The modular (or endoskeletal) prostheses are characterized by an internal pylon-type support part, consisting of light materials such as aluminium, titan and carbon and interchangeable connections and components such as adaptors, knees and feet. The cosmetics consists of a mobile foam cover which glides into a nylon sock or other flexible material.
Prosthetic Feet
Today there probably exist one hundred or more different models of prosthetic feet at the disposal of people with prostheses.The Sach foot – classical in the past (with a hard ankle, i.e. without mobility in the ankle) is with a strengthened foot, resistance, and with an internal liner, surrounded by foam and there are not moving parts.
Monocentric prosthetic feet (with a single axis of rotation) are another possible choice and are usually preferred by the more active users of the prosthetic limbs.
The polycentric feet (with multiple axes of rotation) allow active movement on uneven or rough surfaces, on an incline or grass while they at the same time increase stability and comfort.
Dynamic response feet maintain and release back the energy when a person walks.
One of the advantages of this is the natural, smooth gait.
Children, Young people, sportsmen and active older people – they can all derive great benefit from the use of dynamic response feet.
Pylon-type Support Part
The pylon is the component of the prosthesis which transfers the weight between the socket and the prosthetic foot.Many people prefer dynamic pylons which facilitate the decrease of the impact transmitted to the stump every time the heel hits the ground.
This is particularly important for people participating in activities with a heightened degree of impact such as running and other sports.
The spring-like action of the dynamic pylon also helps forward movement by shrinking when the heel steps on the ground and then releasing when the toes step off the ground.
Some pylons can absorb the axis deviation, which allows rotation of the leg at 45 degrees in both directions, where the degree of resistance can be adjusted depending on the activity.
The absorption of the axis deviation could be an important characteristic for people who play gold or want to do dances.
Prosthetic Knees
Like in the area of prosthetic feet, the market today offers a variety of different models for prosthetic knees. They all fall in two main categories: mechanical and computer-enabled (microprocessor).Mechanical knees could be monocentric (single axis of rotation) or polycentric (multiple axes of rotation).
Monocentric knee functions as a main pivot and is strong, light and cheap. By using friction on sliding it prevents the leg from rotating forward too fast and allows for a constant single walking speed. Some monocentric knees have a manual key, which ensures additional stability for older and less active patients.
Polycentric knees are suitable for active people who would like a more dynamic and stable gait.
Knees could also be pneumatic (air-controlled movement) and hydraulic (liquid-controlled movement). They allow people with prosthetics to walk comfortably at different speeds.
Computerized or Microprocessor-controlled knees are the latest technology in knee prosthetics and offer people with prostheses the most stable and natural gait in comparison to the other knee models.
The embedded microprocessor analyses the gait 50 times per second and automatically regulates the reaction of the knee according to the surface on which it steps, i.e. performing an automatic adjustment of the length and frequency of the steps to the walking speed in real time.
The microprocessor control of the prosthesis ensures dynamics and safety to the fullest extent.
With the Wireless Remote Control, the patient can change the knee settings on their own and choose a different mode according the particular type of activity.
Microprocessor knees are more expensive, but they can be very useful to every prosthetic user, especially to those who are more active or who have undergone multiple amputations.