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PubMed2003

Clinical and workplace factors associated with a return to modified duty in work-related upper extremity disorders.

Return to work following treatment for a work-related upper extremity disorder (WRUED) is affected by a variety of medical, workplace, and personal factors, and returning to modified duty may ease the transition to normal work activities. This study surveyed 165 federal government employees (127 females, 38 males) who were unable to resume their normal work after filing a workers' compensation claim for a WRUED (<90 days from claim filing) and who volunteered for a randomized study of alternative case management strategies. Before randomization, participants completed a baseline survey of upper extremity (UE) symptoms, functional limitations, and workplace factors. At baseline, 58 participants (35%) were working modified duty and 107 participants (65%) were not working. Compared with participants working modified duty, those who were not working were more likely to report: (a). a diagnosis of mononeuropathy, odds ratio (OR)=3.16 (95% confidence interval (CI)=1.37-7.14) versus enthesopathy, (b). higher pain ratings, OR=1.43 (95% CI=1.01-2.01), (c). greater functional limitations, OR=1.63 (95% CI=1.11-2.38), and (d). higher level of ergonomic stressors, OR=1.62 (95% CI=1.09-2.43) in a multivariable logistic regression. Measures of high risk work styles (fast pace and working despite pain) were associated with greater perceptions of ergonomic exposure, but not with work status. The model had 87.9% sensitivity and 43.1% specificity to correctly classify those not working (overall classification 72.1% correct). The results suggest that modified duty for workers with persistent WRUEDs may be enhanced by assessing perceived functional limitation and ergonomic exposure as well as the type and severity of symptoms.

Arm Injuries↗
PubMed1999

Cross-sectional study of the relationship between repetitive work and the prevalence of upper limb musculoskeletal disorders.

BACKGROUND: This study examined the relationship of repetitive work and other physical stressors to prevalence of upper limb discomfort, tendinitis, and carpal tunnel syndrome. METHODS: Three hundred fifty-two workers from three companies participated. Job exposure levels for repetition and other physical stressors were quantified using an observational rating technique. Ergonomic exposures were rated on a 10-point scale, where 0 corresponded to no stress and 10 corresponded to maximum stress. Job selection was based on repetition (three categories: high, medium, and low) to ensure a wide range of exposures. Physical evaluations on all participating workers were performed by medical professionals and included a self-administered questionnaire, physical exam, and limited electrodiagnostic testing. RESULTS: Repetitiveness of work was found to be significantly associated with prevalence of reported discomfort in the wrist, hand, or fingers (odds ratio (OR) = 1.17 per unit of repetition; OR = 2.45 for high vs. low repetition), tendinitis in the distal upper extremity (OR = 1.23 per unit of repetition; OR = 3.23 for high vs. low repetition), and symptoms consistent with carpal tunnel syndrome (OR = 1.16 per unit of repetition; OR = 2.32 for high vs. low repetition). An association was also found between repetitiveness of work and carpal tunnel syndrome, indicated by the combination of positive electrodiagnostic results and symptoms consistent with carpal tunnel syndrome (OR = 1. 22 per unit of repetition; OR = 3.11 for high vs. low repetition). CONCLUSIONS: These findings indicate that repetitive work is related to upper limb discomfort, tendinitis, and carpal tunnel syndrome in workers. Further research with a wider range of exposures is needed to evaluate the effects of other physical stresses alone and in combination.

Adult↗
PubMed1997

Development and evaluation of an observational method for assessing repetition in hand tasks.

