When thinking of advanced prosthetic technology some things which might come to mind are computerized knees or 3-D printed hands. However, these devices may not have been possible without Egyptian sandals and a single, cosmetic big toe.
If we’ve lost you here, let’s take a look back 3,000 years ago to 950-710 B.C.E. and the first known use of a prosthetic device. It is believed that the first user was a noblewoman in ancient Egypt. She was fitted with an artificial big toe to improve cosmesis and wearability of traditional Egyptian sandals. Use of this prosthetic toe was described as being “part function and part identity”.
Today, thankfully, the world of prosthetic technology has evolved leaps and bounds from these early toe days. However, the challenge of prosthetic devices still remains balancing use and cosmesis. Basically, 3,000 years later, it still comes down to “function and identity.” Each year, millions of dollars are spent funding research on emerging prosthetic technology to improve wearability and compliance with devices. Over the last century, as our understanding of biomedical technology has boomed, so has our development of prostheses.
Myoelectric Prostheses
The direction the prosthetic technology field is moving is toward lightweight yet precisely controlled devices. One major area of development is myoelectric prostheses. Myoelectric prostheses use electromyographic (EMG) signals from a muscle or muscle group to perform a specific function. Advances in this technology are being combined with new surgical innovations to gain very specific, targeted muscle innervation. An example of this is a user of a prosthetic hand.
In this case, say the individual underwent surgery to insert sensors into the skin of the residual shoulder and upper chest. The prosthetic hand can be programmed so that when the user flexes the biceps muscle, the sensors relay a command such as opening the thumb. Further work is currently being done to allow users to perform complex tasks by reading patterns of muscle activation.
In the same example, perhaps the user wants to open the thumb and bend the wrist at the same time. The myoelectric prosthesis might receive the signal of biceps muscle activation followed by triceps muscle activation, and know that means open thumb, flex wrist. When working with devices such as hand prostheses where movements are small and require dexterity and coordination, this could mean developing thousands of possible patterns which relay thousands of possible movements.
Osseointegration
Another growing field of prosthetic technology is osseointegration. Osseointegration is the process of anchoring a prosthetic device to a limb through surgical implantation. This has been researched on the upper limb using the humerus, and the lower limb using the femur and tibia.
One benefit of this technique is that no socket is required for a user to wear a prosthetic device. The device, whether it be an elbow, forearm, knee, ankle and/or foot, is attached directly to the surgically implanted anchor. The absence of a socket reduces the risk of pressure injury, improves comfort and increases ease of donning/doffing a device. Additionally, as the socket is often the largest part, the weight of the device is significantly reduced.
Early studies show improved compliance, reduction in nerve pain, and increased proprioception of the prosthetic limb. However, this is a fairly new procedure, beginning in the 1990’s, so long-term success is still being investigated.
Training and usability
An additional area of prosthetic technology which is rapidly evolving is the training and usability of these devices. Prosthetic rehabilitation has grown wildly over the last several years with the introduction of virtual and augmented reality. Studies have shown that training in a virtual environment can improve prosthetic use and control, and that these improvements carry over to real-world tasks. This type of training has been proven especially useful in the myoelectric prostheses mentioned earlier.
Augmented and virtual reality
Additionally, promising research is being completed on the use of augmented and virtual reality to reduce phantom limb pain after amputation. Phantom limb pain is estimated to affect anywhere from 27-85% of individuals with limb amputation and can be a huge barrier to independent living. So, the potential to recommend use of a virtual reality game to improve independence and function sounds like a pretty good deal.
To date, the advances being made on prosthetic technology are continuously expanding. A quick look through the Orthotic and Prosthetic Education and Research Foundation will show dozens of awardees who received funding just last year. Bearing in mind some of this research has already been years in the making, this field is expected to continue on this developmental boom. The hopes are, in the near future prosthetics can look, feel and function like an intact limb or joint. However, compared to the humble beginnings of basically an accessory to a flip fop, these devices have already come so far.
Comments