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Laparoscopic instrument handles design and dimensions are crucial to determine the configuration of surgeons' hand grip and, therefore, can have a deleterious effect on overall surgical efficiency and surgeons' comfort. The aim of this study is to investigate the impact of laparoscopic handle size and hand surface area on surgical task performance. A single-blind, randomized crossover trial was carried out with 29 novice medical students. Participants performed three simulated tasks in "black box" simulators using two scissor-type handles of different sizes. Surgical performance was assessed by the number of errors and time required to complete each task. Hand anthropometric data were measured using a 3D scanner. Execution time was significantly higher when cutting and suturing tasks were performed with the smaller handle. In addition, hand surface area was positively correlated with peg transfer task time when performed with the standard handle and was correlated with cutting task time in small and standard handle groups. We also found positive correlations between execution time and the number of errors executed by larger-handed participants. Our findings indicate that laparoscopic handle size and hand area influence surgical performance, highlighting the importance of considering hand anthropometry variances in surgical instrument design.

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Personal Neglect (PN) is a disorder in which patients fail to attend or explore the contralateral side of their body. An increasing number of studies have considered PN as a form of body representation disorder frequently observed following damage to parietal areas. The extent and the direction of the body misrepresentation is still unclear with recent studies suggesting a general reduction of contralesional hand size. However, little is known about the specificity of this representation and whether the misrepresentation also generalises to other body parts. We explored the features of the representation of the hands and face in a group of 9 right brain damaged patients with (PN+) and without PN (PN-), when compared to a healthy control group. For this, we used a body size estimation task with pictures, in which patients were required to choose the one that most closely matched the perceived size of their body part. We found that PN + patients showed a labile body representation for both hands and face, having a larger distorted representational range. Interestingly, in comparison with PN + patients and healthy controls, PN- patients also showed misrepresentation of the left contralesional hand which could be related to impaired motor performance of their upper limb. Our findings are discussed within a theoretical framework suggesting a reliance on multisensory integration (body representation, ownership, and motor influences) for an ordered representation of the size of the body.

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BACKGROUND: Endoscope controllers are traditionally a one-size-fits-all design. However, this design may not fit the modern workforce in endoscopy-related fields. Our study aims to determine if endoscopic controller size, independent of user dexterity, affects user proficiency. METHODS: 54 endoscopically naive participants completed a baseline dexterity test, followed by large-controller endoscopic and small-controller bronchoscopic simulation exercises. Participants were stratified by surgical glove size (≥7.5 and < 7.5) and gender. RESULTS: Endoscopy time was longer in participants with <7.5 size gloves (p = 0.01) and in females (p < 0.001). However, participants with glove size <7.5 had better dexterity measures (p = 0.04). There was no difference in bronchoscopy time based on glove size (p = 0.61). CONCLUSIONS: Participants with larger hands were more proficient with the larger controller despite being less dexterous than their counterparts. This advantage was less pronounced with the smaller controller. Our findings suggest that endoscopic controllers should be modified in design to accommodate all providers.

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BACKGROUND: Consideration of ergonomic factors is important for the practice of safe and efficient minimally invasive surgery (MIS). Surgeons with smaller glove sizes have previously been reported to have increased difficulties with some minimally invasive instruments. We aim to investigate hand anthropometrics and their relationship to surgeon comfort when using MIS instruments. METHODS: Male and female surgeons from two centres were surveyed on their experience of handling MIS instruments and images obtained of the dorsal and palmar aspects of their dominant hand. Photographs of hands were transformed to calibrated coordinates to enable anthropometric measurements of finger length and width as well as palm width and hand span photogrammetrically. Surgeon-perceived discomfort, fatigue, pressure points and techniques to mitigate difficulty handling instruments were compared to hand measurements. RESULTS: Questionnaires were completed by 58 surgeons; 20 (34%) were consultants, 17 (29%) were women. Glove size ranged from 6 to 8 (median 7.5). Male participants had significantly larger hands than females in all measured dimensions. Female surgeons and those with smaller finger and hand dimensions were significantly more likely to experience difficulty or discomfort across a range of variables when using MIS instruments. CONCLUSIONS: Surgeons with smaller hands reported increased problems handling MIS instruments. This represents an issue of equity in surgery, with women being more significantly affected than men. Hand size varies greatly between surgeons and anthropometric variability should be considered in design of MIS instruments.

