Forearm Length Research Articles

Big city bats: Species-specific effects of the urban matrix on forearm length and fat stores of bats in the West Midlands, United Kingdom (Chiroptera: Vespertilionidae)

The effect of urbanisation on size and fat stores in bats has been poorly studied. We compare morphometric data in bats from two areas in the West Midlands, UK: one predominantly agricultural and one built-up. We examined forearm length and fat stores in 1,102 bats of five species (Myotis daubentonii, M. nattereri, Pipistrellus pipistrellus, P. pygmaeus, Plecotus auritus). All except M. daubentoniid were significantly larger in the urban area; fat stores were greater in rural M. nattereri and P. auritus, and in urban M. daubentonii and P. pygmaeus. For P. auritus, the differences were only significant in males.

Dried eye lens weight as an indicator of age in Rousettus aegyptiacus: Comparison with some other tools of age determination in bats (Chiroptera: Pteropodidae)

The present study deals with the use of the dried eye lens weight as an indicator of age in the Egyptian fruit bat. The accuracy of this tool is checked by comparison with some traditional tools used for age determination in bats; i.e., forearm length, and the third and fifth digit lengths. Fruit bats in the present study were collected over a period of thirteen months extending from June 2017 to June 2018, inclusive, from the Giza Governorate, Egypt. The whole collection of bats thus includes all possible age categories; i.e., young, juveniles, adults, and old adults. The dried eye lenses proved to increase in weight for a longer time of the bat’s life span compared with the other measurements of the body. The use of this weight is thus more suitable for classifying collected bat samples into more relative age classes.

Optimal Immobilization After Fixation of Bennett's Fracture: A Cadaveric Study.

Treating high-level athletes involves a balance between early and safe return to play. Various types of protective immobilization have been recommended after operatively treated Bennett's fracture. The purpose of this study was to investigate if hand-based immobilization offers protection equivalent to forearm-based immobilization. A cadaveric model of Bennett's fracture was created in 8 fresh-frozen, cadaveric forearms. Osteosynthesis was performed using a single headless compression screw. Three matched pairs were casted in either hand-based or forearm length, thumb spica casts, while 2 specimens remained un-casted as controls. Specimens were mounted on a custom testing apparatus. Weights were added in 6.8-kg increments until fixation failed and the fracture displaced. Fluoroscopy was performed after each trial. We used the Kruskal-Wallis non-parametric test to compare the groups. We considered P<.05 statistically significant. Failure of fixation occurred at 6.8 kg in the control specimens. Fixation failed in hand-based and forearm length casts at a mean of 18.1±5.1 kg. We did not find a statistically significant difference between median values of load at failure in kilograms across control specimens and 2 immobilization categories (P=.114). All specimens in the hand-based group sustained additional wrist injuries, while no additional injuries were noted in the forearm length group. Our study results showed that hand-based immobilization provides equivalent protection against fixation failure for operatively treated Bennett's fractures but may predispose athletes to increased risk of wrist injury compared with traditional, forearm-based casting. [Orthopedics. 2024;47(3):157-160.].

A Comparative Study of the Modified Baumann's Angle Between the Dominant and Non-Dominant Sides in a North Indian Pediatric Population.

