Hand Force Measurement Using A Human-Powered Linear Movement

Abstract Background: Cerebral Palsy (CP) is a neurological disorder that affects many motor functions, such as muscle tone. 60-80% of children born with CP neurological movement disorders have functional limitations in the upper extremity, depriving them of the opportunity of experiential learning through repeated reaching, grasping and manipulating objects. To help give the necessary mobility of hand function to those with CP, a therapist must be able to see if the current therapy methods are improving the range of motion. Currently, there are plenty of devices that test the amount of isometric hand strength but, not how much resistance to hand opening there is due to spasticity. Objective: Determine the amount of force it takes to open a subject’s hand, who has Cerebral Palsy. Starting from a closed fist position (0 degrees) to a fully extended position using a human powered mechanism. To test this force measurement device on all grade levels of CP hand function. Hypothesis: The load applied across a cylindrical handle, as it is being pulled away from the subject, will give an accurate readout of how much force it takes to open the hand of a subject with Cerebral Palsy. Method: The amount of force will be measured using a cylindrical handle with a load cell attached at either end. As the study conductor pulls the device away from the subject, via a handle on the opposite end and attached wheels, the hand is forced open causing a load to output. Results: A manual powered car will be pulled by a handle attached to the front of the car. On the opposite end of the car, a handle with an internal load cell at each end will read the amount of force it takes to open the hand. The subject will rest their arm on a 3D designed wrist stabilizer to prevent noise in the output. Conclusions: The current design will be able to provide an objective measure of hand stiffness that can be used to track rehabilitation progress. Future studies on the device’s ability to measures stiffness in other hand impairments are planned.