A comparison of hand anthropometry of females in three ethnic groups

Small Glove Size and Female Gender Are Associated with Greater Reported Difficulty Using Orthopaedic Instruments Among Residents

Introduction

Smaller hand size has been shown to affect ease of instrument use and surgeon injury rates in multiple surgical subspecialties. Women have a smaller average hand size and are more often affected by this issue than men. The goal of this resident survey was to investigate whether hand size and gender impact self-reported difficulty with instrument use among orthopaedic surgery residents.

Methods

Residents were surveyed about how often they experience difficulty using common orthopaedic instruments. Self-reported difficulty using surgical instruments was compared between residents with small glove (SG, outer ≤7.0) vs. large glove (LG, ≥ 7.5) sizes and between male and female residents.

Results

One hundred forty-five residents (118 males and 27 females) completed the survey for a response rate of 3.7%. The SG group contained 35 residents, with 26 females and 9 males. The LG group contained 110 residents, with 1 female and 109 males. The SG group reported more difficulty than the LG group when using 3/6 instruments: the wire-cutting pliers (71.4% vs. 25.5%), universal T-handle chuck (65.7% vs. 21.4%), and large wire driver (60.0% vs. 24.8%). Female residents reported more difficulty than males for 5/6 instruments. Within the SG group, however, there was no difference in self-reported difficulty between female SG and male SG residents for 4/6 instruments.

Conclusions

The predominantly male LG group reported significantly less difficulty than the more gender mixed though still predominantly female SG group. A subanalysis comparing males and females within the SG group found that there was no difference between SG female and SG male residents for 4/6 of the instruments, suggesting that glove size might impact reported difficulty independently from gender. Although the effect of glove size vs. gender is difficult to differentiate in this study, the high rate of difficulty experienced by male and female residents in the SG group should be considered by residency programs, surgeon educators, and instrument manufacturers as the field of orthopaedic surgery continues to become more diverse.

Level of Evidence

III.

Exploring the utility of Geometric Morphometrics to analyse prehistoric hand stencils

Hand stencils are a remarkable graphic expression in Prehistoric rock art, dating back to 42 ka BP. Although these stencils provide direct impressions of the artists' hands, the characterization of their biological profile (i.e., biological sex and age) is very challenging. Previous studies have attempted this analysis with traditional morphometrics (TM), whereas little research has been undertaken using Geometric Morphometrics (GM), a method widely used in other disciplines but only tentatively employed in rock art studies. However, the large variation in relative finger position in archaeological hands poses the question of whether these representations can be examined through GM, or, in contrast, if this creates an unmanageable error in the results. To address this issue, a 2D hand scans sample of 70 living individuals (F = 35; M = 35) has been collected in three standardized positions (n = 210) and digitized with 32 2D conventional landmarks. Results show that the intra-individual distance (mean Procrustes distance between Pos. 1-2 = 0.132; 2-3 = 0.191; 1-3 = 0.292) is larger than the inter-individual distance (mean in 1 = 0.122; 2 = 0.142; 3 = 0.165). Finally, it has been demonstrated that the relative finger positions, as well as the inclusion of all hand parts in the analysis, have an overshadowing effect on other variables potentially involved in the morphometric variability of the hand, such as biological sex.

An investigation of the hand anthropometric database of agricultural workers and integration of the database into tools and protective gear designs

