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The video ultrasound imaging is one of the techniques that is in demand at the present time. The reason of using ultrasound video is to provide a clearer impression of the organ's details or any area in the body to a specialist. Therefore, automated improving of ultrasound video increase a chance of getting a correct diagnosis and it is possible to add as an option in the ultrasound machine (improving the ultrasound video during recording). In this paper, we introduced and applied a novel technique, which depends on the principle of fuzzy inference system, through designing an effective fuzzy rule to treat image regions of low contrast based on the analysis of the image properties. Proposed technique was performed on muscklusketal ultrasound video and musculoskeletal panoramic ultrasound image. The proposed technique is Fuzzy Inference Ultrasound Video (FIUV), a superior result was obtained when it applied on panoramic images compared to ultrasound video. The performance of the FIUV technique with approximately 18% greater than recent technique in the case of panoramic ultrasound images and 4% less than recent technique when was applied on ultrasound video. Therefore, the results showed that the response of the panoramic images to this proposed technique was more than the videography. However, as future work it is possible to modify this method and improve its performance on video imaging.

Context More than half of all spinal cord injuries (SCI) occur at the cervical level leading to loss of upper limb function, restricted activity and reduced independence. Several technologies have been developed to assist with upper limb functions in the SCI population. Objective There is no clear clinical consensus on the effectiveness of the current assistive technologies for the cervical SCI population, hence this study reviews the literature in the years between 1999 and 2019. Methods A systematic review was performed on the state-of-the-art assistive technology that supports and improves the function of impaired upper limbs in cervical SCI populations. Combinations of terms, covering assistive technology, SCI, and upper limb, were used in the search, which resulted in a total of 1770 articles. Data extractions were performed on the selected studies which involved summarizing details on the assistive technologies, characteristics of study participants, outcome measures, and improved upper limb functions when using the device. Results A total of 24 articles were found and grouped into five categories, including neuroprostheses (invasive and non-invasive), orthotic devices, hybrid systems, robots, and arm supports. Only a few selected studies comprehensively reported characteristics of the participants. There was a wide range of outcome measures and all studies reported improvements in upper limb function with the devices. Conclusions This study highlighted that assistive technologies can improve functions of the upper limbs in SCI patients. It was challenging to draw generalizable conclusions because of factors, such as heterogeneity of recruited participants, a wide range of outcome measures, and the different technologies employed.

Transhumeral amputation has a considerable detrimental effect on the amputee’s quality of life and independence. Previous work has already established the potential for exploiting proximal humerus myoelectric and kinematic signals for the effective control of a myoelectric prosthesis. That previous work used a Time-Delay Neural Network (TDNN) to perform the mapping of six electromyographic (EMG) and six kinematic proximal humerus signals to predict elbow flexion/extension. Since that earlier work alternative deep learning and recurrent neural network architectures, well-suited to the processing of high-dimensional time-series data, have come to the fore. The work reported here is a comparative evaluation using the metric of RMS error for the predicted elbow flexion/extension angles output by TDNN, Long Short Term Memory (LSTM) and Echo State Network (ESN) architectures. For the most effective comparison we successfully reproduced TDNN results that were comparable to previous work (with average RMSE of 11.8 degrees on unseen test data). Then using the same training and testing datasets, and networks of broadly similar complexity, we evaluated the effectiveness of the LSTM and ESN approaches. The LSTMs trained here delivered an average RMSE of 10.4 degrees on unseen test data. The ESNs delivered an average RMSE of 16.3 degrees on unseen test data. The current work was not intended to find the best possible LSTM or ESN solution for this problem. Instead the intention was to see if any particular aspects of the network architectures worked better with the particular challenges of transhumeral biomedical engineering data of this sort.

Prosthetic devices for hand difference have advanced considerably in recent years, to the point where the mechanical dexterity of a state-of-the-art prosthetic hand approaches that of the natural hand. Control options for users, however, have not kept pace, meaning that the new devices are not used to their full potential. Promising developments in control technology reported in the literature have met with limited commercial and clinical success. We have previously described a biomechanical model of the hand that could be used for prosthesis control. The goal of this study was to evaluate the feasibility of this approach in terms of kinematic fidelity of model-predicted finger movement and the computational performance of the model. We show the performance of the model in replicating recorded hand and finger kinematics and find average correlations of 0.89 between modelled and recorded motions; we show that the computational performance of the simulations is fast enough to achieve real-time control with a robotic hand in the loop; and we describe the use of the model for controlling object gripping. Despite some limitations in accessing sufficient driving signals, the model performance shows promise as a controller for prosthetic hands when driven with recorded EMG signals. User-in-the-loop testing with amputees is necessary in future work to evaluate the suitability of available driving signals, and to examine translation of offline results to online performance.

