Work-related Carpal Tunnel Syndrome Research Articles

Prevalence of Carpal Tunnel Syndrome and its Associated Risk Factors among Workers of Marble Industries of Abbottabad

Background: Carpal tunnel syndrome occurs when the median nerve that passes through the carpal tunnel is compressed due narrowing of the tunnel at the wrist. Pain, tingling and numbness, at median nerve distribution on fingers and hands are the symptoms of carpal tunnel syndrome.
 Objective: The objective of this study is to find out the prevalence of Carpal Tunnel Syndrome and its associated risk factors in workers of Marble industries of Abbottabad
 Methodology: This descriptive cross sectional study was completed within 6 months. A total of 150 workers were recruited to collect the data. Convenience sampling technique was used. inclusion criteria of this study was only industrial workers of age between ages 20-60 years, Work related carpal tunnel syndrome, Only males were included in this study, so convenient sampling approach was applied for data collection within research time period. The exclusion criteria of this study were those who were unable to complete the questionnaire and particularly those who were diabetic along with carpal tunnel syndrome, Women’s are excluded, Neoplasm, Any systemic disease, Peripheral nerve injury. Boston carpal tunnel syndrome questionnaire were used as tool. Data was collected with the help of questionnaire in Abbottabad. Data was collected from Jadoon marble industry, Taj marble industry, Hazara marble industry and Janzib marble industry Data is entered and analyzed using SPSS 20.0.
 Results: The results of total participant showed age range from 21 to 56, whereas the mean age was 36.52. Prevalence of CTS via Phalen's and Tinnel's test for all the samples was positive for with 11 participant. Statistically, age, work experience and types of work showed significant (P vale>0.05), whereas type of activities had shown highly significant (P value > 0.01) association with CTS. Further, study showed that prevalence of CTS increased with increase in age, experience and increase in force activities.
 Conclusion: The study concluded that marble factory works who work more for 6 hours or having greater year of work experience, increased age, those using repetitive movements or vibratory tools were at high risk of developing carpal tunnel syndrome. Hence awareness campaign needs to be arranged for marble industries worker about awareness of hands posture and management of carpal tunnel syndrome.

Risk Factors for Carpal Tunnel Syndrome in Informal Sector Workers: Literature Review

CTS is one of the diseases that occurs in many workers so it is often referred to as work-related Carpal Tunnel Syndrome. The high number of informal workers allows for high accidents in the workplace. The purpose of this study is to discuss the risk factors for the incidence of CTS in informal sector workers. This research is a descriptive research with the literature review method. The literature search strategy uses a prism flow chart, and inclusion and exclusion criteria. The databases used include: PubMed, Taylor and francis, and Google Scholar. From the 20 articles, 19 of them used the cross-sectional type of research, and 1 article used the case-control type of research. The types of informal work obtained from the 20 articles are: motorcycle taxi drivers, farmers, batik and bead craftsmen, blacksmiths, stone breakers, meatball sellers, coconut peelers, woodcarvers, tailors, angkot drivers, small-scale convection, hairstylists, and butchers. Overall, the journal articles obtained discuss related to the risk factors for the incidence of CTS in informal sector workers. Repetitive movements, length of service, length of work, hand posture (awkward), age, gender, and body mass index were found to influence the incidence of CTS in informal sector workers. Meanwhile, grasping work and a history of diabetes mellitus were not found to be related to the incidence of CTS in informal sector workers.

Work-relatedness of carpal tunnel syndrome: Systematic review including meta-analysis and GRADE.

Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome with a high prevalence among workers. Insights on the physical work-related risk factors is necessary to develop appropriate preventative methods. The objective of this systematic review, including meta-analyses, is to assess which physical work-related risk factors are associated with carpal tunnel syndrome. Systematic literature searches were carried out using PubMed and Embase until September 6, 2021. Studies were included if: (1) CTS was clinically assessed, (2) the studies were prospective cohort studies, and (3) the exposure was reported using terms of exposed/less or nonexposed. Risk of bias was assessed using the Quality in Prognosis Studies (QUIPS) tool. Quality of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE). In total, 9270 patients with CTS from a population of 1,051,707 workers were included from 17 studies. Meta-analyses revealed high-quality evidence for associations between CTS and high exposures to repetition (hazard ratio [HR] 1.87, 95% CI 1.42-2.46), force intensity (HR 1.84, 95%CI 1.22-2.79), exposures above hand activity level of ACGIH (HR 1.75, 95%CI 1.40-2.17), and the Strain Index >10 (HR 1.58, 95% CI 1.09-2.30). No significant associations were found for pinch gripping, hand-arm vibration or force duration. High computer-use exposure was significantly associated with a decreased rate of work-related CTS (HR 0.28, 95% CI 0.12-0.64). This systematic review of prospective cohort studies found high certainty for an increased rate of CTS due to a high Strain Index, exposures exceeding the Activity Level of ACGIH, and high force intensity and high repetition. Workers performing tasks requiring both high force and high repetition even have a higher rate of developing CTS.

Median nerve travel and deformation in the transverse carpal tunnel increases with chuck grip force and deviated wrist position.

BackgroundWe assessed median nerve travel and deformation concurrently to better understand the influence of occupational risk factors on carpal tunnel dynamics, including forceful chuck gripping and deviated wrist positions.MethodsFourteen healthy right-hand dominant participants performed a chuck grip in 6 experimental conditions: two relative force levels (10% and 40% of maximum voluntary effort); three wrist positions (15° radial deviation, 0° neutral, 30° ulnar deviation). Chuck grip forces were measured with a load cell while the transverse cross-section of the carpal tunnel was imaged via ultrasound at the distal wrist crease. Images of the median nerve were analyzed in ImageJ to assess cross-sectional area, circularity, width, and height as well as travel in the anterior-posterior and medial-lateral axes.ResultsWe found a main effect of deviated wrist position on both anterior-posterior and medial-lateral travel, with the greatest nerve travel occurring in 30° ulnar deviation. There was also a significant interaction between chuck grip force and deviated wrist position on cross-sectional area. Specifically, the area decreased with 40% vs. 10% chuck grip force when the wrist was in 30° ulnar deviation; however, there were no changes in 0° neutral and 15° radial deviation.DiscussionOverall, we demonstrated that forceful chuck gripping in deviated wrist positions influenced carpal tunnel dynamics, resulting in both migratory and morphological changes to the median nerve. These changes may, in turn, increase local strain and stress with adjacent structures in the carpal tunnel. Future studies mapping contact stress between structures may further elucidate injury development of work-related carpal tunnel syndrome.

Manufacturing Workers Have a Higher Incidence of Carpal Tunnel Syndrome.

It is unclear whether clerical or labor-type work is more associated with risk for developing work-related carpal tunnel syndrome (WrCTS). National employment, demographic, and injury data were examined from the Bureau of Labor Statistics databases for the years 2003 to 2018. Injuries for clerical and labor industries were compared using linear regression, two-group t test, and one-way analysis of variance (ANOVA) analysis. WrCTS injuries are decreasing over time (B = -1002.62, P < 0.001). The labor industry demonstrated a significantly higher incidence of WrCTS when compared with the clerical industries (P < 0.001). Within labor industries, the manufacturing industry had the highest incidence of WrCTS over time (P < 0.001). Our study showed WrCTS injuries have declined over time. Additionally, our findings may suggest that the labor industry has a stronger association with WrCTS than the clerical industry.

Association of the role of personal variables and nonoccupational risk factors for work-related carpal tunnel syndrome.

