Repetitive Shoulder Research Articles

Effect of reverse manual wheelchair propulsion on shoulder kinematics, kinetics and muscular activity in persons with paraplegia

Objective: Shoulder pain after spinal cord injury (SCI) is attributed to increased mobility demands on the arms and negatively impacts independence and quality of life. Repetitive superior and posterior shoulder joint forces produced during traditional wheelchair (WC) locomotion can result in subacromial impingement if unopposed, as with muscular fatigue or weakness. ROWHEELS® (RW), geared rear wheels that produce forward WC movement with backward rim pulling, could alter these forces. Design: Cross sectional. Setting: Research laboratory at a rehabilitation hospital. Participants: Ten manual WC users with paraplegia. Outcome measures: Propulsion characteristics and right upper extremity/trunk kinematics and shoulder muscle activity were collected during ergometer propulsion: (1) self-selected free speed reverse propulsion with RW, (2) matched-speed reverse (rSW), and (3) forward propulsion (fSW) with instrumented Smartwheels (SW). Inverse dynamics using right-side SW rim kinetics and kinematics compared shoulder kinetics during rSW and fSW. Results: Free propulsion velocity, cycle distance and cadence were similar during RW, rSW and fSW. Overall shoulder motion was similar except that peak shoulder extension was significantly reduced in both RW and rSW versus fSW. Anteriorly and inferiorly directed SW rim forces were decreased during rSW versus fSW propulsion, but posteriorly and superiorly directed rim forces were significantly greater. Superior and posterior shoulder joint forces and flexor, adductor, and external rotation moments were significantly less during rSW, without a significant difference in net shoulder forces and moments. Traditional propulsive-phase muscle activity was significantly reduced and recovery-phase muscle activity was increased during reverse propulsion. Conclusion: These results suggest that reverse propulsion may redirect shoulder demands and prevent subacromial impingement, thereby preventing injury and preserving independent mobility for individuals with paraplegia.

Assessment of musculoskeletal disorders and associated risk factors among dentists in Rajahmundry City: A cross-sectional study

Background: Like any other profession, dentistry is also plagued by many occupational health hazards (OHHs). Musculoskeletal disorders (MSDs) are one of the most common OHHs witnessed among dental practitioners. Aim: This study aimed to assess the prevalence and associated risk factors for MSDs among dental practitioners. Material and Methods: A prevalidated questionnaire was distributed among 150 dentists practicing in Rajahmundry city. The questionnaire was designed to procure information on demographic details and associated risk factors of MSDs experienced by them in the last 6 months. Chi-square test and multivariate regression analysis were employed to find significance among the study parameters and associated risk factors. Statistical analysis was performed using SPSS software (version 23.0, IBM, Chicago, IL, USA), and P < 0.05 was considered to be statistically significant. Results: Among the 150 respondents, 62.7% were males and 37.3% were females. The prevalence of MSD was observed as 58.7% and showed higher rates of pain in the neck (24%) followed by lower back region (20%) and upper back (14.7%). The associated risk factors were found to be number of working hours, number of cases treated per day, posture, and repetitive shoulder and hand movements (P < 0.05). Conclusion: This study revealed a relatively high prevalence of musculoskeletal pain among dentists, and there is a need to implement and practice preventive measures in order to minimize the problem.

The influence of job rotation and task order on muscle responses in females

Job rotation aims to reduce muscle fatigue by switching between functionally different tasks to theoretically lessen the risk of site-specific fatigue and work-related musculoskeletal disorders (WMSDs). The effectiveness of job rotation in mitigating the onset of muscle fatigue is partially known, but there is limited ergonomic data on female populations despite comparatively lower upper body strength and increased risk of WMSDs. Rotating between two functionally different tasks, continuing a single task, and varying task order were assessed in the present study for influence on muscle fatigue indicators in a female population. Participants performed a randomized set of four task combinations involving two unilateral, repetitive shoulder tasks (forward flexion and internal rotation). During these combinations, maximal voluntary force, mean power frequency, average EMG (aEMG) and ratings of perceived exertion (RPE) were recorded. Differences between task combinations and time were tested using a two-way repeated measures ANOVA. Indications of fatigue were limited in the results. Forward flexion (p = 0.004) and internal rotation (p = 0.002) maximum voluntary force declined in all task combinations while RPE increased (p < 0.0001); non-rotating task combinations had the greatest declines in force and increases in RPE. Results from EMG amplitude were less clear, and were muscle and task specific. While non-rotating task combinations had the greatest decrements in aEMG submaximal force, rotating task combinations often had similar decrements, creating limited statistical differences. Changes in aEMG were too small to distinguish an order effect. The EMG results suggest muscular demand overlap between the two tasks, despite being functionally different. The effectiveness of job rotation is partially dependent on selecting tasks that engage distinct muscle groups.

