Comparison of Standard Myoelectric Hand and Bionic Hand Use in Individuals With Upper Limb Amputation

Amputation constitutes a major trauma that substantially affects an individual's functional status and activities of daily living. The functional impairments ensuing from amputation can impede reintegration into normal life, giving rise to social, occupational, and psychological challenges. Amputees frequently encounter significant limitations in activities and participation. These limitations are predominantly related to mobility and self-care. These factors adversely affect the ability to return to work and maintain employment, continue social relationships, engage in leisure pursuits, and be active in community life. A variety of prostheses are employed to restore the functions of an amputated limb and achieve bodily integrity. Individuals with upper limb amputations may utilize cosmetic (passive), body-powered (mechanical, cable-activated), myoelectric, or hybrid prostheses. Myoelectric prostheses are controlled by electromyography (EMG) signals and are powered by rechargeable motors to execute movements. Successful prosthesis use necessitates the individual's physical capacity to operate the device and sufficient cognitive awareness to comprehend and control it. Two prevalent hand types in myoelectric upper limb prostheses are the standard myoelectric hand and the bionic hand. The standard myoelectric hand employs a single motor to provide a robust and consistent tripod grasp. The motor actuates the opening and closing of the first, second, and third digits. The fourth and fifth digits passively follow the others. Bionic hands, in contrast, feature multiple joints in each finger, enabling more natural finger movements, and some models incorporate multiple motors for independent finger control. This expands the range of functional grasp patterns. Instead of a single tripod grasp, they offer various grasp patterns (pinch, trigger, lateral, cylindrical, spherical, hook, key grasp, etc.). While providing users with greater hand dexterity, this increased grasp versatility comes with drawbacks such as higher cost and reduced durability. Moreover, the sequential nature of grasp movements, the necessity for patients to memorize this sequence, and the need to switch modes between grasps (open, dual, triple, co-contraction, button) can pose usability challenges. Consequently, executing a hand function using these grasps can be time-consuming, cognitively demanding, and physically exhausting. Despite over a decade of use, the existing literature on the advantages and disadvantages of bionic hand prostheses is limited and the findings are not entirely compelling. Additionally, these few studies predominantly rely on user reports. Individuals with upper limb amputation who use prostheses demonstrate unnatural or unusual movements in other joints and body regions. To successfully perform activities of daily living and tasks, they adapt the movement of their remaining limbs and develop compensatory movements. As the prosthesis's functionality approaches that of a healthy hand, compensatory movements also diminish. Studies have shown that during the use of upper limb prostheses, shoulder and trunk joint angles are increased compared to healthy individuals, elbow range of motion is limited, and decreased elbow movement is compensated for by increasing shoulder abduction or cervical spine flexion. These compensatory movements result in cognitive and physical fatigue in amputees. This situation is considered one of the factors influencing the discontinuation of prosthesis use. While the literature suggests that the use of bionic hands may reduce these compensatory movements, only one study has compared these angles in individuals using standard myoelectric hands and bionic hands. To our knowledge, there is no study that comprehensively compares quality of life, prosthesis satisfaction, kinematic measurement of compensatory elbow, shoulder, and cervical movements, time-consuming of hand functions, and the degree of fatigue in individuals with upper limb amputation who use bionic or standard myoelectric hands. This study aims to address this gap in the literature, evaluate the functionality of prostheses more objectively by combining various outcome measures, and to pioneer new studies.