Myoelectric Prosthetics

Myoelectric prosthetics (prostheses) differ from other upper limb prosthetic options in the way the terminal device (e.g. hand or hook) is controlled (open and closed). While other styles use harnessing and gross movements of the shoulder, myoelectric prosthetics use the movement of residual limb muscles to control the myoelectric hand. This is done by sensors placed within the socket that detect muscle movements and intuitively create movement at the hand. A benefit of a myoelectric prosthetic device is that they have a much more natural, intuitive way of using moving a prosthetic arm.

There are different types of myoelectric terminal devices that can be used, depending on the needs of the user and their ability to operate the various functions.

Single Grip Terminal Devices

These are simpler myoelectric devices that allow the opening and closing of a single grip position. These could be either a hand or a hook, depending on the users’ needs and requirements. In general, a hand is for lighter-duty activities and a hook would be used in heavier-duty and dirtier environments.myoelectric prosthetics

Multi Grip Devices

These are more sophisticated myoelectric devices that offer multiple grip positions. These always take the form of a hand and use a combination of thumb rotation and varying uses of fingers to allow various grip patterns.Myoelectric hand

Myoelectric Prosthetics Control Strategies

There are different control strategies that can be used in a myoelectric prosthetic arm. These are dependent on the users abilities and available funding.

  • Single Site – as the name suggest this uses a single sensor to detect and initiate movement of the myoelectric hand. this is the simplest form of control
  • Dual site – This uses two sensors to allow voluntary opening and closing of the myoelectric hand. This can also be used to adjust the grip when using multi-grip devices. This is one of the more common control strategies used.
  • Pattern Recognition – This uses a series of up to 8 electrode channels and allows recording/training of muscle movement “patterns” to create the various movements of the multi-grip terminal device. This also allows more intuitive use of powered wrists and elbows.

As with any prosthesis it’s helpful to have a conversation with your prosthetist to figure out what is appropriate for you and suits your needs. Get in touch with our friendly team below through our contact form and we’ll help you in any way we can.

Myoelectric grip options

 

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Prosthetic Hands

Prosthetic hands are devices that are used to replace some of the appearance and function of a human hand. Some prosthetic hands have limited or no movement, but others can grip objects, hold pencils, and even move in a natural way. A prosthetic hand is also known as a terminal device, and this is because it doesn’t always look like a hand.

There are 3 main ways Prosthetic hands are used:

  • Passive – these prosthetics do no open or close. They are often used for cometic purposes but can also serve as a support for some activities such as catching, or stabilising an object etc.
  • Body powered – these prosthetic hands open and close using a harness that is suspended over the shoulders. Movements of the shoulder opens or closes the hand to hold items. These hands either look like a hook or a hand.
  • Myoelectric – these prosthetic hands are controlled electrically using sensors that detect your muscles moving to open or close the prosthetic hand. Similarly, these can be a hook or a hand. Typically, these can also incorporate multiple hand movements to improve the function of the prosthetic hand.

There are many different hands that are designed to do various unique tasks. Often upper limb (arm) prostheses are used for specific tasks and people might use several prosthetic hands interchangeably:

  • Bike riding – this hand allows grasp and release of the handlebars.

prosthetic arms

  • Gym/working out – these kinds of hands allow grasping of various gym equipment and can serve as stabiliser for floor-based workouts e.g., push-ups, planking etc.

prosthetic hand user in the gym

  • Custom tools – these prosthetic hands are generally used for everyday tasks such as preparing and eating food and allow use of tools perhaps for the purpose of the user’s job e.g., cutlery, hammer, saw etc.
  • Gardening/home maintenance – this prosthetic allows the user to grasp of larger two-handed tools e.g., broom, mop, rake, spade etc.
  • Sport specific – these prosthetic hands are designed for the specific sport the user plays or participates in e.g., golf, swimming, and cricket etc.