Several physical stressors, including repetitive, sustained, and forceful exertions, awkward postures, localized mechanical stress, highly dynamic movements, exposures to low temperatures, and vibration have been linked to increased risk of work-related musculoskeletal disorders. Repetitive exertions have been among the most widely studied of these stressors, but there is no single metric for assessing exposure to repetitive work. A new methodology enables repetitive hand activity to be rated based on observable characteristics of manual work. This method uses a series of 10-cm visual-analog scales with verbal anchors and benchmark examples. Ratings for repetition reflect both the dynamic aspect of hand movements and the amount of recovery or idle hand time. Trained job analysis experts rate the jobs individually and then agree on ratings. For a group of 33 jobs, repetition ratings using this system were compared to measurements of recovery time within the cycle, exertion counts, and cycle time. Amount of recovery time within the job cycle was found to be significantly correlated with the analysis ratings (r2 = 0.58), as were the number of exertions per second (r2 = 0.53). Cycle time was not related to the analyst ratings. Repeated analyses using the new method were performed 1 1/2 to 2 years apart on the same jobs with the same group of raters. Ratings for repetition differed less than 1 point (on the 10-cm scale), on average, among the different sessions. These results indicate that the method is sensitive to exertion level and recovery time, and that the decision criteria and benchmark examples allow for a consistent application of these methods over a period of time. This method of rating repetition can be combined with similar scales for other physical stressors.

Cumulative Trauma Disorders↗
PubMed1999

Jumper's knee. Review of the literature.

Jumper's knee is an overuse disease. The initial subjective complaints are well-localized pain, usually occurring after physical activities and often at the lower pole of the patella. The diagnosis of jumper's knee is usually easily established after acquiring a detailed history and a carefully performed physical examination, but the lesion can be mistaken for other disorders or injuries, such as bursitis, meniscal injuries or chondromalacia (1) or other causes of the patellofemoral pain syndrome. Today ultrasonography is the method of choice for the evaluation of jumper's knee as it is both time and cost saving, non-invasive, repeatable, accurate and allows a dynamic image of the tendon, guided injections and control of treatment. Conservative therapy is the treatment of choice in the early stages and includes adequate warm-up, stretching of the quadriceps muscle and physical activity with respect to the pain, and ice pack application after activity. When the pain disappears, the training intensity can be increased. NSAID (Non-Steroidal Anti-Inflammatory Drugs) and local peritendinous injections with long-acting steroids can be a helpful and safe adjuvant to the conservative treatment and should be tried before surgery. Surgical treatment is indicated only if a prolonged and well-supervised conservative treatment program fails in chronic jumper's knee (including local injection with steroid) or in acute total rupture. Review papers concerning jumper's knee are already published (2-5), but in this review the importance of ultrasonography to make the diagnosis, to plan therapy and control the treatment and the safety of peritendinous injection with steroid is pointed out. The scientific documentation for the recommanded treatment (conservative, steroid injection and operation) is, however, insufficient. Many more controlled studies are needed. Ultrasonography and placebo-controlled, double-blinded, cross-over studies for treatment with local injection of steroid are ongoing (6, 7).

Adrenal Cortex Hormones↗
PubMed1999

In vivo finger flexor tendon force while tapping on a keyswitch.

Force may be a risk factor for musculoskeletal disorders of the upper extremity associated with typing and keying. However, the internal finger flexor tendon forces and their relationship to fingertip forces during rapid tapping on a keyswitch have not yet been measured in vivo. During the open carpal tunnel release surgery of five human subjects, a tendon-force transducer was inserted on the flexor digitorum superficialis of the long finger. During surgery, subjects tapped with the long finger on a computer keyswitch, instrumented with a keycap load cell. The average tendon maximum forces during a keystroke ranged from 8.3 to 16.6 N (mean = 12.9 N, SD = 3.3 N) for the subjects, four to seven times larger than the maximum forces observed at the fingertip. Tendon forces estimated from an isometric tendon-force model were only one to two times larger than tip force, significantly less than the observed tendon forces (p = 0.001). The force histories of the tendon during a keystroke were not proportional to fingertip force. First, the tendon-force histories did not contain the high-frequency fingertip force components observed as the tip impacts with the end of key travel. Instead, tendon tension during a keystroke continued to increase throughout the impact. Second, following the maximum keycap force, tendon tension during a keystroke decreased more slowly than fingertip force, remaining elevated approximately twice as long as the fingertip force. The prolonged elevation of tendon forces may be the result of residual eccentric muscle contraction or passive muscle forces, or both, which are additive to increasing extensor activity during the release phase of the keystroke.