Background The literature points towards the fact that paediatric elbow fractures happen more frequently and have greater variability when contrasted with adults. Between 65%-75% of pediatric fractures involve the upper extremity, and supracondylar humerus is the most common of them all. To know the exact site of injury and to estimate the degree of reduction after manipulation, the modified Baumann's angle, the Baumann's angle, the Humero-condylar angle, the Anterior humeral line, and the Radio-capitellar line are the parameters most commonly used. This study was carried out to compare the modified Baumann's angle between both upper limbs in the paediatric population. Methodology This cross-sectional study was conducted in a tertiary health care centre in Northern India for one year from September 1, 2021, to August 31, 2022. We included pediatric patients in the age group of 3-16 years. Age, sex, weight, height, BMI, secondary sexual characters, and handedness were noted in all the children enrolled in our study. In both the dominant and non-dominant sides, the mean arm length, the forearm length, the inter-epicondylar distance, the clinical carrying angle, the radiological carrying angle, and the modified Baumann's angle were calculated. Results A total of 113 children were enrolled in the study. The majority of children (71.7%) had dominance on the right side. In both the dominant side and non-dominant side, mean arm length, forearm length, inter-epicondylar distance, clinical carrying angle, radiological carrying angle, and modified Baumann's angle values were calculated. On evaluating the data statistically, a significant difference between the two sides was observed for all the parameters (p<0.05), except forearm length (p-value -0.954). Multivariate analysis showed that only BMI was significantly negatively associated with modified Baumann's angle (p=0.016), and only age (0.019) and BMI (<0.001) were found to be significantly associated with the difference in modified Baumann's angle. Conclusions The findings of this study will be helpful in the management of elbow disorders and their reconstruction following trauma. A significant difference was found in the modified Baumann's angle between dominant and non-dominant sides, and it also showed a negative significant correlation with arm length, forearm length,and the presence of secondary sexual characteristics. The equations derived in this study will be helpful in the simple derivation of the modified Baumann's angle and its differencefrom simple measurements of the upper limb parameters.

Distribution and Prevalence of Elbow Pain (EP) in Elite Swimmers in Tianjin, China-A Regional Epidemiological Study.

Elbow pain (EP) in overhead sports is a common phenomenon. Swimming is classified as an overhead sport, but a lack of attention regarding EP in swimming has created a gap in the knowledge around elite freestyle swimming in Tianjin, China. The purpose of this study was to identify the distribution and prevalence of EP among elite freestyle swimmers in Tianjin, China. The methodology involved a total of 311 qualified participants who volunteered to undertake all measurements. The main findings showed that 183 of the elite freestyle swimmers in this study had EP (accounting for 58.84% of the total 311 participants), with 147 in slight pain and 36 in critical pain. The characteristics of a heavier body weight, taller height, longer left/right forearm length, and longer weekly average training hours serve as contributing factors to the occurrence of EP issues. Gender, age, weekly average training hours, and left/right forearm length are the primary factors correlating with and influencing the assessment scores. In conclusion, swimmers with longer weekly training hours, older ages, heavier bodyweight, and longer forearm lengths should receive greater attention in relation to EP. Regular assessments at a high frequency serve as a means to identify the risk of EP.

Early life drought predicts components of adult body size in wild female baboons.

In many taxa, adverse early-life environments are associated with reduced growth and smaller body size in adulthood. However, in wild primates, we know very little about whether, where, and to what degree trajectories are influenced by early adversity, or which types of early adversity matter most. Here, we use parallel-laser photogrammetry to assess inter-individual predictors of three measures of body size (leg length, forearm length, and shoulder-rump length) in a population of wild female baboons studied since birth. Using >2000 photogrammetric measurements of 127 females, we present a cross-sectional growth curve of wild female baboons (Papio cynocephalus) from juvenescence through adulthood. We then test whether females exposed to several important sources of early-life adversity-drought, maternal loss, low maternal rank, or a cumulative measure of adversity-were smaller for their age than females who experienced less adversity. Using the "animal model," we also test whether body size is heritable in this study population. Prolonged early-life drought predicted shorter limbs but not shorter torsos (i.e., shoulder-rump lengths). Our other measures of early-life adversity did not predict variation in body size. Heritability estimates for body size measures were 36%-67%. Maternal effects accounted for 13%-17% of the variance in leg and forearm length, but no variance in torso length. Our results suggest that baboon limbs, but not torsos, grow plastically in response to maternal effects and energetic early-life stress. Our results also reveal considerable heritability for all three body size measures in this study population.

