Inter-personal motor interaction is facilitated by hand pairing

The extent to which hand dominance may influence how each agent contributes to inter-personal coordination remains unknown. In the present study, right-handed human participants performed object balancing tasks either in dyadic conditions with each agent using one hand (left or right), or in bimanual conditions where each agent performed the task individually with both hands. We found that object load was shared between two hands more asymmetrically in dyadic than single-agent conditions. However, hand dominance did not influence how two hands shared the object load. In contrast, hand dominance was a major factor in modulating hand vertical movement speed. Furthermore, the magnitude of internal force produced by two hands against each other correlated with the synchrony between the two hands’ movement in dyads. This finding supports the important role of internal force in haptic communication. Importantly, both internal force and movement synchrony were affected by hand dominance of the paired participants. Overall, these results demonstrate, for the first time, that pairing of one dominant and one non-dominant hand may promote asymmetrical roles within a dyad during joint physical interactions. This appears to enable the agent using the dominant hand to actively maintain effective haptic communication and task performance.

Clinical Outcomes of Severely Angulated Fifth Metacarpal Neck Fractures Treated Nonsurgically

Background: Reasonable functional outcomes for nonoperative management of isolated, closed fifth metacarpal neck fractures with up to 70° angulation have been reported; however, reported outcomes for fractures with greater than 70° angulation are limited. This study describes clinical outcomes of nonsurgically treated fifth metacarpal neck fractures with angulation of greater than 70°. Methods: A retrospective review of patients treated between May 1, 2016, and May 1, 2020, included: (1) patients aged 18 years and above with an isolated, closed, fifth metacarpal neck fracture; (2) nonsurgical treatment; (3) healed fractures with angulation greater than 70° measured on oblique radiographs; and (4) minimum 6-month follow-up after injury. Photographic hand motion and patient-rated outcomes (Functional Hand Scale, Quick Disabilities of the Arm, Shoulder, and Hand [QuickDASH], 12-item Short-Form Health Survey [SF-12]) were collected and reported. Results: A total of 364 fractures were identified; 11% (40/364) demonstrated angulation of greater than 70° (range: 71°-82°); and 15 patients (inclusion rate: 38%, 15/40) with mean fracture angulation of 73° (range: 71°-77°) participated in the study. Mean follow-up was 32 months (range: 8-120 months), the dominant hand was injured in 87% (13/15) of patients, and 47% (7/15) of patients worked in manual labor. All patients scored the highest rating of “very good” (range: 26-30 of 30 points) on the functional hand scale. A QuickDASH score of zero (no morbidity) was reported in 80% (12/15) of patients. About 87% (13/15) of patients had average or above-average scores on the SF-12 (mean = 109, range: 84-115). Conclusions: Patients with healed, isolated, closed fifth metacarpal neck malunions with severe angulation greater than 70° demonstrated acceptable functional outcomes based on patient-rated outcomes scoring.

A conceptual model for changes in finger photoplethysmograph signals caused by hand posture and isothermic regulation

Objective. To observe changes in baseline and pulsatile light absorbance (photoplethysmograph, PPG) in the finger-tip, by raising the hand above the horizontal plane in recumbent subjects. We applied current knowledge of the circulation to the finger-tip, particularly arteriovenous anastomoses (AVAs), and the physiology of the venous circulation. Approach. We studied healthy young volunteers in a quiet thermoneutral environment. A finger plethysmograph on the non-dominant hand recorded transmission of red and infra-red light, and the values were converted into absorbance to allow comparisons within and between subjects. Breathing movements were recorded unobtrusively to assess any effect on absorbance and the pulse amplitude of the signals. All body movements were passive: the study arm was elevated in a trough to about 40° above the horizontal plane. The following conditions were studied, each for 15 minutes, using the last 10 minutes for analysis: recumbent, study arm elevated, study arm horizontal, and both legs elevated by 40°. Main results. There was a substantial time-related effect, and considerable variation between subjects. Arm elevation reduced red light absorbance and increased the range of amplitudes of the PPG waveform: only in subjects with large absorbances, did waveform amplitude increase. The other main effect was that spontaneous, thermoregulatory decreases in absorbance were associated with decreases in waveform amplitude. Significance. Finger-tip vessels distend with blood when AVAs open. The vessels pulsate more strongly if venous collapse allows the vessels to become more compliant. The postcapillary circulation is likely to be an important source of pulsation.

