Effect of wrist posture on carpal tunnel pressure while typing

The effect of manual lymphatic drainage on intraneural edema of the median nerve in patients with carpal tunnel syndrome: A randomized controlled trial

BACKGROUND

Intraneural edema is an important factor in the pathophysiology of carpal tunnel syndrome (CTS). Manual Lymphatic Drainage (MLD) is a manual treatment widely used to treat edema in a variety of conditions.

PURPOSE

This study aimed to evaluate the effect of MLD on intraneural edema of the median nerve in CTS patients, as well as its impact on symptom severity and hand function.

STUDY DESIGN

Randomized controlled study.

METHODS

Twenty-seven patients (aged 48.9 ± 9.9) with mild-to-moderate bilateral CTS were recruited for the study. One hand of each subject was allocated to the experimental group and the other hand in the control group randomly. The experimental group underwent MLD, myofascial release (MFR) therapy and conventional physiotherapy (CP). The control group received sham MLD, MFR and CP. Interventions were performed 2 days a week for 6 weeks. The distal motor latency (DML), motor nerve (MNCV), and sensory nerve (SNCV) conduction velocity of the median nerve were evaluated using electrodiagnostic techniques. As secondary evaluations, grip strength, pressure pain threshold, pain intensity, symptom severity, and hand functions were assessed. The cross-sectional area (CSA) of the median nerve was measured by ultrasound. All assessments were performed at baseline and 6 weeks after intervention.

RESULTS

According to the analysis of a two-way repeated measures of ANOVA, the experimental group showed greater improvement in CSA (p < 0.001; η2 = 0.510), DML (p < 0.001; η2 = 0.549), sensory (p < 0.001; η2 = 0.408), and motor conduction velocity (p < 0.001; η2 = 0.419) of the median nerve than the control group. There was no significant difference between the groups in the secondary evaluation results (p > 0.05).

CONCLUSION

MLD may contribute to symptom relief in CTS by reducing intraneural edema in the median nerve.

Investigating the influence of keyboard inclinations on sitting and standing workstations

Given the growing global computer workforce, concerns exist about the escalation of computer related injury with Carpal tunnel syndrome (CTS) being one of the most reported work-related musculoskeletal disorders (WMSDs) among office workers. The optimal range of keyboard angles for sitting and standing positions based on wrist posture, forearm muscle activities and user preference as well as the keyboard location in relation to user position were analysed. 30 volunteers with an above 40 words per minute typing speed participated in this study. Result show that, although user prefer to use positive keyboard angle, the negatively tilted keyboard is more ergonomically friendly at both sitting and standing workstations, reducing muscle activity and awkward wrist posture while maintaining performance. The findings indicate that negative sloped keyboard might have the possibility to reduce the risk of developing CTS in office workers.Practitioner summary: This study determines the range of optimal slope of keyboard angle in a sit and stand workstation. Our results indicate a trend in the negative slope keyboard as an ergonomically friendly option for the intervention to Carpal tunnel pressure.

Sex differences in wrist strength: a systematic review

Sex differences in strength have been attributed to differences in body anthropometrics and composition; these factors are often ignored when generating workplace guidelines. These differences directly impact the upper extremity, leaving female workers exposed to injury risk. The wide range of tools and techniques for measuring upper extremity strength presents a challenge to ergonomists and work task designers; collating outcomes to provide a clear outlook of differences between males and females is essential and the purpose of this work. Four online databases were searched (PROSPERO ID: CRD42022339023) with a focus on articles assessing sex differences in wrist strength. A total of 2,378 articles were screened for relevancy; 25 full-text articles were included in this systematic review. Articles examined movement pairs (ulnar/radial deviation, pronation/supination, and flexion/extension), as well as contraction types (isometric and isokinetic) to observe sex differences in wrist strength. Across all articles, females produced ∼60-65% of male flexion/extension strength, ∼55-60% pronation/supination strength, and ∼60-70% ulnar/radial deviation strength. Overall, females presented lower strength-producing abilities than males, but when considering strength relative to body mass, male-female differences were less pronounced and occasionally females surpassed male strength metrics; typically, this occurred during flexion/extension, particularly in isokinetic contractions. This review has identified a scarcity of articles examining ulnar/radial deviation, pronation/supination, as well as isokinetic contractions; these are needed to supplement workplace exposure guidelines.

Alternative to Reduced Stresses on the Upper Extremity in a Standing Workstation

OBJECTIVE

This study evaluated a standing armrest to provide more acceptable ergonomic guidelines that may reduce the cost of standing computer workstations.

BACKGROUND

Of the many advantages of standing workstations, there have been no efforts to minimize the biomechanical cost, such as larger wrist extension and greater forearm muscle activity than sitting.

METHOD

Sixteen participants were asked to perform a typing task under a combination of the following factors: (1) desk shape (rectangular and concave); (2) desk height (0, +5, -5 cm from 90° elbow flexion); and (3) monitor height (0, -10 cm from the eyes). During the trials, the trunk kinematics, muscle activation levels, and CoP were recorded.

RESULTS

Both arms were further away from the upper body under the concave and +5 desk height than under the normal condition, but significant decreases in the extensor carpi radialis (8.6%), anterior deltoid (28.8%), and L4 paraspinals (5.5%) were observed. Similarly, the wrist extension angle decreased by 10.5° (42%) under this condition, but the posture required a 2.2° (19%) increase in wrist adduction angle. The CoP irregularity was greater under the concave workstation, indicating more complex motion.

CONCLUSION

A higher and concave desk can provide an armrest effect while engaged in a standing workstation by reducing the wrist extension and related muscle activation level, but at the cost of a larger wrist adduction angle.

APPLICATION

Providing a standing armrest (+5 cm height and concave desk) could reduce the stresses on the upper extremities, but a split keyboard should be considered to minimize wrist adduction.

Wrist motion is distinct between touch screen and manual or digital devices

BACKGROUND

Restricted motion during touch screen device use may contribute to wrist overuse injuries. Wrist radioulnar deviation and extension while using touch screen devices and digital or manual counterparts in male and female medical professional dominant and non-dominant hands were quantified to test the hypothesis that mobile touch screen device use reduces wrist motion.

METHODS

An active motion detection system was used to record wrist motion of 12 participants while: tablet swiping and turning book pages; raising a cell and traditional phone to the ear; texting and typing; and entering numbers on a cell phone and manual calculator. Medial and lateral wrist surface range of motion (ROM) and minimum and maximum wrist radial-ulnar deviation and flexion-extension were quantified.

RESULTS

Device, sex and handedness effects were determined (P<0.05). Maximum medial radial deviation and ROM were greater using a cell versus traditional phone. Maximum medial radial deviation was higher in the nondominant wrist during backward tablet swiping and while backward page turning versus tablet swiping. Maximum and minimum medial extension angles and ROM were greater while typing versus texting. Female nondominant hand maximum lateral extension and ROM were greater for typing versus texting and maximum medial extension and lateral extension ROM greater during manual versus cell phone calculator use with handedness combined. Maximum lateral extension and ROM were greater in females versus males using manual calculators.