Dynamic thoracohumeral kinematics are dependent upon the etiology of the shoulder injury.

Obtaining kinematic patterns that depend on the shoulder injury may be important when planning rehabilitation. The main goal of this study is to explore whether the kinematic patterns of continuous and repetitive shoulder elevation motions are different according to the type of shoulder injury in question, specifically tendinopathy or rotator cuff tear, and to analyze the influence of the load handled during its assessment. For this purpose, 19 individuals with tendinopathy and 9 with rotator cuff tear performed a repetitive scaption movement that was assessed with stereophotogrammetry. Furthermore, static range of motion (ROM) and isometric strength were evaluated with a goniometer and a dynamometer, respectively. Dynamic measurements of maximum elevation (Emax), variablility of the maximum angle (VMA), maximum angular velocity (Velmax), and time to maximum velocity (tmaxvel) were found to be significantly different between the tendinopathy group (TG) and the rotator cuff tear group (RTCG). No differences were found in the ROM assessed with goniometry and the isometric strength. The effect of increasing the load placed in the hand during the scaption movement led to significant differences in Emax, VMA, tmaxvel and repeatability. Therefore, only the dynamic variables showed sufficient capability of detecting differences in functional performance associated with structural shoulder injury. The differences observed in the kinematic variables between patients with tendinopathy and rotator cuff tear seem to be related to alterations in thoracohumeral rhythm and neuromuscular control. Kinematic analysis may contribute to a better understanding of the functional impact of shoulder injuries, which would help in the assessment and treatment of shoulder pain.

Outcome of Scapulothoracic Arthroscopy for Painful Snapping Scapula

Introduction:Patients with scapulothoracic syndrome present with pain in the scapulothoracic area aggravated by overhead and repetitive shoulder movements. The aim of our study was to assess the outcome of scapulothoracic arthroscopic treatment in patients with painful snapping scapula in our institution.Methods:Fourteen patients underwent scapulothoracic arthroscopic treatment for painful snapping scapula. Pre-operatively, all these patients had a trial of conservative treatment modalities for at least 6 months.Two portals along the medial border of scapula were used for arthroscopy and instrumentation. In three cases a superior portal was also used. The arm was placed in the “chicken wing” position so that the scapula lifted up from the chest wall. Outcome was assessed using pre and postoperative pain visual analogue score and Oxford Shoulder Score.Results:Of the fourteen patients included in our study, ten were female and four were male patients. Mean age at the time of surgery was 27.6 years. Mean follow up was 35.7 months. Pain visual analogue score improved significantly from a mean of 8.8 preoperatively to 2.5 postoperatively (P value 0.00002). There was also a significant improvement in Oxford Shoulder Score from a mean of 10.8 to 40.9 (P= 0.00001). Mean crepitus score significantly decreased from 2.6 to 0.21 (p < 0.00001). Crepitus completely resolved in eleven patients. In three there was residual palpable crepitus but they had good pain relief.Conclusion:Arthroscopic scapulothoracic treatment provides significant pain relief and functional improvement for painful snapping scapula symptoms not responding to non-surgical treatment modalities.

Surgery for subacromial impingement syndrome in relation to occupational exposures, lifestyle factors and diabetes mellitus: a nationwide nested case–control study

ObjectivesTo estimate the risk of surgery for subacromial impingement syndrome (SIS) in relation to occupational exposures, lifestyle factors and diabetes mellitus.MethodsWe conducted a case–control study nested in a register-based cohort...

