to no thought in using my fingers. I can go bowling and tap dance without worrying about my mobility. I look forward to seeing what comes next in prosthetics and where it can go. Sitting this module has inspired me to look for careers that can aid in this development.

Enhancing Functionality and Quality of Life in Upper Limb Prosthetics

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Introduction

Sensation is a crucial aspect of everyday life; it allows us to feel texture, pressure, and temperature of objects that we interact with.

Now imagine trying to pickup a delicate object without being able to feel it in your hand, how hard do you need to squeeze your fingers to hold it without the object falling out of your hand? Or are you gripping too hard that you might break it? This lack of sensory feedback is a major concern of prosthesis users and here we will explore the methods of sensory feedback.

Here is Dr. Ian Williams discussing developing a prosthesis with sensory feedback:

The role and history of sensory feedback for prosthesis users

The idea of restoring sensory feedback in prosthesis has been around since 1917 when Rosset patented a mechanism (Patent No. DE301108) that relays finger pressure via pneumatic or mechanical means. Many others followed, like the Vaduz prosthetic hand in the 1940s (Patent No. 2567066) which provided voluntary-closing hand and a “bladder” which was connected to the residual limb in the socket to provide force feedback. However, amputees still struggle with using these prosthetics as the user can’t tell what their prosthetic is doing without having to actively look or pay attention to what their prosthetic is doing. This is due to the lack of proprioception. (1)

Vaduz Hand, From Bulletin of Prosthetics Research, BPR 10-6, 1966.

Different types of sensory feedback

There are several methods that attempt to incorporate sensory feedback for upper limb prosthetics that try to provide users with sensory information. (1)

  • Electrostatic feedback
    • Electrostatic feedback involves the use of electrical signals to stimulate the skin and provide sensory feedback.
  • Mechanotactile feedback
    • Involves the use of mechanical pressure or vibrations to stimulate the skin and provide sensory feedback about the position and movement of the limb.
  • Sensory substitution
    • Involves providing sensory information through a different modality than the missing limb such as using visual or auditory feedback to replace the sense of touch in the hand.
  • Invasive feedback
    • Involves the use of implanted sensors to provide feedback about the prosthetic limb.

Additionally something else that needs to be taken into account is the time it takes for the feedback to reach the nervous system and be processed. Therefore, different feedback methods need to consider time delay when designing their systems. (2)

My insights and reflection

Sensory feedback plays a crucial role in bridging the gap between human limbs and artificial limbs. There are undeniable benefits in introducing sensory feedback in prosthesis such as enhanced functionality and improved quality of life including, providing a sense of proprioception to amputees. However, there are still several challenges faced in restoring sensation.

These include:

  • Expanding the range of sensations
    • Allowing the user to feel textures, temperature and also pain.
  • Personalisation and adaptability
    • Everyone is different and the ability to accommodate for a fit, growth and usage of the prosthesis is a huge challenge in meeting individual needs.
  • Affordability and accessibility
    • At this moment advanced prosthetics are prohibitively expensive and only a small handful of people around the world have the opportunity to have even basic sensory feedback.

An ethical and tricky question to consider is: Should we have artificial pain? This is a whole topic that could also lead to another post, but briefly, it has benefits for being a warning mechanism for potential harm, providing a realistic experience and better decision making. However ethical concerns arise if it is morally justifiable to subject users to distress, the level of pain intensity and how are you able to stimulate pain.

References

1.           Antfolk C, D’alonzo M, RosĂ©n B, Lundborg G, Sebelius F, Cipriani C. Sensory feedback in upper limb prosthetics. https://doi.org/101586/erd1268 [Internet]. 2014 Jan [cited 2023 Mar 24];10(1):45–54. Available from: https://www.tandfonline.com/doi/abs/10.1586/erd.12.68

2.           Sensinger JW, Dosen S. A Review of Sensory Feedback in Upper-Limb Prostheses From the Perspective of Human Motor Control. Front Neurosci. 2020 Jun 23;14:345.

The Ethics of Replacement Body Parts: Is It Ethical to Enhance Our Bodies?

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Medium.com

Recently I have been reviewing and watching content regarding our rapid advancements in technology which has given us the ability to replace body parts with prosthetics or other artificial devices. However, with this ability a significant ethical question arises of whether it is ethical to enhance our bodies beyond their natural capabilities. I drew inspiration for this post from the video by the Pew Research Centre included at the end.