Investigation of the Relationship Between Functional Skills, Sensory Functions, and Anthropometric Properties of the Hand in Occupational Therapy Students Using Hierarchical Clustering Analysis

Purpose: This study aims to examine the relationship between functional skills, sensorimotor, and anthropometric variables of the hand in health science students.&#x0D; Material and Methods: The study was carried out on 70 students (21.51± 1.59 years; 61 women, 9 men) from Biruni University. Upper extremity anthropometric measurements were taken from the students. Hand Dynamometer and Pinchmeter were used for hand grip strength, Purdue Pegboard Test for hand dexterity, Semmes-Weinstein Monofilament for two-point discrimination, and Vibration Perception Test were used for sensory functions. Hierarchical cluster analysis was employed to find the clustering trend of the variables.&#x0D; Results: At the end of the research, two main clusters were obtained, of which four sub-clusters belonging to the second one were identified. The main cluster I contains pinch, dipod, tripod, lateral grip force, Purdue pegboard dominant, non-dominant, both, and assembly. Main cluster II contains finger lengths, palmar length, hand grip, total upper extremity length, height, two-point discrimination, vibration, weight, BMI, monofilament, palmar width, segmental arm, forearm, and hand length.&#x0D; Conclusion: As a result of the research, it was determined that pinch grip strength, dexterity, anthropometric and sensory characteristics were related to each other.

Population structure and reproduction of the hairy fruit-eating bat, Artibeus hirsutus, in central-western Mexico

The hairy fruit-eating bat Artibeus hirsutus is endemic to Mexico and is considered a rare species. The little biological and ecological data on this species does not provide much information on its conservation status. The objective of this work was to evaluate the population structure and reproductive activity of a colony of A. hirsutus in west-central Mexico. We visited 12 times Isla Grande Atoyac, Jalisco. The individuals were captured inside the 2 caves with bucket traps or by hand directly from the cave roof, and with mist nets placed within the vegetation. We marked 77 individuals (67 adults, 5 juveniles, and 5 newborns), of which 34 were recaptured. The pooled recapture rate was 58.47%, and it increased from March to October and decreased in November and December. The minimum-number-alive value was higher in February (34) and lower in October (5), with an average of 21.1 individuals. Among the adult bats, 25.3% were males and 74.6% were females, with an overall female-biased sex ratio of 1:3.2. Sexual dimorphism was observed, with a significantly greater forearm length in females (55.7 mm) than males (54.4 mm). The study population showed a seasonal bimodal polyestry reproductive pattern.

Nationwide Stature Estimation from Forearm Length Measurements in Montenegrin Adolescents

Nationwide Stature Estimation from Forearm Length Measurements in Montenegrin Adolescents

Handgrip Strength and its Association with Anthropometric Measurements at Different Anatomical Positions of Arm among Young Individuals

Many studies have studied the relationships between handgrip strength and different Anthropometric variables. However, the hand anatomical position when measuring the handgrip strength was not clear in many studies. This study aims to investigate the relationship between the anthropometric measurements and the handgrip strength at different anatomical positions of the arm among young individuals. 59 young males and 41 females were asked to squeeze the hand dynamometer to their maximum capacity. The maximum handgrip force was recorded for 7 different arm anatomical positions. Using SPSS, an Independent student's t-test was used to compare male and female groups. Pearson’s correlation coefficients were used to determine the correlations between handgrip strength and the anthropometric measurements, weight, and BMI at different arm anatomical positions. Furthermore, the dominance weight was computed to determine the most important predictors of grip strength. Significant correlation between handgrip strength and height and weight at all positions and with hand length for all positions except when the arm was abducted and extended 180 ͦ at the shoulder joint and 180 ͦ at the elbow joint. Arm length, forearm length and handbreadth were also correlated to handgrip strength at three positions, when the arm was adducted with 90 ͦ forward at the elbow joint, when the Arm was abducted with 90 ͦ at the shoulder joint and 180 ͦ at the elbow, and when the arm was abducted with 90 ͦ at the shoulder joint and 90 ͦ at the elbow joint with the forearm perpendicular to the frontal plane. However, these correlations were different when males and females were considered separately. Furthermore, the results showed that the height followed by hand length had the highest prediction power of handgrip strength among young adults. The current results showed the importance of considering the different anatomical positions of the arm when studying the relationship between anthropometric measurements and hand grip strength.

