In myoelectric orthoses or myoelectric prostheses, also called bionic hand prostheses, the EMG (electromyogram) is derived with the aid of surface electrodes on the muscles. The electronic hand is controlled muscularly (= "myo"). These signals from the muscles are then recorded by the respective control unit of the orthosis system and transmitted to the motors in a movement order. In the case of amputations, for example, patients have long been able to be fitted with myoelectric prostheses, especially myoelectric arm prostheses. Until now, the problem has been when a body part, for example the arm, is still present but its motor function is lost, because for a long time there were no suitable solutions for this in terms of disability compensation. Myoelectric orthoses and prostheses can provide support in these cases and thus restore the lost learning ability. As a result, everyday life can be completely redesigned. Grasping objects, holding objects, carrying objects and even fine motor grips are possible again.
How does a myoelectric orthosis work?
Like a mind-controlled hand prosthesis, the myoelectric orthosis, or myoelectric hand-arm prosthesis, detects the weak muscle signals on the surface of the skin and activates the orthotic movement thanks to integrated motors. To control the motors, derived EMG signals (electromyogram) are used. The signal is amplified many times over, so that even patients with severe paralysis can use the myolectrical orthoses. How long the diagnosis and paralysis have existed, for example, is irrelevant for Myo orthoses. The microprocessor-controlled high-tech prosthesis owes its high functionality to electrodes integrated in the socket. These electrodes convert the electrical voltage generated in the muscle strands of the residual limb into movement. Some of the fingers can be controlled individually (multi-articulating) and vibration signals can be used to provide feedback to the user for grip strength.
An industrially manufactured hand fitting is located at the end of the socket. It is selected depending on the individual needs of the prosthesis wearer.
Basically, a distinction is made between two different handpass parts:
Muscle signals are generated by tensing and relaxing the flexor and extensor muscles in the forearm. A microprocessor in the shaft of the prosthesis measures the myoelectric impulses via skin electrodes and uses them to calculate an electrical control signal for the motors of the prosthesis, which then allow the arm and hand to move.
What control systems are available for myoelectric orthoses?
When a limb, for example the arm, is amputated, the brain continues to send these signals even though some of the muscles are no longer present to respond to them. Bionic user control systems now intercept these commands and convert them into commands for the bionic orthosis.
There are the following user control systems:
- Myoelectric direct control - Myoelectric pattern recognition - Myoelectric control with surgically embedded sensors - Magnetomicrometry (MM) - Mechanomyogram (MMG) control - Advanced neural interfaces
The performance of some control systems can be significantly improved by surgical intervention.
Myoelectric control with surgically embedded sensors:
Surgical amputations involve the removal of damaged or diseased body limbs. Nowadays, surgery has the following options:
Reroute severed nerves to reduce limb pain and improve muscle control in the residual limb
reconnect severed muscle pairs to restore proprioception
Implantation of myoelectric sensors for better detection and interpretation of muscle movements.
Attaching electrodes to nerve bundles to facilitate sensory feedback
However, bionic hands will only be able to develop their full potential if true mind control and sensory feedback are restored. This requires a neural interface.
What is a myoelectric system hand?
The basic unit of all myoelectric hands is a functional grasping unit that opposes the thumb with a two-finger group (index and middle fingers). This system performs the pointed grip. The grip unit is then covered by a soft plastic shell, the system palm. This hand is both the shaping and supporting element for the prosthetic glove.
How does a myoelectric hand prosthesis work?
An artificial hand prosthesis has the following hand prosthesis function:
Myoelectrically controlled prosthesis with passive rotation of the hand:
The opening and closing of the hand is done by a muscle signal, while the rotation to the desired position is done by the received hand.
Myoelectrically controlled prosthesis with active rotation of the hand (pro- and supination):
Opening and closing, as well as rotation in both directions, are each performed via a specific muscle signal. A rotation insert is integrated into the prosthesis for this purpose.
Myoelectrically controlled prosthesis with electrical rotation of the hand (pro- and supination):
The hand is opened and closed via a muscle signal. The electrical pro- and supination is switched by slight rotational movements of the residual limb via a rotary control.