CONCLUSIONS

Sex and handedness should instruct touch screen, digital and manual device design and use for optimal performance and injury prevention.

The effect of anthropometric characteristics and electronic device use on median nerve cross-sectional area: A cross-sectional study

INTRODUCTION

This study aimed to identify the relationship between age, body mass index (BMI), weight, height, and wrist circumference and median nerve cross-sectional area (CSA). The study also aimed to examine the difference between CSA in individuals reporting a high amount (>4 hours per day) of electronic device use compared to those reporting a low amount (≤4 hours per day).

MATERIALS/METHODS

One hundred twelve healthy individuals volunteered to participate in the study. Anthropometric, demographic, and self-reported electronic device usage data were collected. A transverse image of the median nerve was captured using ultrasonography from the dominant wrist at the carpal tunnel inlet . A Spearman's rho correlation coefficient was used to examine correlations between participant characteristics (age, BMI, weight, height, and wrist circumference) and CSA. Separate Mann-Whitney U tests were used to examine differences in CSA in those younger and older than age 40, in those with BMI <25 kg/m2 and BMI ≥25 kg/m2, and in high and low-frequency device users.

RESULTS

BMI, weight, and wrist circumference showed fair correlations with CSA. There were significant differences in CSA between individuals younger than 40 and those older than 40 and between individuals with BMI <25kg/m2 and those with BMI ≥25kg/m2. There were no statistically significant differences in CSA in the low- and high-use electronic device groups.

DISCUSSION

Anthropometric and demographic characteristics including age and BMI or weight should be considered when examining the CSA of the median nerve, especially when determining cut-off points for establishing a diagnosis of carpal tunnel syndrome.

Anatomical considerations of US-guided carpal tunnel release in daily clinical practice

Carpal tunnel syndrome is the most frequent compression neuropathy with an incidence of one to three subjects per thousand. As specific anatomical variations might lead to unintended damage during surgical interventions, we present a review to elucidate the anatomical variability of the carpal tunnel region with important considerations for daily clinical practice: several variants of the median nerve branches in and around the transverse carpal ligament are typical and must - similarly to the variant courses of the median artery, which may be found eccentric ulnar to the median nerve - be taken into account in any interventional therapy at the carpal tunnel. Unintended interference in these structures might lead to heavy arterial bleeding and, in consequence, even underperfusion of segments of the median nerve or, if neural structures such as variant nerve branches are impaired or even cut, severe pain-syndromes with a profound impact on the quality of life. This knowledge is thus crucial for outcome- and safety-optimization of different surgical procedures at the volar aspect of the wrist and surgical therapy of the carpal tunnel syndrome e.g., US-guided carpal tunnel release, as injury might result in dysfunction and/or pain on wrist motion or direct impact in the region concerned. For most variations, anatomical and surgical descriptions vary, as official classifications are still lacking.

Carpal tunnel volume distribution and morphology changes with flexion-extension and radial-ulnar deviation wrist postures

Non-neutral wrist postures have been reported to cause decreased carpal tunnel volume (CTV) contributing to impingement of the median nerve and development of carpal tunnel syndrome. Recent analysis found CTV did not change with ±20° flexion-extension (FE), however, CTV decreased with ulnar deviation over the range of -5° to 15° radial-ulnar deviation (RUD). These findings suggest CTV may be too coarse of a measure to reflect the effects of slight non-neutral postures, or that volume is conserved and redistributed due to changes in tunnel morphology with posture. The objective of this study was to assess volume distribution along the length of the carpal tunnel and to quantify regional morphology changes with deviated wrist postures in both FE and RUD. Analysis was performed on a dataset of computed tomography scans collected on ten cadaveric specimens (5 male, 5 female, mean age = 80.7 ± 10.9 years) over a range of FE and RUD postures. The carpal tunnel of each scan was divided into four quartiles of equal length along the tunnel to quantify volume distribution. Volume within the carpal tunnel was seen to redistribute with both FE and RUD. Decreased volume in the distal aspect of the tunnel with flexion and proximal aspect of the tunnel with ulnar deviation may contribute to localized compression of the medial nerve. Measures of mean cross-sectional area, width and depth by quartile provided an indication of the morphology changes associated volume redistribution. Morphology analysis also revealed twisting between the proximal and distal aspects of the tunnel which increased with flexion and ulnar deviation and may further contribute to strain on the median nerve.

Sensor-Based Nerve Compression Measurement: A Scoping Review of Current Concepts and a Preclinical Evaluation of Commercial Microsensors

Background: Chronic nerve compression is the most common indication for nerve surgery. However, the clinical diagnosis still relies on surrogate parameters since devices for direct nerve compression pressure measurement (DNCPM) are clinically unavailable yet. Objectives: To review previous approaches to DNCPM and evaluate presently available microsensor systems for their feasibility and reliability in preclinical nerve compression models. Methods: A scoping literature review was conducted in accordance with the PRISMA-ScR guidelines. A subsequent market research aimed at identifying commercially available sensor systems potentially suitable for DNCPM. Sensors were evaluated for feasibility and safety of perineural sensor positioning, tissue compatibility and measurement reliability in a synthetic nerve compression model and an ex-vivo chicken leg model. Results: A scoping literature review identified 197 potentially eligible studies of which 65 were included in the analysis. Previous approaches to DNCPM predominantly used pressure sensing catheters designed for fluid- or intra-compartmental pressure measurement. A market research identified two piezoresistive sensor systems (IntraSense, SMi, United States; Mikro-Cath, Millar, United States) as potentially suitable for intraoperative DNCPM. In both preclinical models, the detected compression pressure differed significantly between sensors and systems showed substantial measurement variability with a median percent coefficient of variation between 15.5% and 32%. Sensor position was accountable for up to 99.1% of the variance. Conclusion: Measurement variability caused by unreliable sensor positioning is a key limitation of presently available sensors when applied for nerve compression measurements. Redesigned systems with small, flat-shaped and longitudinally oriented sensors and dedicated introducers would facilitate sensor positioning and therefore may allow for reliable measurements.