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BACKGROUND: The adapted 6-step without interlock (A6Sw/oI) hand rub technique, commonly practiced in Japan, adds the "wrist" but omits the "interlock" step compared to the WHO 6-step technique (WHO6S). The first objective of this study was to assess the differences of the two techniques regarding surface coverage. The second objective was to analyze the coverage differences between hand sizes. METHODS: Hospital workers went under stratified quasi-randomization by glove size. The overall mean coverage, and the coverage of the sections of the hands were evaluated by fluorescent dye-based coverage assessment using a digital device with artificial intelligence technology. RESULTS: Total of 427 workers were randomly allocated to WHO6S (N = 215) or the A6Sw/oI (N = 212). The overall mean dorsum coverage by WHO6S and A6Sw/oI was 90.6% versus 88.4% (p < 0.01), and the percentage of the participants with insufficient coverage of the backs of the four fingers ranged from 0.0-7.4% versus 28.2-51.4% (p < 0.001). Dorsum coverage varied largely between hand size for both techniques, and significant differences were found between small and large hands. CONCLUSION: The WHO6S was superior to the locally adapted technique regarding hand surface coverage. Hand size should be considered when assessing coverage differences between procedures. No trial registrations or fundings.

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Body representation disorders are complex, varied, striking, and very disabling in most cases. Deficits of body representation have been described after lesions to multimodal and sensorimotor cortical areas. A few studies have reported the effects of tumors on the representation of the body, but little is known about the changes after tumor resection. Moreover, the impact of brain lesions on the hand size representation has been investigated in few clinical cases. Hands are of special importance, as no other body part has the ability for movement and interaction with the environment that the hands have, and we use them for a multitude of daily activities. Studies with clinical population can add further knowledge into the way hands are represented. Here, we report a single case study of a patient (AM) who was an expert bodybuilder and underwent a surgery to remove a glioblastoma in the left posterior prefrontal and precentral cortex at the level of the hand's motor region. Pre- (20 days) and post- (4 months) surgery assessment did not show any motor or cognitive impairments. A hand localization task was used, before and after surgery (12 months), to measure possible changes of the metric representation of his right hand. Results showed a post-surgery modulation of the typically distorted hand representation, with an overall accuracy improvement, especially on width dimension. These findings support the direct involvement of sensorimotor areas in the implicit representation of the body size and its relevance on defining specific size representation dimensions.

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INTRODUCTION: Up to 89% of physicians who routinely perform endoscopy experience some type of musculoskeletal pain. In this study, we sought to quantitatively analyze provider factors that influence ergonomic strain during live endoscopic procedures. METHODS: Surface electromyography (sEMG) was used to measure ergonomic strain on physicians while performing upper and lower endoscopies. EMG data were normalized to a maximal voluntary contraction (MVC) recording for each muscle group, yielding a %MVC value. Subgroup analyses were performed based on glove size, physician training level, specialty, and handedness. RESULTS: A total of 165 upper (n = 68) and lower (n = 97) endoscopies were recorded. Endoscopists with small hand sizes had significantly higher ergonomic strain in the left anterior and posterior forearm muscle compartments as compared to endoscopists with medium or large hands (%MVC L-anterior: small: 9.1 ± 1.1; medium: 6.4 ± 1.2; large: 5.9 ± 1.6; p < 0.001); (%MVC L-posterior: small: 12.0 ± 0.8; medium: 9.4 ± 1.3; large: 8.8 ± 1.4; p < 0.001). Additionally, upper body muscle groups had significantly higher ergonomic strain in endoscopists with less lifetime endoscopic experience (%MVC R-trapezius: expert: 8.4 ± 1.2; novice: 9.3 ± 1.2; p < 0.05); (%MVC R-deltoid: expert: 6.1 ± 1.4; novice: 8.5 ± 1.3; p < 0.001). There were no significant ergonomic differences between surgeons or gastroenterologists and no differences between right- and left-handed dominant individuals. CONCLUSIONS: Endoscopists with small hands experienced great ergonomic strain in their left forearm. Our data support the widely held belief that "one size does not fit all" and will hopefully spark change in the design of future endoscopes by device manufacturers. Our data also support that the experience level of the endoscopist contributed significantly to ergonomic performance, likely due to postural differences leading to decreased upper body strain. Therefore, it remains critically important to educate young proceduralists on strategies for ergonomic relief early in his or her endoscopic training program that can ameliorate ergonomic strain that accrues over the lifetime of a physician's career.

