The reliability of side to side measurements of upper extremity activity levels in healthy subjects

Determination of the reference range for semi-quantified elasticity of healthy supraspinatus muscles using real-time tissue elastography and its clinical use in patients after rotator cuff repair

BACKGROUND

The quantitative assessment of healthy supraspinatus muscle elasticity may provide clinically useful preliminary information after rotator cuff repairs. We aimed to determine the reference range for supraspinatus muscle semi-quantified elasticity and describe how it can be used clinically after rotator cuff repair.

METHODS

The elasticity of healthy bilateral supraspinatus muscles in 43 participants aged between 24 and 75 years (categorized into two subgroups: <50 and ≥ 50 years) was measured as a strain ratio at 0° and 60° of shoulder abduction using real-time tissue elastography. The reference and modified reference ranges calculated by excluding outliers for elasticity were determined using normal distribution methods for logarithmically transformed data. The modified reference range was applied to eight cases of rotator cuff repair.

FINDINGS

Strain ratios under and over 50 years of age were 1.63 vs. 2.21 at 0° of shoulder abduction (P = 0.028) and 0.92 vs. 1.29 at 60° of shoulder abduction (P = 0.002), respectively. Modified reference ranges for under and over 50 years of age were 0.72-4.17 and 0.98-4.50 at 0° of shoulder abduction and 0.38-1.95 and 0.56-2.76 at 60° of shoulder abduction, respectively. Among eight cases, two showed strain ratios above the reference range at 1 month postoperatively, and rehabilitation protocols were adjusted.

INTERPRETATION

A strain ratio above the reference range, especially above the upper limit at 0° of shoulder abduction, may indicate increased passive stiffness of the musculotendinous unit. Clinically, the reference range has the potential to be used as a baseline after rotator cuff repairs.

Wrist-Worn devices to encourage affected upper limb movement in unilateral cerebral palsy: Participatory design workshops

Background

Unilateral (Hemiplegic) cerebral palsy (UCP) causes weakness and stiffness affecting one sided of the body, often impacting activities of daily living. Upper limb therapy at effective intensity is not accessible to most.

Aim

To determine stakeholder views on design of an approach using wrist-worn devices and a smartphone application to encourage use of the affected upper limb for children with hemiplegia.

Method

Four participatory design workshops and one young people's advisory group workshop incorporating views of five young people with hemiplegia, 13 typically developing peers aged 8-18 years, four parents, three occupational therapists, one teacher and two paediatricians. Two special educational needs co-ordinators were consulted separately. Peers were included to explore a study design whereby each child with hemiplegia would have a participating "buddy". Topics included views on an acceptable wrist-worn device and smartphone application, participant age range, involvement of a buddy, and barriers to using the technology in a school setting. Ethical/welfare considerations included data security, and potential risks around providing smartphones to young children.

Results

Children wanted a comfortable, conventional-appearing wristband incorporating a watch face and a secure, well-fitting strap. They were prepared to wear a band on each wrist. They wanted support with explaining the study to schoolteachers. Most schools restricted smartphone use during the school day: the study design accommodated this. Children agreed with a game as reward but had different views on an acceptable game; direct access to feedback data was preferred by some. Parents commented on the lack of access to upper limb therapy for children with UCP; therapists concurred. The proposed participant age range was widened based on feedback. Typically developing children were prepared to be buddies to help a friend with CP. Stakeholders were reassured by data security explanations and plans to provide internet safety information to participants.

Conclusion

The participatory design process informed plans for the proof-of-concept stage of the study, hopefully leading to an approach that will be fun, easy to integrate into everyday life, and have the capacity to increase use of the affected arm and hand.