Adult↗
PubMed2002

[Repetitive strain injury (RSI): occurrence, etiology, therapy and prevention].

In the Netherlands, work related upper-limb disorders are called Repetitive Strain Injuries (RSI). RSI is not a diagnosis but a catch-all term for symptoms and signs located in the neck, upper back, shoulder, arm, elbow, hand, wrist and fingers. These symptoms may include pain, stiffness, tingling, clumsiness, loss of co-ordination, loss of strength, skin discoloration and temperature differences. Each year, 8% of working Dutch citizens take time off work due to RSI symptoms. Although the number of people claiming disability benefit due to RSI is limited, this figure has risen consecutively over the last three years. There is consensus that repetitive work at a high frequency and possibly accompanied by exertion of force is accompanied by RSI symptoms. There are indications of a relation between visual display unit use and these symptoms. However, these relations have not been established in a longitudinal study of adequate quality. High perceived job stress and a high workload are thought to be related to RSI, and women report more symptoms than men. There is insufficient information available on the role of different coping styles, perfectionism and dealing with symptoms. There is little information on the underlying mechanisms in the development of RSI, the diagnostics, therapy and prevention. In view of the lack of clear diagnostic criteria, suggestions have been made for a standardised description of the symptoms involved in the syndrome. A multidisciplinary treatment is likely to have the most effect. In terms of prevention, an integrated approach aimed at improving the working posture, reduction of static load and job stress and at individual factors is assumed to be the most effective.

Cumulative Trauma Disorders↗
PubMed2003

Repetitive, negligible force reaching in rats induces pathological overloading of upper extremity bones.

UNLABELLED: Work-related repetitive motion disorders are costly. Immunohistochemical changes in bones resulting from repetitive reaching and grasping in 17 rats were examined. After 3-6 weeks, numbers of ED1+ macrophages and osteoclasts increased at periosteal surfaces of sites of muscle and interosseous membrane attachment and metaphyses of reach and nonreach forelimbs. These findings indicate pathological overloading leading to inflammation and subsequent bone resorption. INTRODUCTION: Sixty-five percent of all occupational illnesses in U.S. private industry are attributed to musculoskeletal disorders arising from the performance of repeated motion, yet the precise mechanisms of tissue pathophysiology have yet to be determined for work-related musculoskeletal disorders. This study investigates changes in upper extremity bone tissues resulting from performance of a voluntary highly repetitive, negligible force reaching and grasping task in rats. MATERIALS AND METHODS: Seventeen rats reached an average of 8.3 times/minute for 45-mg food pellets for 2 h/day, 3 days/week for up to 12 weeks. Seven rats served as normal or trained controls. Radius, ulna, humerus, and scapula were collected bilaterally as follows: radius and ulna at 0, 3, 4, 5, 6, and 12 weeks and humerus and scapula at 0, 4, and 6 weeks. Bones were examined for ED1-immunoreactive mononuclear cells and osteoclasts. Double-labeling immunohistochemistry was performed for ED1 (monocyte/macrophage lineage cell marker) and TRACP (osteoclast marker) to confirm that ED1+ multinucleated cells were osteoclasts. Differences in the number of ED1+ cells over time were analyzed by ANOVA. RESULTS: Between 3 and 6 weeks of task performance, the number of ED1+ mononuclear cells and osteoclasts increased significantly at the periosteal surfaces of the distal radius and ulna of the reach and nonreach limbs compared with control rats. These cells also increased at periosteal surfaces of humerus and scapula of both forelimbs by 4-6 weeks. These cellular increases were greatest at muscle attachments and metaphyseal regions, but they were also present at some interosseous membrane attachments. The number of ED1+ cells decreased to control levels in radius and ulna by 12 weeks. CONCLUSIONS: Increases in ED1+ mononuclear cells and osteoclasts indicate that highly repetitive, negligible force reaching causes pathological overloading of bone leading to inflammation and osteolysis of periosteal bone tissues.

Animals↗
PubMed2006

Overexpression of nitric oxide synthases in tendon overuse.