Musculoskeletal ultrasound as a screening-tool for rheumatoid arthritis: results of the “Rheuma-Truck” screening and awareness initiative

Objective To evaluate musculoskeletal ultrasound (MSUS) as a screening tool for rheumatoid arthritis (RA) and osteoarthritis (OA) patients in a rheumatology-screening program. Patients and methods To raise awareness for rheumatic diseases, a mobile rheumatology office was deployed in different cities of Germany (“Rheuma-Truck”). Standardized questionnaire assessment, testing for rheumatoid factor and citrullinated peptide antibodies and medical student driven MSUS of the clinically dominant hand/foot including wrist, MCP-II, -III, -V, PIP-II, -III, MTP-II and -V were offered free of charge to the population. In case of suspicious results, a rheumatologist was consulted. Results In MSUS, 192 of 560 selected volunteers (aged 18–89, mean 52.7 years; 72.9% female) had suspicious findings including synovitis or erosions primarily affecting the MTP-II (11.8%), dorsal wrist (8.9%), and MCP-II (7%). 354 of the 560 volunteers further visited a rheumatologist of whom 76 were diagnosed with RA. According to the ‘US7 Score’, a sum scores ≥ 5 was significantly predictive for RA (odds ratio (OR) 5.06; confidence interval (CI) 0.83–35.32). 313 volunteers displayed signs of OA including osteophytes, while MCP-II (36.2%), MCP-III (14.8%), and the wrist (10.5%) were mostly affected. Diagnosis of RA was favoured over OA if the wrist (OR 4.2; CI 1.28–13.95), MTP-II (OR 1.62; CI 1.0–2.6), and MCP-V (OR 2.0; CI 1.0–3.8) were involved. Conclusion Medical student driven MSUS by the ‘US7 Score’ can facilitate diagnosis of RA in rheumatology-screening programs due to the level of the score and the affected joints. A high rate of unknown OA signs was detected by MSUS. A mobile rheumatology office displays an opportunity to screen patients for RA and OA.

Pinch Anatomy of Forehead: An Injection Guide for Forehead Filler Treatment

With the popularity of filler injections globally, more and more injectors are using them for facial shaping and reversing the aging changes of the face. Detailed knowledge of facial anatomy, especially of important vessels and tissue planes is essential for injectors. While performing filler injections, injectors tend to pinch the tissue layers with their non-dominant hand for ease of doing the procedure. Such deformational forces cause some changes in the anatomy of tissue layers held in a pinch. During a deep pinch, the important arteries in that area can get pulled up in the pinch's tissue layers, or they can stay in their position being unaffected by pinching. The ‘pinch and pull’ can also improve the tissue space for injections, by pulling away the mobile tissue layers from the fixed ones. Knowledge of the ‘pinch anatomy’ in the forehead can be used to the injector's advantage to avoid important arteries and place filler in the correct plane. By knowing the anatomical changes during the pinched state of tissue layers, filler injections in the forehead can be performed with relative safety in the correct tissue plane.

Adding up fine motor skills: developmental relations between manual dexterity and numerical abilities

We explore the relationship between mathematical skills and motor skills across three age groups of normally developing children. The existence of such a relationship is postulated in classical accounts of human development. In contemporary research, the existence of a relationship between motor development and the development of abstract concepts may form a crucial piece of evidence for theories of embodied cognition. Existing studies suggest a link between fine motor skills and various numerical and mathematical tasks in young children; however, there are few attempts to measure the strength of this relationship across different ages. We use a cross-sectional design to investigate the link between fine motor and mathematical skills in children in Kindergarten, 2nd grade, and 4th grade. The results show that correlational patterns vary in the three ages; while in Kindergarten manual dexterity of the dominant hand is related to math skills, in 2nd grade the manual dexterity of the nondominant hand is related to math skills, and finally, in 4th grade no such correlations are observable.