Upper extremity function in the free living environment of adults with traumatic brachial plexus injuries

Transition of data acquisition out of the laboratory, into the real world offers a previously inaccessible perspective of physical function. This proves to be beneficial when assessing surgical intervention, especially after a traumatic brachial plexus injury (BPI) causing loss of motor function in an upper extremity (UE). Moving towards the use of real world data in clinical practice as an outcome measure, this study developed a method to report bilateral UE activity in patients with BPI. Three groups of ten subjects each participated in this study-healthy controls, subjects with traumatic BPI prior to surgical treatment (pre-), and subjects who had surgical reconstruction to treat BPI (post-). Subjects wore four activity monitors on bilateral forearms and upper arms for four days. Tri-axial acceleration data were used to calculate asymmetry indices for forearm and upper arm usage. Analysis revealed a bimodal distribution in the post- group, prompting division of this group into two subgroups based on injury type: pan-plexus and upper trunk. While median asymmetry indices at the forearm and upper arm were decreased in the post- group when compared to the pre- group, these differences were not significant. Compared to controls, the pre-surgery group (p < 0.0001, p < 0.0001) and post-surgery group with pan-plexus injuries (p = 0.0074, p = 0.0242) both exhibited statistically significant differences in forearm and upper arm asymmetry, respectively. Further investigation to establish clinically significant differences in asymmetry index is warranted. Importantly, analyzing the activity of UEs following treatment of a BPI provides objective real world evidence of function.

Heat Stress Increases Movement Jerk During Physical Exertion

Objective: Movement efficiency can be quantified during physical tasks by measuring the rate of change of acceleration (jerk). Jerk captures the smoothness of a motion and has been used to quantify movement for upper extremity and torso-based tasks. We collected triaxial accelerometer data during four physical tasks commonly performed in the work place to determine if jerk increases with physiologic strain.

Methods: Participants completed a circuit of activities that mimicked the demands of manual labor in hot (40°C) and temperate (18°C) conditions. The circuit included walking on a treadmill carrying a load on the shoulder, lifting objects from the floor to the table, using a dead blow to strike the end of a heavy steel beam, and a kneeling rope pull. After the 9 min circuit, the participant had a standing rest for 1 min before repeating the circuit 3 additional times. Participants were instrumented with four 3-axis accelerometers (Actigraph wGT3X) secured to the torso, wrist, and upper arm.

Results: There were 20 trials in the hot condition and 12 trials in the temperate condition. Heart rate and core body temperature increased during both protocols (p < 0.001). Measures of jerk varied by accelerometer location and activity. During treadmill walking, the wrist, torso, arm accelerometers measured higher jerk during the fourth circuit in the hot condition. During the lifting task, mean jerk increased in the hot condition in all accelerometers. Max jerk increased in the temperate condition in the arm accelerometer and jerk cost increased in the hot condition in the torso and arm accelerometers.

Conclusions: Forty minutes of paced work performed in the heat resulted in increased acceleration and jerk in accelerometers placed on the torso, arm, and wrist. The accelerometers most consistently reporting these changes were task specific and suggest that a limited number of worn sensors could identify the onset of fatigue and increased injury risk.

Effects of Sensor Types and Angular Velocity Computational Methods in Field Measurements of Occupational Upper Arm and Trunk Postures and Movements

Accelerometer-based inclinometers have dominated kinematic measurements in previous field studies, while the use of inertial measurement units that additionally include gyroscopes is rapidly increasing. Recent laboratory studies suggest that these two sensor types and the two commonly used angular velocity computational methods may produce substantially different results. The aim of this study was, therefore, to evaluate the effects of sensor types and angular velocity computational methods on the measures of work postures and movements in a real occupational setting. Half-workday recordings of arm and trunk postures, and movements from 38 warehouse workers were compared using two sensor types: accelerometers versus accelerometers with gyroscopes-and using two angular velocity computational methods, i.e., inclination velocity versus generalized velocity. The results showed an overall small difference (<2° and value independent) for posture percentiles between the two sensor types, but substantial differences in movement percentiles both between the sensor types and between the angular computational methods. For example, the group mean of the 50th percentiles were for accelerometers: 71°/s (generalized velocity) and 33°/s (inclination velocity)-and for accelerometers with gyroscopes: 31°/s (generalized velocity) and 16°/s (inclination velocity). The significant effects of sensor types and angular computational methods on angular velocity measures in field work are important in inter-study comparisons and in comparisons to recommended threshold limit values.