Panoramic Musculoskeletal Ultrasound Images (PMUI) is a developed version of ultrasound images. However, low contrast is a concrete problem which impact negatively on the interpretation of important details of PMUI. Therefore, in this paper a new automated contrast enhancement method was presented and examined on the PMUI. A fuzzy technique is the main tool underpinning this method, and it consists of three steps: fuzzification, modification of membership equation and defuzzification. Maximum fuzzy entropy of PMUI was used to optimize parameters of the membership function. The quality of results was examined using quantitative metrics. Based on these assessment metrics, the performance of the fuzzy technique outperforms the performance of other method with 21%. The results achieved are very effective and could be used for preprocessing in computer vision applications.

Individuals with hand amputation suffer substantial loss of independence. Performance of sophisticated prostheses is limited by the ability to control them. To achieve natural and simultaneous control of all wrist and hand motions, we propose to use real-time biomechanical simulation to map between residual EMG and motions of the intact hand. Here we describe a musculoskeletal model of the hand using only extrinsic muscles to determine whether real-time performance is possible. Simulation is 1.3 times faster than real time, but the model is locally unstable. Methods are discussed to increase stability and make this approach suitable for prosthesis control.

Capturing accurate representations of musculoskeletal system morphology is a core aspect of musculoskeletal modelling of the upper limb. Measurements of important geometric parameters such as the thickness of muscles and tendons are key descriptors of the underlying morphology. Though the measurement of those parameters can be estimated manually using cadaveric measurements, this is not an appropriate technique for constructing a personalised musculoskeletal model for an individual. Therefore, this work proposes and applies a novel method for evaluating the geometric parameters of the upper extremity based on automated ultrasound image analysis. The proposed algorithm involves advanced techniques from artificial intelligence and image processing to outline the necessary details of the musculoskeletal morphology from appropriately enhanced ultrasound images. The ultrasound images were collected from 25 healthy volunteers from different parts of upper limb. The results were compared with measurements of a manual evaluation. Our results showed that the average discrepancy between the manual and automatic measures of triceps thickness is 0.115 mm. This represents improved accuracy compared to several current approaches.

Removing or reducing speckle noise is one of the main goals to ensure high quality panoramic ultrasound images of muscles and tendons. The presence of noise in the ultrasound image adds a difficulty in the interpretation of the image by clinicians and researchers. In this work, non-liner filter (local adaptive median filter (LAMF1)) has been developed to do a precise detection for speckle noise pixels and reduce its impact on the ultrasound images. It has been applied on three different types of ultrasound images: Based on using set of assessment metrics: Speckle Suppression Index (SSI), Speckle Suppression Mean Preservation Index (SMPI), Enhanced Edge Index (EEI) and Mean Preservation Speckle Suppression Index (MPSSI)), the new local adaptive median filter (LAMF2) has been compared to LAMF1 and Anisotropic Diffusion Filter (ADF). The performance of developed filter (LAMF2) outperformed the performance of LAMF1 as follows: SSI (3%), SMPI (4.79%), EEI (3.7%) and MPSSI (40%). Besides that, ADF has a high level of SSI, SMPI and MPSSI compared to new filter (LAMF2). However, ADF reported better numerical evaluations (EEI) than LAMF2. It is possible to obtain further performance improvements by combining characteristics of both filters (LAMF2 and ADF).

Introduction: We have previously shown that several tidal breathing parameters measured using SLP varied between asthmatic children and healthy (Hmeidi et al., 2017). However, we did not test the classification power of a model which incorporates the identified parameters.\ud \ud Aim: In this study a classifier was constructed and its performance was evaluated in differentiating asthmatic children from healthy.\ud \ud Method: 30 clinically diagnosed asthmatic children with abnormal spirometry (FEV1