BACKGROUND: The hand anthropometric data is the baseline for design of hand tools and equipment. OBJECTIVE: This study aimed to generate the hand anthropometric database of male and female agricultural workers and compare it with the hand anthropometric data of other regions of India. The use of collected data is illustrated to design hand tools and protective gear. METHODS: Hand anthropometric data were collected from 228 male and 198 female agricultural workers of northeast India. A total of 35 hand dimensions, stature and body mass from different tribes in the age group of 18–60 years were precisely measured. Measured data were statistically analysed to study the effects of gender, ethnicity, and age on hand dimensions. Correlation coefficients were determined among hand dimensions and linear regression equations were developed between highly correlated dimensions. RESULTS: The results show that all hand dimensions of the male and female subjects are significantly different (p < 0.01). Most of the hand dimensions were significantly different (p < 0.05) among different tribes for the male subjects. However, less number of hand dimensions were significantly different among tribes for the female subjects. Age of the subjects has significant effects (p < 0.01) on dimensions related to thickness, depth and circumference of fingers. The use of these data in the ergonomic design of hand tools and personal protective gear is illustrated to increase safety and comfort as well as efficiency of operators. CONCLUSION: There is a difference in the hand dimensions of different tribes of northeast India. This needs to be considered when designing agricultural hand tools and equipment.

Radioulnar interphalangeal joint angles in children and adolescents aged 0 to 19 years

The purpose of this study is to determine the normal ranges of radioulnar (i.e. medial-lateral) finger deviations during growth. We retrospectively measured radioulnar interphalangeal joint angles in 6236 properly aligned thumbs and fingers in trauma radiographs of 4720 patients aged 0 to 19 years. The mean interphalangeal joint angle of the thumb was 0.2° (standard deviation 1.5°). The average proximal interphalangeal joint angles were ulnar deviation of 2.5° (1.7°) for the index, ulnar deviation 1.7° (1.5°) for the middle, radial deviation 1.3° (1.8°) for the ring, radial deviation 2.0° (2.8°) for the little fingers. The distal interphalangeal joint angles were ulnar deviation of 2.5° (1.7°), ulnar deviation 2.1° (1.7°), radial deviation 2.1° (1.7°), radial deviation 5.1° (2.8°) from index to the little fingers. Thumbs were typically straight, whereas the index and middle fingers deviated ulnarly, and ring and little fingers radially. There were no relevant differences in sex or laterality.

The influence of ethnic differences based on upper limb anthropometry on grip and pinch strength

BACKGROUND

Ethnic differences in upper limb anthropometry have significant variations which can influence surgical outcomes and rehabilitation. We hypothesize that there would be a significant difference in the anthropometry based on ethnicity and gender which will reflect on objective measurements.

METHODS

We performed 13 anthropometric measurements of the upper limb, grip and three types of pinch strength in 210 volunteers across seven ethnicities in young adults at our university campus. We compared them statistically based on ethnic and gender differences.

RESULTS

There was a significant correlation noted between grip, palmar and tip to tip pinch strength in 12 of the 13 anthropometric measurements. Key pinch correlated with eight parameters. Mean grip and pinch strength are noted to be more in males and from developed nations across all ethnicities.

CONCLUSIONS

This study shows that there is significant variation between the anthropometric measurements based on gender and ethnicity which correlates with differences in grip and pinch strength.

Shaping Rollable Display Devices: Effects of Gripping Condition, Device Thickness, and Hand Length on Bimanual Perceived Grip Comfort

OBJECTIVE

To examine the effects of the gripping condition, device thickness, and hand length on bimanual perceived grip comfort associated with unrolling hand-held rollable screens.

BACKGROUND

Rollable displays can be rolled and unrolled to change screen size. Although diverse rollable display device concepts have been suggested, little is known regarding ergonomic forms for comfortable screen unrolling.

METHOD

Thirty young individuals (10 in each hand-length group) evaluated three rollable display device prototypes in three gripping conditions (no restriction on using side bezels, minimal use of side bezels, and restriction on the gripping type). Prototypes differed in their right-side thickness (2, 6, and 10 mm). Side bezel regions grasped during screen unrolling and corresponding bimanual grip comfort ratings were obtained.

RESULTS

To improve perceived grip comfort and accommodate user-preferred gripping methods, rollable display devices should be 6 mm (preferably 10 mm) thick (vs. 2 mm) and have at least 20-mm-wide side bezels. Relative to device thickness, gripping conditions were more influential on grip comfort ratings. The "no restriction" condition improved grip comfort ratings and strengthened bimanual coupling in terms of grip comfort ratings.