Myoelectrically controlled prosthesis with electrical rotation of the hand (pro- and supination) by means of four-channel control:
The hand is opened via a muscle signal. Via a stronger contraction, a higher muscle signal is achieved, the system automatically switches from opening and closing to rotation (pro- and supination). A less strong contraction brings the system back to the first function. Co-contraction as a further switching option can also be used, e.g. by briefly tensing both muscle groups.
Pattern Recognition System: Prosthetic hands with pattern recognition (e.g., wrist rotation, wrist flexion, various grips, grip patterns, individually controllable fingers) have a high level of functionality. In this case, the hand is controlled directly via the trained muscle signal.
For which groups of people are myoelectric orthoses suitable?
Primary eligibility for loss of function in arms or hands. This often occurs as a result of stroke, traumatic brain injury, infantile Cerebral palsy, MS (multiple sclerosis), Injury of the brachial plexus, Spinal cord injury, Cervical paraplegia (complete or incomplete), Spinal muscular atrophy or Polyneuropathy.
What is an orthosis and how does it differ from the myoelectric orthosis?
An orthotic or brace is a device worn to support, align or correct a body part. Orthotics are typically used to improve function and prevent injury. There are many different types of orthotics, each designed for a specific purpose. Some common orthotics include ankle braces, knee braces, and back braces.
The term orthosis is a collective term for aids from body-related medicine that are intended to provide the patient with more stability and mobility. Orthoses are used after injuries, for malpositioning of limbs or for rehabilitation.
An orthosis is an orthopedic aid attached to the external body that relieves, stabilizes and corrects joints, muscles and bones. These include bandages, support apparatuses, girdles, corsets and splints. Orthotics can be made of plastic, fabrics, silicones, metals or a mix.
What are the different types of orthoses & how do they differ?
Orthotics are often prescribed by a doctor to treat a specific injury or condition. Some common conditions that orthotics can help with are ankle sprains, knee pain and back pain. Orthotics can also be used to improve athletic performance. If you are considering using orthotics to treat a condition or improve your performance, talk to your doctor to find out what type of orthotic is best for you. Orthotics are a great way to improve function and prevent injury.
Difference between orthosis and prosthesis?
The difference between orthoses and prostheses: Orthoses support limbs and the trunk, relieve pain and prevent postural deformities. Prostheses replace a missing, amputated or incompletely formed body part.
When to use an orthosis? When is orthosis useful? For whom is an orthosis useful?
Prevent, reduce and stabilize malpositions
Restrict or increase joint mobility
compensate for muscle weaknesses or cramps (spasticity)
Reduce or redistribute burdens
Compensate for the length or shape of a body part
Orthoses are aids from the field of orthopedics. They are worn on the body to support, relieve and stabilize the function of existing joints and muscles so that the user can move again. There is a separate type of orthosis for each area of the body. A foot orthosis can provide support in the case of functional deficits of the foot or foot lifting weaknesses. There are arm orthoses as well as leg orthoses.
Orthoses are primarily used for the following diagnoses / indications:
For the correction of malformations
For trauma & injuries
For postoperative care
Who is entitled to an orthosis?
According to Section 33 (1) of the German Social Code, Book V, insured persons of the statutory health insurance are "entitled to be provided with [...] orthopedic and other aids that are required in individual cases in order to - to ensure the success of the treatment of the sick, - prevent an imminent disability or - compensate for a disability."
Who prescribes an orthosis and how is an orthosis prescribed? Does the health insurance pay for an orthosis?
Orthoses are, or should always be, prescribed on a separate prescription. On the prescription, the field number seven for aids is marked with the number seven. Furthermore, the exact indication or diagnosis in the form of the valid ICD-10 code, the number of aids, the product itself and an indication of the aid number (if available) must be included. Important: Have a look at our contradiction section. Here we collect exciting judgements for you, if it concerns cost units. You will find an example here: A 33 year old man has enforced his claim for a Myomo at the Federal Social Court against the DAK health insurance company.
How much does an orthosis cost?