Objective: The goal of the current study was todetermine whether and how much the stabilizing role of theshoulder muscles changes as a function of humeral elevationand the plane of elevation. Methods: A musculoskeletal model,comprising a personalized scapulohumeral rhythm, was usedto calculate the ratio of shear over compressive force (stabilityratio) of three rotator cuff muscles (supraspinatus, infraspinatus,subscapularis) and three superficial shoulder muscles (middledeltoid, clavicular part of pectoralis major, latissimus dorsi)during abduction, flexion and reaching movements in ten healthyadults. Results: The range of the stability ratios was [±0.5] forthe rotator cuff muscles compared to [+5,-2] for the superficialshoulder muscles. In the superior-inferior direction, the stabilityratios of all muscles changed with humeral elevation and forinfraspinatus, subscapularis, latissimus dorsi and deltoid alsowith the plane of elevation. In the anterior-posterior direction,the stability ratios of all muscles changed with humeral elevation,except for the deltoid, and with the plane of elevation, except forthe supraspinatus, with interaction effects in all muscles.Conclusion: The rotator cuff muscles provide greater compressionthan shear forces during all tasks. The stabilizing function ofthe superficial shoulder muscles examined in this study variesduring tasks. Significance: The findings can be used to predictin which movements the shoulder joint becomes more unstableand can be applied to understand how shear and compressiveforces change in populations with abnormal shoulder motion.

ObjectiveThe aim of the study was to evaluate the reported measurement capabilities and predictive validity of the Functional Movement Screen (FMS) for injury.MethodsThis was a prospective observational longitudinal study of 24 male footballers from a single team in England, alongside analysis of an existing database over one season (September 2015–May 2016). A preseason FMS was carried out with scores recorded by an experienced assessor and derived, retrospectively, from the three-dimensional movement data that were simultaneously captured. The assessor scores were compared with the photogrammetric system to determine measurement validity, and predictive validity was quantified by assessing sensitivity and specificity (cut-off score of 14).ResultsThe real-time assessor score matched the photogrammetric score awarded for one of the participants, was higher than the photogrammetric system for 22 participants and was lower than the photogrammetric system in 1 participant. There was no discernible relationship between FMS scores and the competencies required to be met as per the rules articulated for the allocation of a score. A higher number of total injuries were associated with higher FMS scores, whether determined through real-time assessment or codification of kinematic variables. Additionally, neither method of score determination was able to prospectively identify players at risk of serious injury.ConclusionThe FMS does not demonstrate the properties essential to be considered as a measurement scale and has neither measurement nor predictive validity. A possible reason for these observations could be the complexity in the instructions associated with the scale. Further work on eliminating redundancies and improving the measurement properties is recommended.

Structured light plethysmography (SLP) is a light‐based, noncontact technique that measures tidal breathing by monitoring displacements of the thoracoabdominal (TA) wall. We used SLP to measure tidal breathing parameters and their within‐subject variability (v) in 30 children aged 7–16 years with asthma and abnormal spirometry (forced expiratory volume in 1 sec [FEV1]

Introduction: Accurate diagnosis and monitoring of respiratory disease are important for breathing assessment. Conventional lung function techniques such as spirometry are challenging in young children, requiring their full cooperation. Structured Light Plethysmography (SLP) derives tidal breathing measures from thoraco-abdominal (TA) displacement in a non-contact environment. We have shown that IE50 SLP (ratio of inspiratory to expiratory TA displacement rate at 50% of TA displacement) measured by SLP is greater in asthmatic children with airflow obstruction than in healthy children (Hmeidi, H. et al., American Thoracic Society conf. proc. 2016; p10749). Aims: To examine the relationship between SLP-derived breathing parameters and parameters measured using conventional spirometry in children with asthma. Methods: Thirty stable asthmatic children (13 female, 7-16 years), with an FEV1% of SLP and FEV1% was examined using Spearman9s Rho test. Results: A correlation of -0.49 was found betweenIE50 SLP and FEV1% (p=0.005). Conclusion: We have shown that SLP can obtain objective measures of tidal breathing in children with asthma, and that IE50 SLP correlates well with FEV1% measured using spirometry. This novel parameter could be used to quantify the degree of airway obstruction.

To study elbow muscle load sharing we investigated the effect of external flexion-extension (FE) and pronation-supination (PS) moments and elbow angle on muscle activation and oxygen consumption (V O(2)). Two data sets were obtained. First, (n=6) electromyography (EMG) of elbow flexors (long and short heads of biceps brachii, brachioradialis, brachialis) and extensors (long and short heads of triceps brachii and anconeus) was recorded in all combinations of FE and PS moments at three force levels and four elbow angles (50 degrees , 70 degrees , 90 degrees and 110 degrees ). Second, (n=4) EMG and V O(2) of three muscles (both heads of biceps and lateral head of triceps) were measured simultaneously during a subset of the above conditions. Joint angle and therefore both moment arm and muscle length influenced both EMG amplitude and the load sharing between muscles. The principles behind load sharing, however, were difficult to quantify, since it was impossible to distinguish between all individual aspects that affect muscle activity. We found a linear relationship between EMG and V O(2), while joint angle had no major effect. Although in general subjects showed comparable muscle activation patterns, there were also considerable inter-individual differences, which might be explained by the use of different optimisation strategies or differences in morphology.