CONCLUSION

Contrary to current smartphone trends toward thinner and bezel-less designs, hand-held rollable display devices should be sufficiently thick and have sufficiently wide side bezels for screen unrolling.

APPLICATION

Hand-held rollable display devices should be 6- or preferably 10-mm thick (vs. 2 mm) and have at least 20-mm-wide side bezels to ensure higher perceived grip comfort during bilateral screen unrolling.

Hand morphometrics, electrodermal activity, and stone tools haptic perception

OBJECTIVES

Tool use requires integration among sensorial, biomechanical, and cognitive factors. Taking into account the importance of tool use in human evolution, changes associated with the genus Homo are to be expected in all these three aspects. Haptics is based on both tactile and proprioceptive feedbacks, and it is associated with emotional reactions. Previous analyses have suggested a difference between males and females, and during haptic exploration of different typologies of stone tools. Here, we analyze the correlation between electrodermal reactions during stone tool handling and hand morphology to provide evidence of possible allometric factors shared by males and females.

METHODS

Electrodermal analysis was used to investigate some specific parameters involved in these reactions, such as changes in the level of attention and arousal. We analyzed the responses of 46 right-handed adults to 20 distinct stone tools while blindfolded.

RESULTS

Females have smaller hands and a wider range of electrodermal reactions. Within males and females, hand diameters and general hand size do not correlate with the degree of electrodermal level and response.

CONCLUSIONS

Sex differences in electrodemal reaction during stone tool handling are apparently not due to the effect of hand size or proportions. Differences between males and females are better interpreted as real sex differences, either due to a biological or cultural influences. Hand size does not influence the degree of arousal or attention during tool exploration, suggesting that other factors trigger individual reactions. These results add to a general cognitive approach on hand-tool evolution and tool sensing.

Thrifty phenotype versus cold adaptation: trade-offs in upper limb proportions of Himalayan populations of Nepal

The multi-stress environment of high altitude has been associated with growth deficits in humans, particularly in zeugopod elements (forearm and lower leg). This is consistent with the thrifty phenotype hypothesis, which has been observed in Andeans, but has yet to be tested in other high-altitude populations. In Himalayan populations, other factors, such as cold stress, may shape limb proportions. The current study investigated whether relative upper limb proportions of Himalayan adults (n = 254) differ between highland and lowland populations, and whether cold adaptation or a thrifty phenotype mechanism may be acting here. Height, weight, humerus length, ulna length, hand length and hand width were measured using standard methods. Relative to height, total upper limb and ulna lengths were significantly shorter in highlanders compared with lowlanders in both sexes, while hand and humerus length were not. Hand width did not significantly differ between populations. These results support the thrifty phenotype hypothesis, as hand and humerus proportions are conserved at the expense of the ulna. The reduction in relative ulna length could be attributed to cold adaptation, but the lack of difference between populations in both hand length and width indicates that cold adaptation is not shaping hand proportions in this case.

Hand cumulative trauma disorders in Nigerian custom tailors: the need for redesign of manual scissors

Cutting scissors are important working tools for Nigerian custom tailors (CTs) but its usage apparently does not meet the ergonomics need of these artisans. A survey was carried out amongst CTs using questionnaires to obtain their background social-occupational demographics and observation methods to study their work performance, use of scissors and any cumulative trauma disorder (CTD) in their hands. Thicknesses of various fabrics were measured and comparison between Western world's custom tailoring job and the Nigerian type was done. The results showed some CTD risk factors with finger contusions on the 71 CTs evaluated. The right-hand contusions were traced to the constant usage of unpadded manual scissors with ungloved hands. Disparity between Western and Nigerian tailoring practice may account for the high occurrence of disorders in Nigerian CTs. Since hand dimensions are crucial in the design of hand tools, it is therefore concluded that hand anthropometry of Nigerian CTs and soft padding of manual scissors may mitigate CTD burdens on CTs' hands.

