Wrist Extension Orthosis - Research Groups -The Centre for Bioengineering - University of Canterbury - New Zealand

Wrist Extension Orthosis


Spinal Cord Injury (SCI) is one of the most complicated injuries the human body can sustain. Simply surviving a spinal cord accident is a miracle in itself. However unlike most injuries, damage to the spine is irreparable and the person with the injury must prepare themselves for a dramatic change in lifestyle.

Tetraplegia is a type SCI located in the neck region of the spine and results in paralysis of the upper and lower body. Due to the decrease in functionality of the upper extremities, such as the arms and hands, it becomes difficult to perform simple tasks such as writing with a pen or opening a door. These everyday activities which are necessary to function on a day-to-day basis are commonly referred to as Activities of Daily Living (ADL).

C5 tetraplegia is the most common neurological level of legion (14.8%), affecting generally young males. The greatest disadvantage for people with C5 tetraplegia is the loss of hand function and according to many researches 75% of persons with tetraplegia would rather regain hand function than any other function that they have lost, including bowel function, bladder function, sexual function, and even the ability to walk.

Professor Alastair G Rothwell, Head of Department for Christchurch school of medicine and health sciences proposed a solution to provide a person with C5 tetraplegia the means to grasp and manipulate objects. His proposal was that if a mechanical device could provide wrist control, then combined with his surgery of the thumb, he could provide a person with C5 tetraplegia the ability to perform a key pinch grip. This grip would enable a person with C5 tetraplegia to perform activities of daily living and increase their independence and quality of life.

Current Research

The research focused on the concept development phase of the design process. The aim was to create a solution which was not only functional, but also acceptable to the user. The research involved generating and selecting the design requirements specifications and developing various concept solutions. This information was then used to develop the optimal concept design.

The final concept holds the wrist in extension by a spring which connects between the hand and wrist brace. When the user wishes to release the object, they increase the force in the cable running underneath the arm. The increase in force flexes the wrist downwards and the object drops out of the hand. The cable running underneath the arm is controlled by a combination of shoulder abduction and flexion as well as protraction and retraction of the auxiliary shoulder.

The final concept can be hidden under loose clothing making the user appear ‘normal' to avoid unnecessary attention.

People Contributing

The project is under the supervision of Dr. Shayne Gooch, and co-supervised with Professor Harry McCallion and Professor Timothy David. Other researches who have been involved with this project include Lan LeNgoc, Marcus King, Julian Verkaaik, and Jennifer Dunn. The project was funded with a scholarship from Industrial Research Limited (IRL) and also generously supported by the Artificial Limb Centre based at Burwood Hospital.

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