Measurement of lung function can be difficult in young children. Structured light plethysmography (SLP) is a novel, noncontact method of measuring tidal breathing that monitors displacement of the thoraco–abdominal wall. SLP was used to compare breathing in children recovering from an acute exacerbation of asthma/wheeze and an age‐matched cohort of controls. Children aged 2–12 years with acute asthma/wheeze (n = 39) underwent two 5‐min SLP assessments, one before bronchodilator treatment and one after. SLP was performed once in controls (n = 54). Nonparametric comparisons of patients to healthy children and of pre‐bronchodilator to post‐bronchodilator were made for all children, and also stratified by age group (2–5 vs. 6–12 years old). In the asthma/wheeze group, IE50SLP (inspiratory to expiratory flow ratio) was higher (median 1.47 vs. 1.31; P = 0.002), thoraco–abdominal asynchrony (TAA) and left–right asynchrony were greater (both P

Upper extremity neuroprostheses use functional electrical stimulation (FES) to restore arm motor function to individuals with cervical level spinal cord injury. For the design and testing of these systems, a biomechanical model of the shoulder and elbow has been developed, to be used as a substitute for the human arm. It can be used to design and evaluate specific implementations of FES systems, as well as FES controllers. The model can be customized to simulate a variety of pathological conditions. For example, by adjusting the maximum force the muscles can produce, the model can be used to simulate an individual with tetraplegia and to explore the effects of FES of different muscle sets. The model comprises six bones, five joints, nine degrees of freedom, and 29 shoulder and arm muscles. It was developed using commercial, graphics-based modeling and simulation packages that are easily accessible to other researchers and can be readily interfaced to other analysis packages. It can be used for both forward-dynamic (inputs: muscle activation and external load; outputs: motions) and inverse-dynamic (inputs: motions and external load; outputs: muscle activation) simulations. Our model was verified by comparing the model calculated muscle activations to electromyographic signals recorded from shoulder and arm muscles of five subjects. As an example of its application to neuroprosthesis design, the model was used to demonstrate the importance of rotator cuff muscle stimulation when aiming to restore humeral elevation. It is concluded that this model is a useful tool in the development and implementation of upper extremity neuroprosthetic systems.

The ability of mathematical models of the shoulder to accurately replicate physiological muscle moment arms is unknown. The purpose of this study was to compare model-predicted and experimentally measured moment arms for the rotator cuff muscles during arm elevation.Moment arms obtained from six mathematical models and seven experimental studies were compared for the supraspinatus, infraspinatus, teres minor, and subscapularis for elevation in the scapular plane.All of the included models generated moment arms that generally fell within the range of experimentally measured data.The quantitative agreement between model-predicted and experimentally measured moment arms supports the use of the included models for biomechanical shoulder analyses.

Introduction: Measurement of lung function aids diagnosis and treatment of respiratory conditions, but spirometry is not possible in young children. SLP is a novel technique for measuring chest and abdominal wall movement during tidal breathing that would allow us to obtain measurements in patients where this is not currently possible. Aims: We investigated the use of SLP for measuring tidal breathing in children aged 3-17 years. Methods: Using a Thora-3Di™ (PneumaCare, Cambridge, UK), a structured light pattern was projected onto the chest and abdomen of a seated child. Movement with respiration is captured using stereo-photogrammetry to produce a trace of tidal breathing. Clinically-useful respiratory indices can be calculated such as respiratory rate (RR), inspiratory time ratio (Ti/Ttot) and ratio of inspiratory to expiratory flow at 50% of tidal movement (IE50). The relative contribution of chest wall movement to total movement (RC2Tot) can also be captured. Results: 44 children (22 female) aged 3-17 years underwent assessment with SLP. Normative data are summarized in the table below. Conclusion: We have demonstrated the feasibility of obtaining objective measures of tidal breathing using SLP in children.