The purpose of this study was to identify personal variables and nonoccupational risk factors for carpal tunnel syndrome and to analyse the strength of association of these factors. We performed a case-control study with 162 cases and 300 controls. We studied consecutive patients with an electrophysiologically confirmed diagnosis of symptomatic carpal tunnel syndrome. Univariate analysis was performed in the case group and control comparing them for presence of various risk factors. Multivariate analysis was carried out through logistic regression. The mean BMI and age were greater in the case group than in the control. Multivariate analysis showed that BMI (OR = 1.05, 95% CI = 1.01-1.11) and arterial hypertension (OR = 4.63, 95% CI = 2.88-7.44) were the only factors significantly associated with carpal tunnel syndrome. The age, cigarette smoking and alcohol drinking were at the edge of significance. Carpal tunnel syndrome is the most common peripheral neuropathy and has been related to occupational activities in some but not all studies. Clarifying this relationship has important implications for workers' compensation systems. Based on our findings, BMI and arterial hypertension are considered to be the most significant risk factors of carpal tunnel syndrome in our study.

The bilaterality of idiopathic carpal tunnel syndrome among manual workers.

To evaluate: a) the prevalence of bilateral idiopathic carpal tunnel syndrome (CTS) in manual workers; b) a correlation between the duration of unilateral and bilateral CTS symptoms; c) a correlation between the onset of CTS symptoms in the unilateral dominant/non-dominant hand and the time of developing bilateral CTS; and d) findings of the nerve conduction study (NCS) in symptomatic and asymptomatic hands of patients with unilateral CTS. Clinical and neurophysiological examinations were conducted along with a detailed analysis of job exposure of 332 manual workers admitted to the Occupational Medicine Department, the Nofer Institute of Occupational Medicine, with suspected occupational CTS. Eventually, 258 patients were excluded from the study: 34 with associated neuropathies and 206 with other conditions potentially associated with CTS. Cases with work-related CTS (18) were also excluded. A total of 74 patients were diagnosed as idiopathic CTS. In idiopathic CTS, the right hand was affected in 15 (20.3%) patients, the left hand in 4 (5.4%) patients, and both hands in 55 (74.3%) patients. Symptoms duration was longer in the patients with bilateral CTS (4.01 years) than in those with a unilateral right (1.7 years, p = 0.002) or left hand condition (2.8 years, p = 0.313). Median nerve impairment at the wrist was revealed by NCS in 6 left and 2 right asymptomatic hands. The findings of the study indicate the need for "alerting" patients with unilateral CTS about the risk of the disease developing in the contralateral hand. Therefore, NCS should be routinely performed in the asymptomatic hands of patients with unilateral CTS, which is essential for the prevention of neuropathies, especially among manual workers performing repetitive manual tasks. Int J Occup Med Environ Health. 2020;33(2):151-61.

Carpal tunnel syndrome among laboratory technicians in relation to personal and ergonomic factors at work

Work-related carpal tunnel syndrome (CTS) has been reported in different occupations, including laboratory technicians, so this study was carried out to determine the prevalence and the associated personal and ergonomic factors for CTS among laboratory technicians. A cross-sectional study was conducted among 279 laboratory technicians at King Fahd Hospital, Saudi Arabia, who filled in a self-administered questionnaire, including questions regarding their demographic criteria, occupational history, job tasks, workplace tools, ergonomic factors at work, and symptoms suggestive of CTS. Physical examinations and electrodiagnostic studies were carried out for those who had symptoms suggestive of CTS to confirm the diagnosis. Univariate and multivariate analysis were performed for both personal and physical factors in association with confirmed CTS among laboratory technicians. The prevalence of CTS among the laboratory technicians was 9.7% (27/279). The following were the statistically significant risk factors for CTS among them: gender (all cases of CTS were female, P=0.00), arm/hand exertion (OR: 7.96; 95% CI: 1.84-34.33), pipetting (OR: 7.27; 95% CI: 3.15-16.78), repetitive tasks (OR: 4.60; 95% CI: 1.39-15.70), using unadjustable chairs or desks (OR: 3.35; 95% CI: 1.23-9.15), and working with a biosafety cabinet (OR: 2.49; 95% CI: 1.11-5.59). CTS cases had significant longer work duration (17.9 ± 5.6 years) than CTS non-case (11.5 ± 7.4 yeas) with low OR (1.108). This study demonstrates some personal and ergonomic factors associated with CTS among the laboratory technicians, including female gender, arm/hand exertion, pipetting, repetitive tasks, working with a biosafety cabinet, and an unadjusted workstation.