One of the key ethical concerns surrounding replacement body parts is the question of what it means to be human. Humans have historically viewed themselves as distinct from other animals because of our unique combination of physical, emotional, and intellectual capacities. The introduction of artificial enhancements to our bodies could blur the lines of what it means to be human, and could even lead to the creation of new, non-human species. This raises important questions about how we define humanity, and what the implications of altering our bodies could be for our identity as humans.

ScientificAmerican.com

Another ethical issue that arises with replacement body parts is the potential for inequality. While the technology for artificial replacements has become more accessible in recent years, it still remains out of reach for many people, particularly those in less developed countries or who do not have access to proper healthcare. If only a select few individuals are able to afford or access these enhancements, it could lead to a new form of inequality where those who can enhance their bodies are more advantaged than those who cannot.

There is also the concern that replacement body parts could become a form of social pressure. If certain enhancements become popular or even necessary to keep up with societal norms, it could create an environment where people feel pressured to modify their bodies even if they do not want to. This could lead to a lack of individual autonomy and could even be seen as a form of discrimination against those who choose not to enhance their bodies.

However, there are also arguments in favour of replacement body parts and enhancing our bodies. One of the primary benefits is the ability to improve the quality of life for individuals who have experienced physical limitations due to injury or illness. By replacing a lost limb or enhancing an impaired sense, individuals can regain their independence and improve their overall well-being.

Archive Photos//Getty Images

Additionally, the development of replacement body parts has the potential to drive medical innovation forward. The same technology used to create prosthetics and artificial enhancements could also be used to develop new treatments for a variety of medical conditions however it would inevitably also be used military purposes as well.

To summarise the ethics of replacement body parts and the idea of enhancing our bodies is a complex issue with no easy answers. While there are certainly concerns about the potential implications of modifying our bodies, there are also clear benefits to individuals and society as a whole. As we continue to advance in technology and medical innovation, it will be important to carefully consider the ethical implications of these advancements and to work towards a future where everyone has access to these life-changing technologies.

Hip Replacement 101- and all that could go wrong.

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I have recently had the opportunity to meet a very successful surgeon who specialises in Hip replacement and trauma surgery. Prof. Douglas Dunlop was kind enough to invite me to his clinic where a one hour conversation inspired me to write this blog. He gave me a lot of insight about hip replacement surgery and with that, exactly what could go wrong.

Initially Prof. Dunlop showed me a couple images of hip replacement x-rays, such as the exemplar. One in particular was an image of an anonymous patient, an elderly male who had undergone multiple hip replacement surgeries. Prof. Dunlop and I have discussed why more than one surgery was needed, which leads me to talk about Hip replacement, and it’s potential risks. It might be miss-leading for me to use that title considering it’s impossible to write about every setback, but I will aim to discuss the ones I have learned about.

Going back to the patient. Initially the male had a 3M Capital hip, which due to poor performance lead to revision. Prof. Dunlop explained that the femoral head of the implant became loose in the joint along with the cement holding it together. The friction exerted on the socket lead to osteolysis and screws were needed to keep the implant in the shallow socket. I will not be going into a lot of detail on the 3M Capital hip, but upon further research I have stumbled upon a risk assessment document. It pinpointed that revision was more common in males, and the findings from the report were conclusive; the 3M Capital hips had higher revision rates than other commonly used prosthesis. In addition, with each round of surgery, the hip stem needed to get larger. To make room for a new implant, the femur needs to be reamed. This in turn sacrificed the bone, increasing the risk of fracture, along with loosening of the prosthesis or infection.

Why do hips fail?

I was surprised to hear that the patient had over 3 hip replacement surgeries. On that note its very important to not only think about the failure of the prosthesis, but also why they are initially needed.

In our discussion, Prof. Dunlop identified the two most common causes of surgery in his patients; arthritis and hip dysplasia.

Hip dysplasia is a medical condition where the hip socket does not fully cover the femoral head. This in turn creates a very shallow socket, which is very susceptible to osteolysis. Friction damages the labrum that lines the joint and can lead to hip labral tear, causing pain and discomfort. Arthritis gives rise to similar symptoms and can have multiple causes.

(MORE) problems with prosthetics.

Wear and tear has a honorary mention on this blog. It seems to be one of the leading culprits for hip surgery, damaging not only the bone, but the implant itself. Below is a list of a couple other things that could go wrong:

  • Loosening – causes pain and can lead to an inflammatory response
  • Dislocation of the prosthetic
  • Tendonitis – inflammation and injury of tendons
  • Fractures – example of stiffer hips made of cobalt chrome with 3.4% fracture rate and CPT (Zimmer brand) previously used at Southampton General with a high fracture rate.