Lung function assessment is important in diagnosing and monitoring treatment in asthma. Conventional spirometry requires effort and cooperation of the patient, is challenging in young children and therefore not performed routinely. Structured light plethysmography (SLP) is a non-contact means of assessing lung function that may be useful in such cases. The aim of this study was to assess the use of SLP in determining changes in tidal breathing parameters following treatment with bronchodilator in children with acute asthma. Children admitted to the ward with asthma and on regular bronchodilator treatment were recruited for participation (n=33). Assessment of tidal breathing using a Thora-3Di ™ SLP device was carried out pre- and post-bronchodilator treatment. One-tailed t-tests were used to determine significant changes in tidal breathing parameters determined by SLP. Results showed that the rib-cage versus abdominal contribution to breathing decreased significantly following bronchodilator intervention (46% to 42%, p=0.016) towards the value seen in normative data for the same age group (40%). Other parameters such as respiratory rate, inspiratory time ratio (Ti/Ttot) and ratio of inspiratory to expiratory flow at 50% of tidal movement (IE50) were not significantly affected by bronchodilator treatment. However, variability of Ti/Ttot (as determined by coefficient of variation) did reduce following intervention (0.122 to 0.109, p=0.049). We have shown that SLP can be used in children with acute asthma to acquire objective measures of tidal breathing, and that changes in symmetry such as rib-cage contribution to breathing can be quantified.

Inverse-dynamic models often use cost functions to solve the load-sharing problem. Although it is often assumed that energy is minimised, most cost functions are based on mechanically related measures like muscle force or stress. The aim of this study was to analyse the relationships of two cost functions with experimentally determined data on muscle energy consumption. Four subjects performed isometric contractions generating combinations of elbow flexion/extension and pro/supination moments. Muscle oxygen consumption (VO2) of the m. biceps breve, m. biceps longum, m. brachioradialis and m. triceps laterale was measured with near infrared spectroscopy. Both cost functions were implemented into an existing inverse-dynamic shoulder and elbow model and the individual cost values per muscle were calculated, normalised and subsequently compared to experimental VO2 values. The minimum stress cost function led to a good correspondence between VO2 and cost for the m. triceps laterale but for the flexor muscles cost was significantly lower. A newly proposed energy-related cost function showed, however, a far better correspondence. The inclusion of a linear term and muscle mass in the new criterion led model results to correspond better to experimental results. The energy-related cost function appeared to be a better measure for muscle energy consumption than the stress cost function and led to more realistic predictions of muscle activation.

OBJECTIVE: To estimate the differences in glenohumeral contact forces and shoulder muscle forces between able-bodied subjects and subjects with paraplegia and tetraplegia during wheelchair-related activities of daily living (ADLs).DESIGN: Kinematics and external forces were measured during wheelchair ADLs (level propulsion, weight-relief lifting, reaching) and processed by using an inverse dynamics 3-dimensional biomechanical model.SETTING: Biomechanics laboratory.PARTICIPANTS: Five able-bodied subjects, 8 subjects with paraplegia, and 4 subjects with tetraplegia (N = 17).INTERVENTIONS: Not applicable.MAIN OUTCOME MEASURES: Glenohumeral contact forces and shoulder muscle forces.RESULTS: Peak contact forces were significantly higher for weight-relief lifting compared with reaching and level propulsion (P < .001). High relative muscle force of the rotator cuff was seen, apparently needed to stabilize the joint. For weight-relief lifting, total relative muscle force was significantly higher for the tetraplegia group than for the able-bodied group (P = .022).CONCLUSIONS: Glenohumeral contact forces were significantly higher for weight-relief lifting and highest over the 3 tasks for the tetraplegia group. Without taking paralysis into account, more muscle force was estimated for the subjects with tetraplegia during weight-relief lifting.

van Drongelen S, van der Woude LH, Janssen TW, Angenot EL, Chadwick EK, Veeger DH. Mechanical load on the upper extremity during wheelchair activities. Arch Phys Med Rehabil 2005;86:1214–20. Objective To determine the net moments on the glenohumeral joint and elbow joint during wheelchair activities. Design Kinematics and external forces were measured during wheelchair activities of daily living (level propulsion, riding on a slope, weight-relief lifting, reaching, negotiating a curb) and processed in an inverse dynamics biomechanic model. Setting Biomechanics laboratory. Participants Five able-bodied subjects, 8 subjects with paraplegia, and 4 subjects with tetraplegia. Interventions Not applicable. Main Outcome Measure Net moments on the glenohumeral joint and elbow joint. Results Peak shoulder and elbow moments were significantly higher for negotiating a curb and weight-relief lifting than for reaching, level propulsion, and riding on a slope. Overall, the elbow extension moments were significantly lower for subjects with tetraplegia than for those with paraplegia. Conclusions The net moments during weight-relief lifting and negotiating a curb were high when compared with wheelchair propulsion tasks. Taking the effect of frequency and duration into account, these loads might imply a considerable risk for joint damage in the long term.