Impacts of inter-annual climate variability on reproductive phenology and postnatal development of morphological features of three sympatric bat species

Inter-annual variation in weather conditions has been shown to affect the reproductive phenological patterns of many organisms. Because of their relatively small body size and dependence on ectothermic prey, temperate-zone insectivorous bats are particularly sensitive to adverse spring environmental conditions that affect the duration of gestation and timing of parturition in these animals. This study aimed to compare phenological recruitment, birth seasonality and synchrony and morphological changes during postnatal growth in Rhinolophuseuryale, Rhinolophusferrumequinum and Myotisemarginatus in two consecutive years representing a typical dry (2015) and an extremely wet climatic event (2016) in a nursing colony in Kerend cave, western Iran. Females of these three bat species arrived from their wintering cave to the nursing colony in late April to mid-May each year. Synchrony of parturition as defined by amount clustering of births within a year assessed by circular statistics showed that for R. euryale and R. ferrumequinum the angular variance in dry year were significantly (P < 0.05) lower than in wet year, indicating a low level of synchrony in 2016. Similar comparison showed that births from M. emarginatus were highly synchrony, and there were no significant differences in timing of births among years (P > 0.05). Generalized estimating equation (GEE) for R. euryale indicated that for body mass and forearm length tests of parallelism (interaction term or growth rate) and tests for equal intercepts (y-intercepts or group term) were significant (P < 0.001). In R. ferrumequinum, the initial (y-intercepts) forearm length and body mass were not significantly (P > 0.05) different between the 2 years, but the tests for parallelism showed a significant decrease in growth rates of body mass and forearm length in the wet year (P < 0.05). Similar comparison in M. emarginatus indicated that for body mass, tests of parallelism were significantly different (P = 0.004), while tests for equal intercepts were not (P = 0.23). Our results suggest that climate changes may have unequal effects on different bat species due to differences in foraging habitat, niche partitioning, reproductive requirements and foraging strategies.

Relationship of carrying angle with grip strength and anthropometric measurements in young adults

Background and purposeIncrease or decrease in the carrying angle may affect the functional activity and lead to elbow instability and pain during exercise or activity of daily living. Grip strength is commonly evaluated as a component of hand function in clinical settings as an indicator of disease and functional activity. The objective of this study was to find out correlation of carrying angle with grip strength and anthropometric measurements in healthy young adults.MethodologyTwo hundred three participants (female 121 and male 82) with mean age 22.95 ± 2.11 years were included as per the inclusion and exclusion criteria. Carrying angle was measured by goniometer, and grip strength was measured by handheld dynamometer. Anthropometric data like forearm length and hand span was measured by the measuring tape and ruler scale respectively.ResultsSpearman’s correlation test showed that carrying angle is negatively correlated with grip strength (r = − 0.18; p < 0.05) and forearm length (r = − 0.14; p < 0.05) on the left side but no significant correlation on the right side. Body height and carrying angle have negative correlation on the right (r = − 0.20, p < 0.05) and left sides (r = − 0.23, p < 0.05).ConclusionAs the carrying angle increases, grip strength decreases. The height and length of the forearm are inversely related to the carrying angle. Grip strength is directly proportional with forearm length and hand span. Early identification of increased carrying angle will help in the prevention of various complications and identification of biomechanical alteration in sports activities.

Presumptive First Record of Myotis aurascens (Chiroptera, Vespertilionidae) from China with a Phylogenetic Analysis.

Bat groups have a high degree of species diversity, and the taxonomic status and phylogenetic relationships among bat species have always been research hotspots. Due to the fact that morphological characteristics do not always reflect the evolutionary relationships among species, mitochondrial DNA has been widely used in the study of species relationships due to its maternal inheritance pattern. Myotis aurascens has been suggested as a possible synonym for M. davidii. However, the status of this classification has been controversial. In this study, the morphological and molecular characteristics of a M. aurascens captured from Inner Mongolia, China, were analyzed to determine its taxonomic status. In terms of morphological features, the body weight was 6.33 g, the head and body length were 45.10 mm, the forearm length was 35.87 mm, and the tragus length was 7.51 mm. These values all fell within the species signature data range. Nucleotide skew analysis of the protein-coding genes (PCGs) suggested that only five PCGs (ND1, ND2, COX2, ATP8, and ND4) showed AT-skew value within the mitogenome of M. aurascens. Except for ND6, the GC-skew values of the other PCGs were negative, reflecting the preference for C and T bases compared to G and A bases. Molecular phylogenetic analyses based on mitochondrial PCGs indicated that M. aurascens was a distinct species from M. davidii and phylogenetically closer to M. ikonnikovi, M. alcathoe, and M. mystacinus. Genetic distance analysis also showed that M. aurascens and M. davidii were distantly related. Therefore, the integrated analysis demonstrated that M. aurascens should be considered a distinct species rather than a synonym of M. davidii. Our study could provide a reference for enriching species diversity and research on conservation in China.