PRACTITIONER SUMMARY

Cumulative trauma disorders on the hands of low-income Nigerian CTs needed investigation. This was done via self-assessment and observational methods of the artisans’ work system. Frequent usage of unpadded manual scissors with un-gloved hands cause and exacerbate the problem. Hand anthropometry of users is crucial in scissors manufacturing.

Effects of military load carriage on kinematics of gait

Manual load carriage is a universal activity and an inevitable part of the daily schedule of a soldier. Indian Infantry soldiers carry loads on the waist, back, shoulders and in the hands for a marching order. There is no reported study on the effects of load on gait in this population. It is important to evaluate their kinematic responses to existing load carriage operations and to provide guidelines towards the future design of heavy military backpacks (BPs) for optimising soldiers' performance. Kinematic changes of gait parameters in healthy male infantry soldiers whilst carrying no load (NL) and military loads of 4.2-17.5 kg (6.5-27.2% body weight) were investigated. All comparisons were conducted at a self-selected speed. Soldier characteristics were: mean (SD) age 23.3 (2.6) years; height 172.0 (3.8) cm; weight 64.3 (7.4) kg. Walk trials were collected using a 3-D Motion Analysis System. Results were subjected to one-way ANOVA followed by Dunnett post hoc test. There were increases in step length, stride length, cadence and midstance with the addition of a load compared to NL. These findings were resultant of an adaptive phenomenon within the individual to counterbalance load effect along with changes in speed. Ankle and hip ranges of motion (ROM) were significant. The ankle was more dorsiflexed, the knee and hip were more flexed during foot strike and helped in absorption of the load. The trunk showed more forward leaning with the addition of a load to adjust the centre of mass of the body and BP system back to the NL condition. Significant increases in ankle and hip ROM and trunk forward inclination (> or =10 degrees ) with lighter loads, such as a BP (10.7 kg), BP with rifle (14.9 kg) and BP with a light machine gun (17.5 kg), may cause joint injuries. It is concluded that the existing BP needs design improvisation specifically for use in low intensity conflict environments. STATEMENT OF RELEVANCE: The present study evaluates spatial, temporal and angular changes at trunk and limb joints during military load carriage of relatively lighter magnitude. Studies on similar aspects on the specific population are limited. These data can be used for optimising load carriage and designing ensembles, especially a heavy BP, for military operations.

A study of correlation of hand and foot dimensions for personal identification in mass disasters

The identification of isolated extremities is an issue of great significance in the investigation of the identity of victims of mass disasters and fatal assaults. In forensic investigations, the dimensions of the hand and foot have been used for determination of sex, age and stature of an individual. However, the data on correlation within and between hand and foot dimensions are very limited. The present research aims at analysing the anthropometrical relationships within and between hand and foot dimensions. The study was conducted on 240 Rajputs (120 males and 120 females) from North India. The results showed a significant correlation between and within the dimensions of hands and feet. Multiplication factors, linear and multiple regression models are derived to reconstruct the hand and foot even when a single dimension is available from the extremities. Besides medico-legal implications, the study may have significance in plastic and reconstructive surgery.

Hand anthropometry in Bangladeshis living in America and comparisons with other populations

An anthropometric study of a convenience sample of 51 female and 50 male adults of Bangladeshi origin (mean age 41.3 years), living in the United States, but who spent most of their lives in Bangladesh, was conducted. Standard measurements were taken on 24 dimensions of the right hand that were relevant to the design of hand tools, gloves and access spaces using a standard sliding calliper. Analysis of the results showed significant differences in palm and finger segment lengths, breadths and depths between genders in Bangladeshis and also within each gender between Bangladeshis and other populations. The differences between Bangladeshis and other populations were of about the same magnitude as the differences between genders in Bangladeshis. The data gathered may be used for the design of hand tools, gloves, machine access spaces and hand-held devices and for selection of hand tools for use by Bangladeshis. The study also allows inter-population comparisons that can enhance the understanding of hand anthropometry.