 

Please contact your prosthetist if you have any further questions, we are willing to go above and beyond to create a prosthetic hand to suit your needs and help you reach your goals.

 

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Prosthetic Arms

Our APC Prosthetics team can custom design prosthetic arms for you, for improved comfort and function using lightweight, reliable materials. Our team will work closely with you to agree on a prosthesis that is the appropriate fit for you based on level of amputation, functional capabilities, goals, and activities you enjoy to the best of your abilities.

Prosthetic Arms Cosmetic Prosthesis – Passive Prosthesis

prosthetic arms

A cosmetic prosthetic arm does not usually provide active functionality and they are commonly designed to resemble a lifelike arm. These can be used as a supportive guide when using your opposite limb and for maintaining muscle usage of the proximal muscles. Some options available to make this resemble a limb can include a cosmetic stocking, silicone cover or exoskeletal prosthesis with a pigment mixed in to match the colour of the skin. If there is a specific design that you have in mind and you’d prefer to have a pattern, logo, or picture on your prosthesis, it is important to discuss this with your prosthetist so we can design the perfect prosthetic to suit you.

Pictured here is a Passive Prosthetic Arm which allows this paediatric client to ride their bike. The terminal device can be easily unscrewed and replaced with other devices which makes this very versatile for the clients needs, goals and ambitions.

Specialty Prosthesis

There are a few options available, the most common type of specialty prostheses are body powered which allow the user to control the hand or hook by a harness system fitted around their chest and shoulder. Another option is the externally powered prostheses controlled by a battery powered electric motor, with sensors that pick up the EMG signal on the skin to control the prosthetic arms elbow or wrist. Hybrid systems can be used for above elbow amputees and are a combination of externally and body powdered prostheses which provide a functional elbow and hand.

To achieve the best outcomes for our clients, we are willing to go above and beyond to create a prosthesis to best suit your needs whether this be a cosmetic or a specialty prosthetic arm. If you would like to learn more about upper limb prosthetics click here.

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What Materials are Commonly used for Prosthetics?

The prostheses that are delivered to our clients are broken down into two groupings of prosthetic materials. The top of a prosthesis is a custom manufactured socket which is fabricated onsite within the APC prosthetic workshop. Moving downwards on the prosthesis is the second grouping of materials including structural components, prosthetic joints (i.e. hands/feet) and everyday consumables (i.e. liners/knee sleeves). These are always client-specific and ordered from a variety of prosthetic wholesale providers around the globe. Read below to find out further information on these materials used for prosthetics.

Materials used for Prosthetics

1. Prosthetic Sockets

Diagnostic Socket

To begin the journey of a definitive prosthesis, our clients are initially fit with a ‘Diagnostic Socket’ which is manufactured from their plaster cast. The primary aim of this socket is to optimise the socket fit, refine the alignment and ensure the prosthesis absolutely meets all necessary functional and comfort goals.

Materials Used for prostheticsA diagnostic socket utilises materials in prosthetics which are suitable for a short-term trial period. These include thermoplastic sheets which are heat blistered and vacuumed onto the clients plaster cast. Following this step, the socket is attached to a lamination anchor which provides the connection between the custom-manufactured prosthetic socket and the remaining prosthetic componentry (ie. Prosthetic foot). To ensure safety and security, the anchor is secured to the socket. This can be done in a variety of ways from wrapping it in a fibreglass bandage, laminating carbon fibre or fibreglass over it. Once this is achieved, the diagnostic socket is ready for a short trialling period!

 

Utilising a rigid thermoplastic is beneficial in two ways. Firstly, it allows for reheating and adjustment so that pressure areas can be relieved. Secondly, the clear plastic allows the prosthetist to inspect the fit across the entire residual limb whilst the prosthesis is donned.