Bats (Mammalia: Chiroptera) in urban-rural interfaces: community structure associated with pathogen screening in São Paulo-the largest metropolitan region in Brazil.

Little is known about the influence of the urban environments on bat species 'ecology. The urbanization process potentially lead to critical ecological changes in bat communities' intra and interspecific pathogenic transmissions dynamics. To date, the monitoring of pathogens in bats in Brazil has only been done with bats found dead or alive in households, from rabies surveillance systems. The present work aimed to investigate how urbanization influenced bat richness, relative abundance and pathogen occurrence. Most captured bats were Phyllostomidae, especially Sturnira lilium, Artibeus lituratus, A. fimbriatus, Glossophaga soricina, and Platyrrhinus lineatus, among others. From preserved-rural towards urban areas the lesser the bat richness, the higher the relative abundance of the captured bats. Noise level, luminosity and relative humidity correlated with bat abundance. The proportion of genders, sexually active bats and their size (weight, right forearm length, and body condition index) were stable throughout the investigation. Still, the proportion of pregnant females was higher in Spring and the number of juveniles in Summer, evidencing the seasonality of reproduction. Several Enterobacteria were isolated, evidencing a significant role of bats in the circulation of pathogens of medical and veterinary interest. These results are crucial in the pursuit of a harmonious coexistence between humans, bats and domestic animals in areas with different levels of anthropization.

Solving the taxonomic identity of Hipposideros cineraceus sensu lato (Chiroptera: Hipposideridae) in the Thai-Malay Peninsula, with the description of a new species.

A new species of small Hipposideros in the bicolor group is described based on specimens from Thailand and Malaysia. It can be distinguished from other small Hipposideros in Southeast Asia by a combination of external, craniodental, and bacular morphology, as well as echolocation call frequency. The new species has a distinct rounded swelling on the internarial septum of the noseleaf, with a forearm length of 35.3-42.6 mm, greatest skull length of 15.94-17.90 mm, and a call frequency of maximum energy of 132.3-144.0 kHz. Although clearly different in morphology, the new species forms a sister clade with H. kunzi and H. bicolor in the phylogenetic trees based on mitochondrial DNA. In addition, this study reports echolocation and genetic data, with a confirmed record of H. einnaythu from Thailand for the first time. The new species most closely resembles H. einnaythu. However, it differs in the details of the noseleaf and craniodental morphology, and it has a genetic distance of 9.6% and 10.4% based on mitochondrial COI and ND2, respectively. It is currently documented from five localities: two in peninsular Thailand, at Hala Forest in Yala Province, and Phru To Daeng Swamp Forest in Narathiwat Province, one from peninsular Malaysia at Krau Wildlife Reserve in Pahang, and another two in Sabah, Malaysian Borneo at Gunung Kinabalu, and near Madai Caves. However, it is likely that many previous records of "H. cineraceus" from Borneo refer to this species. Most records of the species are from lowland evergreen rainforest, though one record from Sabah was at 1800m. The roosting sites for this new species are currently unknown. Future research with a combination of data such as genetics, echolocation and morphology would be necessary to further determine the species geographic distribution in Southeast Asia.

