Measurement of the strength of upper limbs in cervical injury users to design a propulsion wheelchair mechanism

Abstract

It is known that the propulsion technique of manual wheelchair it is mechanically inefficient, due to the relationship given by the propulsion force and the distance obtain, and the number of repetitions put the user at risk in developing cumulative trauma compromising joint and tissue. At least 70% of user will suffer secondary injuries because of constant and prolonged used of their manual wheelchair. The users with cervical injury, are exposed in higher physical risk of not getting prescribe technological assistive; due to the fact to the consequences of this type of injuries they present weakness muscles required for the propulsion such as: triceps brachii, middle deltoid, serratus anterior, extensor carpi radial and ulnar extensor carpi, furthermore they have no grip because they have damage at dermatome C6, C7, C8-T1, taking into account that in regular users 50% of the necessary force is lost at the moment they grip the rim to move forward, which represent for this type of user a heavy physical risk that can cause cumulative trauma disorders. We are looking to develop assistive technology for a better propulsion technique that suits their remaining capabilities, empower them and make them self-sufficient as possible. In order to do that, a mechanism that allow us to measure the force in a difference range of motions of the upper limbs and force hands grip has been created, taking into consideration for the final design we are measuring anthropometric dimensions of the Mexican users and their personal records to better satisfy their needs. With all this information we will be able to have a better understanding of the problematic by applying the quantitative and qualitative data in a methodology of design.