Why use 4 bar linkage in prosthetics?
Four-bar linkage knees provide greater toe clearance during the swing phase of walking than do single-axis knees. A plot of hip-toe distance versus knee-flexion angle demonstrated four-bar knees are able to shorten the limb with less knee flexion than is needed using a single-axis knee.
What is a polycentric knee?
Polycentric knees, also referred to as “fourbar” knees, are more complex in design and have multiple axes of rotation. Their versatility is the primary reason for their popularity. They can be set up to be very stable during early stance phase, yet easy to bend to initiate the swing phase or to sit down.
What is hydraulic knee?
Hydraulic and pneumatic knees allow adjustment of walking speed by the use of hydraulics (either liquid or air) within the knee. This type of knee is often used for more active patients who vary their walking speeds and do not need assistive walking devices. Hydraulics can be used with single axis or polycentric knees.
Can you walk without a patella?
Though the kneecap is not needed for walking or bending your leg, it makes your muscles more efficient and absorbs much of the stress between the upper and lower portions of the leg. Climbing stairs and squatting can put up to seven times your normal body weight on the kneecap and the joint behind it.
How does an intelligent prosthetic knee work?
Intelligent walking The intelligent knee joint continuously monitors which phase of the gait cycle the prosthesis wearer is in and adjusts in real time. As a result, the user of the prosthesis has a more natural gait and can move the knee joint more easily.
What is bent knee prosthesis?
The BKP treats the patient as a case of knee disarticulation/above knee amputation, the person essentially rests his weight on the bent knee and the weight is distributed to the anterior proximal tibia, the patella tendon, patella, and the thigh corset. The residual limb is forced posterior.
What makes a polycentric knee a safety knee?
This knee is sometimes referred to as the “safety” knee. The polycentric knee has a variable center of rotation allowing for stability at all phases of gait. The 4 bar linkage also allows the knee to collapse better during the swing phase of gait, essentially shortening the shin and allowing the foot to clear the ground easier.
What makes a 4 bar prosthetic knee better?
The 4 bar linkage also allows the knee to collapse better during the swing phase of gait, essentially shortening the shin and allowing the foot to clear the ground easier. This collapsing feature also allows the knee to bend easier for sitting and is the ideal knee for knee disarticulation or long above knee amputees.
How does pneumatic control work on a prosthetic knee?
Pneumatic control will compress the air as the knee is flexed and then stores the energy and releases it with knee extension. Spring coils can be added for more control during gait. Pneumatics or hydraulics are also added to computerized prosthetic knees.
What are the different types of prosthetic knees?
Introduction Prosthetic knees can be divided into Mechanical or Computerized. Mechanical knees can then be subdivided into single-axis and multiaxis/polycentric knees. All prosthetic knee require some sort of stability mechanism, this can be manual or a weight-activated locking system.