Definitive Socket

Once the prosthetic socket fit and alignment have been optimised, the diagnostic socket is ‘duplicated’ creating an identical plaster mould which allows our client to continue to wear their prosthesis whilst an APC technician concurrently manufactures their ‘definitive socket’. In addition, the duplication process allows for an identical alignment to likewise be captured which streamlines the definitive fitting process and removes the need for major alignment adjustments.

The materials used for prosthetics and the definitive socket vary considerably depending on the client’s presentation, suspension method and socket interface. Irrespective of these variables, all definitive sockets will undertake at least 2 separate laminations, they can manufacture with a single lamination however 2 is more common with varying amounts of prosthetic materials.

The plaster cast will be first either sealed with lacquer, a compressible liner, PETG or a flexible inner depending on what the prosthetist has deemed most suitable to the client. Next, a client-specific amount of carbon fibre, aramid fibre or fibreglass braid/matte is laid onto the socket and reinforced with unidirectional carbon fibre tape. It’s then sealed under vacuum with an acrylic resin which penetrates and solidifies the material. The initial lamination is focused on creating a strong, structured framework.

As the alignment has been duplicated in a jig transfer, the lamination anchor is attached in a similar process to diagnostic sockets. However, for the fabrication of the definitive socket, a great deal of detail and attention is paid to create a cosmetic appearance with the use of foam and putties.

The second lamination utilises similar materials to the first, however, its focus instead shifts towards strength and security of the lamination anchor to the socket. Importantly, each lamination is completely different because every client presents slightly differently in terms of, mobility, weight and intended activities (such as running).

Specialised Sockets (Design)

Many clients opt for a specific design to finish their prosthetic sockets ranging from Indigenous Art to sports teams – there is such a variety! Clients are encouraged to bring in fabrics, old t-shirts or designs which they desire on their final socket.

Specialised Sockets (Waterproof)

As an Island Nation with blistering summers, waterproof prostheses are essential! The lamination process is largely similar; however, it includes two additional laminations to finish with a cosmetic appearance which reflects the sound side limb. The APC technician precisely shapes foam around the socket according to the client’s measurements. This process removes the need for standard tube clamps and pylons which rust in water-based environments.

Specialised Sockets (Cosmetic Finish)

Similarly, to a waterproof prosthesis, a cosmetic finish utilises a foam which is shaped by an APC technician according to client measurements. Tracings of the sound side limb can be taken to ensure the prosthesis is as aesthetically appeasing as possible.

Specialised Sockets (Recreational)

Recreational socket materials used for prosthetics

The initiation of the National Disability Insurance Scheme (NDIS) has allowed many clients the opportunity to explore a recreational prosthesis such as running blades, rock climbing arms/legs, weight-lifting arms, surfing legs, cycling legs and many more. The custom design and materials used in prosthetics, allow for many recreational prostheses to be achieved.

Final and definitive prostheses reflect the great deal of detailed hours undertaken by both the prosthetist and technician to create custom-manufactured prosthetic sockets.

2. Prosthetic Componentry

Underneath the prosthetic socket is the second grouping of prosthetic materials – componentry. These are manufactured on a large scale by prosthetic wholesale companies across the globe producing materials in prosthetics such as feet/hands, connective componentry, pins/locks, valves, pylons, adaptors, liners etc.

Importantly, despite being mass-produced, the prosthetist orders componentry which specifically meet a client’s presentation, goals and intended activity. For example, one prosthetic foot may entail up to 10 different weight categories, it’s essential to obtain the current category for the client to ensure the best possible outcome.

I. Feet

  • Wood, plastic, and foam are usually materials used in prosthetic feet designed for individuals who have low activity levels and require stability
  • Carbon fibre feet is also one of the materials used in prosthetic feet designed to meet one’s functional needs for shock absorption and energy efficiency

II. Connective Componentry

  • Aluminium, stainless steel, carbon and titanium are materials used in prosthetic connective componentry.
  • Standard adapters are used to build the prosthesis, connecting the socket to a prosthetic joint and/or to a terminal device/foot.
  • Functional adapters such as torsion and rotation adapters help make every day and/or recreational activities easier for patients by expanding the abilities of their prostheses.