Tendon disorders with a chronic nature, including the rotator cuff, are extremely common, and represent a major clinical problem. Mechanical overload has been proposed as an important etiologic factor in tendinopathies. Nitric oxide (NO), a free radical produced by nitric oxide synthases (NOSs), is a potent regulator and stimulator of biological processes including tendon degeneration and healing. It is also involved in response to mechanical stimuli in different tissues. In an animal model of acutely injured tendon healing temporal and differential expression of NOS isoforms has been demonstrated, suggesting that different patterns of NOSs expression may have different biological functions. Therefore, we hypothesized that tendon overuse may result in a differential upregulation of NOSs, particularly iNOS. An animal model of supraspinatus tendon overuse was utilized, which consisted of treadmill running. A group of animals of the same strain and age subjected to normal cage activity were used as controls. Following a 4-week exercise protocol supraspinatus tendons were harvested, RNA was extracted, and subjected to competitive reverse transcription and polymerase chain reaction (RT-PCR) to determine the expression levels of inducible-, endothelial-, and neuronal-NOS isoforms (i-, e-, and nNOS). The mRNA expression of all three NOS isoforms increased in the supraspinatus tendons as a result of overuse exercise. iNOS and eNOS mRNA expression increased fourfold (p < 0.01), and there was an increase, but statistically not significant, in nNOS mRNA expression in the overused tendons when compared with the controls. This study is the first to show that NOS isoforms are upregulated in rotator cuff tendon as a result of chronic overuse, and suggests the involvement of nitric oxide in the response of tendon tissue to increased mechanical stress.

Animals↗
PubMed2026

Comparative proteomic analysis reveals the pathological mechanisms of overuse achilles tendinopathy and the therapeutic mechanisms of ESWT and PRP.

BACKGROUND: Achilles tendinopathy is a common musculoskeletal disorder with limited self-repair capacity. Although extracorporeal shock wave therapy (ESWT) and platelet-rich plasma (PRP) are widely used, their therapeutic mechanisms remain unclear. METHODS: A rat model of overuse Achilles tendinopathy was established by uphill treadmill running. Tendon morphology and structure were assessed by ultrasound and histology, and proteomic profiling was performed to identify differentially expressed proteins (DEPs) and enriched pathways. RESULTS: Ultrasound revealed subcutaneous edematous infiltration after overuse, and histology showed disorganized collagen fibers and altered cellular density. Compared with the normal group, the injury group showed 429 DEPs, which were enriched in pathways related to actin cytoskeleton and complement and coagulation cascades. Both ESWT and PRP treatments ameliorated these overuse-induced pathological changes. Compared with the rest group, the ESWT group showed 30 DEPs, while the PRP group showed 244, with 17 DEPs overlapping between the two comparisons. In the ESWT group, enriched pathways included actin cytoskeleton organization, protein stabilization, and sulfur metabolism. In the PRP group, enriched pathways included Fc&#x3b3;R-mediated phagocytosis, lysosome, and endoplasmic reticulum protein processing. Compared with the normal group, the ESWT group showed 32 DEPs, whereas the PRP group showed only one (Serpina6), which was the only protein shared between the two comparisons. CONCLUSION: ESWT and PRP improve tendon healing in overuse Achilles tendinopathy through different molecular mechanisms. The PRP group showed a proteomic profile more similar to the normal group than the ESWT group. These findings provide a molecular basis for optimizing clinical treatment strategies.

Animals↗
PubMed1995

Prediction and portrayal of repetitive stress-induced lower limb pain disorders among soldiers in basic training using videothermography.