Accelerometry as an objective measure of upper-extremity activity

Most studies evaluating the effectiveness of treatments targeting shoulder pathologies use subjective outcome measures such as self-administered questionnaires. To date, there are no validated tools that objectively measure shoulder-specific functional activity. The purpose of this study was to validate wearable accelerometers as an objective proxy for shoulder activity. Ten healthy volunteers wore accelerometers placed at both wrists, the dominant upper arm and the chest while performing standardised shoulder and non-shoulder activities. Recorded tridimensional acceleration was computed into activity counts for epochs of 10 s. Receiver operating characteristics (ROC) curves were built to determine the optimal configuration to classify shoulder-type activities. For single accelerometer placement, the area under the ROC curve (AUC) was optimal for the 10-s epoch (AUC = 0.779) using the wrist placement, with a sensitivity of 94.1% and specificity of 67.5%. The combined upper arm and chest placement had an AUC of 0.985 (94.8% sensitivity, 94.8% specificity). Dual-accelerometer placement (upper arm and chest) is the optimal configuration to classify shoulder activity. However, a sole wrist-based accelerometer can be used as an objective proxy for shoulder activity in long-term unsupervised monitoring with excellent sensitivity and acceptable specificity.

A New Shoulder Orthosis to Dynamically Support Glenohumeral Subluxation

OBJECTIVE

In this paper we presented a novel shoulder subluxation support that aims to reduce the stress on the passive structures around the shoulder of patients with glenohumeral subluxation and glenohumeral-related shoulder pain. The device applies a force to the upper arm without impeding the functional range of motion of the arm. Our design contains a mechanism that statically balances the arm with two elastic bands.

METHODS

A technical evaluation study was conducted to assess the performance of the orthosis. Additionally, two patients evaluated the orthosis.

RESULTS

The results of the technical validation confirm the working of the balancing mechanism. The pilot study demonstrated that the shoulder support increased the feeling of stability of the shoulder joint and, to a lesser extent, decreased shoulder pain. Furthermore, both patients reported that the orthosis did not impede their range of motion.

CONCLUSION

In this research we developed a shoulder orthosis based on two statically balanced springs that support the shoulder of patients with glenohumeral subluxation that have residual shoulder muscle force. Compared to existing shoulder supports, our design does not impede the range of motion of the arm, and continues to provide a stabilizing force to the shoulder, even if the arm is moved away from the neutral position. Tests with two participants showed promising results.

SIGNIFICANCE

The device presented in this work could have a significant impact on the shoulder function which may improve rehabilitation outcome and improve the quality of life of patients suffering from glenohumeral subluxation and shoulder pain.

Usability Evaluation of a VibroTactile Feedback System in Stroke Subjects

Background

To increase the functional capabilities of stroke subjects during activities of daily living, patients receive rehabilitative training to recover adequate motor control. With the goal to motivate self-training by use of the arm in daily life tasks, a sensor system (Arm Usage Coach, AUC) was developed that provides VibroTactile (VT) feedback if the patient does not move the affected arm above a certain threshold level. The objective of this study is to investigate the usability of this system in stroke subjects.

Method

The study was designed as a usability and user acceptance study of feedback modalities. Stroke subjects with mild to moderate arm impairments were enrolled. The subjects wore two AUC devices one on each wrist. VT feedback was given by the device on the affected arm. A semi-structured interview was performed before and after a measurement session with the AUC. In addition, the System Usability Scale (SUS) questionnaire was given.

Results

Ten ischemic chronic stroke patients (39 ± 38 months after stroke) were recruited. Four out of 10 subjects have worn the VT feedback on their dominant, affected arm. In the pre-measurement interview, eight participants indicated a preference for acoustic or visual over VT feedback. In the post evaluation interview, nine of 10 participants preferred VT over visual and acoustic feedback. On average, the AUC gave VT feedback six times during the measurement session. All participants, with the exception of one, used their dominant arm more then the non-dominant. For the SUS, eight participants responded above 80%, one between 70 and 80%, and one participant responded below 50%.

Discussion

More patients accepted and valued VT feedback after the test period, hence VT is a feasible feedback modality. The AUC can be used as a telerehabilitation device to train and maintain upper extremity use in daily life tasks.

Alteration and recovery of arm usage in daily activities after rotator cuff surgery

BACKGROUND

The objective measurement of dominant/nondominant arm use proportion in daily life may provide relevant information on healthy and pathologic arm behavior. This prospective case-control study explored the potential of such measurements as indicators of upper limb functional recovery after rotator cuff surgery.

