The difference between mechanical and microprocessor-controlled knees
Information comparing the working logic of two above-knee prosthetic approaches, how they behave in daily life and how they are evaluated for different people.
What is the basic distinction?
In above-knee prostheses, the knee joint is one of the most decisive components of walking. The movement of this joint can be managed with two different approaches: mechanical knee systems and microprocessor-controlled knee systems. Both approaches serve the same purpose, namely safe and balanced walking; however, they differ in how they adjust the resistance of the knee.
In mechanical knees, resistance works on a fixed logic through preset hydraulic or mechanical mechanisms. In microprocessor-controlled knees, on the other hand, sensors continuously detect walking and a computerized control unit aims to adapt the behavior of the knee to the situation. Which approach is suitable is assessed individually by the specialist physician and team, taking into account the person's amputation level, activity level, safety needs and lifestyle.
Comparing the two approaches
The headings below introduce the general working logic of the two systems; the contribution of each approach to the person is assessed individually.
Mechanical knee systems
The resistance of the knee is determined by settings made in advance and usually works on a fixed logic. It aims to offer predictable walking under certain speed and surface conditions; the user is expected to adapt their walking to the system.
Microprocessor-controlled knee systems
Sensors continuously detect walking and the control unit tries to adjust the resistance of the knee to the situation. They are designed to offer additional support in adapting to changes in speed, slope and surface; the system needs to be adjusted to the person.
Stance and swing phase
Walking is roughly divided into two main phases. The stance phase is the stage in which the foot is in contact with the ground and the body weight is carried; here, controlled behavior of the knee is important for safe support. The swing phase is the stage in which the foot is in the air and carried forward; here, the knee is expected to move fluidly.
Mechanical systems manage these two phases with settings made in advance. Microprocessor-controlled systems, on the other hand, aim to adapt the resistance to the phase by evaluating sensor data for both phases. How this difference is reflected in daily life varies from person to person, and goals are always set individually.
- Controlled behavior of the knee in the stance phase is intended to support a sense of confidence during standing and support moments.
- Fluid movement in the swing phase is important for adapting to different walking speeds.
- Adapting the transition between the two phases aims for a more natural feeling of walking.
Key topics in the adaptation process
The difference between the systems becomes more noticeable in certain situations in daily life.
Slopes and ramps
Adapting the resistance of the knee on sloped surfaces such as hills and ramps aims to contribute to more controlled movement.
Mobility at home
In indoor areas such as the kitchen or living room, the behavior of the knee when changing direction and when stopping and starting affects comfort.
Descending stairs
In situations such as going down stairs, the controlled resistance of the knee may help guide the movement safely.
Example situations from daily life
The situations below give a general introduction to the daily use of the two approaches; results differ from person to person.
Getting around the city
In an urban environment where curbs, ramps and stairs occur together, adapting to different surfaces is a topic that affects walking comfort.
Spending time outdoors
In garden and outdoor activities, the behavior during standing and the support phase aims to contribute to the person feeling secure.
Walking on changing surfaces
On irregular surfaces such as a rocky path, the knee adapting to the situation is one of the supports aimed at maintaining balance.
Assessment and the right choice
Which of the two approaches is suitable does not depend on the features of the system alone, but on the person as a whole. Activity level, daily living needs, safety needs and general state of health are considered together. A system being suitable for one person does not mean it will be equally suitable for another.
For this reason, above-knee prosthetic fitting begins in line with a prescription or medical report issued by a specialist physician and continues through the stages of assessment, measurement, production, trial and gait training. Adjusting the system to the person and checking it regularly are an integral part of safe use.
- The choice is determined according to the person's activity level and safety needs.
- The fitting begins with a specialist physician's prescription or medical report.
- Gait training supports making effective use of the chosen system.
Frequently asked questions
What is the main difference between a mechanical and a microprocessor-controlled knee?
Mechanical knees manage resistance on a fixed logic with settings made in advance; microprocessor-controlled knees, on the other hand, aim to adapt the resistance to the situation by detecting walking with sensors and computerized control.
Is a microprocessor-controlled knee suitable for everyone?
No. Suitability is assessed individually by the specialist physician and team, taking into account the person's amputation level, activity level, safety needs and general state of health.
How does the behavior of the two systems differ in the stance and swing phases?
Mechanical systems manage both phases with settings made in advance; microprocessor-controlled systems try to adapt the resistance to the phase by evaluating sensor data.
How is the suitable system decided?
The decision is made by the specialist physician and team by evaluating the person's lifestyle and needs as a whole; it covers the stages of assessment, measurement, trial and gait training.
This content is for information purposes only; consult your physician for diagnosis and treatment. Fittings are carried out at our licensed center addresses in line with a specialist physician's prescription/medical report.