The importance of prosthetic knee joints for thigh amputees
Prosthetic knee joints are essential for patients with thigh amputations.
The motion function of the human knee joint is quite complicated, and the types and varieties of prosthetic knee joints are also the most in all prosthetic components. The knee joint is an important functional component in knee prostheses, thigh prostheses and hip and thigh prostheses, and it is also the most complex component.
The most basic requirement of a prosthesis for the function of the knee joint is that the knee joint can remain stable during the support period and bend the knee during the swing period. There are many types of knee joints with different functions. According to the number of rotation axes, knee joints are divided into single-axis knee joints and multi-axis knee joints.
According to the stability control method during the support period, knee joints are divided into manual locking joints, weight-bearing self-locking joints, and geometric locking joints. According to the swing period control method, knee joints are divided into single pendulum joints, friction control joints, pneumatic joints, hydraulic joints, and microelectronic control joints. Depending on the material, there are knee joints made of single alloy steel, stainless steel, and titanium alloys, as well as knee joints made of aluminum alloy and stainless steel, carbon fiber and stainless steel. For thigh prostheses with long residual limbs and knee dissecting prostheses, there are also specially designed knee dissecting joints.
Prosthetic knee joints should ensure stability during the support period and provide appropriate knee moments during the swing period to achieve flexible and natural swing. When the foot is off the ground and enters the swing phase during walking, the movement of the calf depends on the swing of the thigh and the torque of the knee joint. The size and pattern of knee joint torque are related to walking speed, road conditions and human body parameters. Knee joint torque can be provided by friction, spring force, pneumatic device, and hydraulic device. But they can only be adjusted once according to the condition of the amputee during the assembly of the prosthesis.
The gait following of the thigh prosthesis is very important, because if the joint damping cannot be changed, the prosthesis cannot change with the change of the pace of the healthy limb, resulting in asymmetrical gait and increased energy consumption of the amputee, which will cause great discomfort. sense. The traditional simple prosthesis uses mechanical damping, and its size cannot be adjusted or automatically changed with the pace. Therefore, the knee joint rotation speed in the flexion and extension phases of the prosthesis during the gait swing period is asymmetric with the healthy limb, and its stability during the standing period It is also mainly ensured by self-locking device or manual lock. In the 1960s and 1970s, prosthetic knee joints began to use hydraulic/pneumatic devices as damping elements. The swing speed can be controlled by hydraulic or pneumatic cylinders in the knee joint to use the needs of amputees to speed up or slow down the pace.