METHODS

Data on dominant/nondominant arm usage were acquired with body-worn sensors for 7 hours. The postsurgical arm usage of 21 patients was collected at 3, 6, and 12 months after rotator cuff surgery in the sitting, walking, and standing postures and compared with a reference established with 41 healthy subjects. The results were calculated for the dominant and nondominant surgical side subgroups at all stages. The correlations with clinical scores were calculated.

RESULTS

Healthy right-handed and left-handed dominant arm usage was 60.2% (±6.3%) and 53.4% (±6.6%), respectively. Differences in use of the dominant side were significant between the right- and left-handed subgroups for sitting (P = .014) and standing (P = .009) but not for walking (P = .328). The patient group showed a significant underuse of 10.7% (±8.9%) at 3 months after surgery (P < .001). The patients recovered normal arm usage within 12 months, regardless of surgical side. The arm underuse measurement was weakly related to function and pain scores.

CONCLUSION

This study provided new information on arm recovery after rotator cuff surgery using an innovative measurement method. It highlighted that objective arm underuse measurement is a valuable indicator of upper limb postsurgical outcome that captures a complementary feature to clinical scores.

Tri-axial accelerometer analysis techniques for evaluating functional use of the extremities

Activity monitors provide an objective mechanism for evaluating patient function. It is unclear what similarities or unique information may be yielded using different analyses. Fifteen patients scheduled to undergo shoulder arthroplasty and fifteen matched control subjects wore tri-axial accelerometer activity monitors bilaterally at the lower (wrist) and upper (biceps) arm for 3days. Measures of central tendency, variance, sample entropy, and asymmetry were calculated. A novel technique to evaluate time distribution of activity intensity was also performed. Within both groups there was a difference in central tendency and variance when comparing dominant and non-dominant limbs for both the lower (

CONTROLS

Mean Activity, P<0.001; Max Activity, P<0.001;

PATIENTS

Mean Activity, P=0.044; Max Activity, P=0.009) and upper (

CONTROLS

Mean Activity, P<0.001; Max Activity, P=0.046;

PATIENTS

Mean Activity, P=0.002; Max Activity, P=0.049) arm. Within group differences were also present for lower arm entropy in both groups (CONTROLS, P<0.001; PATIENTS P=0.041), and at the upper arm for patients (P=0.003). There were differences between groups for the asymmetry index for both the lower (P=0.033) and upper arm (P=0.005), and maximum activity level of the lower arm (P=0.05). Between group differences were present for time distribution of activity intensity, as the involved upper arm of patients was inactive for a greater time than controls (P=0.013). These results highlight unique information provided by multiple analysis methods, and include a novel approach of evaluating the distribution of time spent across variable intensity activities.

Us'em: the user-centered design of a device for motivating stroke patients to use their impaired arm-hand in daily life activities

Stroke leaves the majority of its survivors with an impairment of the upper extremity that affects their ability to live independently and their quality of life. Rehabilitation research shows that practice of everyday life activities in a natural context may sustain or even improve arm-hand performance, even during chronic stages after stroke. Based on this insight we designed, developed and evaluated Us'em; this consists of two watch-like accelerometry devices that provide feedback to stroke patients regarding the usage of their impaired versus their non-affected upper extremity. System usability and treatment credibility/expectancy were evaluated positively by therapists and patients.

Wrist activity monitor counts are correlated with dynamic but not static assessments of arm elevation exposure made with a triaxial accelerometer

There is evidence in the literature of a link between workplace arm elevation exposure and atraumatic shoulder injuries. However, there are several methods that can be used to assess this exposure. The goal of the present study was to compare the outcomes of an activity monitor attached to the wrist and a triaxial accelerometer mounted on the humerus. Twenty-one workers wore both sensors over the course of a full workday. While the activity monitor data was not significantly correlated with any static humeral parameters, it was strongly correlated with all dynamic parameters. The use of a simple, commercially available activity monitor might offer an inexpensive alternative for the assessment of a large number of subjects over multiple workdays to determine the relationship between dynamic motion and occupation shoulder injuries in the future.

PRACTITIONER SUMMARY

Arm overuse has been linked to occupation-related shoulder injuries. An activity monitor attached to the wrist and a triaxial accelerometer mounted on the humerus were compared in a field trial. The results demonstrate that, under certain conditions, a commercially available activity monitor might be a useful tool for exposure assessment.