Testing the visual-motor coordination and reaction speed in children aged between 10–14 years old

The present study aimed to debate a topic less addressed by most people, which involved research on a group of 20 students from rural areas, aged 10–14 years, which consists of performing two tests, namely the Ruler drop test and the Hand-eye coordination test, which aims at the reaction speed of the dominant and non-dominant hand and also the hand-eye coordination capacity of the subjects. The paper aimed to identify whether somatic factors and age influence the results of the group. In order to perform the two tests, it was necessary, for the beginning, information related to the study group, information on weight, age, height, dominant hand, respectively dominant eye. These represented the point of interest of the research, being reported individually to the test results, thus constituting the study basis of statistics. After obtaining the results, we concluded that a significant significance is encountered when comparing the dominant hand with the non-dominant one, obtaining a positive value for the dominant hand. At the same time, we interpreted after the research that females tend to have a much faster reaction speed, more significant than the males when it comes to using the non-dominant hand. The hypothesis was confirmed, with differences in somatic factors’ influence, but the others do not show significant values except those stated above. In addition to the practical part, the research involves an interesting theoretical foundation being reached aspects related to proprioception, coordination, speed, ways of using tests, and the opinion of other researchers who have conducted similar studies.

Visual Reaction Time: How it Relates to Body Mass Index, Dominant and Non-dominant Hand in Healthy Young Females

Reaction time is an indirect index of the processing speed of the central nervous system. It is affected by several factors including dominant and non-dominant hands and obesity. Obesity can be measured by body mass index. Thus, the aim of this study was to find out the relationship between body mass index, dominant and non-dominant hand with visual reaction time in healthy young females. A cross-sectional study was conducted in the Department of Physiology, among 89 females. The height and weight were recorded, and the body mass index was calculated. The subjects were divided into four groups, underweight, normal weight, overweight, and obese according to WHO criteria. Visual reaction time was measured using the ruler drop method in milliseconds. The data were analyzed by using the paired t-test and one-way ANOVA using the IBM Statistical Package for the Social Sciences version 22. Out of 89 participants, 26 (29.21%) were underweight, 47 (52.80%) had normal weight, 12 (13.48%) and four (4.49%) were overweight and obese with mean reaction time in the dominant hand and non-dominant hand were (176.75±16.68 vs. 186.58±16.21), (175.12±15.03 vs. 185.43±15.64), (188.74±16.07 vs. 190.70±17.88), and (200.7±9.77 vs. 210.50±9.50) respectively. All participants were right-handers. In right-handers, the right hand reacted faster than the left hand. Reaction time was prolonged in underweight, overweight,and obese; when compared with normal weight individuals. Our study showed that the reaction time of people appears to be influenced by body mass index, dominant, and non-dominant hand, which was an indirect measure of the sensory motor association.

Systolic and Diastolic Inter-Arm Blood Pressure Difference: A Cross-Sectional Study Of 3030 Young Healthy Adults

More than 100 years ago, the difference in blood pressure (BP) between arms was first reported. Recent studies have shown that different blood pressure between the right and left arm leads to cardiovascular events. Three thousand and thirty volunteers participated in our study. The sIABP was equal in 163 of 3030 persons (5.37%), dIABP was equal in 222 out of 3030 persons (7.32%), from a total of 792/3030 persons (26.1%) sIAD > 10 mmHg, and dIAD > or =10 mmHg was found in 927 out of 3030 persons (33.5%) in the right arm, and 32.4% in the left arm. In 2692 of 3030 volunteers BP, initially recorded in the dominant hand (right arm), showing sIAD> or = 10 mmHg was found in 943 (37.1%) volunteers, and when the first measurement was done in 338 left-handed volunteers it showed sIAD> or = 10 mmHg in 112 of 338 (34.1%), P < 0.001; 95% confidence interval for systolic right hand were (115.73: 116.73), and for systolic left hand 95% confidence interval were (113.17:114.15). Furthermore, height, residential area, and heart rate above 90 bpm had a significant effect on IAD (P =. 041, .002, <001, respectively). In conclusions significant inter-arm systolic and diastolic BP differences above (10 mm Hg) is common in the young, healthy population. Hand dominance is a significant consideration while measuring blood pressure. It is mandatory to measure blood pressure in both arms in a sitting position with a stable condition.