Upper Extremity Prostheses: Harnessing and Control
Harness and Control Systems Below Elbow
Harness and control systems are integral components in assistive technology and prosthetics. Below-elbow harnessing, commonly used in upper limb prosthetics, is crucial for controlling prosthetic devices for individuals with below-elbow amputations. These systems enhance functionality, mobility, and ease in performing daily tasks.
What is Below Elbow Harnessing?
Below-elbow harnessing is a mechanism that enables the control of a prosthetic limb for individuals with amputations at or below the elbow. The harness typically consists of straps and buckles that work with the prosthetic’s control system. The primary goal is to offer a stable, comfortable fit while ensuring accurate response to the user’s movements.
The harness is worn around the shoulder and upper arm, secured with adjustable straps. These straps connect to a cable system linked to the prosthetic device, enabling control through the motion of the remaining limb or body part. Natural body movements are translated into actions for the prosthetic, facilitating tasks such as gripping, lifting, or manipulating objects.
Types of Harness and Control Systems
Several types of harness and control systems are designed for below-elbow prosthetics, varying in sophistication, comfort, and functionality. These systems can be categorized into body-powered and electrically powered (or myoelectric) systems.
1. Body-Powered Systems
Body-powered prosthetics use a mechanical connection between the harness and the prosthetic limb. User movements activate a cable system controlling the device. These are typically more affordable and require less maintenance but may have limited functionality.
a. Cable-Controlled Harness
In a cable-controlled system, the user moves their residual limb or shoulder to pull a cable, operating the prosthetic. This system is adjustable and durable, suitable for active lifestyles.
b. Voluntary Opening (VO) and Voluntary Closing (VC) Systems
These systems function based on force applied to the harness. A voluntary opening system opens the prosthetic when tension is released, while a voluntary closing system requires force to close it.
2. Myoelectric Systems
Myoelectric control systems use electrical signals from the user’s muscles. Electromyographic (EMG) sensors on the residual limb detect impulses, translating them into movement commands. These prosthetics offer smoother, more natural movements.
a. Direct Control Systems
Direct control systems allow activation of specific movements by contracting residual limb muscles. EMG signals are interpreted by the prosthetic controller.
b. Pattern Recognition Systems
Pattern recognition systems interpret a broader range of muscle signals, recognizing patterns associated with different movements. These systems provide more control and flexibility.
3. Hybrid Systems
Hybrid systems combine body-powered and myoelectric technologies, offering low maintenance and durability along with refined control and precision.
Conclusion
Below-elbow harnessing and control systems are fundamental to prosthetic limb functionality. While body-powered systems are simple and affordable, myoelectric and hybrid systems offer advanced capabilities. The choice depends on lifestyle, preferences, and user needs. As technology evolves, these systems will become more refined, providing greater control and mobility.
Shoulder Amputee Harnessing
Shoulder amputations are complex, and harnessing plays a critical role in enabling users to control the prosthetic. Proper harnessing is essential for functionality in everyday tasks.
What is Shoulder Amputee Harnessing?
Shoulder amputee harnessing involves straps, cables, and mechanisms designed to support a prosthetic arm for individuals with above-shoulder amputations. The harness stabilizes the prosthesis and enables activities like lifting and grasping. It must provide comfort and functionality, compensating for the loss of the upper arm and shoulder joint.
Importance of Shoulder Amputee Harnessing
A well-designed harness enables efficient control, mimicking natural limb movements. It distributes the weight evenly, preventing sores and discomfort. A well-fitting harness significantly improves the user’s quality of life and independence.
Types of Shoulder Amputee Harnessing Systems
Systems primarily fall into body-powered and myoelectric controls, with hybrid systems combining both.
1. Body-Powered Harnessing Systems
These rely on mechanical components and cables to transmit body movements to the prosthetic. They typically use shoulder and chest straps.
a. Cable-Controlled Body-Powered System
Remaining shoulder or torso muscles generate force to operate the prosthetic. This system is simple and durable but requires more effort.
b. Prosthetic with Locking System
A locking system ensures the prosthetic remains in position until activated, maintaining control.
2. Myoelectric Harnessing Systems
These use electrical signals from muscles to control movements. Sensors detect signals and transmit them to the prosthetic.
a. Electromyographic (EMG) Control
EMG sensors detect muscle signals, providing precise control with less effort.
b. Pattern Recognition Systems
Pattern recognition analyzes muscle patterns for intuitive control, making the experience smoother.
3. Hybrid Systems
Hybrid systems combine body-powered and myoelectric technologies, offering versatility.
Conclusion
Shoulder amputee harnessing systems are crucial for restoring functionality. Each type addresses unique needs, ensuring minimal effort and a natural experience. Advancements continue to enhance performance and comfort.
Clinical Aspects of Upper Extremity Prostheses
Upper extremity prostheses restore function and enhance the quality of life for individuals with upper limb amputations. Clinical aspects include selection, fitting, rehabilitation, and ongoing management.
