Multi-Grip Prostheses: Features, Benefits, and Future Trends

Upper limb prosthetics have advanced significantly in recent years, and multi-grip prostheses now stand at the forefront of this innovation. These prostheses have revolutionised the field of upper limb prosthetics, offering enhanced dexterity, control, and extending functionality for users. Unlike traditional single-grip prostheses, multi-grip prostheses offer a range of grip patterns that allow users to perform a much wider array of tasks, from delicate actions, such as picking up small objects to holding and using a pen to write. 

This comprehensive guide explores the key features of multi-grip prostheses, the benefits they provide, how they are controlled, maintenance tips, the materials they are made from, limitations, usage tips, and examples from leading manufacturers such as Ossur, Ottobock, and Taska.  

What Are Multi-Grip Prostheses? 

Multi-grip prostheses are advanced prosthetic devices designed to replicate the look and functionality of a human hand. Unlike single-grip devices, which can only open and close in a single motion, multi-grip prosthesis offer a variety of grip types. These grips allow users to perform a broader range of tasks, mimicking the natural movements of the human hand more effectively. 

This versatility has significant implications for prosthesis users, improving their quality of life by enabling them to engage in everyday tasks with greater ease and precision. 

Key Features of Multi-Grip Prostheses 

• Variety of Grip Patterns: One of the key features of multi-grip prostheses is the multi-grip hand that has the ability to switch between different grip patterns, each designed for specific tasks. Common grip types include: 
  

Pinch Grip: This grip allows users to grasp small objects between the thumb and forefinger, ideal for tasks like picking up keys or writing with a pen. 

Precision Pinch: For tasks that require fine control, this grip allows for delicate manipulation of very small objects. 

Tripod Grip: Similar to the pinch grip, but involving the thumb, forefinger, and middle finger. It's useful for holding objects like utensils or tools. 

Power Grip: Designed for holding larger or heavier items, the power grip engages all fingers to wrap around an object, such as a bottle or handle. 

Hook Grip: This grip is suited for lifting objects by using a hooked formation of the fingers, useful for carrying bags or hanging items. 

Lateral Grip: This grip allows the thumb to press against the side of the hand, useful for holding flat objects like keys, paper or cards.

These are just some of the wide range of grips offered by multi-grip prostheses giving users the ability to perform more complex tasks with greater precision and control than ever before. 

• Advanced Dexterity: The multiple grip options allow for refined control, resulting in more natural and nuanced movements. This enhanced dexterity is especially beneficial for individuals who require fine motor skills in their daily activities, such as typing, cooking, or even playing musical instruments. The more advanced the prosthesis, the closer the movements resemble natural hand function. 
  

• Myoelectric Control: Multi-grip prostheses are often controlled using myoelectric signals. This means that small electrical signals generated by the user’s muscles are detected by sensors of the prosthesis, allowing the user to control the device with natural muscle contractions. Users can open and close the hand, switch between different grip patterns, and perform tasks with greater intuitive control. The advantage of myoelectric control is that it provides a more seamless user experience, allowing the prosthesis to function in response to natural muscle contractions. 
  

Range of Tasks That Multi-Grip Prostheses Can Perform 

Multi-grip prostheses enable users to complete an extensive variety of tasks that are often challenging with traditional prosthetics. The wide range of grips available opens up new opportunities for users, allowing them to engage in both simple and complex activities. Some common tasks that these prostheses can perform include: 

• Holding Objects: Users can hold items like cups, phones, keys, and utensils with ease. 
   

• Typing on a Keyboard: The finger point position of the hand is useful for interacting with keyboards or touchscreens. 
   

• Lifting Heavy Items: The power grip provides the necessary strength for holding or lifting larger objects. 
   

• Performing Delicate Tasks: Fine motor control is possible with pinch grips, enabling activities like threading needles, handling coins, or manipulating small objects. 
   

• Personal Care: Multi-grip prostheses can assist in personal care tasks, such as brushing teeth, combing hair or holding grooming tools. 
   

The versatility of these prostheses means users can participate in activities they may have previously found difficult or impossible, leading to greater independence and confidence. 

How Multi-Grip Prostheses Are Controlled 

The control mechanism behind multi-grip prostheses is the key to their success. Without it, performing the various grips seamlessly would be extremely challenging. 

• Myoelectric Control: As mentioned earlier, myoelectric prostheses use sensors to detect electrical signals from the user’s muscles. By contracting specific muscles, the user can control the movements of the prosthetic hand. These signals allow the user to perform various grips and tasks with natural ease. However, to control multiple grip types using traditional technology is an almost impossible task for any user. This is where Pattern Recognition makes all the difference.
  

• Pattern Recognition: Advanced multi-grip prostheses utilise pattern recognition technology, which takes myoelectric signals a step further by learning and interpreting the electrical signal patterns emitted by the user. Pattern recognition systems create a personalised model of the user’s muscle contractions, allowing for more accurate and intuitive control of the prosthesis. 
  

• Switch Control: In some cases, multi-grip prosthetics may be controlled using switches, buttons, or other manual control mechanisms. While this is less common in modern devices, some users prefer the simplicity of mechanical control for certain functions. 
  

