Research Article | Open Access
Effects of Arm Weight Support Training to Promote Recovery of Upper Limb Function for Subacute Patients after Stroke with Different Levels of Arm Impairments
Purpose. The goal of this study was to investigate the effects of arm weight support training using the ArmeoSpring for subacute patients after stroke with different levels of hemiplegic arm impairments. Methods. 48 inpatients with subacute stroke, stratified into 3 groups from mild to severe upper extremity impairment, were engaged in ArmeoSpring training for 45 minutes daily, 5 days per week for 3 weeks, in addition to conventional rehabilitation. Evaluations were conducted at three measurement occasions: immediately before training (T1); immediately after training (T2); and at a 3-week follow-up (T3) by a blind rater. Results. Shoulder flexion active range of motion, Upper Extremity Scores in the Fugl-Meyer Assessment (FMA), and Vertical Catch had the greatest differences in gain scores for patients between severe and moderate impairments, whereas FMA Hand Scores had significant differences in gain scores between moderate and mild impairments. There was no significant change in muscle tone or hand-path ratios between T1, T2, and T3 within the groups. Conclusion. Arm weight support training is beneficial for subacute stroke patients with moderate to severe arm impairments, especially to improve vertical control such as shoulder flexion, and there were no adverse effects in muscle tone.
Robots are one of the major technological revolutions in the past decade in rehabilitation training approaches for arm recovery. Robotic therapy stimulates active, assistive paretic limb movement in a reliable, controllable, repeatable, quantifiable, and flexible way that makes it an ideal tool to evaluate kinematic and kinetic measurements, implement rehabilitation paradigms, and facilitate motor recovery from stroke and other neurological diseases . One of the great advantages of robots is that they allow for a higher dosage and/or intensity of delivery of training to take place than conventional rehabilitation therapy . Robotic devices take the form of either an end-effector or an exoskeleton. In an exoskeletal system, the paretic limb is enclosed in an actuated robotic suit that conforms to the patient’s limb configuration. It can capture full specification of the limb configuration and the force applied and allows forces to be measured independently at each joint. This provides valuable ordinal data for data analysis and evaluation of patients. However, a criticism of actuated upper extremity robots is that they allow patients to move with robotic actuators apart from the patient’s effort and attention, which negatively affects their motor recovery .
The ArmeoSpring is a passive instrumented arm orthosis with a spring mechanism for adjustable arm weight support in a large 3D workspace, and it can be used as a real-time input device with its ancillary software Armeocontrol. It originated from T-WREX, which was developed by Reinkensmeyer et al. (2002)  to provide an additional orthosis with elastic bands to counterbalance arm weight and assist in arm movement with more degrees of freedom across a large workspace [3, 4]. Position sensors and grip sensors allow feedback on movement and grip force . The ArmeoSpring is particularly useful for patients with low muscle strength, especially patients who have lost the function of or have restricted functions in their upper extremities caused by various neurological disorders.
Two randomized control trials (RCT) were conducted on the T-WREX system [5, 6]. In the first RCT, the T-WREX group had significantly higher gains in arm improvement (but not hand use), ability to do functional tasks, and reaching an increased range of motion compared to that of the control group at their 6-month follow-up . The improved motor outcome was modest and functionally insignificant .
A single-blind RCT found that additional ArmeoSpring training led to significant improvements in shoulder adduction-abduction and normalized jerk compared with conventional training in acute stroke patients . A single-group ArmeoSpring study for mild to moderate cases of hemiparesis found significant improvements in movement ability and some upper arm functions at 12-week and 4-month follow-ups . Although studies show greater improvement of motor control of hemiplegic arms after application of robotic therapy, so far, there are no studies on whether ArmeoSpring different training modules are beneficial and whether ArmeoSpring is beneficial for people with different levels of arm impairments after stroke. The conclusion of a review in technology for supporting upper limb training after stroke also highlights the importance of future trials include outcome assessments to give evidence for the influence of technology-supported training on arm-hand function, patients’ functional levels, and participation . Therefore, the aim of this study is to investigate the effects of arm weight support training using ArmeoSpring by applying it to subacute patients after stroke with different levels of hemiplegic arm impairments and to evaluate the kinetic, kinematic, and functional outcomes before training, after training, and at a 3-week follow-up.