The Effects of Bioimpedance Analysis Results and Upper Extremity Anthropometric Measurements on Grip Strength in Young Adults

Aim: Among the hand functions, grasping is an important function for the continuity of daily living activities. The assessment of grip strength is crucial for identifying athletic prowess, neuromuscular illnesses, assessing potential side effects following hand surgery, and treatment plans. It was aimed to examine whether bioimpedance analysis (BIA) and upper extremity anthropometric measurements are effected grip strength in young adults. Material and Methods: The study was conducted on 110 young adults, 55 males and 55 females, aged 18-25 years. Individuals with a history of trauma, musculoskeletal problems, and cardiac, respiratory, metabolic, or systemic diseases were not included in the study. Non-flexible tape measure, Harpenden anthropometric set, digital caliper, hand dynamometer, and skinfold caliper were used for anthropometric measurements. Body fat percentage and lean body mass, muscle mass, basal metabolic rate, and total body fluid parameters were investigated by bioelectrical impedance measurement. Three measurements were taken to reduce the error rate, and the average of these measurements was considered. Results: Excluding arm circumference, forearm length, and wrist circumference from anthropometric measurements, and mineral from BIA parameters; anthropometric measurements and BIA results were found to be statistically significantly correlated with grip strength. Conclusion: Upper extremity anthropometric measurements and BIA were associated with grip strength and varied according to gender. Significant correlations were found between grip strength with most of the anthropometric parameters and BIA.

A global assessment of the ‘island rule’ in bats based on functionally distinct measures of body size

AbstractAimThe ‘island rule’ postulates that on islands large continental animals become smaller, and small continental animals become larger. Its generality has been supported by some studies but contested by others. Bats are cosmopolitan and speciose mammals thus are ideal to test ecogeographic patterns. Based on three functionally distinct measures of body size, I compare mainland and island variation in bats at the order to subspecies level.LocationGlobally.TaxonChiroptera.MethodsI compiled information from literature on the skull length, forearm length, and body mass of 251 bat species in 840 locations. For conspecific bats from different locations, I calculated size divergences, and categorized them as within‐mainland (M–M), mainland‐to‐island (M–I), or island‐to‐island (I–I). I used a modified size ratio to quantify divergences, analysis of variance, non‐parametric tests, and effect sizes to complement statistical significances.ResultsOn islands, cranial size increases, wing length becomes more uniform, and body mass decreases more often than not. The first trend would support the island rule, but had a small effect size. Families differ considerably in how they vary geographically. Species are ranked very differently based on functionally distinct size measures. Divergences are uniform across M–M, M–I, and I–I ranges, and large between bats of different subspecies.Main ConclusionsLikely owing to limitations imposed by flight and echolocation, bats do not follow the island rule. The absence of correlation between how bats are ranked based on them indicates that functionally distinct size measures are not necessarily coadaptive. High vagilities may lead to low local differentiation, but interfamilial variation shows this differentiation to also depend on other factors. Body sizes converge to species‐specific optima, not to supraspecific optima as predicted by theoretical studies. Size differences are reflected in taxonomy more often if observed across M–I ranges.

Weather, ultrasonic, cranial and body traits predict insect diet hardness in a Central Mexican bat community

Insectivorous bats exhibit food preferences for specific attributes in their prey. Hardness has been defined as an important prey attribute, and in some cases a limiting factor in foraging decisions for smaller compared to larger bat species. The goal of this study was to identify which factors influence the selection of prey hardness in a vespertilionid bat community. We investigated food consumed by bats by analyzing fecal samples obtained from eight bat species coexisting in a mountain ecosystem of central Mexico and correlate non-phylogenetically and phylogenetically prey hardness to weather, bat´s body, cranial and ultrasonic call structure variables. Results showed that diet of vespertilionid bats was mainly represented by Diptera, Neuroptera, Lepidoptera and Coleoptera consumption. The qualitative prey hardness index (From soft 1 to hard 5) ranked bats as: Myotis melanorhinus, Corynorhinus mexicanus, Myotis volans, Myotis californicus (< 3); Myotis velifer (< 4); Eptesicus fuscus, Idionycteris phyllotis and Myotis thysanodes (> 4.2). Prey hardness was positively correlated to minimum and mean temperatures, bat´s body weight, total and forearm lengths, cranial variables as: zygomatic breadth, mandibular length, height of the coronoid process, lower molar width, C-M3 superior and inferior rows length and upper molar width; and negatively to ultrasonic variables as total slope, call duration, low and high frequencies, band width and frequency maximum power. Considering phylogenies, prey hardness positively correlated to mandibular length, C-M3 inferior and superior rows lengths (p < 0.05). Our results showed that environmental, morphological and echolocation variables can be used as predictors of preferred insect prey in a community of vespertilionid bats.