OBJECTIVE: Thermography has been widely espoused for both detecting and portraying pain problems. Development of repetitive stress-induced lower limb pain during army basic training is a relatively common occurrence. This study was designed to assess the usefulness of thermography for differentiating soldiers who developed lower limb pain during training from those who did not. This information was intended to be used to determine the usefulness of pretraining thermograms taken just as people came into the army in predicting which trainees would develop these conditions during training. DESIGN: Videothermographic pictures were taken of the lower limbs of 639 newly enlisted soldiers who had just arrived at a large U.S. Army base but had not yet begun basic training. The amount of symmetry was correlated with the development of lower limb pain. Each soldier reporting lower limb pain and "controls" with nonpain problems (usually minor colds) received a thermographic evaluation identical to the original evaluation when they came for their medical examination. RESULTS: Among prebasic trainees, 37% showed 1.0 degrees C of asymmetry somewhere in their lower limbs, 14% were asymmetrical by between 1.1 degrees and 2.0 degrees C, 5% by 3.0 degrees C and 4% by 4.0 degrees C or more. Thus, only 40% of the prebasic trainees were within accepted "normal" limits before participating in training. Thirty-nine percent of those with asymmetrical thermograms developed lower limb pain compared with 28% of those with symmetrical thermograms (significant at p < 0.05). It was impossible to predict from any thermographic measurement on the lower limbs which soldiers were most likely to develop lower limb pain. This held true even for those pretrainees with the greatest asymmetries. Eighty-four percent of trainees reporting lower limb pain produced abnormal thermograms regardless of whether or not they produced abnormal thermograms prior to training. CONCLUSION: Thermograms were of little value for either predicting or portraying repetitive stress-induced lower limb pain in this population.

Cumulative Trauma Disorders↗
PubMedDate not supplied

Differences in somatosensory hand organization in a healthy flutist and a flutist with focal hand dystonia: a case report.

Focal hand dystonia is a disabling, involuntary disorder of movement that can disrupt a successful musician's career. This problem is difficult to treat, to some extent because we do not fully understand its origin. Somatosensory degradation has been proposed as one etiology. The purpose of this case study was to compare the differences in the somatosensory hand representation of two female flutists, one with focal dystonia of the left hand (digits 4 and 5) and one a healthy subject (the control). Noninvasive magnetic source imaging was performed on both subjects. The somatosensory evoked potentials of controlled taps to the fingers were measured with a 37-channel biomagnetometer and reported in terms of the neuronal organization, latency, amplitude, density, location, and spread of the digits on each axis (x, y, and z). The somatosensory representation of the involved hand of the flutist with dystonia differed from that of the healthy flutist. The magnetic fields evoked from the primary somatosensory cortex had a disorganized pattern of firing, with a short latency and excessive amplitude in the involved digits of the affected hand, as well as inconsistency (decreased density). In addition, the patterns of firing were different in terms of the location of the digits on the x, y, and z axes and sequential organization of the digits. This study confirms that somatosensory evoked magnetic fields can be used to describe the representation of the hand on the somatosensory cortex in area 3b. Degradation in the hand representation of the flutist with focal hand dystonia was evident, compared with the hand representation of the healthy flutist. It is not clear whether the sensory degradation was the cause or the consequence of the dystonia. The questions are whether re-differentiation of the representation could be achieved with aggressive sensory retraining and whether improvement in structure would be correlated with improvement in function.

Adult↗
PubMed1995

Relations between upper limb soft tissue disorders and repetitive movements at work.

To make a preliminary assessment of whether upper limb soft tissue disorders might be associated with activities at work, we have conducted a case-control study of subjects attending orthopedic clinics in three cities. All subjects between the ages of 16 and 65 years, in whom defined soft tissue conditions of the upper limb were diagnosed by the participating orthopedic surgeons, were invited to take part. Controls were subjects attending the same clinics within the same age range whose clinical diagnosis did not include disease of the upper limb, cervical or thoracic spine. Information concerning repetitive movements of the upper limbs at work was elicited by questionnaire. Five hundred eighty cases and 996 controls were studied, representing 96% and 93%, respectively, of those invited to participate. The diagnoses of the cases included soft tissue conditions affecting the shoulder, elbow, forearm, wrist, thumb, hand, and fingers. The diagnoses of the controls included traumatic, degenerative, and inflammatory conditions, mostly of the legs and lower back. Women predominated among the cases (70%) and men among the controls (56%). Of 221 female cases with injury to the wrist and forearm, 32 were cleaner/domestics (14.5%) compared to 35 to 439 controls (8%), a difference statistically significant at the 2 1/2% level. Other jobs significantly overrepresented (5% level) among female cases with injuries at various anatomical sites included hairdressers, secretary/temps, assembly line workers, and machine operators (type unspecified). Among male cases, electricians were significantly overrepresented (5% level). Jobs for which there was a suggestion (p < 0.1) of overrepresentation among cases included butchers and teacher/lecturers (both males only) and the combined job groups (chosen a priori for analysis) of keyboard operators, machine operators, and music teachers (all three jobs, females only).