For more information on materials used for prosthetics please get in contact with the team below!

 

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Prosthetic Fingers

The objectives in upper limb prosthetics is to meet the requirements for our clients work, lifestyle and recreational needs of each amputee in order to reach a pleasing outcome. Technological advancements over the decades  have been made in body powered prostheses, external powered prostheses, hybrid systems and the sockets & interface. Improvements made with upper limb prosthetics, specifically in myoelectric units has vastly increased the opportunities and possibilities for prothesis such as Prosthetic Fingers.

Body Powered Prosthesis

The most common type is the Body powered Prostheses. They allow their prosthetic user to control the terminal device (that being a hook, hand or prosthetic fingers) that fits around the users shoulder or chest via a harness. The body powered prosthesis is reliable, durable and can be used for places where dust and water are present though some have found it cumbersome and uncomfortable.

Externally Powered Prosthesis

Externally powered prostheses use a battery powered electric motor to control the terminal device, which removes the need for a harness. The sensors that are implanted in the socket, picks up an EMG signal on the skin and sends that signal to a processor which controls the functions of the motor. The motor then powers the elbow/wrist or terminal devices. Training with your prosthetist and occupational therapist along with the training apps which is essential to have a successful outcome. The apps available with the myo-electric have the option of allowing for custom movements or settings for specific movements that fit your needs in most cases. To be considered for a candidate for a Myo-electric there must be enough viable muscle sites.

Hybrid Systems

Hybrid Systems are a combination of externally and body powered prostheses. This specific type of prosthetics can be used for Trans-humeral (above-elbow) amputees. By allowing restoration of elbow and hand this has allowed one of our clients to get back on his motorbike. The elbow joint is controlled via a harness system and the hand or hook is controlled through an external power source such as myo-electrically.

Upper limb prosthetics is a highly customised process in not only the prosthesis itself but for the socket design as well. Being highly customisable allows the socket for your upper limb and prosthetic fingers not only for adults but for our paediatric clients as well. To find out more about our Upper Limb Prosthetics click here.

Prosthetic Fingers

 

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Care for your Skin

How to clean your residual limb

Being a new amputee now requires you to take care of the skin on your residual limb. We have created a simple 3 step process that shows how to best clean your residual limb. A combination of washing the limb with soap and moisturising the limb regularly will not only make it easier to wear your prosthesis, but will also reduce the frequency of rashes, bacterial infections etc., from appearing on your residual limb. For more information about other skin issues, please download the Residual limb care guide at the bottom of the page.

Step 1: Wash with a mild soap (pH = less than 7)

Step 2: Moisturise after wash to prevent dryness. Only apply moisturiser in the evening.

Tip: If you are a new amputee or have high volume fluctuations in your limb, it’s recommended to shower at night. The heat of the shower and your limb hanging down can make it harder to don your prosthesis in the morning when most users experience their highest volume of the day already. Give it a go!

Care for your Prosthesis

Upper Limb (UL) users: Your socket should be cleaned weekly. You should regularly clean the hand and/or cosmetic glove.

Transtibial (BK) users: Your socket should be cleaned weekly.

Transfemoral (AK) Users: Your socket should be cleaned daily.

 

How to clean your socket & components

When cleaning your socket, wipe your socket with a damp cloth and a mild detergent and dry it thoroughly before you put it back on. It is not necessary to use an antiseptic to clean your socket.

Tip: Never use Dettol or other solvents to clean your socket or liner.

 

Wet/Dirty Prosthesis: It’s important to clean the components as well as the socket. Tip your prosthesis upside down to empty any water out of the foot shell. Use a shoe horn to lever off the foot shell. Remove, clean and dry the spectra sock (nylon sock between the foot shell and carbon fibre foot). Rinse out and dry the foot shell. Put the spectra sock back over the carbon fibre foot and use a shoe horn to reattach the foot shell.

