Compensatory Movements With Axon-Hook and Greifer in Transradial Amputees

Overview

Upper limb amputees often report musculoskeletal pain due to exaggerated shoulder abduction movements. Previous studies on prosthetic hands showed that wrist orientation contributes to reduce shoulder compensatory movements. The hypothesis of this research is that prosthetic hooks may also provide better functional outcomes when offering wrist adjustments and a design that favors a good visualization of the grips. The objective of this study is to compare shoulder abduction, manual dexterity and satisfaction when using Axon-Hook and Greifer myoelectric hooks during repetitive tasks. Shoulder abduction and manual dexterity results are also compared with the sound side.

Depending on patient's expectations, different prosthetic solutions can be offered. If prosthetic hands, being at the same time functional and aesthetic solutions, are widely used, for some professional or leisure activities, myoelectric users will have a better functional response with a non-morphologic terminal device such as a hook. Axon-hook and Greifer are two myoelectric hooks proposed by Otto Bock HealthCare. Greifer (Myobock system) has two movable strong hooks and a wrist that can be orientated medially or laterally. Axon-Hook (Axon-Bus system) has thin hooks for a good visualization of the grip, one being fixed for more precision, and a flexible wrist that can be orientated and locked in flexion and extension position. Previous studies on myoelectric hands showed that functionalities of prosthetic components such as type of hand or type of wrist, have an influence on compensatory movements, which can explain musculoskeletal pains. The hypothesis of the study is that Axon-Hook may reduce shoulder abduction and improve patient satisfaction. No significant difference is expected regarding manual dexterity. This randomized corossover trial compares shoulder abduction, manual dexterity and satisfaction while using Axon-Hook and Greifer. Shoulder abduction and manual dexterity results are also compared with the sound side.