Adolescent↗
PubMed1995

Biomechanical risk factors for occupationally related low back disorders.

A continuing challenge for ergonomists has been to determine quantitatively the types of trunk motion and how much trunk motion contributes to the risk of occupationally-related low back disorder (LBD). It has been difficult to include this motion information in workplace assessments since the speed at which trunk motion becomes dangerous has not been determined. An in vivo study was performed to assess the contribution of three-dimensional dynamic trunk motions to the risk of LBD during occupational lifting in industry. Over 400 industrial lifting jobs were studied in 48 varied industries. The medical records in these industries were examined so that specific jobs historically categorized as either low, medium, or high risk for occupationally-related LBD could be identified. A tri-axial electrogoniometer was worn by workers and documented the three-dimensional angular position, velocity, and acceleration characteristics of the lumbar spine while workers worked at these low, medium, or high risk jobs. Workplace and individual characteristics were also documented for each of the repetitive lifting tasks. A multiple logistic regression model indicated that a combination of five trunk motion and workplace factors predicted well both medium risk and high risk occupational-related LBD. These factors included lifting frequency, load moment, trunk lateral velocity, trunk twisting velocity, and trunk sagittal angle. Increases in the magnitude of these factors significantly increased the risk of LBD. The analyses have enabled us to determine the LBD risk associated with combined changes in the magnitudes of the five factors. The results indicate that by suitably varying these five factors observed during the lift collectively, the odds of high risk group membership may decrease by over ten times. These results were related to the biomechanical, ergonomic, and epidemiologic literature. The five trunk motion and workplace factors could be used as quantitative, objective measures to redesign the workplace so that the risk of occupationally-related LBD is minimized.

Biomechanical Phenomena↗
PubMed2005

An interpreter's interpretation: sign language interpreters' view of musculoskeletal disorders.

INTRODUCTION: Sign language interpreters are at increased risk for musculoskeletal disorders associated with work. Previous studies have used survey techniques to identify potential risk factors and approaches to their medical management. Little is known about risk factors and management of symptoms in this group from the perspective of the interpreter. Such qualitative information should help inform future research related to this professional group. METHOD: One thousand ninety-two sign language interpreters recruited from the Registry of Interpreters for the Deaf completed an open-ended question that was a component of a national prevalence survey. Responses were evaluated using content analysis. Inter and intra rater reliability were high (.88 and .92, respectively). RESULTS: Risk factors for initiation and/or exacerbation of symptoms included: difficult job, interpreting setting (educational), interpreting style (e.g., posture, self generated force), and emotional and physical stressors. Exercise (e.g., stretching, aerobics) was a common prevention strategy. Conventional medical treatment was used as the first line approach to symptom control. Self-care methods such as exercise, diet and warm up prior to interpreting were also reported. While massage and chiropractic care was used as commonly as in the general population, acupuncture was found to be used more often. Coping strategies that were more active (e.g. exercise, diet, more control over work schedule) were also reported as useful. CONCLUSIONS: These findings provide a description of factors that interpreters view as important in the development and exacerbation of hand and wrist pain. The results also indicate that interpreters used many self-management approaches. Future research should carefully investigate the utility of such approaches using well-controlled designs. Also, because of its widespread use in this group the evaluation of acupuncture in the management of these symptoms appears warranted. The qualitative approach used in the present study permitted an analysis of the worker perspectives regarding risk and management of these work related symptoms. This information can be used to further inform future research.

Adult↗
PubMed1993

Multidisciplinary rehabilitation of chronic work-related upper extremity disorders. Long-term effects.