Work-related carpal tunnel syndrome treatment: a cross-sectional study among 106 patients.

The objective is to assess the influence of sociodemographic, professional and clinical variables on the choice of treatment of work-related carpal tunnel syndrome (CTS). An exhaustive and trans-sectional study was conducted over a period of eight years, from 1st January 2006 to 31 December 2013 in the Department of Occupational Medicine at University Hospital of Mahdia, Tunisia. The study population was represented by patients with work-related carpal tunnel syndrome. Data collection was based on a questionnaire sheet, describing social, occupational and medical characteristics of patients. The study population was characterized by a large female dominance, representing 95.3% with an average age of 42±7.8 years. Patients medically treated represented 38.7% and 61.3% had had surgical treatment. After binary logistic regression, surgical indication of CTS was significantly correlated to diabetes (p=0.017), other musculoskeletal disorders (p=0.02), functional signs of CTS (acrocyanosis p=0.05; muscle weakness p=0.015; radiating pain p=0.01; painful discomfort of the hand, the forearm or arm p=0.027) and to the atrophy of thenar muscles (p=0.018). According to this study, the choice of therapy for occupational CTS depends only on clinical data. More detailed studies will be needed to refine these results.

Experiences with preventing carpal tunnel syndrome in an automotive plant.

Carpal tunnel syndrome (CTS) is a common occupational disease. The aim was to assess the effect of preventive measures in automotive assembly workers. The analysis summarizes data from annual crosssectional studies. The 7-year analysis of data was based on medical records obtained from an occupational physician and inspections carried out at the workplace where targeted preventive measures were introduced, including better ergonomic arrangement of the workplace, technical adjustments facilitating the work, preventive nerve conduction studies (NCS) testing of the median nerve once a year, switching of workers and their targeted rotation within the workplace. The NCS testing of median nerve conduction at the wrist was the basic objective method for assessment of the prevalence and severity of CTS. Over the study period, the sample comprised 1804 workers at risk for repetitive overuse of the upper extremities, of whom 281 were females with a mean age of 38.5 years and 1523 were males with a mean age of 31.4 years. Over the study period, a total of 13 cases of CTS were recognized as an occupational disease in the plant, 8 of which occurred within the first 2 years from the initiation of production. Introduction of preventive measures decreased the prevalence of median neuropathy from 18.3% of examined extremities in 2011 to 10.5% in 2013 (p = 0.003). In early 2014, the production pace increased and this was accompanied by a rise in abnormal NCS findings to 16.9%. Over the study period, the rate of sensorimotor neuropathy decreased in favor of merely sensory neuropathies, which have been most frequent since 2013. The percentage of employees whose contracts were terminated due to median neuropathy decreased steadily from 5.5% to 0.4%. Targeted prevention of work-related CTS is effective as evidenced by the decrease in the prevalence of median neuropathy detected by NCS. Int J Occup Med Environ Health 2017;30(1):45-54.

Biomechanical risk factors and flexor tendon frictional work in the cadaveric carpal tunnel

Pathological changes in carpal tunnel syndrome patients include fibrosis and thickening of the subsynovial connective tissue (SSCT) adjacent to the flexor tendons in the carpal tunnel. These clinical findings suggest an etiology of excessive shear-strain force between the tendon and SSCT, underscoring the need to assess tendon gliding characteristics representative of repetitive and forceful work. A mechanical actuator moved the middle finger flexor digitorum superficialis tendon proximally and distally in eight fresh frozen cadaver arms. Eighteen experimental conditions tested the effects of three well-established biomechanical predictors of injury, including a combination of two wrist postures (0° and 30° flexion), three tendon velocities (50, 100, 150mm/sec), and three forces (10, 20, 40N). Tendon gliding resistance was determined with two light-weight load cells, and integrated over tendon displacement to represent tendon frictional work. During proximal tendon displacement, frictional work increased with tendon velocity (58.0% from 50–150mm/sec). There was a significant interaction between wrist posture and tendon force. In wrist flexion, frictional work increased 93.0% between tendon forces of 10 and 40N. In the neutral wrist posture, frictional work only increased 33.5% (from 10–40N). During distal tendon displacement, there was a similar multiplicative interaction on tendon frictional work. Concurrent exposure to multiple biomechanical work factors markedly increased tendon frictional work, thus providing a plausible link to the pathogenesis of work-related carpal tunnel syndrome. Additionally, our study provides the conceptual basis to evaluate injury risk, including the multiplicative repercussions of combined physical exposures.