Prof. Dunlop also highlighted that often a ceramic head is used in combination with a metal stem for the prosthetic. Many surgeons are now moving away from monoblock prosthetics as the acetabular component cannot be changed.

Where to go from there?

Hip prosthesis may lead to a lot of uncertainty, but just like any other invasive procedure it comes with risks and benefits. I once met a lovely woman called Anne; she has had both her knees and one hip replaced, and yet she has no complaints. In fact she said that the surgery was “life changing”. It allowed her to carry out day to day activities at the age of 87!

Despite ‘all that could go wrong’, it is very important not to overshadow all the benefits that come with prosthesis. The risks can be analysed, prompting researchers and surgeons to develop more successful treatment options and prosthetic joints with less complications. It is fascinating to see what the future of prosthesis may hold!

A large review study demonstrated that hip replacements last 25 years in approximately only 58% of patients.

Centeno-Schultz clinic
For more on Prof. Douglas Dunlop

Getting back on your feet- I Mean Literally

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As comparison to now and a few decades ago, the field of bioengineering has come a long way, especially in the field of prostheses. Throughout our engineering lectures thus far, what particularly struck me was the week in which we had covered prostheses and limbs in our lectures. This was because they have such a huge number of applications in which can be used to help people return to living a normal life (at least as best as they can).

As someone who is passionate about the field of sports medicine, what triggered me to do further research into what prostheses were like in earlier ages- like the 90s in comparison to the ones now, specifically ones specialised for athletes.

  • The picture on the left is what prosthetics had looked like during the mid-90s. Earlier prosthetics were often made of wood, leather and metal that limited movement.
  • The image in the middle displays what prosthetics look like now. It shows that advances in material and design have enabled prosthetic limbs we use now to be more functional and comfortable. Making use of lightweight yet very durable materials like carbon fibre and thermoplastics.
  • The image on the right is what a specialized prosthetic for athletes looks like now, they make use of a device with a curved blade, which provides a good balance between flexibility and strength to withstand high- impact activities like sprinting and jumping.

From these design and material advances, more endeavors have been made to aid people in somewhat returning to a normal life (as well as attempts to make less expensive alternatives for those who can’t afford certain prosthetic’s), and furthermore provide less fortunate people an opportunity to at least recover from trauma.

A research study, taken by the University of Southampton, published in the journal of Global health. Talks about how they’re helping countries like Cambodia plan future prosthetics and orthotics.

It mentions: “thanks to a grant from Global challenges Research Fund, the University’s People Powered Prosthetic group and Exceed Worldwide, a Non-governmental Organisation (NGO) which trains specialist staff and provides P&O services- like supplying prosthetic limbs, braces, wheelchairs and community support- were able to access and, for the first time, analyse routinely collected data from existing electric patient records in an aggregated and anonymous way”

This indicates that by determining patterns in the cause of injury and disease from which amputations are required. Together with cross referencing data from the data from current patients, applications of prosthetics can be made specifically for these people, which can provide opportunities to return to work and sustain both themselves and their family.

CASE STUDY- AN ATHLETES POV

From another perspective- of someone with congenital (birth) defects- more specifically an athlete would be Richard Whitehead (a Paralympic gold medalist in London 2012, and silver medalist in Tokyo 2020). He was born with a congenital condition with which had left him with a ‘double through knee amputation’ meaning he was born without the bottom half of his legs.

Even with this condition, he went on to set a world record for athletes with double amputation (which took place at the 2010 Chicago marathon). Unfortunately, he was unable to compete in the marathon at London 2012 as there was no category for leg amputees, and was refused permission by the IPC to compete against upper limb amputees.

Because of this he turned to sprinting to compete at the 2012 Paralympics. Here was where he obtained gold in the 200m T42 Athletics event, setting a world record time of 24.38 seconds. And later on in 2013 was appointed the first ever patron of Sacroma UK, a bone and soft tissue cancer charity.

CONCLUSION

From just the past few decades (as mentioned before) technological advances, aiding both design and material advances have allowed us to consistently come up with new and innovative ways to get people back on their feet both figuratively and literally. And its yet to show and slowing down in its rate of improvement.

Overall, from cases such as Richard Whitehead, who had taken his condition as something that will not stop him from reaching his dream. As well as other cases like the people from the research study who were provided with a means to recover from traumatic events like natural disasters. It’s clear to see that prosthetics have become an integral part in the lives of these people. And taking these examples, as starting points for more research, more persistent endeavours can be made from which, more ingenious solutions can be introduced and applied to treatment for potential patients in the future.