Background. Functioning of the upper extremity after implantation of an endoprosthesis remains limited despite the achieved pain relief. Upper extremity kinematics can give insight into function after shoulder arthroplasty. Data on ranges of motion related to the performance of a selection of activities of daily living can aid the clinician in evaluating the outcome of the shoulder and elbow arthroplasties. Methods. Cross-sectional descriptive study of range of motion and activities of daily living kinematics, conducted on nonimpaired subjects. The shoulder and elbow motions of 24 healthy female subjects are measured with an electromagnetic tracking device while performing 8 range of motion tasks and five activities of daily living. The angles of shoulder and elbow are calculated during these tasks. Results. A data set with upper extremity joint angles has been obtained. Large glenohumeral rotations are found for the tasks that require high elevation angles. Large axial rotations of the humerus are found for two of the activities of daily living tasks: the perineal care task and the hair-combing task. Large elbow flexions were seen in the following tasks: combing hair, washing the axilla and eating with a spoon. Interpretation. This study shows a suitable method to describe range of motion and activities of daily living and can serve as a starting point for developing a database on how activities of daily living are performed in a larger population and which joint angles are required to perform these tasks. Results can be used to identify restrictions in upper extremity functioning in patients with shoulder impairments. 2005 Elsevier Ltd. All rights reserved.

Modern lightweight stab-resistant body armour has been developed in response to the operational requirements and the experiences of police forces. While a high degree of protection may be afforded to the wearer, this has usually been achieved at the expense of weight, stiffness, and comfort. The use of a test method to measure the protection level of a proposed design against a target specification is inherent in the design and development process. This study reviews data used to establish recent improvements in standard test methods, and shows that deficiencies in current standards may well lead to over-specification of body armour. It is shown that more detailed characterization of real human stabbing actions is needed and the test situation needs to be viewed as a multibody, dynamic interaction if results are to be obtained that reflect the reality of an attack. The information will be of particular interest to body armour manufacturers and researchers working to improve armour design.

Objective. To explain loss of shoulder function following scapular neck malunion in terms of biomechanical changes around the gleno-humeral joint. Design. Biomechanical modelling study. Background. Residual rotation of the scapular neck after fracture can lead to pain and loss of function, and the indications for surgical intervention are contested. Methods. A 3D, large-scale, musculo-skeletal model of the upper limb was used to compare shoulder biomechanics in the case of scapular neck malunion with normal anatomy. Abduction of the humerus was simulated with three models: normal anatomy, 24° and 40° inferior scapular neck rotation. Results. Predicted muscle activation differed greatly between the control and the fracture cases. The motion required additional muscle effort for the maintenance of gleno-humeral stability in the fracture cases. Higher moments in the plane of abduction were generated by the teres major, pectoralis major and biceps brachii muscles with high humeral elevation angles. The rotator cuff muscles were severely shortened in the post-fracture cases and the forces in these muscles were greatly reduced in a test of loaded abduction with the humerus at 90°. Conclusions. Given the function of the rotator cuff muscles as stabilisers of the gleno-humeral joint, it is concluded that the loss of force in these muscles, together with other changes in muscle activation, will lead to loss of arm function in patients with scapular neck malunion. Relevance. These findings will contribute to the improved treatment of patients with scapular neck malunion by identifying important factors in the consideration of surgical intervention.

Objective . To determine why certain tendon transfers are mechanically more effective than other tendon transfers for the treatment of a massive rotator cuff tear. Design . A tendon transfer procedure of latissimus dorsi, teres major or a combination of these two to the insertions of either teres minor, infraspinatus, supraspinatus, or subscapularis is simulated using a biomechanical musculoskeletal model of the upper extremity. Background . Massive rotator cuff tears are not easily repaired. To compensate for the loss of rotator cuff function techniques such as muscle transfers are developed. Methods . Three range of motion tasks were used as input to the Delft shoulder and elbow model. The muscle parameters of the Delft shoulder and elbow model were modified to simulate a rotator cuff tear. A biomechanical analysis of the transferred muscles was performed, taking outcome variables such as moment arms, muscle length and muscle force into account. Results . Due to the massive rotator cuff tear, an elevation and external rotation moment is lost. When the tendon was transferred to the insertions of infraspinatus or supraspinatus, the humerus was capable of elevating and externally rotating. Conclusions . On the basis of mechanical parameters such as moment arms, muscle length and force it can be concluded that a tendon transfer of the teres major to the supraspinatus insertion will produce the best functional outcome in the treatment of massive rotator cuff tears. Relevance To find biomechanical evidence for an optimal tendon transfer that will lead to improved treatment of patients with a massive rotator cuff tear.