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Perception of the size of body parts, for instance the hand, has been shown to be distorted in healthy participants, with over- and underestimations of width and length, respectively. Illusory manipulations of body shape and size have highlighted the flexibility of the body representation and have also been found to update immediate perceptions of body size and surrounding objects. Here, we examined whether underlying misperceptions of hand width and length can be modified through exposure to illusory changes in hand size using a mirror visual feedback (MVF) paradigm. While questionnaire responses indicated subjective susceptibility to both magnified and minified manipulations, objective hand size estimates only showed significant differences following exposure to minifying mirrors. These variations might reflect differences in the way that stored representations are accessed or updated in response to size manipulations. Secondly, the findings further reinforce differences between subjective and objective outcomes of illusions on subsequent body perception.

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BACKGROUND: Static muscular activity of muscles activated in the use of the conventional PC mouse is believed to represent a higher risk for the musculoskeletal health of the user than dynamic muscular activity. OBJECTIVE: This paper presents a compounded muscular activity dynamics indicator (akin to percent relative range), enabling comparison between computer handheld pointing devices. METHODS: This muscular dynamism approach considers baseline muscular activity (APL, ECR, ECU and ED) relative to the Maximum Voluntary Contraction as well as the dynamics of muscular activation. The latter is computed as the ratio of the difference between APDF90 and APDF10 divided by APDF50 (APDF-Amplitude Probability Distribution Function for the 90th, 50th and 10th percentiles). The paper demonstrates the approach with results of comparative evaluation of a horizontal, a slanted and a vertical PC mouse, through surface EMG monitoring of 20 participants performing standardized graphical task with the devices. RESULTS: Hand size impacts muscular activity dynamics in these four muscles, which supersedes differences in device geometry, across the range of devices tested. CONCLUSION: Smaller devices relative to hand size foster more dynamic muscular activity.

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To locate our body in the space, we rely on an implicit representation of body size and shape: the body model. Evidence about the implicit representation of bodily dimensions in obesity is rare. Nevertheless, it seems to suggest that such representation is not altered in obesity compared to healthy weight individuals. To probe further this hypothesis, we investigated the implicit representation of hand dimensions with a landmark localisation task, comparing individuals with obesity and healthy weight individuals. Furthermore, as body model distortions may be related to tactile acuity, the tactile acuity threshold was measured using a two-point discrimination task. In accordance with the previous evidence, we observed that healthy weight participants showed a significant underestimation of finger length and overestimation of hand width. Interestingly, comparable body model distortions were shown also in participants with obesity. No differences in tactile acuity emerged between the two groups; also, when considering the whole sample, as tactile acuity decreases hand width overestimation increases. Thus, obesity seems to have no effect on the characteristics of the body model relative to the hand. Accordingly, the physiological mechanisms supporting the development of the implicit representation of hand dimensions in the healthy weight population may be preserved in obesity.

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Whereas we experience our body as a coherent volumetric object, the brain appears to maintain highly fragmented representations of individual body parts. Little is known about how body representations of hand size and shape are built and evolve during infancy and young adulthood. This study aimed to investigate the effect of hand side, handedness, and age on the development of central hand size representation. The observational study with comparison groups was conducted with 90 typically developing Belgian school children and young adults (48 male and 42 female; age range = 5.0-23.0 years; 49 left-handed and 41 right-handed). Participants estimated their hand size and shape using two different tasks. In the localization task, participants were verbally cued to judge the locations of 10 anatomical landmarks of an occluded hand. An implicit hand size map was constructed and compared with actual hand dimensions. In the template selection task, the explicit hand shape was measured with a depictive method. Hand shape indexes were calculated and compared for the actual, implicit, and explicit conditions. Participants were divided into four age groups (5-8 years, 9-10 years, 11-16 years, and 17-23 years). Implicit hand maps featured underestimation of finger length and overestimation of hand width, which is already present in the youngest children. Linear mixed modeling revealed no influence of hand side on finger length underestimation; nonetheless, a significant main effect of age (p = .001) was exposed. Sinistrals aged 11 to 16 years showed significantly less underestimation (p = .03) than dextrals of the same age. As for the hand shape, the implicit condition differed significantly with the actual and explicit conditions (p < .001). Again, the implicit shape index was subjected to handedness and age effects, with significant differences being found between sinistrals and dextrals in the age groups of 9 and 10 years (p = .029) and 11 to 16 years (p < .001). In conclusion, the implicit metric component of the hand representation in children and young adults is misperceived, featuring shortened fingers and broadened hands since a very young age. Crucially, the finger length underestimation increases with age and shows a different developmental trajectory for sinistrals and dextrals. In contrast, the explicit hand shape is approximately veridical and seems immune from age and handedness effects. This study confirms the dual character of somatoperception and establishes a point of reference for children and young adults.