 

Cosmetic Cover: If you have a cosmetic cover, it is important to keep this clean as well. A hard cover can generally be cleaned in the same manner as your socket. A soft/foam cover with stockings – you can wash the stockings as you would any hosiery/delicates. Wipe the foam with a slightly damp cloth and allow to dry before redonning the stockings.

Tip: Remember, keeping your prosthesis clean and drying after getting wet is crucial for maintaining longevity of the components and preventing rust or damage.

Upper Limb Prosthetics

The main objectives in upper limb prosthetics are to meet the vocational, recreational and lifestyle needs of each amputee and to achieve an aesthetically pleasing outcome. Upper limb prosthetics management is a highly customised process.

Significant technological advancements in recent decades, especially the use of myo-electric units and targeted muscle reinnervation (TMR) have vastly increased the possibilities and capabilities of many Upper limb prosthetics users.

The basic components of Upper Limb Prosthesis are:

  • Terminal device – attached to the distal end of the prosthesis to provide function. This may include hands, hooks, other activity specific devices.
  • Socket – envelopes the residual limb and provides the foundation of the prosthesis
  • Harness – provides stability and suspension of the prosthesis and combines with the control system to provide function; &
  • may also include a wrist, elbow and shoulder joint.

There are several different types of prostheses for upper extremities. Your prosthetist will work closely with you, your rehabilitation specialist and other allied health team such as PT & OT to devise the solution right for you.

Upper limb prosthetics

Body Powered Prostheses (Conventional)

Body powered prostheses are the most common type of upper limb prostheses. They allow the prosthetic user to control the terminal device (usually a hook or a hand) via a harness system that fits around the chest and shoulder. This type of prosthesis is reliable, durable and can be used in environments involving dust and water though it can be cumbersome and uncomfortable for some.

Externally Powered Prostheses (Myo-electric)

Externally powered prostheses use a battery powered electric motor to control the terminal device, eliminating the need of a harness system. Sensors, embedded in the socket, pick up an EMG signal on the skin and transfer it to a processor which controls the functions of the motor. This motor then powers the elbow/wrist or terminal device. Intensive training with your prosthetist and occupational therapist is essential to ensure a successful outcome. Many myo-electric devices come with training apps that you can use in the comfort of your own home. You can also add in custom movements or settings for your specific needs in most cases. There must be enough viable muscle sites to be considered a candidate for this style of prosthesis.

Hybrid Systems

Hybrid systems are a combination of externally and body powered prostheses. This type can be used for Trans-humeral (above-elbow) amputees, providing functional restoration of elbow and hand. Usually, the elbow joint is controlled via a harness system and the terminal device is controlled through an external power source, for example myo-electrically.

Cosmetic Prosthesis

This type of prosthesis is traditionally considered purely cosmetic and does not provide functional restoration. However, there are many benefits and uses of ‘cosmetic’ Upper limb prosthetics, including but not limited to using as a support/brace when using your contralateral limb (eg. Holding down paper with your prosthesis as you write) and maintaining muscle usage/limiting wastage of the proximal muscles. Having the cosmetic prosthesis present is often beneficial for regaining a sense of self confidence, and often has a positive effect on mental health. A cosmetic glove is applied to match individual skin colour.

Socket & Interface

The purpose of the prosthetic socket is to transmit forces from the residual limb to the prosthesis. The socket suspension, interface/liner design and prescription will be chosen to work with you level of amputation, residual limb shape and available funding.

Specialty upper limb prosthesis

Upper Limb Prosthetics – More Information

For more information on Upper Limb Prosthesis, view the following pages:

 

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Support Services

Physiotherapy, Occupational Therapy & Exercise Physiology

Physiotherapy is currently available onsite at APC ‘s Alexandria and Northmead offices to assist amputees in varying stages of their prosthetic usage:

  • Gait re-education from initial fitting of the first prosthesis through to advanced functioning (eg. return to recreational activities, running, gym programs).
  • Upgrading/teaching the use of a new prosthetic prescription.
  • A program for the use of micro-processor knee joints.