Objective. To determine what the most effective tendon transfer is in the case of a dysfunctional rotator cuff. Design. A tendon transfer procedure of latissimus dorsi, teres major or a combination of these two to the insertions of either teres minor, infraspinatus, supraspinatus, or subscapularis is simulated using a biomechanical musculoskeletal model of the upper extremity. Background. Massive rotator cuff tears are not easily repaired. To compensate for this loss of rotator cuff function other techniques like muscle transfers are developed. Methods. Three range of motion tasks and six activities of daily living of 24 subjects were measured. Kinematics from these tasks were used as input to the Delft Shoulder and Elbow Model. The muscle parameters of the Delft Shoulder and Elbow Model were modified to simulate a rotator cuff tear and the ability to perform the measured tasks with and without simulated transfer procedures was checked. Results. The highest improvements (28–30%, P =0.00) in the ability to perform tasks were observed after a simulated tendon transfer of either both muscles or teres major alone attached to the supraspinatus or infraspinatus insertion. Although all transfer procedures produce significant improvements ( P =0.00), there is a significant difference between the procedures (Chi square=58.8, P =0.00) dependent on attachment site. Conclusions. According to the simulation procedure used in the current study, a tendon transfer of teres major and latissimus dorsi or teres major alone to the supraspinatus insertion appears to be the most effective procedure in the case of a dysfunctional rotator cuff. Practical factors, like subacromial space, volume of the muscles and tendons, tensile properties and the ability to split the muscles, will finally determine which is the prefered transfer option. Relevance. To find biomechanical evidence for an optimal tendon transfer for patients with a dysfunctional rotator cuff.

Movements of the human upper extremity are difficult to measure, due to the specific structure of the limb. All arm movements are a combination of movements of the humerus relative to a moveable base: the scapula. Measurement of movements is, however, strongly hampered by the fact that the scapular movement is difficult to track when skin-based landmarks are used. A second complicating factor is the fact that a skin-based proximal landmark on the humerus is difficult to define, which directly affects attempts to describe accurately the movements of that segment. To solve these problems, special measurement procedures have been developed, which include the identification of landmarks for the scapula and the humerus and recording procedures for segment movements or the estimation of landmarks. Also, a definition of the three-dimensional description of motion is presented. These measurement procedures have now been applied in several experiments and have been proven to be successful.

Electrical stimulation is a promising technology for the restoration of arm function in paralysed individuals. Control of the paralysed arm under electrical stimulation, however, is a challenging problem that requires advanced controllers and command interfaces for the user. A real-time model describing the complex dynamics of the arm would allow user-in-the-loop type experiments where the command interface and controller could be assessed. Real-time models of the arm previously described have not included the ability to model the independently controlled scapula and clavicle, limiting their utility for clinical applications of this nature. The goal of this study therefore was to evaluate the performance and mechanical behaviour of a real-time, dynamic model of the arm and shoulder girdle. The model comprises seven segments linked by eleven degrees of freedom and actuated by 138 muscle elements. Polynomials were generated to describe the muscle lines of action to reduce computation time, and an implicit, first-order Rosenbrock formulation of the equations of motion was used to increase simulation step-size. The model simulated flexion of the arm faster than real time, simulation time being 92% of actual movement time on standard desktop hardware. Modelled maximum isometric torque values agreed well with values from the literature, showing that the model simulates the moment-generating behaviour of a real human arm. The speed of the model enables experiments where the user controls the virtual arm and receives visual feedback in real time. The ability to optimise potential solutions in simulation greatly reduces the burden on the user during development.

This study aimed to compare glenohumeral stability during functional tasks in subjects with previous dislocation injury against non-injured controls. Six subjects with previous injury and six controls were asked to complete hand-positioning tasks against external forces applied in six directions. Arm kinematics, muscle activations and hand forces were measured and used as input to an inverse-dynamic model of the shoulder that optimised muscle forces to solve the load-sharing problem. Glenohumeral stability was calculated using the direction of the joint reaction force vector in the glenoid. The simulations showed that GH stability was significantly lower in the previously injured group compared to the controls, and that the direction of exerted forces had a significant effect on GH stability, with the hand pushing away from the body and medially producing significantly lower stability. GH stability was significantly lower in the previously injured group for all six force directions, even though all participants were back to normal activities and reported no symptoms from their injuries.