Biomechanical risk factors for carpal tunnel syndrome: a pooled study of 2474 workers

BackgroundBetween 2001 and 2010, five research groups conducted coordinated prospective studies of carpal tunnel syndrome (CTS) incidence among US workers from various industries and collected detailed subject-level exposure information with...

Costs of occupational musculoskeletal disorders (MSDs) in the United States

BackgroundFor the years 1992–2010 musculoskeletal disorders (MSDs) accounted for 29–35% of all occupational injuries and illnesses involving days away from work in the United States (US) (AFL-CIO, 2012). According to the American Federation of Labor and Congress of Industrial Organizations (AFL-CIO) 2012 report ‘Death on the Job’, for the years 1992 through 2010 the percent of cases involving MSDs in private industry were highest in 2000 (35%) and lowest in 2007 (29%). In 2010, the median number of days away from work for MSDs was 11 compared to 8 for all occupational injury cases involving days away from work; the median number of days away from work for Carpal Tunnel Syndrome (CTS) was 25, more than three times as high as for all other BLS injuries involving days away from work (BLS, 2011). This study estimated the costs of work related MSDs, and given that the number of days lost due to CTS is very high, it also estimated the costs of CTS separately in the United States (US) for the years 2003 through 2007. MethodsThe costs of work related MSDs and CTS in the US were estimated using the cost-of-illness, human capital method (Leigh et al., 2000), using some of the costs from the literature. This method decomposes costs into direct and indirect categories. Estimates of total cost of MSDs and CTS were obtained from the product of average costs of MSDs and CTS and the number of MSDs and CTS. The number of MSDs and CTS were obtained from BLS data. ResultsThe number of reported work-related MSDs declined from 435,180 in 2003 to 335,390 in 2007 and the reported number of CTS also declined from 22,110 in 2003 to 11,920 in 2007. The direct costs of MSDs and CTS were respectively $1.5 billion and $0.1 billion for the year 2007. The indirect costs were $1.1 billion and $0.1 billion for MSDs and CTS respectively for the year 2007. DiscussionThis study found that the total costs of work-related MSDs and CTS declined during the period 2003 through 2007 but the average costs per case went up signifying that medical costs and other associated costs increased during this period. Relevance to industryThe costs of MSDs are important to the industries too as a significant part of these costs are borne by the employers. Industries with higher prevalence of MSDs are affected more in terms of lost productivities due to the employees' days away from work because of MSDs. In cases of MSDs causing permanent disabilities, new hiring and training costs are also a part of the losses experienced by the employers.

Meta-analysis: association between wrist posture and carpal tunnel syndrome among workers.

