New Advances in Prosthetic Medical Application Solutions
By Chris A. Harmen
One major hurdle that the medical profession faces is providing effective prosthetics for amputees that can mimic the real motion and stability of an actual leg. Restoring a full range of motion to a patient who has lost a leg is the overall goal of medical application solutions.
The human body and leg are both amazing things when in operation. The body reacts naturally to its environment – the muscles and tendons are used to dampen movement and adjust limb movement to pace, terrain, and ground conditions. All of these complex motions and corrections happen unconsciously as a reflex. Putting one leg in front of the other is a gross simplification. A prosthetic leg that is just a solid piece with a hinge for a knee is woefully inadequate.
Any synthetic solution would have to incorporate a complex system of feedbacks and motors in order to simulate real movement and allow a patient to move without awkward motion that could eventually lead to back problems or stress on the compensating uninjured leg. The entire leg would have to be light weight and high strength in so that it may be practical. All of the moving parts would also have to be able to deliver enough power to propel a full grown adult while still meeting size and weight constraints.
A Practical Medical Application Solution
The physical power and dampening effects of a replacement prosthetic is achieved through the use of DC micro-motors. These DC micro-motors with metal brushes deliver high torque in an extremely compact and lightweight package. The high efficiency motor operation allows the battery operated leg to be used for up to two days before a recharge is necessary.
The DC micro-motor is a high performance 10mm model that functions via friction gears in a nested, planetary set. This DC gearmotor serves to adjust a damping valve. With each step, the dampening effect can range from its maximum level to almost zero and then quickly back again.
When considering any medical appliance for patient use, wide ranges of operating conditions have to be taken into consideration. Whether it is hot and wet, or cold and dry, all the components have to hold up to their environment. Each component has to be able to provide support for a maximum load or else it is considered a failure state.
DC micro-motors are capable of handling many years of continuous use, but every contingency has to be planned for. In the case of a mechanical failure, the leg will automatically switch to a full dampening mode. At this point, the prosthetic will effectively act as a wooden leg. It will be capable of holding a person’s weight, but will not be capable of powered movement.
Being able to provide realistic motion to a lost limb is every amputees dream and the ambition of the medical community. Using miniaturized DC micro-motors allows that dream to be realized. Packing a high torque motor into a small, efficient component has proven to be highly effective in designing the next generation of prosthesis.