The cost of a hand orthosis, for example, depends on whether you are a private or statutory health insurance patient. If you want to buy an orthosis privately, you can expect costs between €20 and €1,000. Otherwise, you apply for the aid at the health insurance. In most cases, the costs of an orthosis or splint are covered by the health insurance.
How high is the statutory co-payment for orthoses?
According to the definition in § 33 paragraph 8 SGB V, insured persons who have reached the age of 18 make a co-payment for each aid that is dispensed at the expense of the statutory health insurance. The amount of the co-payment is based on § 61 SGB V and amounts to 10% of the dispensing price, but at least 5.00 EUR and at most 10.00 EUR; however, in each case not more than the cost of the product itself. The collection of the statutory co-payment must be made by the service provider in accordance with § 43b SGB V. The collected payment is to be offset against the reimbursement claim of the service provider against the health insurance fund.
How long do orthoses have to be worn?
Many orthoses are worn only temporarily until the respective complaint has healed. Accordingly, the duration of wear and the healing process are directly related. In the case of physical disabilities, however, orthoses can also become a lifelong companion.
What is an ankle orthosis?
An orthosis is often prescribed for sports injuries such as torn ligaments or Achilles tendonitis. In this case, the ankle joint is stabilized by a U-shaped ankle orthosis, which also secures the lower leg with Velcro fasteners.
What is a foot orthosis?
Foot orthoses are primarily prescribed for foot malpositions in order to support or stabilize the foot and toes during purchase. A special case is the therapy of clubfoot, a mostly congenital foot malposition, for which orthoses are used in addition to casts and splints.
What is a wrist orthosis?
Wrist orthoses are prescribed for swelling and injuries of the hand. The wrist orthosis immobilizes the joints of the hand and fingers. However, this should only be done for as long as necessary, as the joints could stiffen. For this reason, the wrist orthosis is fitted and applied in the so-called intrinsic-plus position. In this position, the wrist tilts slightly towards the back of the hand, while the finger joints are bent towards the inside of the hand.
Especially in the case of carpal tunnel syndrome, a constriction of the median nerve, with numbness and pain in the hand, a wrist orthosis can reduce the strain on the pain.
What is an elbow orthosis?
Elbow orthoses are primarily used in cases of inflammation to protect tendons and muscles. The orthosis uses spring mechanisms to ensure controlled flexion and extension of the joint, while reducing mobility.
What is a finger orthosis?
Finger orthoses are used to immobilize joints or improve their mobility.
What is the difference between hand prosthesis and partial hand prosthesis?
If the hand prosthesis requires amputation up to the wrist, it is referred to as hand disarticulation. A hand prosthesis replaces the entire hand. In the case of a partial hand prosthesis, all procedures between a finger amputation and a hand amputation are referred to as partial hand amputation. Partial or partial hand prostheses replace individual fingers or thumbs as well as parts of the hand.
What is a passive hand prosthesis?
A passive prosthesis, also called a habitus prosthesis, is primarily used to restore your body image as realistically and inconspicuously as possible. In this case, the term "passive" must not be associated with function, but with a passive prosthesis, everyday bimanual activities can be performed again, such as holding and moving objects. It is therefore also a kind of cosmetic hand prosthesis.
Can you ride a motorcycle with a prosthetic hand?
Yes, this is possible again. Contact us. We work with manufacturers who specialize in motorcycling.
Which is the best prosthetic hand?
Feel free to look up diagnoses in our guide and find out about the selection of the best hand prostheses. Let us advise you and we will make the pre-selection for you.
Can you ride a bicycle with a prosthetic hand?
Of course it is possible. However, we recommend to start slowly and use a low entry bike. This bike has a specially designed frame that allows you to ride comfortably and also reach the ground with both feet without getting off.
Is the hand orthosis covered by health insurance?
It depends entirely on your case. Please consult your doctor about this. In most cases, if the aid is justified on the basis of your diagnosis, the health insurance company will pay for the hand orthosis. Private payers have of course the possibility to get the hand orthosis themselves. The price of the hand orthosis depends on the product. A myoelectric hand orthosis starts at four-digit sums.
Where can I buy a smart hand prosthesis?