Physiotherapy at APC Prosthetics is provided by Cathy Howells, a registered physiotherapist with a special interest in amputee rehabilitation and over 30 years’ experience working exclusively with amputees.

It is important as an amputee or someone with limb difference to maintain good muscle strength, flexibility and stability, to ensure your ability to use your prosthesis continues well into your later years. Working regularly with a physio throughout your life as a prosthetic user, can act as a reminder to engage the muscles you may not be using as much as you should be, or to help you kick some bad gait habits you may have developed. OTs can help you learn how to use your prosthesis (especially Upper Limb) for specific tasks and training, along with recommending any modifications that need to be made to your home or car. EPs are great for ongoing amputee targeted training, or if you have a sport or recreational activity you would like to learn to get back to or start doing since being an amputee.

How you access a physiotherapist and other allied health services depends on your funding.

  • ENABLE: https://www.enable.health.nsw.gov.au/
    • A referral from your GP will be required, you can get 5 free PT visits per year if you are on a care plan. We can assist by writing a referral to back up your need for this support service.
  • NDIS: https://www.ndis.gov.au/
    • Talk to your planner at your next plan review to ensure there is sufficient funding available for the number of visits you require for the length of plan. Your prosthetic AT Assessment and request will advocate for any additional services deemed necessary for you to succeed with your prosthesis and goals.
  • INSURANCE: This will be negotiated with your case manager.
  • PRIVATE: There is always the option to go directly to a PT etc if covered by private health insurance or by paying directly. Your prosthetist can write a letter of referral/handover to communicate with your chosen provider in order to best help you succeed.

Medical Services 

The team at APC Prosthetics work closely with your rehabilitation specialist to ensure you receive the best treatment outcomes based on your health, healing and any other medical conditions that may affect your prosthetic use. Due to the long history of APC attending many amputee clinics for over 20 years, we have solid communication and a multidisciplinary team approach that leads to the quality service you will receive.

 

Support Services:

  • LIMBS4LIFE: https://www.limbs4life.org.au/
    • Limbs4Life is a charity that provides peer support options, amputee resources and wellbeing information. They also provide independent support to help you navigate disability and health-care system. They also offer social events and activities for amputees of all ages.
  • AMPUTEES NSW: https://www.amputeesnsw.org.au/
    • Amputees NSW is a volunteer based community organisation that provides support to anyone affected by limb difference. They aim to improve access to quality programmes, and news of upcoming events.

Specialty Prostheses

Specially designed prostheses are often required when an amputee wants to perform activities that exceed day to day ambulation or activities.

APC Prosthetics continues to lead the profession in prosthetic innovation. Our team is internationally recognised in specially designed and sporting prostheses in a broad range of activities including athletics, skiing, cycling, golf, weightlifting and more. If you are interested in competitive or social sporting activities, we are happy to provide contact details for the respective sports institutes and sporting bodies.

Waterproof Prostheses

The most common specialty prosthesis is a waterproof prosthesis, which enables the amputee to use the prosthesis for tasks involving water, such as showering, swimming, or accessing the beach. Recent development of waterproof fibreglass feet have provided great advances in water-based recreational activity, and specially designed devices are also available to allow for the use of flippers.

Recreational Prostheses

The development of “hybrid” prosthetic components has expanded greatly, in particular the numerous designs of prosthetic feet which allow the amputee to access a wide range of recreational activities without compromising general walking e.g. Cheetah Xplore, Pro-Flex XC Torsion, etc.

Task Specific Prostheses

A prosthesis used for a specific task/sport/activity – e.g. A weightlifting arm, drawing attachment, skiing or running prosthesis, etc.

If you have any questions about specially designed prostheses, please contact us.

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