What Is a Microprocessor Knee?
A microprocessor knee joint is a lower limb prosthetic component that adjusts the resistance of the prosthetic knee to the user's gait by means of sensors, software and a built-in processor. The aim is to provide more stable, balanced and efficient movement by imitating the natural gait cycle as closely as possible.
The selection and programming of such devices are carried out by the prosthetics specialist (orthotics and prosthetics technician) according to individual gait characteristics, in line with the specialist physician's assessment and prescription.
The Gait Cycle: Stance and Swing
All prosthetic knee joints are designed to imitate the two basic phases of natural gait:
- Stance phase: The foot is in contact with the ground. The leg is slightly bent; while providing the resistance to bear body weight, it also acts as a shock absorber.
- Swing phase: The foot is in the air and swings forward. The knee bends further, allowing the foot to move on to the next step without catching on the ground.
Microprocessor systems can continuously monitor these phases and adapt in real time to situations such as speeding up and slowing down.
The Difference Between Mechanical and Microprocessor Knees
Mechanical knee joints are generally controlled by a mechanical lock, friction or pneumatic/hydraulic fluid systems. In these systems, since mostly only body weight activates the stance control mechanism, gait may be less natural.
Microprocessor knee joints, on the other hand, process sensor data to adapt fluid-based resistance to the person's gait. As a result, situations such as walking at different speeds and descending ramps and stairs may become more controlled.
Key Functional Features
- Gait adaptation: Flexion resistance and the swing phase can be adjusted automatically with real-time sensor data.
- Stumble support: When a possible stumble is detected, it may help the person regain balance by increasing knee resistance.
- Standing control: An intuitive standing function may be offered that helps distribute weight evenly over both legs on sloped or uneven ground.
- Durability: The resistance of devices to dust and water is indicated by the IP protection rating; it varies by model.
- Activity modes: Additional movement modes for specific activities can be programmed by the prosthetics specialist.
Activity Levels
The activity (mobility) level is a rating from 1 to 4 that indicates the person's general physical condition and potential to benefit from prosthetic options:
- Level 1: The prosthesis is generally used for transfers and short, slow movement on level ground; basic indoor walking is the goal.
- Level 2: Low obstacles such as curbs, single steps and uneven ground can be negotiated slowly.
- Level 3: Walking at moderate to high speeds, changing speed and negotiating most natural obstacles are possible.
- Level 4: Movement indoors and outdoors without restriction and with high functional demands is the goal.
The assessment of activity level and the determination of the appropriate solution are carried out through the joint assessment of the physician and the prosthetics specialist.
Factors That Play a Role in the Assessment
Which group of components is suitable varies from person to person. In the assessment made by the specialist physician, the following factors are generally considered together:
- Activity level and daily use goals: Which movements and activities the person aims to carry out in daily life.
- Level of limb loss and general condition: The amputation level, the condition of the residual limb and general health status.
- Physician's assessment and indication: Determining the solution deemed appropriate as a result of the clinical examination.
Clinical Evidence
Scientific research shows that microprocessor knee joints have been evaluated, in comparison with mechanical knees, in terms of reducing the risk of falls and improving gait symmetry. Each individual's results vary according to the amputation level, the condition of the residual limb and general health status.
This content is for informational purposes; you should consult your physician for diagnosis and treatment.