The Correlation of Carpal Tunnel Pressure with Clinical Outcomes following Ultrasonographically-Guided Percutaneous Carpal Tunnel Release

Background: To evaluate the correlation between carpal tunnel pressure (CTP) and the clinical presentations, and to explore the possible predictors for the postoperative recovery pattern in patients with carpal tunnel syndrome (CTS). Materials and Methods: Consecutive patients with idiopathic CTS following percutaneous ultrasound-guided carpal tunnel release (UCTR) were enrolled. CTP was measured preoperatively and immediately after operation. The Boston Carpal Tunnel Questionnaire (BCTQ) and the cross-sectional area (CSA) of median nerve were recorded preoperatively and at 1, 3, and 12 months postoperatively. Results: 37 patients (37 hands; 8 men and 29 females; median age, 59.0 years) were enrolled. CTP significantly decreased immediately from 40.0 (28.0−58.0) to 13.0 (8.0−20.0) mmHg after UCTR. BCTQ scores significantly improved at 1 month postoperatively, and the improvement trend persisted until 12 months postoperatively (p < 0.001). Preoperative CTP was positively correlated with preoperative CSA and preoperative BCTQ scores (p < 0.05, all). Using group-based trajectory modeling, all patients were categorized into the “gradual recovery” or “fast recovery” group. Higher preoperative CTP was significantly associated with a faster recovery pattern (odds ratio: 1.32). Conclusions: Preoperative CTP was well correlated with the clinical presentations and might be a useful predictor for the postoperative clinical recovery pattern.

Effects of slight flexion-extension and radial-ulnar deviation postures on carpal tunnel volume

BACKGROUND

Non-neutral wrist postures are a commonly reported risk factor for carpal tunnel syndrome. It is unclear how slight flexion-extension and radial-ulnar deviation postures affect the carpal tunnel. The objective was to determine the effects of slight non-neutral postures by quantifying carpal tunnel volume.

METHODS

Computed tomography images were collected on ten cadaveric specimens in target postures of -20°, -10°, -5°, 0°, 5°, 10°, and 20° of flexion and - 10°, -5°, 0°, 5°, and 10° of radial-ulnar deviation. Surface meshes of the carpal tunnel, carpal bones, radius, and third metacarpal were generated with manual segmentation. Carpal tunnel volume was calculated as the volume between proximal and distal boundaries defined with anatomical landmarks and the orientation of the tunnel. The precise wrist posture of each scan was determined with inertial-based coordinate systems of the radius and third metacarpal.

FINDINGS

Through multiple linear regression it was determined that, over the observed range of postures, flexion-extension angle does not have a significant effect (p = 0.99) while radial-ulnar deviation angle has a significant effect of -5.9 mm³/degree (p = 0.003). The findings were consistent with previous studies of postural effects on carpal tunnel pressure.

INTERPRETATION

For the treatment and prevention of carpal tunnel syndrome, results suggest that attention should be given to slight radial-ulnar deviation postures (<10°), while slight flexion-extension postures (<20°) are of lesser consequence to carpal tunnel volume.

Comparative efficacy of the dorsal application of Kinesio tape and splinting for carpal tunnel syndrome: A randomized controlled trial

BACKGROUND

Carpal tunnel syndrome (CTS) symptoms are problematic especially when signs and symptoms are not substantial enough to require surgical intervention. Conservative treatments have mixed effectiveness, yet are one of the best options for mild to moderate CTS. Kinesio tape is an emerging modality, as it provides biomechanical support while allowing movement.

PURPOSE

The purpose of this study was to determine the efficacy of dorsal application of Kinesio tape on occupational performance as measured by pain and function in individuals with mild to moderate CTS, as compared with the accepted nonsurgical intervention of general cockup orthosis and lumbrical stretching exercises versus sham tape.

STUDY DESIGN

Single-blind randomized controlled trial.

METHODS

Forty-four participants (68 wrists) with CTS were randomized to one of three interventions: Kinesio tape group, sham group, or standard protocol group. Each completed baseline and four subsequent measurements of numeric pain rating scale, visual analog scale (VAS), Boston Carpal Tunnel Questionnaire (BCTQ), grip and pinch, with application of intervention every three days. Daily symptom journals were completed, standard protocol group recorded wearing schedule and exercises.

RESULTS

In the forearm and wrist, a significant reduction in median numeric pain rating scale pain scores in Kinesio tape group was observed (r = 0.76, P = .01; r = 0.77, P = .01; respectively), but not in the standard protocol group (r = 0.51, P = .17; r = 0.53, P = .11) and sham group (r = 0.46, P = .30; r = 0.39, P = .43) with a minimal clinically important difference of 1.0. In the Kinesio tape group, the forearm (24%) and wrist (36%) reached the clinical significance as compared with the standard protocol forearm (18%) and wrist (32%). The minimal clinically important difference for pain reduction on the visual analog scale was 1.64. Kinesio tape and sham group had significant improvement in function, but not the standard protocol group.

DISCUSSION

This study provides promising evidence for the use of Kinesio tape as a possible conservative intervention for management of symptoms in individuals with mild to moderate CTS. The study also illuminates new considerations of younger, active individuals reporting signs and symptoms of CTS as well as mechanism of effects on pain reduction.

CONCLUSIONS

Kinesio tape provided additional improvement in pain and function as compared to the standard approach.

Digitalization of Musculoskeletal Risk Assessment in a Robotic-Assisted Assembly Workstation

The ergonomic assessment of adopted working postures is essential for avoiding musculoskeletal risk factors in manufacturing contexts. Several observational methods based on external analyst observations are available; however, they are relatively subjective and suffer low repeatability. Over the past decade, the digitalization of this assessment has received high research interest. Robotic applications have the potential to lighten workers’ workload and improve working conditions. Therefore, this work presents a musculoskeletal risk assessment before and after robotic implementation in an assembly workstation. We also emphasize the importance of using novel and non-intrusive technologies for musculoskeletal risk assessment. A kinematic study was conducted using inertial motion units (IMU) in a convenience sample of two workers during their normal performance of assembly work cycles. The musculoskeletal risk was estimated according to a semi-automated solution, called the Rapid Upper Limb Assessment (RULA) report. Based on previous musculoskeletal problems reported by the company, the assessment centered on the kinematic analysis of functional wrist movements (flexion/extension, ulnar/radial deviation, and pronation/supination). The results of the RULA report showed a reduction in musculoskeletal risk using robotic-assisted assembly. Regarding the kinematic analysis of the wrist during robotic-assisted tasks, a significant posture improvement of 20–45% was registered (considering the angular deviations relative to the neutral wrist position). The results obtained by direct measurements simultaneously reflect the workload and individual characteristics. The current study highlights the importance of an in-field instrumented assessment of musculoskeletal risk and the limitations of the system applied (e.g., unsuitable for tracking the motion of small joints, such as the fingers).

Increased Risk of Carpal Tunnel Syndrome in People With Spinal Cord Injury: A Nationwide Longitudinal Follow-Up Study

OBJECTIVE

To investigate the long-term risk of carpal tunnel syndrome (CTS) in people with spinal cord injury (SCI).

DESIGN

Retrospective cohort study.

SETTING

Taiwan's Longitudinal Health Insurance Database 2005, containing data about 1 million people randomly sampled from among those registered in the National Health Insurance Program as of 2005.

PARTICIPANTS

The SCI group consisted of 1681 subjects with SCI, and the comparison group comprised 6724 propensity score-matched subjects without SCI (N=8405). The variables included in propensity-score matching were age, sex, comorbid conditions, and socioeconomic status.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The occurrence of newly diagnosed CTS, defined by at least 1 hospital discharge or 2 outpatient visits with a diagnosis of CTS.

