Introduction
Upper limb amputees, shoulder abduction, shoulder pain, Shoulder abduction
Upper limb amputees equipped with a prosthetic device display unnatural or unusual movements with their other joints and segments [Several publications [Kinematic assessments using motion capture technologies have proven to be valuable for identifying movement strategies in the able-bodied population [Thus, it has been shown that transradial amputees with body-powered prostheses displayed relatively normal shoulder abduction/adduction when performing two standardized tasks (Cup Transfer and Pasta Box) in the standing position, but they compensated with trunk movement and decreased shoulder flexion/extension motion [The impact of loss of degrees of freedom (DOF) at wrist and finger levels was evaluated in able-bodied subjects, performing the BBT in the standing position by simulating the limitations induced by conventional prostheses with bracing and strapping. The simulation showed a decrease in BBT performance and an increase in shoulder abduction by about 20° throughout the test [It is important to limit shoulder abduction amplitude and duration because they are risk factors for shoulder pain and MSD, as shown in studies on occupational risks and posture at work in able-bodied subjects. Many studies or reports in the field of ergonomics thus give thresholds for arm elevation and/or shoulder abduction as well as thresholds for the length of time these positions can be maintained before a risk of shoulder MSD appears [Compensation studies have been performed with both myoelectric and body-powered prostheses [Depending on the subject’s expectations and life project, various prosthetic solutions are available with different control systems and terminal effectors. Among them, myoelectric systems provide functional and esthetic solutions when associated with a prosthetic hand. Nevertheless, some users appreciate having a myoelectric hook for certain professional or leisure tasks, because this non-morphologic tool offers more strength and precision than a prosthetic hand. Otto Bock HealthCare Products GmbH has developed two myoelectric hooks, the Greifer and the Axon-Hook. Concerning DOF, the Greifer allows radial/ulnar deviation, while the Axon-Hook allows wrist flexion/extension. Concerning shape, the Axon-Hook is less bulky than the Greifer.No study has been published on the Axon-Hook yet, but one case report comparing the efficiency of the Greifer with three other terminal effectors when performing the BBT and bimanual tasks of daily [By analogy with observations of prosthetic hands [In this context, this study aimed to compare compensatory shoulder movements and the percentage of time spent with shoulder abduction > 60° using motion analysis in transradial amputees successively equipped with the Greifer and the Axon-Hook while performing a standardized task (BBT).Manual dexterity (quantity of blocks moved), user satisfaction with the Greifer and Axon-Hook and hook preferences were also reported.Shoulder abduction (amplitudes and durations) and manual dexterity with each hook on the prosthetic (P) side were also compared with the non-amputated (NA) side.