“PREVALENCE OF SHOULDER PAIN IN PETROL PUMP WORKERS”

Shoulder pain (SP) is the most common problem in workers exposed to repetitive shoulder activity in their occupation. The petrol pump workers, who have repetitive activities of shoulder joint by picking and keeping the nozzle at petrol pump station. This repetitive activity increases the demand on the muscles, ligaments, soft tissues of musculoskeletal system. This activity is carried out in standing posture. So the purpose of the present study is to know the prevalence of shoulder pain in petrol pump workers. So, the aim of the present study the prevalence of shoulder pain in petrol pump workers. A Observational –Cross sectional study done on 100 Petrol Pump Workers selected randomly with the job profile of filling the fuel with nozzle in vehicles 20 – 40 years of age working since &gt; 6months, without any shoulder injury, trauma and neurological musculoskeletal problem. Questionnaire was prepared and validated. Non Parametric Test Were Applied. In this study only 49% Petrol Pump Workers people had shoulder pain where as 51% did not shoulder pain had. The study shows that Petrol Pump workers ageing from 31 – 40 years who have experience of profession more than 5 years often suffer from shoulder pain which may be associated with repetitive activity of shoulder and faulty posture while working.

Upper arm elevation and repetitive shoulder movements: a general population job exposure matrix based on expert ratings and technical measurements

ObjectivesWe recently constructed a general population job exposure matrix (JEM), The Shoulder JEM, based on expert ratings. The overall aim of this study was to convert expert-rated job exposures for...

Neurogenic Thoracic Outlet Syndrome Presenting as Chronic Elbow Pain After Obstacle Course

HISTORY: A 20-year-old female US Naval Academy freshman sustained a left elbow injury after repetitive shoulder abduction movements while completing a required obstacle course. She denied specific trauma, including a fall. There was no numbness, tingling, or radiation of pain. Five days later, she reported her left elbow pain to her physician. Originally diagnosed with an elbow contusion versus epicondylosis, the patient’s progressive left elbow pain lasted for more than 6 months when she developed ulnar dysesthesias in her hand. PHYSICAL EXAMINATION: Examination revealed diffuse elbow tenderness with swelling. Normal neurovascular examination was demonstrated. Elbow strength and range of motion were normal. Neck and shoulder exams demonstrated no abnormalities. Swelling resolved in one week. Exam remained unchanged for several months before she developed ulnar distribution pain. Then, an Allen test reproduced and worsened her elbow pain and neurologic symptoms. DIFFERENTIAL DIAGNOSIS: 1. Elbow Contusion 2. Chronic Regional Pain Syndrome 3. Intraarticular Body, Elbow Fracture 4. Brachial Plexopathy 5. Thoracic Outlet Syndrome TEST AND RESULTS: Left elbow anterior-posterior, lateral radiographs: — no acute osseous abnormality Left elbow MRI: — likely resolving bony contusion of radial head without evidence of fracture CT Left Elbow: —normal evaluation of the left elbow EMG left upper extremity: —normal electrodiagnostic study Left brachial plexus MRI: —normal left brachial plexus Chest MRI, with contrast: —findings consistent with thoracic outlet syndrome localized to costoclavicular space Left upper extremity venogram: —no evidence of venous occlusion or compression FINAL/WORKING DIAGNOSIS: Neurogenic Thoracic Outlet Syndrome TREATMENT AND OUTCOMES: 1. Relative rest, ice, compression and NSAIDs for 4 weeks without improvement. 2. Activity modification and trial of acupuncture demonstrated minimal improvement in presenting elbow pain. 3. Left scalene block with complete relief of symptoms, indicating neurogenic thoracic outlet syndrome. 4. Partial left first rib resection with resolution of chronic left elbow pain and ulnar nerve dysesthesias. 5. Range of motion, shoulder, and neck strengthening exercises started gradually 6 weeks post-surgery.