The prevalence of work-related upper extremity disorders has significantly increased in the past decade. Persistent pain, loss of function, and associated work disability in patients with work-related upper extremity disorders appears to be affected by multiple factors including physical capabilities in relation to work demands, ergonomic risk factors on the job, and psychological factors related to worker traits, psychological readiness to return to work, and ability to manage symptoms. The complex nature of these disorders suggests the utility of a multidisciplinary program targeted at these factors. The present study is an investigation of the long-term vocational outcome of a multicomponent rehabilitation program that includes physical conditioning, work conditioning, work-related pain and stress management, ergonomic consultation, and vocational counseling/placement. Two groups equivalent on measures of duration of work disability, pain severity, fear of reinjury, psychological distress, perceived work environment, age, and education level were exposed to either the comprehensive work rehabilitation intervention (n = 19) or usual care (n = 15). Return-to-work status was determined at an average of 17 months posttreatment (range, 3 to 35 months) for the treatment group and an average of 18 months postevaluation (range, 5 to 30 months) for the usual care group. Findings indicated that 74% of the treatment group returned to work or were involved in state-supported vocational training in contrast to 40% of the control group (P < .05). For those who returned to work, 91% of the treatment group were working full-time in contrast to 50% of the control group (P < .05). Although the treatment group demonstrated a higher return-to-work rate than controls, the work reentry rate was not as high as similar approaches with work-related low back pain (80% to 88% return-to-work rate). These findings suggest the need to modify treatment components to facilitate an increased return-to-work rate. Areas that may prove useful include a greater emphasis ergonomic modifications at the workplace to reduce the risks of repetitiveness, force, awkward posture, and insufficient work/rest cycles, as well as efforts to modify work style directly in order to reduce the impact of ergonomic stressors on the ability to perform essential job tasks. In combination with traditional work hardening efforts directed at improving strength and flexibility of the upper extremities and work-related pain and stress management training, these ergonomic and work-style modification efforts may contribute to increases in the percentage of work disabled cases who successfully return to competitive work.

Arm Injuries↗
PubMed1999

Histopathology of common tendinopathies. Update and implications for clinical management.

Tendon disorders are a major problem for participants in competitive and recreational sports. To try to determine whether the histopathology underlying these conditions explains why they often prove recalcitrant to treatment, we reviewed studies of the histopathology of sports-related, symptomatic Achilles, patellar, extensor carpi radialis brevis and rotator cuff tendons. The literature indicates that healthy tendons appear glistening white to the naked eye and microscopy reveals a hierarchical arrangement of tightly packed, parallel bundles of collagen fibres that have a characteristic reflectivity under polarised light. Stainable ground substance (extracellular matrix) is absent and vasculature is inconspicuous. Tenocytes are generally inconspicuous and fibroblasts and myofibroblasts absent. In stark contrast, symptomatic tendons in athletes appear grey and amorphous to the naked eye and microscopy reveals discontinuous and disorganised collagen fibres that lack reflectivity under polarised light. This is associated with an increase in the amount of mucoid ground substance, which is confirmed with Alcian blue stain. At sites of maximal mucoid change, tenocytes, when present, are plump and chondroid in appearance (exaggerated fibrocartilaginous metaplasia). These changes are accompanied by the increasingly conspicuous presence of cells within the tendon tissue, most of which have a fibroblastic or myofibroblastic appearance (smooth muscle actin is demonstrated using an avidin biotin technique). Maximal cellular proliferation is accompanied by prominent capillary proliferation and a tendency for discontinuity of collagen fibres in this area. Often, there is an abrupt discontinuity of both vascular and myofibroblastic proliferation immediately adjacent to the area of greatest abnormality. The most significant feature is the absence of inflammatory cells. These observations confirm that the histopathological findings in athletes with overuse tendinopathies are consistent with those in tendinosis--a degenerative condition of unknown aetiology. This may have implications for the prognosis and timing of a return to sport after experiencing tendon symptoms. As the common overuse tendon conditions are rarely, if ever, caused by 'tendinitis', we suggest the term 'tendinopathy' be used to describe the common overuse tendon conditions. We conclude that effective treatment of athletes with tendinopathies must target the most common underlying histopathology, tendinosis, a noninflammatory condition.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2006

Comparison of muscle activity associated with structural differences in dental hygiene mirrors.