Functional electrical stimulation (FES), the coordinated electrical activation of multiple muscles, has been used to restore arm and hand function in people with paralysis. User interfaces for such systems typically derive commands from mechanically unrelated parts of the body with retained volitional control, and are unnatural and unable to simultaneously command the various joints of the arm. Neural interface systems, based on spiking intracortical signals recorded from the arm area of motor cortex, have shown the ability to control computer cursors, robotic arms and individual muscles in intact non-human primates. Such neural interface systems may thus offer a more natural source of commands for restoring dexterous movements via FES. However, the ability to use decoded neural signals to control the complex mechanical dynamics of a reanimated human limb, rather than the kinematics of a computer mouse, has not been demonstrated. This study demonstrates the ability of an individual with long-standing tetraplegia to use cortical neuron recordings to command the real-time movements of a simulated dynamic arm. This virtual arm replicates the dynamics associated with arm mass and muscle contractile properties, as well as those of an FES feedback controller that converts user commands into the required muscle activation patterns. An individual with long-standing tetraplegia was thus able to control a virtual, two-joint, dynamic arm in real time using commands derived from an existing human intracortical interface technology. These results show the feasibility of combining such an intracortical interface with existing FES systems to provide a high-performance, natural system for restoring arm and hand function in individuals with extensive paralysis.

The Delft Shoulder and Elbow Model (DSEM), a musculoskeletal model of the shoulder and elbow has been extensively developed since its introduction in 1994. Extensions cover both model structures and anatomical data focusing on the addition of an elbow part and muscle architecture parameters. The model was also extended with a new inverse-dynamics optimization cost function and combined inverse-forward-dynamics models. This study is an update on the developments of the model over the last decade including a qualitative validation of the different simulation architectures available in the DSEM. To validate the model, a dynamic forward flexion motion was performed by one subject, of which the motion data and surface EMG-signals of 12 superficial muscles were measured. Patterns of the model-predicted relative muscle forces were compared with their normalized EMG-signals. Results showed relatively good agreement between forces and EMG (mean correlation coefficient of 0.66). However, for some cases, no force was predicted while EMG activity had been measured (false-negatives). The DSEM has been used and has the potential to be used in a variety of clinical and biomechanical applications. Electronic supplementary material The online version of this article (doi:10.1007/s11517-011-0839-7) contains supplementary material, which is available to authorized users.

Neuroprostheses can be used to restore movement of the upper limb in individuals with high-level spinal cord injury. Development and evaluation of command and control schemes for such devices typically requires real-time, “patient-in-the-loop” experimentation. A real-time, three-dimensional, musculoskeletal model of the upper limb has been developed for use in a simulation environment to allow such testing to be carried out non-invasively. The model provides real-time feedback of human arm dynamics that can be displayed to the user in a virtual reality environment. The model has a three degree-of-freedom gleno-humeral joint as well as elbow flexion/extension and pronation/supination, and contains 22 muscles of the shoulder and elbow divided into multiple elements. The model is able to run in real time on modest desktop hardware and demonstrates that a large-scale, 3D model can be made to run in real time. This is a prerequisite for a real-time, whole arm model that will form part of a dynamic arm simulator for use in the development, testing and user training of neural prosthesis systems.

Individuals with C5/C6 spinal cord injury (SCI) have a number of paralyzed muscles in their upper extremities that can be electrically activated in a coordinated manner to restore function. The selection of a practical subset of paralyzed muscles for stimulation depends on the specific condition of the individual, the functions targeted for restoration, and surgical considerations. This paper presents a musculoskeletal model-based approach for optimizing the muscle set used for functional electrical stimulation (FES) of the shoulder and elbow in this population. Experimentally recorded kinematics from able-bodied subjects served as inputs to a musculoskeletal model of the shoulder and elbow, which was modified to reflect the reduced muscle force capacities of an individual with C5 SCI but also the potential of using FES to activate paralyzed muscles. A large number of inverse dynamic simulations mimicking typical activities of daily living were performed that included (1) muscles with retained voluntary control and (2) many different combinations of stimulated paralyzed muscles. These results indicate that a muscle set consisting of the serratus anterior, infraspinatus and triceps would enable the greatest range of relevant movements. This set will become the initial target in a C5SCI neuroprosthesis to restore shoulder and elbow function.

This paper describes a significant ongoing effort by our research group to develop a functional electrical stimulation-based neuroprosthesis capable of restoring essential arm and hand function to individuals with high cervical (C1-C4) spinal cord injury, a condition referred to as high tetraplegia. These injuries are at the highest level of the spinal cord and leave those afflicted with extensive paralysis below the neck — typically such individuals are left with volitional control of just the head, neck, and in some cases shoulder shrug. Individuals with high tetraplegia are usually totally dependent on others for all aspects of care, and traditional rehabilitation procedures result in limited functional improvement [1].Copyright © 2007 by ASME