• Mobile App Control: Several prosthetic manufacturers have developed mobile apps that allow users to control their prosthetic hand via a smartphone or tablet. These apps enable users to select grip patterns, monitor battery levels, and even customize settings to suit their individual needs. 
  

Waterproof Capabilities in Multi-Grip Prostheses 

Waterproof prosthetics are highly sought after, as they allow users to engage in water-based activities, from taking a shower to swimming. However, not all multi-grip prostheses are waterproof, and this is a critical feature for individuals who lead active lifestyles. 

One example of a waterproof multi-grip prosthetic hand is the Taska Hand, a groundbreaking device designed for use in wet environments. Users can submerge the Taska Hand in water, making it ideal for tasks like washing dishes, swimming, or handling wet objects. Its durable and sealed design prevents water from entering and damaging the internal electronics. 

Maintenance Tips for Multi-Grip Prostheses 

Proper care and maintenance of multi-grip prostheses are essential for ensuring their longevity and functionality. Here are some key maintenance tips: 

• Regular Cleaning: It’s important to clean your prosthesis regularly, especially after exposure to dirt, water, or sweat. Use a damp cloth to wipe down the exterior of the device, and avoid using harsh chemicals that may damage the materials. 
  

• Inspect for Wear and Tear: Regularly inspect your prosthesis for signs of wear and tear, particularly around the joints, fingers, and wrist. If you notice any damage, contact your prosthetist for repairs or replacement. 
  

• Charge the Battery: If your prosthesis is myoelectric, ensure that you charge the battery regularly. Most modern prostheses have rechargeable batteries, and keeping them charged will prevent unexpected downtime. 
  

• Follow Manufacturer Guidelines: Always adhere to the manufacturer’s recommendations for maintenance and cleaning. Each prosthesis has specific requirements based on the materials and components used. 
  

Materials Used in Multi-Grip Prostheses 

The materials used in multi-grip upper limb prosthetics are selected for their durability, flexibility, and lightweight properties. Common materials include: 

• Silicone: Used in prosthetic liners, cosmetic gloves and fingers for flexibility and comfort. 
   

• Carbon Fibre: Known for its strength and lightweight properties, carbon fibre is often used in the frame or outer shell of the prosthesis. 
   

• Aluminium or Titanium: These metals are used for joints and connectors due to their strength, durability, and resistance to corrosion. 
   

• Plastic Composites: High-grade plastics are often used in the housing and non-moving parts of the prosthesis for their lightweight and cost-effective properties. 
  

Limitations of Multi-Grip Prostheses 

While multi-grip prosthetics offer numerous benefits, there are a few limitations that users should be aware of: 

• Weight: Some multi-grip prosthetic hands can be heavier than simpler prosthetic designs, which may lead to user fatigue after extended use. 
  

• Cost: Advanced multi-grip prosthetics can be expensive, especially when equipped with myoelectric control systems or additional features like waterproofing. 
  

• Battery Life: For myoelectric devices, battery life can be a limitation. While battery technology has improved, users may need to recharge their prosthesis frequently if they use it for extended periods throughout the day. 
  

• Limited Waterproof Models: While some models, such as the Taska Hand, are waterproof, many multi-grip prostheses are not designed for full submersion in water, limiting their use in certain environments. 
  

Usage Tips for Multi-Grip Prostheses 

Here are some practical tips for getting the most out of your multi-grip prosthesis: 

• Practice Makes Perfect: Spend time practicing with your prosthesis to learn how to switch between different grip patterns efficiently. 
   

• Customize Settings: If your prosthesis comes with a mobile app or control panel, take advantage of customization options to fine-tune the grip patterns and sensitivity to your preferences. 
   

• Stay Active: Engage in a wide variety of tasks to build familiarity with your prosthesis, whether it's cooking, exercising, or performing personal care. 
   

• Consult Your Prosthetist: Regular check-ins with your prosthetist will ensure that your device remains properly fitted and that you're using it to its full potential. 
  

Future Trends in Upper Limb Prosthetics 

The future of upper limb prosthetics is promising, with several emerging trends that aim to enhance the user experience: 

• Improved Sensory Feedback: Researchers are working on prosthetic hands that can provide users with sensory feedback, allowing them to "feel" the objects they are holding. This would significantly improve control and dexterity. 
   

• Brain-Controlled Prosthetics: Advances in brain-computer interface (BCI) technology could enable direct control of prosthetic limbs via brain signals, creating a more intuitive user experience. 
   

• Lighter and More Efficient Materials: The development of lighter, stronger materials will help reduce the weight of prosthetic devices, making them more comfortable to wear for extended periods. 
   

• 3D Printing: The use of 3D printing technology may lead to more affordable and customizable prosthetics, enabling users to design prostheses that fit their unique needs and preferences. 
   

Conclusion 

Multi-grip upper limb prostheses represent a significant advancement in the world of prosthetic devices. With their wide range of grip patterns, enhanced dexterity, and intuitive control mechanisms, they enable users to perform an extensive variety of tasks with confidence and ease. While there are still some limitations to overcome, the future of upper limb prosthetics is bright, with exciting developments on the horizon, such as sensory feedback, brain-controlled devices, and lighter materials. Leading manufacturers like Ossur, Ottobock and Taska continue to push the boundaries of what prosthetics can achieve, offering hope and improved quality of life for individuals with limb loss.