RESULTS

The incidence density of CTS in the SCI group was 7.55 per 1000 person-years (95% confidence interval [CI], 6.03-9.33), and in the comparison group, 4.61 per 1000 person-years (95% CI, 4.08-5.19). The hazard ratio (HR) of CTS for the SCI group was therefore 1.59 (95% CI, 1.24-2.03). Additionally, the HR of CTS for the cervical-SCI subgroup, 1.90 (95% CI, 1.21-2.97) was considerably higher than that of its noncervical counterpart, 1.47 (95% CI, 1.09-1.98).

CONCLUSIONS

People with both cervical and noncervical SCI have an increased risk of developing CTS, as compared with those without SCI. Moreover, the CTS risk appears to be higher for individuals with cervical SCI than their noncervical SCI counterparts.

Computer workstation ergonomics: Current evidence for evaluation, corrections, and recommendations for remote evaluation

STUDY DESIGN

Literature Review INTRODUCTION: Computer use in the workplace has increased substantially since the start of the information age in the mid-1980s through 2020. Desktops, laptops, and tablets are essential tools for communication and project management. As a result of the COVID-19 pandemic, many workers have transitioned to work from home (WFH) to sustain public health emergency guidelines, and it is anticipated that many WFH jobs will be maintained post-pandemic. The transition to WFH occurred rapidly without time to establish ideal workstations. Ergonomic assessments that were typically performed in person needed to be performed using virtual technology.

PURPOSE OF THE STUDY

The purpose of this review is (1) to describe the components of a computer workstation evaluation; (2) to offer suggestions for identifying computer workstation problems that may be contributing to the client's musculoskeletal (MSK) pain and symptoms; (3) to provide suggestions that may improve the safety and comfort at the computer workstation, and (4) to suggest a method of completing the workstation analysis virtually, without onsite in-person evaluation.

METHODS AND RESULTS

There is a paucity of peer-reviewed literature regarding computer workstation evaluations to be performed in person, let alone using a virtual method. The components of computer workstation evaluations have been recommended by regulatory agencies that survey injuries in the workplace. Prior to 2020, these evaluations were done in person at the office workstation. Modifications in data collection were needed to transition the analysis to a reliable virtual format. The remote method described provides a consistent approach that engages the client in the process.

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

Background

We 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.

Methods

Fourteen 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.

Results

We 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.

Discussion

Overall, 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.

Carpal Tunnel Syndrome: A National Survey to Monitor Knowledge and Operating Methods

The aim of this article was to investigate the knowledge, management, and clinical practice of Italian physiotherapists concerning patients with carpal tunnel syndrome (CTS). A national cross-sectional survey consisted of 24 questions was administered from December 2019 until February 2020. A Chi-squared independence test was run to study any difference between subgroups of the sample and responses to the questionnaire. Five hundred and eight respondents completed the survey. Most respondents (n = 225/508; 44.3%) are under 29 years old, female (n = 256/508; 50.4%) and have been working as physiotherapists for less than 5 years (n = 213/508; 41.9%). Most of respondents correctly knows about the cause (n = 455/508, 89.6%), main signs and symptoms of CTS (n = 415/508, 81.70%) and administer education, manual therapy, myofascial techniques and therapeutic exercises (n = 457/508, 89.88%). Three hundred and sixty-four (71.68%) respondents were aware of the influence of psychosocial factors on the patient’s outcomes. The survey showed greater adherence to evidences by physiotherapists holding a master’s degree. The results are mostly comparable with other surveys structured all over the world on the same topic. Italian physiotherapists management of the CTS was not always in line with current evidence. Interventions such as education, manual therapy, therapeutic exercise, nerve and tendon glide techniques are widely used, while the orthotic is only offered by half of the sample.

Modification of intra-carpal tunnel pressure after Z-lengthening of the transverse carpal ligament

Background Flexor retinaculum reconstruction techniques or simply Flexor Retinaculum Z-lengthening have been proposed to preserve Flexor Retinaculum continuity after carpal tunnel release. Their effectiveness is based solely on symptom relief. There has been no analysis of the effects on intra-carpal tunnel pressure of Flexor Retinaculum-lengthening techniques. Objective was to compare intra-carpal tunnel pressure outcomes between complete division and Z-lengthening of the Retinaculum in a cadaveric model of carpal tunnel release. Methods Experimental study of carpal tunnel pressure after surgical Flexor Retinaculum modification in 10 fresh-frozen forearm and hand cadaveric specimens. The Kyphon™ Balloon Kyphoplasty system was used to measure the pressure before and after infusing 1, 2, 3, 4 and 5 ml of saline solution when untreated (Flexor Retinaculum continuity stage I), when Z-lengthened (Flexor Retinaculum continuity stage II), and after complete Flexor Retinaculum division (Flexor Retinaculum continuity stage III). Finding Intra-carpal tunnel pressure increased with larger volume of infused saline solution, although mean pressures were lower after Z lengthening or complete division of the Retinaculum than at baseline. Analysis of linear regression coefficients indicated significant differences as a function of FR continuity stage (F(2,18) = 18.38, p < 0.001), while the Bonferroni test revealed significant differences in slopes between stages I and III (p = 0.003), between stages I and II (p < 0.02), but not between stages II and III (p > 0.05). Interpretation The effectiveness of carpal tunnel release and the reduction in intra-carpal tunnel pressures obtained by Z-lengthening of the FR were similar to those observed after its complete division, while preserving FR continuity.

An ergonomic comparison of three different patient transport chairs in a simulated hospital environment

The purpose of this study was to compare caregiver muscle activation and joint angles between two ergonomic transport chairs designed to mitigate discomfort and safety risks associated with patient transport, the Stryker® Prime TC and the Staxi® Medical Chair, and a depot wheelchair. Twenty-three caregivers completed level walking and ramped tasks with each device and an 84 kg manikin. Surface electromyography for the upper extremities and back muscles and motion data were collected. The Staxi showed a statistical trend for higher wrist extensor and flexor carpi ulnaris activity compared to the Stryker chair (p ≤ 0.078) and greater wrist flexion than the Stryker and depot chairs (p ≤ 0.004). The depot chair showed greater peak trunk flexion than the Stryker chair (p = 0.004). Overall results suggest that ergonomic chair design may improve joint positioning of the trunk and elbows when operating patient transport chairs over level and ramped surfaces.

Morphological Changes of the Median Nerve Within the Carpal Tunnel During Various Finger and Wrist Positions: An Analysis of Intensive and Nonintensive Electronic Device Users

PURPOSE

To investigate the effects of static hand postures during various finger and wrist positions on morphological changes of the median nerve within the carpal tunnel in intensive and nonintensive electronic device users.

METHODS

Forty-eight university students, equally divided into intensive and nonintensive users (≥5 h/d and <5 h/d of electronic device usage, respectively), were randomly selected after questionnaire responses and evaluated clinically and by ultrasonography.

