Description:

The Kayak Prosthetic Wrist is a wearable device designed to aid a  Transhumeral or Transradial amputee by mimicking the action required to draw a stroke through the water. The Design is based on using a ball joint as the mechanism to replicate the biomechanics of the wrist motion. Integrated into the prosthetic is a quick-release mechanism. This enables the user to quickly release the paddle if they fall out or are required to release the paddle quickly. The device threads onto a common M12 thread.
Design Challenge
There are currently no suitable off-the-shelf solutions for Kayak athlete amputees that aid a fluid technique/paddle stroke. The available devices are large and heavy. This places strain on the arm and does not provide the range of motion required to perform a good technique. A patient with a Transhumeral amputation wanted to complete the Coast to Coast Multisport Race (Bike, Run, Kayak). This involves a 70km kayak down grade 2 -3 rapids. The off-the-shelf device limited her ability to navigate through the rapids and maintain a straight line as she was unable to place enough power through the amputated side.
To move the kayak requires effort (“propulsion” or “propulsive forces”) to overcome the forces slowing the kayak down (“resistance” or “resistive forces”). The greater the difference between the propulsive and resistive forces, the higher the speed.
The body is the paddler’s engine. A paddler only has a certain amount of strength. The technique is about finding the most effective or efficient way to transfer the paddler’s strength through the paddle to move the boat. Using the body effectively for paddling means doing three things - paddlers can generate more propulsion by:
• Using the right muscles;
• In the right order/at the right time
• In their optimal range
The paddle is the tool that transfers the paddler’s force into the water. The paddle works most effectively when it is oriented vertically and pulled directly opposite to the direction of the kayak’s travel.
The kayak stroke is a continuous, cyclic motion. However, to help understand and build a common language of technique, the stroke is divided into four phases. These are:
• Set-up
• Catch
• Drive phase
• Exit
Solution
Kayak Prosthetic Wrist is a Lightweight 3D Printed device consisting of two parts. A customisable ball that clamps to a Paddle shaft and a Quick release clamp is installed onto a transhumeral or transradial prosthetic. The clamp is secured to the ball to complete the assembly. The ball and quick release create a ball joint. Allow the wrist to react fluidly during the stroke. This design enables a kayak to perform the correct technique to transfer the paddler’s strength through the paddle to move the boat and Prevent injury.

Design Impact
The impact of this solution is significant in that it supports people with amputation to engage in sporting kayaking activities, without compromising technique. It is an example of Peke Waihanga - Artificial Limb and Orthotic Service - Aotearoa vision of 'independent and productive lives for those we care for'. Everything we do is focused on improving the lives of those we care for; they receive whole-of-life, world-class services that deliver what they need at each stage of their journey. We adapt and customise technology to change lives. We are responsible to those we care for understanding, accessing and bringing them the best technology solutions and initiatives that Peke Waihanga budgets allow.