Impact of Michelangelo Prosthetic Hand: Findings from a Crossover Longitudinal Study

INTRODUCTION Over the past 8 yr, new myoelectrically controlled, multi-articulated hands have become available that allow human-like movements and improved grasping capabilities compared with traditional tridigital (TD) myoelectric devices [1-2]. As such, they can potentially address both functional [3] and cosmetic [4] user needs and have positive psychosocial implications [5-9]. However, the actual impact of these technologies on patients' lives has been documented in only two case reports [10-11]. The question remains whether advanced devices may be more suited for some people with amputation and less for others based on underlying patient characteristics [12-15]. The aim of the present study is to provide preliminary evidence of the potential benefits of the new "hand-wrist system" Michelangelo (M) (Ottobock Healthcare Products GmbH; Vienna, Austria) in comparison with traditional myoelectric solutions in a sample of participants with transradial amputation. Both functional and psychosocial outcomes were assessed [16]. Specifically, we hypothesized increased manual dexterity and easier execution of activities of daily living (ADLs) along with improvements in social interactions and greater prosthesis satisfaction. METHODS Participants Six participants with upper-limb amputation referred to the same prosthetic center of the Italian Workers' Compensation Authority (INAIL Prosthetic Center, Vigorso di Budrio, Bologna, Italy) participated in this study. All participants were male, had a work-related traumatic amputation at the transradial level, and met the inclusion criteria reported in Table 1 (pseudonyms were used to protect subject identities). Participant median age was 47 yr (range: 35-65 yr), and the median time since amputation was 15 yr (range: 4.5-48.0 yr). Most participants had a high school education (83.3%) and were married or lived with a partner (66.7%). Three reported phantom limb sensation and pain experiences that did not, however, affect prosthesis use. All participants used their prosthesis for >8 h/d. Prosthetic Device The M is a multi-articulated hand-wrist system. It uses standard myoelectric control, typically through two electrodes that capture the contraction of the forearm muscles. Because of the particular finger alignment and the motorized thumb, the M can perform seven grasping patterns and hand positions (Figure 1). With the thumb in opposition, the M can realize an opposition power grip and a tripod pinch with the index and middle fingers. When the thumb moves into abduction, the M can realize a lateral power grip and a lateral pinch with respect to the index finger. The fingers can be fully extended to reach an open palm position (e.g., for holding a plate). In addition, during opening and closing, fingers move into abduction-adduction; this feature can be exploited to hold flat objects, e.g., grasping a paper or collecting multiple glasses at once. The hand can also assume a neutral position similar to the attitude of the hand when relaxed alongside the body; the hand returns automatically to this position when inactive for a fixed amount of time. The M is a hand-wrist system because the hand is proximally connected to a passive joint replicating wrist flexion-extension and pronation-supination; the wrist flexion-extension can be either locked in eight different angles or be used in the full range of motion against the resistance of a spring that resets the wrist to the neutral position. [FIGURE 1 OMITTED] The first commercial version of the M (2013) was fitted to all patients. Study Design and Procedure A multifactorial assessment protocol was applied to assess the functional and psychosocial effect of the M (Figure 2). The functional assessment consisted of a series of practical tests and self-report functional scales; practical tests were performed with the standard TD myoeletric hand (Ottobock Healthcare Products GmbH) of each patient, the intact hand, and the M. …