RESULTS

Intensive users reported more wrist/hand pain with a high severity score than nonintensive users. They also had larger median nerve cross-sectional areas, flattening ratios, and perimeters than nonintensive users, and showed less median nerve deformation under various finger and wrist positions. Compared with the neutral wrist position with all fingers extended for both intensive and nonintensive users, the cross-sectional areas decreased under finger flexion and grip, as well as wrist extension-flexion and radial-ulnar deviation. Overall, the average median nerve size of the dominant hand was much larger than that of the nondominant hand, especially for intensive users.

CONCLUSIONS

Wrist deviation from neutral can lead to more pronounced deformation of the median nerve than finger flexion for both intensive and nonintensive users. To minimize compression on the median nerve, it is important to keep the wrist as near to the neutral position as possible during computer-related work and avoid keeping the thumb and fingers in a static flexed position when using mobile devices, especially for single-hand use.

CLINICAL RELEVANCE

On the basis of this observational study, intensive users had enlarged and flattened median nerves as well as decreased nerve deformation during hand motions compared with nonintensive users. As overuse of electronic devices may adversely affect the median nerve, caution may be warranted.

Hand Pain and Sensory Deficits: Carpal Tunnel Syndrome

The Academy of Orthopaedic Physical Therapy and the Academy of Hand and Upper Extremity Physical Therapy have an ongoing effort to create evidence-based clinical practice guidelines (CPGs) for orthopaedic and sports physical therapy management and prevention of musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability and Health (ICF). This particular guideline focuses on hand pain and sensory deficits in carpal tunnel syndrome. J Orthop Sports Phys Ther 2019;49(5):CPG1-CPG85. doi:10.2519/jospt.2019.0301.

Differences in typing forces, muscle activity, wrist posture, typing performance, and self-reported comfort among conventional and ultra-low travel keyboards

This study investigated the relative impact of ultra-low travel keyboards on typing force, muscle activity, wrist posture, typing performance, and self-reported comfort/preference as compared to a conventional keyboard. In a repeated-measures laboratory-based study, 20 subjects were invited to type for 10 min on each of five keyboards with different travel distances of 0.5, 0.7, 1.2, 1.6 (ultra-low travel keyboards), and 2.0 mm (a conventional keyboard). During the typing sessions, we measured typing force; muscle activity in extrinsic finger muscles (flexor digitorum superficialis and extensor digitorum communis), shoulder (trapezius) and neck (splenius capitis); wrist posture; typing performance; and self-reported comfort/preference. While using the ultra-low travel keyboards, subjects typed with less force and wrist extension, and had more ulnar deviation (p's < 0.0001) compared with conventional keyboard. However, these differences in typing forces were less than 0.5 N and less than 4° for both wrist extension and ulnar deviation. The general trend of data did not show any consistent or substantial differences in muscle activity (less than 2 %MVC) and typing performance (<5 WPM in speed; < 3% in accuracy), despite the observed statistical difference in the finger flexors and extensors muscle activity (p's < 0.19) and typing performance (p < 0.0001). However, the subjects preferred using conventional keyboards in most of the investigated self-reported comfort and preference criteria (p's < 0.4). In conclusion, these small differences indicate that using ultra-low travel keyboards may not have substantial differences in biomechanical exposures and typing performance compared to conventional keyboard; however, the subjective responses indicated that the ultra-low keyboards with the shortest key travel tended to be the least preferred.

Physical ergonomic risk factors of carpal tunnel syndrome among rubber tappers

This study evaluated physical ergonomic risk factors associated with carpal tunnel syndrome (CTS) among rubber tappers in Thailand. The Boston Carpal Tunnel Syndrome Questionnaire and Phalen's test and Tinel's sign were used to identify 133 cases with CTS and 401 non-CTS controls. Video recordings and Rapid Upper Limb Assessment used to evaluate the level of ergonomic risk in right and left hand postures. Significant physical ergonomic risk factors of CTS were higher number of trees tapped at or below knee level and collecting latex. Among right-handed tappers, tapping at higher than chest level involved significantly higher proportion of right wrist flexion and/or extension, and left wrist radial and/or ulnar deviation and twist than tapping at a lower level.

Developing and evaluating the feasibility of administering the SLUMP questionnaire for evaluating ergonomic exposures to laptop use in university students

BACKGROUND

Laptop computer use may lead to the development of health problems. However, few methods exist to measure laptop use in undergraduate students.

OBJECTIVES

To develop a web-based questionnaire to measure ergonomic exposures to laptop use and to test the feasibility of administration in university students.

METHODS

We pilot tested the administration of the Student Laptop Use and Musculoskeletal Posture (SLUMP) questionnaire to 44 second year undergraduate students. We measured the participation rate, completion of questions, and sought feedback for improving the questionnaire.

RESULTS

The participation rate was 75% (33/44). Students needed 10-12 minutes to complete the questionnaire. Participants suggested adding half hour intervals for questions measuring breaks and improving the clarity by emphasizing the sections focusing on academic, recreational and employment laptop use.

CONCLUSION

Our pilot study suggests that the SLUMP questionnaire is appropriate for "in-class" measurement of ergonomic exposures to laptop use in university students.

Keyboards types of selected electronic devices and the occurrence of pain in the shoulder girdle and upper limb - a review of literature

Introduction: Nowadays, computers, personal telephones (smartphones) and other electronic devices are widely used in many areas of everyday life, making them indispensable tools in the workplace, as well as other environments, e.g. at home. Studies from recent years have shown that the mere use of a computer keyboard for many hours carries the risk of pain in the hand, forearm, arm, shoulder girdle, neck and other parts of the motor organs. Aim: The aim of the literature review carried out in this work was to determine what potential threats are posed by standard keyboards and smartphone touch keypads, as well as the comparison of standard and ergonomic keyboards. Material and methods: The following databases were searched: PubMed, ResearchGate and Cochrane Library, in which 13 articles meeting the inclusion and exclusion criteria were found (6 regarding standard keyboards, 3 concerning ergonomic keyboards and 4 related to smartphone keypads). Results: The results of these studies indicate exposure to dysfunctions of the musculoskeletal system associated with typing on keyboards, especially when writing fast, with high pressure, in unnatural positions of the wrists and forearms and during long-term writing. Ergonomic keyboards can be a good alternative to standard keyboards, especially for those who use one for more than four hours a day. This literature review indicates the need for more research, especially randomized clinical trials among a large population. Conclusions: 1. The use of keyboards of selected electronic devices with different ergonomic characteristics has an adverse effect on the functionality of the shoulder girdle and upper limb, mainly generating painful symptoms with different clinical characteristics. 2. The most important influence on the occurrence of functional disorders and pain complaints concerning the shoulder girdle and upper limb when using a keyboard with different ergonomic characteristics regards the strength of pressure on the keys, speed of typing as well as long-lasting and forced positioning of the wrists and forearms. Keyboards, ergonomics, pain

