Humans are mobile creatures. The tendency to move and not stay in one place for too long is something that is ingrained in our DNA. So naturally, when we face restrictions along these lines, it can be very limiting. And our limbs, being our primary means of interacting with the world, can limit movement significantly if their function is lost. For this reason, a few researchers from the Massachusetts Institute of Technology made it their mission to help amputees regain what they lost and eventually came up with a groundbreaking new solution.
Proprioception is a sense within our brain that tells it where our body parts are and what they are doing. This essentially makes it an instrumental part for any sort of human movement. So, when creating prosthetic, functional limbs scientists have always tried to come up with ways to simulate this feedback mechanism. But scientists have understanbly not been able to crack this complicated problem; Not until now that is.
A team led by M.I.T biomedical engineer, Hugh Herr managed to figure it out and created a functional prosthetic leg with proprioception. The method Hugh Herr and his team used involved a lot of new concepts. Since our muscles are linked together, they enable motion by working with each other through expansion and contraction. And when the muscles are tied to a bone as in the case of a traditional amputee surgery, movement gets limited due to the breaking of the dynamic intermuscle relationship. The new method, however, involves grafting new muscle pairs onto the amputation site of a patient with an amputation that is below the knee.
Then. electrodes attached to the skin detect electrical activity in the grafted muscles and utilize it to control motors in the prosthetic leg’s ankle. This is made possible as the sensors in the artificial foot transmit proprioceptive feedback to the muscles. When this method was tested out on a patient, the procedure surprisingly restored almost natural limb control. It even enabled reflexive behavior as the researchers observed instances where the patient unconsciously flexed his robotic foot while walking up the stairs. Moreover, through the inclusion of torque sensors in the ankle that sends feedback, it allowed the patient to make even more precise movements such as increasing and decreasing the amount of force applied on a pedal, etc.
Prosthetics has advanced immensely over the past few years. Our researchers have come so far that now it feels like we are almost on the brink of achieving feats that were only seen in science fiction. With this new prosthetic system, not only do amputees gain back limb functionality but also gain back the feeling of being in control of their body. And the value of that feeling is something that cannot be measured. Based on these developments and the rate at which we are progressing, it is safe to assume that the future will be bright and filled with possibilities.