For simple hand prostheses, we recommend your local medical supply store; alternatively, ask your doctor for advice. However, if you are looking for a high-tech hand prosthesis that can feel and intuitively apply all grip techniques, please let us advise you. We will recommend a suitable partner from our network.
Are there also prosthetic hands for children?
There are many manufacturers who offer hand prostheses children versions. Let us advise you.
Are there alternatives to myoelectric orthoses? What is the MM (Magnetomicrometry Systems) procedure?
A new possibility is to completely replace myoelectric systems with magnetomicrometry (MM) technology. How does it work? Small magnetic beads are implanted in each muscle. With the help of magnetic fields, sensors now continuously measure the distance between the implanted beads. The length and speed of muscle movement is measured and determined. This movement is then used to control the movement of the orthosis. MM sensors are incredibly precise and do not rely on skin contact.
But does that make any sense at all, because medicine is trying to enable patients to reach for something we want. For example, to grasp an object, one must know both the current position of the hand and the desired position.
We track the positions of our hands using proprioception. For example, when you want to bend your arm toward your chest, you tighten your biceps, which stretches your triceps. Your brain intuitively controls the muscle states to calculate the position of your arm. That's why you can close your eyes while doing this.
What is AMI (Agonist-Antagonist-Myoneural Interface)?
A newer procedure called agonist-antagonist-myoneural interface (AMI) restores this ability to recognize by having surgeons restore the muscle pairs.
Myoelectric or MM sensors are used to detect and interpret the movement of the muscles. Bionic orthoses therefore reflect these movements and the brain is again able to track the position of the limbs.
What is still missing is the so-called sensory feedback.
What is sensory feedback?
Neural interfaces were first used in 1924. Their introduction began with the cochlear implant and the pacemaker in the 1950s. Building on this, scientists developed brain-computer interfaces (BCI) in the 1970s. These concepts then evolved, for example, with funding for programs such as Hand Proprioception and Touch Interfaces (HAPTIX), which was launched in 2015 by the U.S. government's Defense Advanced Research Projects Agency (DARPA). Previously, neural interfaces were used for both control and sensory feedback.
Today this looks different:
DARPA two-way neural interface In this model, electrodes interacted directly with motor and sensory nerves, but the procedure also leads to problems, such as increased cost, a risk of scarring, and crosstalk. Therefore, nowadays, myoelectric sensors are used for the control functions and a neural interface for the sensory feedback. This is called DAPRA.
DARPA's hybrid neural interface for bionic hands provides the main advantage of this hybrid model over a purely myoelectric system, namely that the user's actions are better informed by sensory feedback. To make this process inflationary useful, a few challenges remain:
Abolition of invasive interventions
Risk: scars and infections Solution: The magnetic MM beads could be developed to be injectable.
Signal processing improvement
Risk: Not only do all signals have to be further amplified to a high degree, but sending them is also very computationally intensive. Solution: Artificial intelligence can solve the problem
Risk: Technology and primarily research must become more cost-effective Solution: Technologies such as 3D printers and falling chip costs can reduce costs in the long term.
What is the risk of wearing an orthosis?
We recommend contacting your doctor. You may experience the following symptoms:
What is neurorehabilitation?
Neurorehabilitation as a generic term deals with all neurological clinical pictures, both in medicine and in therapy and as aids. Primarily, this includes central nervous disease patterns in which the brain and or the spinal cord was damaged.
Traumatic brain injury
To do this, you need to understand how our body works. Nerves are transmitters of messages from the muscles. When we want to move, our brain sends these messages to the muscles and spinal cord. This transmitter system is called the nervous system, or CNS for short. However, in the above indications, it happens that the CNS has been chronically damaged. This in turn restricts mobility, because the information no longer reaches the muscles completely. Orthoses provide support here by stabilizing the limbs. In the case of pronounced paralysis, as in the case of a cross-section, wheelchairs (Scewo), stair lifts or electromobiles provide support.
In the course of medical development, however, there are nowadays other possible solutions. FES, pronounced "functional electrical stimulation," for example, in which the nerves near the affected muscles are stimulated. As a result, they receive signals again and can trigger the movement impulse, like a kind of jumper cable.