A survey of hand anthropometry of female rural farm workers in Ibadan, western Nigeria

An anthropometric survey measuring 18 dimensions of the right hand in 37 female rural farm workers living in Ibadan, western Nigeria was conducted. The means, standard deviations and percentile values are reported for these. The means of the collected data are compared with those for females from the UK, from Hong Kong and from America, using data from other published studies. The results suggest that the Nigerian female hand is wider and thicker, but shorter than that of their foreign counterparts. Such differences have implications for design and evaluation of hand tools for the Nigerian female population.

Comparison of the size of plates for fracture fixation with the size of phalanges and metacarpals in cadavers of Asian origin

The size and volume of plates and screws for fracture fixation of the hand (1.5-mm screws and titanium miniplates, 2.0-mm screws and stainless-steel AO miniplates, and 2.7-mm screws and stainless-steel AO miniplates) were compared against the phalanges and metacarpal bones and the surrounding soft tissue from male cadavers of Asian decent. In the cadaver study, it was first established that the difference between anatomic measurements and radiologic measurements for the interarticular bone length and midshaft width were not significant (p = .09). Second, the volume occupied by the bone showed a close association to interarticular bone length. This finding would suggest that the volume occupied by the bone may be estimated from the radiographs. When the length of the plates was compared to that of the bones, the analysis showed 4-hole and 6-hole 1.5-mm titanium miniplates, and the 4-hole and 6-hole 2.0-mm AO plates were not suitable for the middle phalanx, although only rarely are fractures in the middle phalanx fixed with plates. For the proximal phalanx, only the 4-hole 1.5-mm and 2.0-mm plates were suitable in length. The 6-hole 2.0-mm AO plate was found to be suitable for only the longer proximal phalanx of the middle digit. For the metacarpals, the 5-hole 2.7-mm AO plate was found not to be suitable for the thumb (in length) and the ring digit (in width). The commonly used plates and screws for fracture fixation of the hand may not be suitable in size for groups of people with smaller hand sizes, in particular some Asians and women.

A review of machine-guarding recommendations

A series of machine-guarding drawings were developed during the 1940s, which represent the relationship between gap size and safe distance. Since the development of these drawings, larger and more comprehensive anthropometric surveys have been conducted, but they have never been compared with the drawings. The purpose of this investigation was to determine whether these original recommendations presented in the drawings are still consistent with data in the larger anthropometric surveys, especially relating to women and minorities, who are now much more prevalent in the American workplace. In this study, data from six anthropometric surveys were compared with the original machine-guarding recommendations. To minimize the percentage of the population at risk, the length dimensions were chosen from the 99th percentile male population, and thickness dimensions were chosen from the 1st percentile female population. Many of these recommendations were found to be valid, although several important modifications were suggested. Several currently recommended dimensions show no correlation to the incompressible joints utilized in this study, and it is recommended that they be eliminated. The recommendations are presented in tables of maximum gap size and minimum distance.

Photogrammetric technique applied to anthropometric study of hands

Being concerned with physical anthropometric dimensions to explore avenues of research on hands and their working strategies, a research study was made to develop a suitable method by using available photogrammetric resources. The paper discusses the optimums of details found by this study, viz., the use of a Wild C-40 stereometric camera (for obtaining stereoscopic photographs) and the use of a Wild A7 stereorestitution instrument equipped with digital data acquisition accessories (for obtaining all dimensional information). Three-dimensional data at 21 specific points and for nine specific distances were obtained on each hand of ten persons. Test observations indicate, inter alia, a dimensional accuracy of the order of +/- 0.3 mm obtainable through the working system. Cartographic presentations made in support of the digital data are found to be of help. This also permits to obtain additional data as may be necessary at times. Photogrammetry has the advantage of reducing and maintaining to a minimum all sorts of manipulations necessary in such studies.