Recently, robotic devices were developed as a non-invasive solution to enhance intact motor pathways or manipulate the upper limbs for functional improvement (Capello et al., 2018). A number of different robotics are currently used for rehabilitation and they can be classified based on the type of robot, actuation method (energy source, e.g. electric motor), form of transmission (transfer of motion, e.g. cables) and sensors used (Yue et al., 2017). The two most common types of robotic devices used include end-effectors and exoskeletons (Yue et al., 2017). End-effectors are attached to the end of a robotic arm (e.g. robotic hand) and are designed to interact with the environment, externally to the patient (Yue et al., 2017). In contrast, exoskeletons are worn by the patient and include mechanical joints that align to the subject’s own joints, which assist the impaired user to move their own upper limbs (Sicuri et al., 2014; Yue et al., 2017; Capello et al., 2018). Importantly, both types of robotic devices may be used to deliver high quality and high volume repetitions. It was recently suggested that repetitive movement exercise may promote functional recovery through the enhancement of adaptive plasticity (Frullo et al., 2017; Capello et al., 2018). A large body of literature has described the efficacy of robot-assisted rehabilitation for recovery of upper extremity motor function in stroke patients (Lo et al., 2010; Klamroth-Marganska et al., 2014; Frullo et al., 2017). However, there is a paucity of data on the efficacy of robot-assisted rehabilitation for recovery of upper extremity motor function in SCI.
The methodological details and results from nine studies are listed in Table 7.
The field of robotic devices for SCI rehabilitation is constantly evolving as technology advances. As a result of this, the majority of articles published in this area focus on testing newly designed robotic devices via non-randomized pilot studies that contain small sample sizes. Accordingly, it is difficult to draw any definitive conclusions about the efficacy of robotic rehabilitation itself. It is more appropriate to discuss emerging trends with specific types of robotic devices for SCI rehabilitation.
Several studies examined the feasibility and efficacy of robotic exoskeletons. All of the studies found that use of a robotic exoskeleton is feasible, however, the real world functionality of it may be limited and hard to use based on individual functioning. For example, one study found that use of a bionic glove was only successful in patients that had voluntary control over their wrist, while another found that at home use of the device may be impractical. In contrast, other studies conducted using different types of exoskeletons (e.g. GRIPIT and a soft robotic based glove) found significant improvements in writing and hand function while wearing the device. GThe efficacy of exoskeleton use is controversial and may vary depending on the type of exoskeleton used and the overall functioning of the patient.
Only a few studies examined the feasibility and efficacy of an end-effector robotic device. However, all of the studies demonstrated improvements in upper extremity function while using the device. It should be noted that end effectors are robotic devices aimed at replacing upper extremity function instead of rehabilitating the patient. With the current technology available, robotic end-effectors are often cumbersome and large with complex interfaces. As such, Coignard and colleagues (2013) found that use of one at home is much less feasible than in a clinical setting. At present, this makes the feasibility of robotic end-effector rehabilitation fairly low. As technology advances, robotic end-effectors may evolve to be more adaptable in an at-home setting. Future research should focus on the long-term efficiacy, as well as determining usability through functional impact questionnaires (e.g. FIM and ADL).
There is level 2 evidence (from one prospective controlled study; Frullo et al. 2017) that subject-adaptive upper extremity robotic exoskeleton therapy is feasible, however, no gains in arm function were observed.
There is level 4 evidence (from one pre-post study; Capello et al. 2018) that use of a fabric-based soft robotic glove significantly improves hand function when completing activities of daily living in individuals with SCI.
There is level 4 evidence (from one pre-post study; Kim et al. 2017) that the GRIPIT exoskeleton quantitatively and qualitatively improves writing when compared to conventional pen holders, although it is more difficult to wear.
There is level 4 evidence (from two pre-post studies; Backus et al., 2014; Cortes et al., 2013) that an end effector can be safely used in patients with tetraplegia to significantly improve upper limb function.
There is level 4 evidence (from one post-test study: Tigra et al., 2018) that an end effector robotic device may improve hand grasping function in individuals with SCI.
There is level 4 evidence (from two case series; Popovic et al., 1999; Prochazka et al., 1997) that the Bionic Glove increases motor and upper limb function in individuals with SCI.
There is level 5 evidence (from one observational study; Coignard et al., 2013) that in a home environment the functionality of an end effector may be limited.
Upper extremity robotics improve hand function in individuals who have suffered upper limb paralysis following a spinal cord injury. However, further research is necessary to determine the efficacy of upper extremity robotic exoskeletons as part of a robotic rehabilitation program.