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The objectives of this study were: (i) to analyse anthropometric parameters and throwing speed from seven meters in amateur male handball players of different ages; (ii) to know the relationship between anthropometric parameters and throwing. One hundred seventy-six male handball players (16.5 ± 5.1 years old) participated in the study, classified according to their age: senior (n = 35), U18 (n = 30), U16 (n = 37), U14 (n = 50) and U12 (n = 24). All participants were evaluated by anthropometric measurements (height, weight, body mass index, arm span, hand width) and throwing speed from 7 m standing. A one-way analysis of variance with a Bonferroni post hoc test was used to establish the differences between teams. Pearson's simple correlation coefficients were calculated between analyse anthropometric parameters and throwing speed. Multiple linear regression was used to predict the throwing speed. Only BMI was related with throwing speed in all age groups (0.506 > r < 0.813, p < 0.05). Throwing speed was predicted (24-72%) with only one or two variables in each model. The selected variables were: BMI, arm span in U16 model and height U14 model, and the BMI, arm span and height are proved to be good predictors of TS in male handball players.

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This study aimed to compare thumb kinematics and upper limb muscle activity, and the influence of hand size, when texting on a keypad smartphone and a touchscreen smartphone. Furthermore, the study compared exertion, discomfort, and performance when texting on the two phones. The thumb kinematics were tracked using a 3D motion analysis system and muscle activity was registered in six upper limb muscles using surface electromyography in 19 participants. When texting on the touchscreen phone compared to the keypad phone thumb flexion (p = 0.008) and flexion/extension range of motion were smaller (p = 0.02), the thumb was on average less internally rotated (p = 0.02), and activity (50th and 90th percentile) of the thumb and forearm muscles was lower (p ≤ 0.05). The differences in thumb flexion were found only in the group with shorter hands and the differences in muscle activity was found only in the group with longer hands. These findings suggest there are differences in risks for developing musculoskeletal disorders during smartphone use with different key activation mechanisms and different hand sizes.

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BACKGROUND: There is a trend in some countries to recommend the use of surgical hand disinfectants at volumes as low as 4 ml per application. AIM: To determine whether the volume applied and hand size influence the efficacy of surgical hand disinfection. METHODS: Thirteen experiments, according to EN 12791, resulting in 269 datasets from 75 subjects were analyzed. Hands were first washed for one minute with soap. The pre-values were obtained by rubbing the finger tips in tryptic soy broth for one minute. Each subject treated his/her hands with n-propanol (60%, v/v), with as many portions as necessary to keep the hands wet for three minutes (6-12 ml). Bacterial post-values were taken from one hand (immediate effect); the other hand was gloved for three hours (sizes 7-9). The second post-value was taken when the glove was removed (3 h effect). RESULTS: The mean immediate log10 reduction of CFU was 2.56 ± 1.12. The glove size had no significant effect on the efficacy of disinfection (p = 0.182; ANOVA). However, a volume of 6 ml was significantly less effective than 9 ml for glove sizes of 7.5-8 (p < 0.05; Tukey post hoc analysis). The mean log10 reduction after 3 h was 2.12 ± 1.24. A volume of 6 ml was again significantly less effective than 12 ml for glove size 7 and than 9 ml for glove sizes 7.5-8 (p < 0.05). CONCLUSIONS: The application of small volumes of surgical hand disinfectant when using the EN 12791 reference procedure is likely to yield poor efficacy results, regardless of hand size.