A Hands-Free Interface for Controlling Virtual Electric-Powered Wheelchairs

This paper focuses on how to provide mobility to people with motor impairments with the integration of robotics and wearable computing systems. The burden of learning to control powered mobility devices should not fall entirely on the people with disabilities. Instead, the system should be able to learn the user's movements. This requires learning the degrees of freedom of user movement, and mapping these degrees of freedom onto electric-powered wheelchair (EPW) controls. Such mapping cannot be static because in some cases users will eventually improve with practice. Our goal in this paper is to present a hands-free interface (HFI) that can be customized to the varying needs of EPW users with appropriate mapping between the users' degrees of freedom and EPW controls. EPW users with different impairment types must learn how to operate a wheelchair with their residual body motions. EPW interfaces are often customized to fit their needs. An HFI utilizes the signals generated by the user's voluntary shoulder and elbow movements and translates them into an EPW control scheme. We examine the correlation of kinematics that occur during moderately paced repetitive elbow and shoulder movements for a range of motion. The output of upper-limb movements (shoulder and elbows) was tested on six participants, and compared with an output of a precision position tracking (PPT) optical system for validation. We find strong correlations between the HFI signal counts and PPT optical system during different upper-limb movements (ranged from r = 0.86 to 0.94). We also tested the HFI performance in driving the EPW in a virtual reality environment on a spinal-cord-injured (SCI) patient. The results showed that the HFI was able to adapt and translate the residual mobility of the SCI patient into efficient control commands within a week's training. The results are encouraging for the development of more efficient HFIs, especially for wheelchair users.

Effort Thrombosis (Paget-Schroetter Syndrome)

Effort thrombosis, also known as Paget-Schroetter Syndrome and venous thoracic outlet syndrome (VTOS), refers to primary thrombosis of the subclavian-axillary vein at the costoclavicular space. Most patients present after experiencing axillo-subclavian vein thrombosis, and the thrombosis often results from vigorous athletic activities requiring repetitive arm and shoulder motions (e.g., weight lifting, swimming)as well as occupations that require repetitive motions with elevated upper extremities This review covers effort thrombosis in detail, examining its clinical and diagnostic evaluations, treatment, operative and postoperative management, and complications. An algorithm details the approach to the patient with effort thrombosis. Figures include the anatomy of the costoclavicur space, B-mode and duplex color-flow imaging of the proximal left subclavian vein, crossed occlusive thrombus, anatomic landmarks for planning infraclavicular approach incision, rib resection, venoplasty with an 8 × 40 mm balloon, completion venogram postvenoplasty, the supraclavicular approach using a self-retaining retractor system, post resection of the anterior scalene muscle, and post left first rib decompression chest x-ray. Tables list common clinical findings in VTOS, less frequent clinical findings in VTOS, and postoperative complications. This review contains 15 highly rendered figures, 3 tables, and 40 references.

Investigation of Fatigability during Repetitive Robot-Mediated Arm Training in People with Multiple Sclerosis.

BackgroundPeople with multiple sclerosis (MS) are encouraged to engage in exercise programs but an increased experience of fatigue may impede sustained participation in training sessions. A high number of movements is, however, needed for obtaining optimal improvements after rehabilitation.MethodsThis cross-sectional study investigated whether people with MS show abnormal fatigability during a robot-mediated upper limb movement trial. Sixteen people with MS and sixteen healthy controls performed five times three minutes of repetitive shoulder anteflexion movements. Movement performance, maximal strength, subjective upper limb fatigue and surface electromyography (median frequency and root mean square of the amplitude of the electromyography (EMG) signal of the anterior deltoid) were recorded during or in-between these exercises. After fifteen minutes of rest, one extra movement bout was performed to investigate how rest influences performance.ResultsA fifteen minutes upper limb movement protocol increased the perceived upper limb fatigue and induced muscle fatigue, given a decline in maximal anteflexion strength and changes of both the amplitude and the median frequency of EMG the anterior deltoid. In contrast, performance during the 3 minutes of anteflexion movements did not decline. There was no relation between changes in subjective fatigue and the changes in the amplitude and the median frequency of the anterior deltoid muscle, however, there was a correlation between the changes in subjective fatigue and changes in strength in people with MS. People with MS with upper limb weakness report more fatigue due to the repetitive movements, than people with MS with normal upper limb strength, who are comparable to healthy controls. The weak group could, however, keep up performance during the 15 minutes of repetitive movements.Discussion and ConclusionAlbeit a protocol of repetitive shoulder anteflexion movements did not elicit a performance decline, fatigue feelings clearly increased in both healthy controls and people with MS, with the largest increase in people with MS with upper limb weakness. Objective fatigability was present in both groups with a decline in the muscle strength and increase of muscle fatigue, shown by changes in the EMG parameters. However, although weak people with multiple sclerosis experienced more fatigue, the objective signs of fatigability were less obvious in weak people with MS, perhaps because this subgroup has central limiting factors, which influence performance from the start of the movements.