BackgroundCarpal tunnel syndrome (CTS) is a common work-related peripheral neuropathy. In addition to grip force and repetitive hand exertions, wrist posture (hyperextension and hyperflexion) may be a risk factor for CTS among workers. However, findings of studies evaluating the relationship between wrist posture and CTS are inconsistent. The purpose of this paper was to conduct a meta-analysis of existing studies to evaluate the evidence of the relationship between wrist posture at work and risk of CTS.MethodsPubMed and Google Scholar were searched to identify relevant studies published between 1980 and 2012. The following search terms were used: “work related”, “carpal tunnel syndrome”, “wrist posture”, and “epidemiology”. The studies defined wrist posture as the deviation of the wrist in extension or flexion from a neutral wrist posture. Relative risk (RR) of individual studies for postural risk was pooled to evaluate the overall risk of wrist posture on CTS.ResultsNine studies met the inclusion criteria. All were cross-sectional or case–control designs and relied on self-report or observer's estimates for wrist posture assessment. The pooled RR of work-related CTS increased with increasing hours of exposure to wrist deviation or extension/flexion [RR = 2.01; 95% confidence interval (CI): 1.646–2.43; p < 0.01: Shore-adjusted 95% CI: 1.32–2.97].ConclusionWe found evidence that prolonged exposure to non-neutral wrist postures is associated with a twofold increased risk for CTS compared with low hours of exposure to non-neutral wrist postures. Workplace interventions to prevent CTS should incorporate training and engineering interventions that reduce sustained non-neutral wrist postures.

133 Results of a Myotonometrical Muscle Study in Patients with Work-Related Hand Overload Disorder

IntroductionImplementation of the new myotonometrical diagnostic method in occupational medicine enables non-invasive, easy and quick evaluation of the functional state of muscles.AimsUse of the myotonometrical method to study hand muscles...

Carpal tunnel syndrome in manual tea harvesters

This study aims to present the physiopathological and surgical aspects of carpal tunnel syndrome (CTS) related to manual tea harvesting based on nerve conduction studies and clinical scoring systems. Clinical and neurophysiological scores as well as clinical and occupational variables were statistically analyzed using Boston questionnaire, modified criteria of Italian CTS study group, and modified neurophysiologic grading system of Italian CTS study group in 56 agricultural laborers who underwent surgery due to severe CTS. A statistically significant correlation was found among the clinical stages of the patients and age, working duration and duration of symptoms. There was a statistically significant relationship among neurophysiologic grades of the CTS in patients and the duration of symptoms and functional outcomes before and after surgery. We concluded that manual tea harvesting might be an occupational risk factor for work-related CTS development. Surgical treatment of CTS among manual tea harvesters revealed satisfactory results.

Work‐related carpal tunnel syndrome in Washington State workers' compensation: Utilization of surgery and the duration of lost work

Work-related carpal tunnel syndrome (CTS) is a leading cause of lengthy disability. This population-based retrospective cohort study used Washington State workers' compensation claims for CTS to characterize associations between utilization of CTS surgery and duration of lost work. The sample included all claims (n = 8,224) filed during 1990-1994 (followed through 2000) and receiving lost-work compensation. Sixty-four percent of studied workers had CTS surgery. Among workers with >1 month of lost work, the total duration was much shorter when workers had surgery, versus those who did not (median 4.3 and 6.2 months, respectively; P < 0.001); there was no difference when disability extended >6 months. When workers had surgery, disability was less likely to end before 6 months if non-CTS conditions were present, surgery occurred >3 months after claim filing, or employment was in an industry with high incidence of CTS; disability was more likely to end if the diagnosing provider and operating surgeon had higher CTS claims volume. Physical and rehabilitation medicine services were associated with lower probability of returning to work, with or without surgery. There is a need to scrutinize the role of surgery and physical-rehabilitation medicine modalities in the management of CTS covered by workers' compensation. The findings suggest disability can be minimized by establishing the CTS diagnosis as early as possible and, if surgery is appropriate, conducting surgery without substantial delay and maximizing post-operative efforts to facilitate return to work. Use of surgery >6 months after filing should be considered with great caution.