The quantitative evaluation of the relationship between the forces applied to the palm and carpal tunnel pressure

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy occurring in upper limbs. The etiology, however, has not been fully understood yet. Median nerve could be compressed by either increase of carpal tunnel pressure (CTP) or direct impingement when it is forced toward to carpal ligament especially in wrist flexion leading to CTS development. Thus, the increase of carpal tunnel pressure is considered an important role in CTS development. It has been identified that forces applied to the palm would affect the CTP. However, the quantitative relationship between palmar contact force and CTP is not known. The purpose of this study was to quantitatively evaluate the relationship between palmar contact force and CTP. Eight human cadaveric hands were used. The CTP was measured with a diagnostic catheter-based pressure transducer inserted into the carpal tunnel. A custom made device was used to apply forces to the palm for the desired CTP. Palmar contact forces corresponding to the determined CTP level were recorded respectively. The testing was repeated with different ranges of tension applied to the flexor digitorum superficialis tendon of the third finger. The tensions were constant at 50 g for the other flexor tendons and median nerve. The results showed that CTP increased linearly with the force applied to the palm. When CTP was 30 mmHg, mean values of the contact force to the palm was 293 g (SD: 15.2) including all tensions. These results would help to understand the effect of daily activities with hands on CTP.

Ultrasound elastography for carpal tunnel pressure measurement: A cadaveric validation study

Carpal tunnel pressure is a key factor in the etiology of carpal tunnel syndrome. Numerous approaches have been conducted to measure carpal tunnel pressure. However, most techniques are invasive and take time and effort. We have developed an innovative approach to noninvasively assess the tunnel pressure by using the ultrasound surface wave elastography (USWE) technique. In a previous study it was shown that the shear wave speed in a tendon increased linearly with increasing tunnel pressure enclosed the tendon in a simple tendon model. This study aimed to examine the relationship between the carpal tunnel pressure and the shear wave speeds inside and outside the carpal tunnel in a human cadaveric model. The result showed that the shear wave speed inside the carpal tunnel increased linearly with created carpal tunnel pressure, while the shear wave speed outside the carpal tunnel remained constant. These findings suggest that noninvasive measurement of carpal tunnel pressure is possible by measuring the shear wave speed in the tendon. After fully establishing this technology and being applicable in clinic, it would be useful in the diagnosis of carpal tunnel syndrome. For that reason, further validation with this technique in both healthy controls and patients with carpal tunnel syndrome is required. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:477-483, 2018.

Effect of the release exercise and exercise position in a patient with carpal tunnel syndrome

[Purpose] This study examined the effect of the release exercise and exercise position in carpal tunnel syndrome (CTS). [Subject] A 40-year-old, right-hand-dominant man presented with CTS, with pain and progressive tingling and numbness in the right hand. [Methods] The subject performed three exercises: (1) release, (2) wrist flexor stretching, and (3) wrist extensor stretching. In session 1, the subject performed exercises 2 and 3 in the standing position for 2 weeks. In session 2, the subject performed all three exercises in the supine position for 2 weeks. [Results] The pressure pain threshold decreased after session 1 and decreased further after session 2, and the Phalen’s test and Tinel sign became progressively less positive. [Conclusion] Exercises in the supine position, including release exercises, are recommended for CTS.

Usage Position and Virtual Keyboard Design Affect Upper-Body Kinematics, Discomfort, and Usability during Prolonged Tablet Typing

Purpose

The increase in tablet usage allows people to perform computer work in non-traditional office environments. The aim of this study was to assess the effects of changes in tablet keyboard design on postures of the upper extremities and neck, discomfort, and usability under different usage positions during prolonged touch-typing.

Methods

Eighteen healthy participants familiar with touch-screen devices were randomized into three usage positions (desk, lap, and bed) and completed six, 60-minute typing sessions using three virtual keyboard designs (standard, wide, split). Electrogoniometers continuously measured the postures of the wrists, elbow, and neck. Body discomfort and system usability were evaluated by questionnaires before and immediately after each typing session.

Results

Separate linear mixed effects models on various postural measures and subjective ratings are conducted with usage position as the between-subject factors, keyboard design and typing duration as the with-in subject factors were conducted. Using the tablet in bed led to more extended wrists but a more natural elbow flexion than the desk position. The angled split virtual keyboard significantly reduced the extent of wrist ulnar deviation than the keyboard with either standard or wide design. However, little difference was observed across the usage position and keyboard design. When the postural data were compared between the middle and end of typing sessions, the wrists, elbow, and neck all exhibited a substantially increased range of joint movements (13% to 38%). The discomfort rating also increased significantly over time in every upper body region investigated. Additionally, the split keyboard design received a higher usability rating in the bed position, whereas participants had more satisfactory experience while using the wide keyboard in the traditional desk setting.

Conclusions

Prolonged use of tablets in non-traditional office environments may result in awkward postures in the upper body that may expose users to greater risks of developing musculoskeletal symptoms. Adequate virtual keyboard designs show the potential to alleviate some postural effects and improve the user experience without changing the tablet form factors.

Carpal tunnel syndrome: primary care and occupational factors

Carpal tunnel syndrome (CTS) affects about 1% of working-aged people and is the commonest cause of hand pain in manual workers. CTS is a clinical diagnosis and does not warrant any further investigation in the presence of mild and suggestive CTS. Although the recommended non-surgical management is still a matter of debate, nocturnal splinting or steroid injection are recommended in most countries, with strong to moderate level of evidence for short-term efficacy. Patients with an uncertain diagnosis or severe symptoms, should undergo nerve conduction studies with referral to a hand specialist.

A vertical mouse and ergonomic mouse pads alter wrist position but do not reduce carpal tunnel pressure in patients with carpal tunnel syndrome

Non-neutral wrist positions and external pressure leading to increased carpal tunnel pressure during computer use have been associated with a heightened risk of carpal tunnel syndrome (CTS). This study investigated whether commonly used ergonomic devices reduce carpal tunnel pressure in patients with CTS. Carpal tunnel pressure was measured in twenty-one patients with CTS before, during and after a computer mouse task using a standard mouse, a vertical mouse, a gel mouse pad and a gliding palm support. Carpal tunnel pressure increased while operating a computer mouse. Although the vertical mouse significantly reduced ulnar deviation and the gel mouse pad and gliding palm support decreased wrist extension, none of the ergonomic devices reduced carpal tunnel pressure. The findings of this study do therefore not endorse a strong recommendation for or against any of the ergonomic devices commonly recommended for patients with CTS. Selection of ergonomic devices remains dependent on personal preference.

Computer use and carpal tunnel syndrome: A meta-analysis

BACKGROUND

Studies have reported contradictory results on the role of keyboard or mouse use in carpal tunnel syndrome (CTS). This meta-analysis aimed to assess whether computer use causes CTS.