Treating the Invisible Pain: Prosthetics and Phantom Limb Pain

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I was initially intrigued by the concept of Phantom Limb Pain (PLP) because I was fascinated by how someone could experience pain in a body part they no longer possessed. The depiction of PLP in the sci-fi movies I watched when I was younger seemed to be a figment of the imagination; it appeared to be a mysterious occurrence, somewhat fantastical and an element of creative licence adding dramatic effect.

After further research, I discovered that this perplexing phenomenon is real, not make-believe! The basis of PLP although unclear, is suggested to be due to changes in an amputee’s brain organisation; more specifically, alterations in the somatosensory cortex responsible for processing sensory information such as sight and touch, thus affecting the perception of pain sensitivity.

For those who are unaware, PLP can occur within the first few days after amputation; and can persist without intervention. The symptoms vary from the perceived ability to voluntarily move the phantom limbs to intense pain and tingling sensations. PLP treatment is usually with pharmacotherapy, and prosthetic use is considered an adjuvant therapy.

So where do prosthetics come in?

A prosthesis is an artificial device that substitutes for part of the body that is absent due to amputation as a result of a disease or traumatic injury.

Weiss et al. (1999) investigated how increased use of the residual limb by a prosthetic could alleviate PLP by comparing the amount of PLP experienced by upper extremity amputees who wore either the Sauerbruch prosthesis or a cosmetic prosthesis. The Sauerbruch prosthesis allows for the performance of several activities by being connected to one of the muscles of the arm through a surgically created tunnel with cables that operate a rod inserted into the arm, allowing for the contraction and relaxation of the muscle connected to the prosthesis and therefore promotes substantial use of the residual limb. Contrastingly, a cosmetic prosthesis has little functional value and usually leads to the non-use of the affected limb in most individuals who use one. The study concluded that individuals using the Sauerbruch prosthesis have substantially less PLP due to direct motor control of and somatosensory feedback from the prosthetic hand originating in the muscle of the residual limb than those using a cosmetic prosthesis.

The original Sauerbruch arm
Cosmetic Prosthesis
Depiction of the functionality of the Sauerbruch Prosthesis

Modern myoelectric prostheses function like the Sauerbruch prosthesis, however, they utilise electrodes in the prosthesis to detect nerve and muscle activity along the residual limb musculature, which triggers motors in the prosthetic to control and produce the movement intended.

Basic Diagram of a myoelectric limb

Final Thoughts:

The understanding of PLP and prosthetics as an adjuvant treatment allowed me to consider further; whether cosmesis of prosthetics(making artificial limbs look lifelike, similar to the original missing limb) aids the alleviation of PLP, as the somatosensory cortex also processes visual information.

My learning extended to another study suggesting that the correction of body perception may modulate PLP. This hypothesis stems from the prosthetic ownership concept, whereby prosthetic use is experienced as part of the body rather than an attached device foreign to it. This added to my insight into the prosthetic treatment of PLP as the brain combines visual input and direct cortical-somatosensory electrical stimulation by the prosthetic, creating a multisensory illusion that an artificial limb actually belongs to the body, thereby reverting the somatosensory cortex to a healthy state.

Overall, PLP accounts for a significant reduction in the quality of life of amputees; thus, the development of prostheses with somatosensory feedback and a cosmesis effect is a promising therapeutic tool to reduce PLP.

Sustainability in Replacement Body parts

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Replacement body parts are a central part of the medical world with anything from an organ to a finger able to be replaced in a human body. With the world population growing and the expectation for a certain quality of life rising, demand for replacements are at an all time high but the issue coupled with this demand is the environmental impact of designing, producing and implanting replacement body parts into patients. One of the biggest issues in the world today is the battle against climate change and not only how individuals can combat this issue but how bigger corporations like the NHS can contribute to the fight, and as a knock on effect, this alters the way in which replacement body parts can be manufactured.

Waste in the NHS

Biodegradable materials in medicine

I’ve always been a keen enthusiast of lowering carbon footprint and doing my part to contribute towards sustainability in the world and I’m also very keep on advancing medicine but the true inspiration for this literature came from my work experience at Bournemouth Hospital in the orthopaedics unit. Shadowing an anaesthesiologist allowed me to encounter many different angles of a working hospital but the most interesting area was the orthopaedics unit. I watched several knee replacement surgeries and the hundreds of pieces of sterile machinery and equipment used in the replacements but also the amount of waste produced. It made me question all the waste produced on the bigger scale and the negative environmental impact the manufacturing of the tools and prosthesis used in everyday surgeries and procedures.