A total of 48 inpatients admitted consecutively to a regional rehabilitation hospital were recruited by convenience sampling. The principal inclusion criteria were (i) being diagnosed with cerebral vascular disease either by a CT scan or MRI in a medical report and compatible with unilateral hemispherical involvement; (ii) being within 1 week to 6 months after stroke; (iii) being able to understand verbal instructions and follow two-step commands according to the Mini-Mental State Examination (MMSE) ; (iv) exhibiting severe to mild unilateral upper limb paresis, defined as levels 1–6 in the Functional Test for the Hemiplegic Upper Extremity (FTHUE)  (this ranges from beginning voluntary motion of the hemiplegic shoulder and elbow to beginning to be able to combine components of strong mass flexion and strong mass extension patterns in the hand); and (v) having predominant spasticity over elbow flexion with scores on the Modified Ashworth Scale (MAS)  of less than Grade 3.
Participants were excluded if they (i) had significant impairment in visual acuity, visual perception, and unilateral neglect (the star cancellation subtest in the Behavioral Inattention Test ≤51) ; (ii) had unstable medical conditions including unstable angina, symptomatic cardiac failure, uncontrolled hypertension (>170/110 mmHg), chronic obstructive pulmonary disease, major poststroke depression, active neoplastic disease, or significant orthopedic or chronic pain; (iii) had received botulinum toxin injections prior to the study; and (iv) had previously participated in robotic therapy in the upper extremities.
Patients were categorized into three groups according to the functional levels of the FTHUE . Group 1 was for patients who just began to show voluntary movement of their shoulder and elbow (i.e., severe arm impairment; functional levels 1-2), Group 2 was for patients who had a more active range of movement in their shoulder and elbow (i.e., moderate arm impairment; functional levels 3 and 4), and Group 3 was for patients who demonstrated more mass combination or isolated proximal or distal control movement (i.e., mild arm impairment; functional levels 5 and 6). Patients who fell within the exclusion criteria categories or contraindicated as recommended by the manual were not involved in the training system.
ArmeoSpring facilitates the patient’s own active movements as directed through specific virtual reality computer tasks or games that allow for self-training with immediate performance feedback (Figure 1). It is an ergonomic and adjustable arm support that counterbalances the weight of the patient’s arm to enhance residual arm functions and active movement across a large three-dimensional workspace. It has a grip sensor to combine training of the hand and arm function. The built-in sensors and ancillary software can record the patient’s active arm movement at each joint during the training activities.
The goal of the ArmeoSpring training modules is to teach patients to move through a smooth path with a minimum jerk trajectory with immediate feedback. All training modules were designed according to the minimum motion the participants achieved according to the upper limb functional level in the FTHUE . The test was developed according to Brunnstrom’s developmental stages of stoke recovery according to a hierarchy of seven functional difficulty levels, and it has been validated in Hong Kong by adding culture-specific tasks, such as using chopsticks . The activities and difficulty levels were chosen to challenge the functional level of the patient’s upper extremity. Because the aim of the overall training was to help the patient reach the next stage of recovery, when patients showed improvement within a functional level, therapists moved them to a more advanced training module.
The training module for Group 1 was for patients who had just started to exhibit voluntary movement of the shoulder and elbow, and the training tasks involved only one- and two-dimensional tasks at a lower level of difficulty. Training modules for Group 2 involved activities with a greater range of shoulder and elbow movement such as one- and two-dimensional activities at a higher level of difficulty and consisted of more two-dimensional tasks. The one- and two-dimensional tasks can be divided into either horizontal or vertical catching tasks (Figure 2). An example of horizontal catching is catching a moving red ball with a robotic arm in a horizontal plane, and an example of vertical catching is catching a ladybug with the robotic arm in a vertical plane. Training modules for Group 3 involved more mass combination or isolated proximal or distal control movements. The training tasks involved one-, two-, and three-dimensional tasks with a focus on three-dimensional tasks at a higher level of difficulty, for instance, forearm pronation and supination and activating the grip control sensor for grip-power training. The three-dimensional tasks included a forward reaching action by perceiving the depth of the target.
This was a prospective single-group cohort study. This study was approved by the human subjects’ ethics committee of the hospital. All participants signed informed consent forms. All participants received daily 45-minute sessions for the arm weight support training, 5 days per week for 3 weeks in addition to conventional rehabilitation training in the hospital, which included 60-minute activities of daily living training and affected arm horizontal and vertical reaching activities in occupational therapy, 60-minute biomechanical training in upper and lower limbs as well as gait training in physiotherapy, 30-minute speech therapy by appointment, and occasional patient and family discussions with healthcare workers at the rehabilitation hospitals.
Two ArmeoSpring devices were set up in the occupational therapy department in the hospital. Each device was designated for either left or right arms. Four occupational therapists were trained on the procedures for setting up the device on patients. After setting up the ArmeoSpring training tasks, participants were instructed to engage in training without a therapist present. To put the patient in the ArmeoSpring, the therapist has to adjust the arm orthosis to fit the patient’s dimensions according to the setup procedures. Before setting up training activities, the patient has to be calibrated on the range of active movement on the computer’s working plane. Once the workplace setup is complete, the therapist can select the appropriate preset training modules of activities from a wide range of functional activities in the form of virtual reality practice for the patient.