METHODS

Literature searches were conducted in several databases until May 2014. Twelve studies qualified for a random-effects meta-analysis. Heterogeneity and publication bias were assessed.

RESULTS

In a meta-analysis of six studies (N=4964) that compared computer workers with the general population or other occupational populations, computer/typewriter use (pooled odds ratio (OR)=0.72, 95% confidence interval (CI) 0.58-0.90), computer/typewriter use ≥1 vs. <1h/day (OR=0.63, 95% CI 0.38-1.04) and computer/typewriter use ≥4 vs. <4h/day (OR=0.68, 95% CI 0.54-0.87) were inversely associated with CTS. Conversely, in a meta-analysis of six studies (N=5202) conducted among office workers, CTS was positively associated with computer/typewriter use (pooled OR=1.34, 95% CI 1.08-1.65), mouse use (OR=1.93, 95% CI 1.43-2.61), frequent computer use (OR=1.89, 95% CI 1.15-3.09), frequent mouse use (OR=1.84, 95% CI 1.18-2.87) and with years of computer work (OR=1.92, 95% CI 1.17-3.17 for long vs. short). There was no evidence of publication bias for both types of studies.

CONCLUSIONS

Studies that compared computer workers with the general population or several occupational groups did not control their estimates for occupational risk factors. Thus, office workers with no or little computer use are a more appropriate comparison group than the general population or several occupational groups. This meta-analysis suggests that excessive computer use, particularly mouse usage might be a minor occupational risk factor for CTS. Further prospective studies among office workers with objectively assessed keyboard and mouse use, and CTS symptoms or signs confirmed by a nerve conduction study are needed.

Effects of different computer typing speeds on acceleration and peak contact pressure of the fingertips during computer typing

[Purpose] This study showed the effects of different computer typing speeds on acceleration and peak contact pressure of the fingertips during computer typing. [Subjects] Twenty-one male computer workers voluntarily consented to participate in this study. They consisted of 7 workers who could type 200-300 characteristics/minute, 7 workers who could type 300-400 characteristics/minute, and 7 workers who could type 400-500 chracteristics/minute. [Methods] This study was used to measure the acceleration and peak contact pressure of the fingertips for different typing speed groups using an accelerometer and CONFORMat system. [Results] The fingertip contact pressure was increased in the high typing speed group compared with the low and medium typing speed groups. The fingertip acceleration was increased in the high typing speed group compared with the low and medium typing speed groups. [Conclusion] The results of the present study indicate that a fast typing speed cause continuous pressure stress to be applied to the fingers, thereby creating pain in the fingers.

Is carpal tunnel syndrome related to computer exposure at work? A review and meta-analysis

OBJECTIVE

A meta-analysis on epidemiological studies was undertaken to assess association between carpal tunnel syndrome (CTS) and computer work.

METHODS

Four databases (PubMed, Embase, Web of Science, and Base de Donnees de Sante Publique) were searched with cross-references from published reviews. We included recent studies, original epidemiological studies for which the association was assessed with blind reviewing with control group. Relevant associations were extracted, and a metarisk was calculated using the generic variance approach (meta-odds ratio [meta-OR]).

RESULTS

Six studies met the criteria for inclusion. Results are contradictory because of heterogeneous work exposure. The meta-OR for computer use was 1.67 (95% confidence interval [CI], 0.79 to 3.55). The meta-OR for keyboarding was 1.11 (95% CI, 0.62 to 1.98) and for mouse 1.94 (95% CI, 0.90 to 4.21).

CONCLUSION

It was not possible to show an association between computer use and CTS, although some particular work circumstances may be associated with CTS.

Effect of grip type, wrist motion, and resistance level on pressures within the carpal tunnel of normal wrists

Elevated carpal tunnel pressure (CTP) has been associated with carpal tunnel syndrome. This study systematically evaluated the effect of wrist motion resistance and grip type on CTP during wrist motion typical of occupational tasks. CTP during four wrist motion patterns, with and without resistance, and with and without gripping, was measured in vivo in 14 healthy individuals. CTP measured during compound motions fell between that measured in the cardinal planes of wrist flexion/extension and radial/ulnar deviation. Generally, with no active gripping there was little pressure change due to wrist angular displacement or resistance level. However, concurrent active pinch or power grip increased CTP particularly in motions including extension. CTP typically did not increase during wrist flexion, and in fact often decreased. Extension motions against resistance when employing a pinch or power grip increase CTP more than motions with flexion. Results could help inform design or modification of wrist motion intensive occupational tasks. © 2014 The Authors.

Altered median nerve deformation and transverse displacement during wrist movement in patients with carpal tunnel syndrome

RATIONALE AND OBJECTIVES

Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome. Strong pinch or grip with wrist flexion has been considered a risk factor for CTS. Studying median nerve displacement during wrist movements may provide useful information about median nerve kinematic changes in patients with CTS. The purpose of this study was to evaluate the deformability and mobility of the median nerve in patients with CTS compared to healthy subjects.

MATERIALS AND METHODS

Dynamic ultrasound images were obtained in 20 affected wrists of 13 patients with CTS. Results were compared to complementary data obtained from both wrists of 10 healthy subjects reported in a previous study. Shape and position of initial and final median nerve were measured and analyzed for six defined wrist movements. The deformation ratios for each movement were defined as the median nerve area, perimeter, and circularity of the final position normalized by respective values assessed in the initial position. The median nerve displacement vector and magnitude were also calculated.

RESULTS

The deformation ratio for circularity was significantly less in patients with CTS compared to healthy subjects during wrist flexion (P < .05). The mean vector of median nerve displacement during wrist flexion was significantly different between patients with CTS and healthy subjects (P < .05). The displacement magnitude of the median nerve was found to be less in patients with CTS compared to healthy subjects during most movements, with the exception of wrist extension with fingers extended.

CONCLUSIONS

Patients with CTS differ from normal subjects with regard to mobility and deformability of the median nerve.

Wrist posture affects hand and forearm muscle stress during tapping

Non-neutral wrist posture is a risk factor of the musculoskeletal disorders among computer users. This study aimed to assess internal loads on hand and forearm musculature while tapping in different wrist postures. Ten healthy subjects tapped on a key switch using their index finger in four wrist postures: straight, ulnar deviated, flexed and extended. Torque at the finger and wrist joints were calculated from measured joint postures and fingertip force. Muscle stresses of the six finger muscles and four wrist muscles that balanced the calculated joint torques were estimated using a musculoskeletal model and optimization algorithm minimizing the squared sum of muscle stress. Non-neutral wrist postures resulted in greater muscle stresses than the neutral (straight) wrist posture, and the stress in the extensor muscles were greater than the flexors in all conditions. Wrist extensors stress remained higher than 4.5 N/cm² and wrist flexor stress remained below 0.5 N/cm² during tapping. The sustained high motor unit recruitment of extensors suggests a greater risk than other muscles especially in flexed wrist posture. This study demonstrated from the perspective of internal tissue loading the importance of maintaining neutral wrist posture during keying activities.