Impact of sustainability on replacement body parts

A visit from MatOrtho in a module workshop highlighted how the pressure for the NHS to have net zero emissions by 2045 put immense pressure on them as manufacturers of replacement body parts to find more eco-friendly ways of producing what they already produce. With there already being so many limitations and restrictions to the way prosthesis can be produced, finding sustainable ways to carry on with their work is proving challenging but what I question is, at what point can you justify the production of carbon emissions in order to improve the quality of someones life through the creation of replacement body parts?

I was surprised to find the arguments of some claiming that the state of global health is a greater issue than the quality of life of those with a debilitating injury or loss of a limb but with the rise of sustainability activists like Greta Thunberg, the whole world needs to be thinking of ways to be more sustainable, not just the bigger corporations.

What does this mean for the future of replacement body parts?

3D printed heart using organoids and stem cells

Medicine is constantly advancing and nearly everyday there are discoveries or advances in the scientific world that lead to the improvement or saving of someones life so at what point do you limit that? As of 2022, there were 7000 patients on a waiting list for an organ transplant in the UK but this number is expected to decrease as organoids have opened up a whole new pathway in the world of organ transplants.

However this research could be restricted with the increasing regulations placed upon industries in order to preserve global health. But, if you were to break it right down to the foundations of transplants and prosthesis to the patients and family, if you were given the option to change your mothers, fathers, partners life by giving them the opportunity to undergo replacement surgery but the outcome may result in damaging the planet, would you go through with it? I know I would.

Should ICD’s be classed as Prosthesis or Orthosis?

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A few weeks ago we had a lecture and a workshop all about prosthesis. Before the lecture I thought it would mostly be about prosthetic limbs and joint replacements. I didn’t consider the wide variety of things that could be considered prosthesis and I also didn’t think about orthosis.

I was particularly interested when he mentioned there is some debate as to whether pacemakers should be classed as prostheses or orthoses.

An X-ray image of my brother’s torso with his ICD fitted. This image was from a year after its implantation when he fell out of a tree and snapped the wire!

This in particular interested me as my brother has a heart condition called Long QT syndrome where, as you may guess, he has a prolonged QT interval of his heartbeat. Due to this, when he was a child, he collapsed three times and each of these times, his heart stopped. Therefore, at the age of ten, he had an Implantable Cardioverter Defibrillator (ICD) implanted subcutaneously.

A few fun facts about ICDs and people who have them:

Every 8-10 years he has to have it replaced as the battery wears out, and he gets an updated model – like a phone upgrade!

Also – magnets interfere with its function; therefore, he is unable to go through metal detectors at the airport, and when we hug him, we can’t have our phones in our hands!

Now back to the debate:

The definition of a prosthesis is an artificial device that replaces a missing or impaired body part. This can be internally e.g. a hip replacement, or externally e.g. a prosthetic leg.

An orthosis is defined as a device used to modify the structural and functional characteristic of the neuromuscular and skeletal systems through systems such as immobilisation or support. Orthoses are also usually external e.g. a foot orthotic corrects flat feet and other foot injuries.

An example of an ICD. Medtronic is the brand of ICD my brother has.

Next, what is the difference between a pacemaker and an ICD?

ICDs are similar to pacemakers. According to the NHS website, pacemakers send electrical impulses to your heart to keep it beating regularly and not too slowly. However, ICDs monitor the heart and send a larger electrical shock to the heart to restart it when it stops or to make the heart rate stop beating abnormally or dangerously.

So where does it fit in the prosthesis vs orthosis debate?

Tested against the definition of a prosthesis:

ICDs do not replace a missing body part, but it does replace the impaired function of the sinoatrial node, the body’s natural pacemaker.

And against the definition of an orthosis:

First of all, it is internal not external which is already rare for an orthosis. It doesn’t modify the structure of the heart, but it does modify the function in the event of abnormally high heart rate or when the heart stops.

The heart is not part of the skeletal system, but is it part of the neuromuscular system? The neuromuscular system is defined as the system affecting nerves and muscles. The heart is a muscle and also has electrical activity, so yes, it is.

The debate comes about because it does not fit either definition perfectly, I don’t think there is necessarily an answer. However, in my opinion it fits the description of being an orthosis more than it fits the description of being a prosthesis. Therefore, I would class ICDs as internal orthoses.

This is a video from the British Heart Foundation talking about ICDs