Effects of repetitive shoulder activity on the subacromial space in manual wheelchair users.

This study investigated (1) the effect of repetitive weight-relief raises (WR) and shoulder external rotation (ER) on the acromiohumeral distance (AHD) among manual wheelchair users (MWUs) and (2) the relationship between shoulder pain, subject characteristics, and AHD changes. Twenty-three MWUs underwent ultrasound imaging of the nondominant shoulder in an unloaded baseline position and while holding a WR position before and after the WR/ER tasks. Paired t-tests and Spearman correlational analysis were used to assess differences in the AHD before and after each task and the relationships between pain, subject characteristics, and the AHD measures. A significant reduction in the subacromial space (P < 0.01) occurred when subjects performed a WR position compared to baseline. Individuals with increased years of disability had greater AHD percentage narrowing after WR (P = 0.008). Increased shoulder pain was associated with AHD percentage narrowing after ER (P ≤ 0.007). The results support clinical practice guidelines that recommend MWUs limit WR to preserve shoulder function. The isolated repetitive shoulder activity did not contribute to the changes of subacromial space in MWUs. The ultrasonographic measurement of the AHD may be a target for identifying future interventions that prevent pain.

Scapular Stress Fracture in Water Polo

Water polo is an intense sport with extreme physical contact and repetitive shoulder motion that predisposes to injury. The continuous scapular motion and recruitment of the scapular stabilizers to maintain buoyancy expose water polo athletes to the risk of scapular stress fracture. Suspicion should arise when evaluating water polo athletes presenting with shoulder pain.

Effects of rotation frequency and task order on localised muscle fatigue and performance during repetitive static shoulder exertions

Though widely considered to reduce physical exposures and increase exposure variation, there is limited evidence that rotating between tasks is effective in reducing the risk of work-related musculoskeletal disorders (WMSDs). The purpose of this study was to assess the effects of rotation, specifically focusing on rotation frequency and task order, on muscle fatigue and performance when rotating between tasks that load the same muscle group. Twelve participants completed six experimental sessions during which repetitive static shoulder abduction tasks were performed at two exertion levels for one hour either with or without rotation. Compared to only performing a higher or lower exertion task, rotating between the two tasks decreased and increased fatigue, respectively. Increasing rotation frequency adversely affected task performance, and task order had a minor effect on muscle fatigue. These rotation parameters may be important considerations when implementing rotation in the workplace. Practitioner Summary: Rotation is widely used and assumed to reduce the risk of WMSDs, yet little research supports that it is effective in doing so. Results here show that specific aspects of a rotation scheme may influence muscle fatigue and task performance, though further research is needed under more realistic task conditions.

Relationship between construction workers' musculoskeletal disorders and occupational health service activities

Construction work consists of numerous factors that influence workers' occupational health and that load the musculoskeletal system in particular. Musculoskeletal disorders are responsible for over a third of all sick leaves lasting over nine days in the construction industry. Occupational health services (OHS) were organized for 85% of the construction workers in our study. The proportion of construction workers who had suffered from chronic or repetitive neck and shoulder, shoulder or arm, or low-back disorders was 55.6%, 44.8% and 42.1%, respectively. Those who felt that they had received enough information, advice or guidance from OHS concerning work posture, work performance or work tools were more often those who had not suffered from shoulder or arm disorders (60.9% vs. 39.1%, p=.024, respectively) or low-back disorders (63.6% vs. 36.4%, p=.034, respectively) during the last month than those who had. Those who had received enough support from OHS concerning maintenance of work ability were more often workers who had not suffered from low-back disorders during the last month than those who had (63.3% vs. 36.7%, p=.004, respectively). OHS should focus more on workers who would really benefit from their activities at a particular time and in a particular situation (primary, secondary or tertiary prevention) and who are themselves devoted to improving their health.