User-oriented evaluation of mechanical single-channel axial pipettes

Hand tools should be designed so that they are comfortable to use, fit the hand and are user-oriented. Six different manual, single-channel axial pipettes were evaluated for such objective outcomes as muscular activity, wrist postures and efficiency, as well as for subjective outcomes concerning self-assessed features of pipette usability and musculoskeletal strain. Ten experienced laboratory employees volunteered for the study. The results showed that light and short pipettes with better tool comfort resulted in reduced muscular activity and perceived musculoskeletal strain when they were compared with a long and heavy pipette. There were no differences in the efficiency between the different pipettes. Combining both the objective and subjective measures enabled a broader evaluation of product usability. The results of this study can be used both in product development and as information on which to base the purchase of new pipettes for laboratory work.

Peripheral nerve: from the microscopic functional unit of the axon to the biomechanically loaded macroscopic structure

Peripheral nerves are composed of motor and sensory axons, associated ensheathing Schwann cells, and organized layers of connective tissues that are in continuity with the tissues of the central nervous system. Nerve fiber anatomy facilitates conduction of electrical impulses to convey information over a distance, and the length of these polarized cells necessitates regulated axonal transport of organelles and structural proteins for normal cell function. Nerve connective tissues serve a protective function as the limb is subjected to the stresses of myriad limb positions and postures. Thus, the tissues are uniquely arranged to control the local nerve fiber environment and modulate physical stresses. In this brief review, we describe the microscopic anatomy and physiology of peripheral nerve and the biomechanical properties that enable nerve to withstand the physical stresses of everyday life.

Description, reliability and validity of a novel method to measure carpal tunnel pressure in patients with carpal tunnel syndrome

Elevated carpal tunnel pressure is an important pathomechanism in carpal tunnel syndrome (CTS). Several invasive methods have been described for direct measurement of carpal tunnel pressure, but all have two important limitations. The pressure gauge requires sterilisation between uses, which makes time-efficient data collection logistically cumbersome, and more importantly, the reliability of carpal tunnel pressure measurements has not been evaluated for any of the methods in use. This technical note describes a new method to measure carpal tunnel pressure using inexpensive, disposable pressure sensors and reports the within and between session reliability of the pressure recordings in five different wrist positions and during typing and computer mouse operation. Intraclass correlation coefficients (ICC[3,1]) were calculated for recordings within one session for healthy participants (n = 7) and patients with CTS (n = 5), and for recordings between two sessions for patients with CTS (n = 5). Overall, the reliability was high. With the exception of two coefficients, the reliability of the recordings at different wrist angles varied from 0.63 to 0.99. Reliability for typing and mouse operation ranged from 0.86 to 0.99. The new method described in this report is inexpensive and reliable, and data collection can be applied more efficiently as off-site sterilisation of equipment is not required. These advances are likely to promote future research into carpal tunnel pressure, such as investigation of the therapeutic mechanisms of various conservative treatment modalities that are believed to reduce elevated carpal tunnel pressure.

Progress in vibrotactile threshold evaluation techniques: a review

Vibrotactile threshold (VT) testing has been used for nearly a century to investigate activation of human somatosensory pathways. This use of vibrotactile stimuli provides a versatile tool for detecting peripheral neuropathies, and has been broadly used for investigation of carpal tunnel syndrome. New applications include investigation of drug-induced neuropathies and diabetes-related neuropathies. As a feedback device, the vibrotactile stimuli could be used as an information delivery system for rehabilitative feedback devices for upper limb musculoskeletal disorders or as information channels for the visually impaired. This review provides a comprehensive review of the advancement in VT measurement techniques over time and a comparison of these techniques in terms of various hardware features used and the testing protocols implemented. The advantages and limitations of these methods have been discussed along with specific recommendations for their implementation and suggestions for incorporation into clinical practice.

Determination of the position on which the median nerve compression is at the lowest in carpal tunnel syndrome and clinical effectiveness of custom splint application

To evaluate the clinical effectiveness of wrist splint usage arranged by determining the optimal position on which the median nerve is compressed the least through sonographic examination for patients with carpal tunnel syndrome (CTS). This study was a prospective, clinical trial with a 6-week follow-up. Twenty-four patients diagnosed clinically and electromyographically with CTS were included in the study. A total of 37 wrists were studied on. When the patients were grouped according to the optimal position, Group I comprising 16 (43.24%) wrists was at 15 degree flexion, Group II comprising 12 (32.43%) wrists was neutral, Group III comprising 6 (16.22%) wrists was at 15° extension and Group IV comprising 3 (8.11%) wrists was at 30° extension configurations. Groups I, II and III were included in clinical follow-up. Symptom severity score (SSS), functional status score (FSS), Grip strength and Pinch strength were used for the clinical follow-up and evaluation of the patients. When pre- and post-treatment were compared, a statistically significant recovery was detected in all three groups in respect to SSS (Group I P < 0.01, Group II P < 0.05, Group III P < 0.05). A statistically significant recovery was detected for FSS only in Group I (P < 0.05) and for Grip strength in Group II (P < 0.05). When the groups were compared among themselves, no statistically significant difference was detected for any of the parameters (P > 0.05). In this study, by sonographic examination of the patients included in the study with CTS, we saw that the optimal position on which the median nerve is compressed the least varies depending on the individual and we determined that this position was 15° flexion most frequently for our patients. We also observed that in clinical follow-up of wrist splint usage arranged on custom optimal position results in significant recovery.

The effects of split keyboard geometry on upper body postures

Split, gabled keyboard designs can prevent or improve upper extremity pain among computer users; the mechanism appears to involve the reduction of awkward wrist and forearm postures. This study evaluated the effects of changes in opening angle, slope and height (independent variables) of a gabled (14 degrees) keyboard on typing performance and upper extremity postures. Twenty-four experienced touch typists typed on seven keyboard conditions while typing speed and right and left wrist extension, ulnar deviation, forearm pronation and elbow position were measured using a motion tracking system. The lower keyboard height led to a lower elbow height (i.e. less shoulder elevation) and less wrist ulnar deviation and forearm pronation. Keyboard slope and opening angle had mixed effects on wrist extension and ulnar deviation, forearm pronation and elbow height and separation. The findings suggest that in order to optimise wrist, forearm and upper arm postures on a split, gabled keyboard, the keyboard should be set to the lowest height of the two heights tested. Keyboard slopes in the mid-range of those tested, 0 degrees to -4 degrees, provided the least wrist extension, forearm pronation and the lowest elbow height. A keyboard opening angle in the mid-range of those tested, 15 degrees, may provide the best balance between reducing ulnar deviation while not increasing forearm pronation or elbow separation. These findings may be useful in the design of computer workstations and split keyboards. The geometry of a split keyboard can influence wrist and forearm postures. The findings of this study are relevant to the positioning and adjustment of split keyboards. The findings will also be useful for engineers who design split keyboards.