Long-term trends in carpal tunnel syndrome

To assess temporal trends in carpal tunnel syndrome (CTS) incidence, surgical treatment, and work-related lost time. Incident CTS and first-time carpal tunnel release among Olmsted County, Minnesota, residents were identified using the medical records linkage system of the Rochester Epidemiology Project; 80% of a sample were confirmed by medical record review. Work-related CTS was identified from the Minnesota Department of Labor and Industry. Altogether, 10,069 Olmsted County residents were initially diagnosed with CTS in 1981-2005. Overall incidence (adjusted to the 2000 US population) was 491 and 258 per 100,000 person-years for women vs men (p < 0.0001) and 376 per 100,000 for both sexes combined. Adjusted annual rates increased from 258 per 100,000 in 1981-1985 to 424 in 2000-2005 (p < 0.0001). The average annual incidence of carpal tunnel release surgery was 109 per 100,000, while that for work-related CTS was 11 per 100,000. An increase in young, working-age individuals seeking medical attention for symptoms of less severe CTS in the early to mid-1980s was followed in the 1990s by an increasing incidence in elderly people. The incidence of medically diagnosed carpal tunnel syndrome (CTS) accelerated in the 1980s. The cause of the increase is unclear, but it corresponds to an epidemic of CTS cases resulting in lost work days that began in the mid-1980s and lasted through the mid-1990s. The elderly present with more severe disease and are more likely to have carpal tunnel surgery, which may have significant health policy implications given the aging population.

Impact of compensation on work outcome of carpal tunnel syndrome

Work-related carpal tunnel syndrome (CTS) is a complex and costly condition. There is some evidence that the employment outcome may be worse in cases of CTS where the condition is being considered for compensation. To examine whether workers' compensation status is an important determinant of outcome of CTS. Cases, with a Workers' Compensation Board (WCB) claim, and referents, in work but without a WCB claim, were identified from the practice of a single specialist physician. Data on history prior to and at the time of diagnosis, and events since diagnosis, were collected from clinical records and by a telephone-administered questionnaire. Prior events, severity, treatment and outcome associated with a WCB claim were assessed by logistic regression. Interviews were successfully completed for 46 cases and 50 referents. In the model adjusted only for age and gender, claimants had a worse outcome in terms of changing job or stopping work with time loss from work due to CTS [odds ratio (OR) 5.1, 95% confidence interval (CI) 1.9-13.3]. The OR was much influenced by the inclusion of treatment in the model (OR = 9.6, 95% CI 1.6-58.6) with WCB cases more likely to have surgical and physiotherapy treatments. Cases with a WCB claim cost more to treat and reported greater loss in income than those not seeking compensation. Although these data are limited, the results are suggestive of poorer outcome among WCB claimants despite greater use of treatment and comparable severity of disease.

Evaluating the Carpal Tunnel using MRI Based Modelling

Carpal tunnel syndrome is a compression neuropathy of the median nerve at the wrist. Deviated wrist posture has been linked to work-related carpal tunnel syndrome, yet it is unclear how posture changes carpal tunnel (CT) size and shape. In addition, it is not clear how these factors contribute to median nerve compression. PURPOSE: 1) to evaluate errors associated with 3D reconstruction from MR images and 2) to develop individual models to predict posture-related changes in CT volume. METHODS: Axial MR images were used to create wrist models of 6 individuals. Each carpal tunnel was modeled as a modified cylinder consisting of two surfaces; one for the carpal arch and one for the transverse carpal ligament (TCL) and flexor retinaculum complex. Carpal bone motions were applied to the CT surfaces to predict changes in tunnel dimensions and orientation with wrist deviation relative to neutral (30° flexion to 30° extension). RESULTS: “Land marked” volumes, those contained by the anatomical boundaries of the CT, were significantly smaller than volumes reconstructed directly from MRI in all postures (by an average of 977 mm3). Land marking improved the between-individual consistency of measurements, and suggested that previous studies may have overestimated CT volume by as much as 20–30%. Comparison of internal and external measures, in the neutral posture, revealed that land marked volume and average cross-sectional area were more closely related to wrist width (adjusted R2 of 0.76 and 0.88, respectively) than wrist circumference (adjusted R2 of 0.25 and 0.19, respectively). Model predicted volumes were not significantly different than land marked volumes determined from MRI reconstruction (6% decreases in flexion and extension). CONCLUSION: These data suggest posture-related changes in CT volume are likely not sufficient to explain CT pressure changes with wrist posture, and support incorporation of carpal tunnel contents. Supported by NSERC grant #217382.