Effects of physical and mental demands on shoulder muscle fatigue

Mental demands have been associated with increased risk of injuries; however, its influence on muscle fatigability remains unclear. The aim of this study was to investigate the interaction of mental workload and physical workload on muscle fatigability during repetitive shoulder work. Twelve young participants, balanced by gender, performed shoulder abduction exercises until exhaustions at three levels of physical workload (low (5% maximum voluntary contraction (MVC)), moderate (35% MVC), and high (55% MVC)) in the absence and presence of a mental arithmetic test. Endurance time and rate of strength decline were employed as indicators of muscle fatigue. Concurrent physical and mental processing was found to adversely decrease muscle endurance by ~25% at the moderate intensity level. Furthermore, concurrent demands were associated with faster rate of strength decline compared to the control, irrespective of the physical intensity level. Findings from the current study provide evidence of the adverse effects of mental workload on muscle capacity (i.e., endurance and fatigue). It is therefore important to consider potential changes in worker capacity with concurrent physical and cognitive demands before designing work tasks/products.

An analysis of occupational factors related to shoulder discomfort in diagnostic medical sonographers and vascular technologists

Three-fourths of diagnostic medical sonographers (DMS) and vascular technologists (VT) experiencing discomfort due to job demands indicate having discomfort in the shoulder region. An analysis of factors related to shoulder discomfort highlighted salient factors requiring further investigation and intervention. The respondents were a convenient sample of DMS and VT that answered a survey, hosted on a secure website. The responses of 2,163 DMS and VT from a survey of a representative sample were analyzed to determine personal factors, work demands, and workstation design characteristics of those experiencing discomfort in the shoulder region. Frequencies and response distributions were calculated and cross tabulation with chi-square analysis was completed. A majority of respondents with shoulder discomfort have co-morbid reports of discomfort in other locations. While overall sonographer discomfort is linked to age and years of experience, shoulder discomfort was also noted to be linked to specific workstation characteristics. A lack of adjustability in equipment, picture archiving and communication system (PACS) workstations, and positions required to complete bedside exams contributes to discomfort due to sustained and repetitive shoulder abduction and twisting of the neck and trunk. There is a need for studies investigating redesign of equipment and workstations or interventions with DMS and VT specifically focused on improving adjustability and improved positioning of sonographers in order to reduce shoulder discomfort while performing job demands.

Shoulder Muscle Oxygenation during Repetitive Tasks

The purpose of this study was to quantify shoulder muscle oxygenation during repetitive shoulder exertions that were similar to motions found in automobile assembly tasks. Ten subjects participated...

Constrained handgrip force decreases upper extremity muscle activation and arm strength

Many industrial tasks require repetitive shoulder exertions to be performed with concurrent physical and mental demands. The highly mobile nature of the shoulder predisposes it to injury. The purpose of this study was to determine the effects of simultaneous gripping, at a specified magnitude, on muscle activity and maximal arm force in various directions. Ten female subjects performed maximal arm exertions at two different heights and five directions using both specified (30% maximum voluntary grip) and preferred (self-selected) grip forces. Electromyography was recorded from eight muscles of the right upper extremity. The preferred grip condition produced grip forces that were dependent on the combination of arm height and force direction and were significantly greater (arm force down), lower (to left, up and push forward), or similar to the specified grip condition. Regardless of the magnitude of the preferred grip force, specifying the grip resulted in decreased maximal arm strength (by 18–25%) and muscle activity (by 15–30%) in all conditions, indicating an interfering effect when the grip force was specified by visual target force-matching. Task constraints, such as specific gripping demands, may decrease peak force levels attainable and alter muscle activity. Depending on the nature of task, the amount of relative demand may differ, which should be considered when determining safety thresholds.