PURPOSE: Ergonomic studies suggest that the commonly used pinch grasp, held in a static position, is a contributing factor for dental Hygienists' development of work-related musculoskeletal disorders (WMSDs) such as carpal tunnel syndrome (CTS), Trigger Thumb, de Quervain's stenosing tenosynovitis, and carpometacarpal (CMC) osteoarthritis. The pinch grasp is commonly used by the dental hygienist while holding the dental mirror in the non-dominant hand. In response to this concern, manufacturers are redesigning dental mirror handles. The value of these re-designed products is based solely on anecdotal evidence. To date, minimal research has been done to examine the non-dominant mirror hand. The purpose of this study was to objectively evaluate dental mirror handle design using surface electromyography (sEMG) to compare muscle activity associated with grasping the mirror. METHODS: This randomized controlled clinical trial utilized a two-by-two repeated measures statistical design. Data was collected on a convenience sample of 19 (N=19) healthy dental hygiene students in their last year of study. Data collection was divided into two phases to maintain a balanced study. The independent variables in phase I were diameter and weight. The independent variables in phase II were weight and padding. Muscle activity was measured while grasping various dental hygiene mirrors in 30-second increments using sEMG. Following data collection subjects designated which mirror felt most and least comfortable to compare subjective data with objective data. RESULTS: Three statistically significant results occurred. In phase II, padding (p=.01) demonstrated the largest reduction of muscle activity in the flexor pollicis brevis, by decreasing mean muscle activity by 3.7 microv. The interaction of diameter and weight (p=.01) in phase I reduced the mean muscle activity in the extensor digitorum by .8 microV and weight (p=.02) in phase II decreased the muscle activity in the extensor digitorum by .62 microV. Self-reports of comfort reported by the subjects in this study were not consistent with the measurements of muscle activity using sEMG. CONCLUSION: Ergonomic adaptations to dental hygiene mirror handles were associated with increases and decreases in muscle activity. The clinical impact of this is amplified as force is exerted. Furthermore, it may be possible to reduce WMSDs for dental hygienists by using instrument designs during the workday. Self-reports of comfort by the subjects in this study did not calibrate with the measurements of muscle activity using sEMG. Additional research is needed to further isolate the external variables of the study and to determine what actual reduction in muscle activity is significant for maintaining musculoskeletal health.

Adult↗
PubMed1995

Sports and recreation injuries in US children and adolescents.

OBJECTIVES: To estimate and describe morbidity from sports and recreation injuries in children and adolescents. DESIGN: Survey conducted by the National Center for Health Statistics--the Child Health Supplement to the 1988 National Health Interview Survey. SETTING: The general community. PARTICIPANTS: Representative sample of the noninstitutionalized civilian US population. Five percent of the eligible households did not participate. The subject of this report is 11,840 children and adolescents aged 5 to 17 years. MAIN OUTCOME MEASURES: Medically attended nonfatal injuries resulting from sports and recreation, and serious sports injuries, defined as injuries resulting in hospitalization, surgical treatment, missed school, or half a day or more in bed. Sports and recreation injuries were defined as those occurring in a place of recreation or sports, or receiving any of the following International Classification of Diseases, Ninth Revision (ICD-9) E-codes: struck in sports, fall in sports, bicycle-related injury, riding an animal, water sports, overexertion, fall from playground equipment or other vehicles, primarily skates and skateboards. RESULTS: The estimated annual number of all injuries from sports and recreation in US children and adolescents is 4,379,000 (95% confidence interval = 3,147,000 to 5,611,000); from serious sport injuries, 1,363,000 (95% confidence interval = 632,000 to 2,095,000). Sports account for 36% of injuries from all causes. Cause and nature of injury are strongly related to age. Sports do not account for a disproportionate number of serious or repeated injuries compared with other causes of injuries. CONCLUSION: Sports activities account for a large number and substantial proportion of all injuries to children and youth.

Adolescent↗