1. Assessment and Prosthesis Selection
Assessment involves evaluating the amputation level, functional goals, lifestyle, and health conditions. Factors include:
- Amputation Level: Influences the type of prosthetic.
- Skin Condition and Residual Limb: Essential for proper fitting.
- Functional Goals: Determines the type of prosthesis needed.
- Psychosocial Factors: Assesses emotional readiness.
2. Types of Upper Extremity Prostheses
Major categories include:
- Body-Powered Prostheses: Use cables and harness for control.
- Myoelectric Prostheses: Use electrical signals for control.
- Hybrid Prostheses: Combine body-powered and myoelectric technologies.
- Cosmetic Prostheses: Designed for appearance, not function.
3. Fitting and Alignment
Proper fitting is essential for comfort and functionality. Adjustments ensure secure fit and natural movement.
4. Rehabilitation and Training
Rehabilitation includes:
- Motor Training: Learning to control the prosthesis.
- Functional Training: Performing tasks like eating and dressing.
- Psychological Support: Coping with body image and adjustment.
5. Maintenance and Follow-Up
Regular maintenance and follow-up ensure longevity and functionality. Patients are educated on home maintenance.
Conclusion
Clinical aspects involve a comprehensive process to provide a functional prosthetic. Proper training and support are essential for successful use.
Training in the Use of Upper Extremity Prostheses
Training is crucial for adapting to a new prosthetic limb. It involves learning to use the prosthesis effectively in daily activities.
Types of Upper Extremity Prostheses
- Body-Powered Prostheses: Operated by body movements.
- Myoelectric Prostheses: Use electrical signals from muscles.
- Hybrid Prostheses: Combine body-powered and myoelectric elements.
- Cosmetic Prostheses: Designed for appearance.
- Activity-Specific Prostheses: Customized for specific activities.
Training Process
Training is individualized and involves several phases:
- Initial Familiarization: Learning to put on and use the prosthesis.
- Functional Training: Practicing common activities.
- Advanced Skill Development: Tasks requiring greater dexterity.
- Ongoing Adaptation and Maintenance: Adjustments and continued training.
Conclusion
Training requires collaboration between the user, prosthetist, and rehabilitation professionals. Proper instruction enhances independence and quality of life.
Electromechanical Myoelectric and Other Powered Prostheses
Electromechanical and myoelectric prostheses use electrical or mechanical systems for natural limb movements. They restore mobility and independence for individuals with upper extremity loss.
Types of Electromechanical and Myoelectric Prostheses
- Myoelectric Prostheses: Operate via electrical signals from muscle contractions.
- Externally Powered Prostheses: Use external energy sources like motors and batteries.
- Hybrid Prostheses: Combine myoelectric and body-powered controls.
- Motorized Prostheses: Powered by electric motors.
- Powered Elbow and Shoulder Prostheses: Provide greater mobility.
Benefits and Challenges
Benefits
- Natural Movement: Myoelectric prostheses offer a natural range of motion.
- Enhanced Functionality: Perform complex movements.
- Intuitive Control: Controlled by muscle contractions.
Challenges
- Cost: More expensive than body-powered prostheses.
- Maintenance and Durability: Require regular maintenance.
- Complexity of Use: Extensive training may be needed.
Conclusion
Electromechanical and myoelectric prostheses provide functional and natural limb movements. Despite higher costs, advancements offer improved quality of life.
Study of Publication Sources for Upper Limb Prostheses
Staying updated on upper limb prosthetics is crucial for healthcare professionals and individuals. Updated information helps refine treatment plans and improve designs.
Types of Upper Limb Prostheses
- Body-Powered Prostheses: Operate through cable systems.
- Myoelectric Prostheses: Use electrical signals from muscles.
- Hybrid Prostheses: Combine body-powered and myoelectric controls.
- Activity-Specific Prostheses: Designed for particular tasks.
- Cosmetic Prostheses: For aesthetic purposes.
Key Sources for Updated Information
- Peer-Reviewed Journals: Reliable sources for research.
- Journal of Prosthetics and Orthotics (JPO)
- Prosthetics and Orthotics International
- Journal of Rehabilitation Research and Development (JRRD)
- National Institute of Disability, Independent Living, and Rehabilitation Research (NIDILRR)
- Veterans Affairs (VA) Research
- American Academy of Orthotists and Prosthetists (AAOP) Annual Meeting
- International Conference on Rehabilitation Robotics (ICORR)
- International Society for Prosthetics and Orthotics (ISPO) World Congress
- PubMed
- IEEE Xplore
- Google Scholar
- Össur
- Ottobock
- Rehabilitation Institute of Chicago (RIC)
Conclusion
Staying updated requires engaging with various sources. These sources ensure continuous improvement in prosthetic devices, offering greater independence and quality of life.