To ensure the patient’s safety, an additional safety belt was designed to prevent patient falls and compensatory trunk movements during training. The device and system were checked regularly for any defects. Defects were reported to the company agent immediately. Trainings were also stopped if there was an increase in spasticity to Grade 3 or above on the Modified Ashworth Scale (MAS) .
Evaluations were conducted, and data was collected at three measurement occasions: immediately before training (T1); immediately after completion of the three-week training (T2); and at a three-week follow-up after completion of the three-week intervention (T3), by a rater blind to participants who had received ArmeoSpring training. The primary outcome measures were (i) the Fugl-Meyer Assessment (FMA) Upper Extremity Score and Hand Score to measure arm impairments ; (ii) active range of motion (AROM) of shoulder flexion and shoulder abduction, elbow resting range and elbow flexion, and forearm supination and pronation; and (iii) power grip. (i) The secondary outcome measures were muscle tone of elbow as evaluated by the MAS  and (ii) the Functional Independence Measure (FIM) was used to measure basic functional performance (evaluated at T1 and T2 only) . The FMA has 22 items measured on a 3-point scale with a maximum total score of 66. The total score can be further divided into Upper Extremity Subscore (shoulder and elbow) (max. score = 36) and hand subscores (wrist, grips, and coordination) (max. score = 30) .
Armeocontrol, an ancillary software program, captured secondary kinetic outcomes. They included (i) the hand-path ratio (as captured by horizontal and vertical catching levels 1–4), which indicates the extent to which the user deviates from the ideal straight line between two objects when moving from one to the next (Figure 2); (ii) the percentage of completed and time scores as captured by - and -axes during horizontal and vertical catching (Figure 1). values represent positions of the endpoint in the lateral direction (left to right); values are in the vertical direction (up to down), and values correspond to the horizontal direction (far to close). All values are reported relative to the first joint (in the horizontal arm of the ArmeoSpring) where the arm orthosis is attached. A perfect linear movement has a hand-path ratio of 1. A hand-path ratio of 2 indicates that the length of the patient’s hand trajectory was twice as long as the shortest line connecting the points.
After removing dropout cases, all available data were analyzed in an intention-to-treat analysis. The “last observation carried forward” (LOCF) method was used; that is, if a subject dropped out, missing values were replaced by the last assessment score of that variable. We used Pearson chi-square and one-way ANOVAs to compare baselines of categorical and continuous data, respectively. We used univariate ANOVAs to compare within-group differences in each group three measurement occasions, T1, T2, and T3, and one-way ANOVAs to compare the between-group differences in the gain scores: Gain 1 between initial assessment (T1) and assessment at the end of ArmeoSpring training (T2) and Gain 2 between T1 and assessment at 3-week follow-up (T3). We used Tukey’s honestly significant difference method (HSD) for post hoc comparison to find significant differences for pairs of groups. Because seven instruments were used in measuring outcomes, a conservative level of statistical significance by the Bonferroni correction was set at for within-group comparisons (i.e., 0.05 divided by three occasions) and for between-group comparisons (i.e., 0.05 divided by seven instruments).
Table 1 shows participant demographics and comparison of baselines in outcome measures. All participants completed training and postassessment but there were 5 dropouts at T3, that is, 3-week follow-up, because of lost contact. There were no significant differences between the three groups in baseline measures (). The only significant difference was arm impairment levels as stratified by the FTHUE for group allocation and 2 main brain lesion sites (). There were no significant differences in Vertical Catch (level 1) or Horizontal Catch (level 1) of hand-path ratio between any groups ().
|Note: FTHUE Functional Test for the Hemiplegic Upper Extremity; MMSE Mini-Mental State Examination. |
FIM Functional Independence Measure; MAS Modified Ashworth Scale; Pearson chi-square for n (%).
-test for mean SD; .
Table 2 shows the results of within-groups comparison in each group at three measurement occasions and between-group comparisons of gain scores between the three groups. Results of within-group comparisons showed that Group 3 had no significant difference among the three measurement occasions except the Upper Extremity Score and the Hand Score of the FMA, time score of Vertical Catch, percentage and time scores of Horizontal Catch, and FIM (). Interestingly, Group 2 had significant differences across all three measurement occasions except for percentage scores of Horizontal Catch (). Group 1 had significant improvements in all kinetic and kinematic parameters ( to 0.007) except for hand-path ratios ().