Volar versus dorsal approach for supinator to posterior interosseous nerve transfer: An anatomical study in cadavers.

Supinator to posterior interosseous nerve (SPIN) transfer allows reconstruction of finger/thumb extension and thumb abduction for low radial nerve palsy, incomplete C6 tetraplegia, and brachial plexus injury affecting C7-T1. No study has compared dorsal versus volar approach to perform SPIN transfer. This comparison is studied in the present work, assessing supinator motor branch length and ability to achieve nerve transfer from either approach. Ten fresh frozen cadavers were randomly allocated to receive either a dorsal or volar approach to PIN and supinator radial and ulnar branches (RB=radial, UB=ulnar). Supinator head innervation patterns were documented. RB and UB lengths, forearm lengths measured from ulnar styloid to olecranon, visualization of extensor carpi radialis brevis (ECRB) motor nerve without additional dissection, and ability to perform tension-free nerve transfer were assessed. Nine of 10 specimens had supinator branches innervating both heads. The ECRB nerve was visualized in all volar but only one dorsal approach. No significant differences in forearm length were found. Volar with elbow extended: mean RB length was 35±7.8 mm and UB was 37.8±9.3 mm. Dorsal with elbow extended: mean RB length was 30±4.1 mm and UB was 38.8±7.3 mm. Dorsal with elbow flexed 90°: RB was 25.6±3.8 mm and UB was 34.8±4.8 mm. No significant differences were found in branch lengths between approaches (dorsal vs. volar UB, p=.339; dorsal vs. volar RB, p=.117). All limbs achieved tension-free coaptation. Neither approach demonstrated superiority in achieving tension-free nerve transfer. Volar permitted immediate identification of ECRB nerve whereas this was only visualized in one dorsal specimen without additional dissection. Overall, the volar approach allows direct coaptation in elbow extension, mimicking maximal physiologic tension for neurorrhaphy. It simultaneously permits additional procedures for pinch reconstruction via single exposure, circumventing limb/microscope maneuvering, dorsal dissection, and increased operative time. Ultimate choice of approach should depend on surgeon familiarity and potential need for additional simultaneous transfers.

Measuring fascicle lengths of extrinsic and intrinsic thumb muscles using extended field-of-view ultrasound

Complex motion of the human thumb is enabled by the balanced architectural design of the extrinsic and intrinsic thumb muscles. Given that recent imaging advances have not yet been applied to enhance our understanding of the in vivo properties of thumb muscles, the objective of this study was to test the reliability and validity of measuring thumb muscle fascicle lengths using extended field of view ultrasound (EFOV-US). Three muscles (FPL: flexor pollicis longus, APB: abductor pollicis brevis, and ECU: extensor carpi ulnaris) were imaged in eight healthy adults (4 female; age, 21.6 ± 1.3 years; height, 175.9 ± 8.3 cm)[mean ± SD]. Measured fascicle lengths were compared to cadaveric data (all muscles) and ultrasound data (ECU only). Additionally, to evaluate how fascicle lengths scale with anthropometric measurements, height, forearm length, hand length, and hand width were recorded. The EFOV-US method obtained precise fascicle length measurements [mean ± SD] for the FPL (6.2 ± 0.5 cm), APB (5.1 ± 0.3 cm), and ECU (4.0 ± 0.4 cm). However, our EFOV-US measurements were consistently different (p < 0.05) than prior cadaveric data, highlighting the need to better understand differences between in vivo and ex vivo fascicle length measurements. Fascicle length was significantly related to only hand length (r2 = 0.56, p = 0.03) for APB, highlighting that anthropometric scaling may not accurately estimate thumb muscle length. As the first study to apply EFOV-US to measure thumb muscle fascicle lengths, this study expands the utility of this imaging technology within the upper limb.