Movable surface models of hand joints using visible korean / Modelos de superficies móviles de articulaciones de manos utilizando visible Korean

SUMMARY: The human hand can make precise movements utilizing several joints of various articular types. To understand hand movements more accurately, it is essential to view the actual movements of bones and muscles considering the X, Y, and Z axes in the joints. This study aimed to investigate the joint movements in a hand using movable surface models, including these axes. These movable surface models of the hand will improve medical students' understanding of hand movements around the joints. To achieve this aim, 70 surface models were adopted from a Visible Korean model. Using Maya software, 20 virtual joints with X, Y, and Z axes included nine distal and proximal interphalangeal joints, five metacarpophalangeal joints, five carpometacarpal joints, and one wrist joint were created. Bone surface models were elaborately polished to maintain their original shape during movement. Muscle surface models were also processed to display the deformation of the muscle shape during movement. The surface models of the hand joints were moved by virtual control of the joints. We saved 87 movable surface models of the hand, including bones, muscles, and joint axes in stereolithography format, and compiled a Portable Document Format (PDF) file. Using the PDF file, the joint movements in a hand could be observed considering the X, Y, and Z axes alongside the stereoscopic shapes of the bones and muscles. These movable surface models of the hand will improve medical students' understanding of hand movements around the joints.

RESUMEN: La mano humana puede realizar movimientos precisos utilizando varias articulaciones de diferentes tipos articulares. Para comprender los movimientos de las manos con mayor precisión, es esencial ver los movimientos reales de los huesos y los músculos considerando los ejes X, Y y Z de las articulaciones. Este estudio tuvo como objetivo investigar los movimientos articulares en una mano utilizando modelos de superficies móviles, incluidos estos ejes. Estos modelos de superficie móvil de la mano mejorarán la comprensión de los estudiantes de medicina de los movimientos de la mano alrededor de las articulaciones. Para lograr este objetivo, se adoptaron 70 modelos de superficie de un modelo coreano visible. Con el software Maya, se crearon 20 articulaciones virtuales con ejes X, Y y Z que incluyeron nueve articulaciones interfalángicas distales y proximales, cinco articulaciones metacarpofalángicas, cinco articulaciones carpometacarpianas y una articulación de muñeca. Los modelos de superficie ósea se pulieron minuciosamente para mantener su forma original durante el movimiento. También se procesaron modelos de superficie muscular para mostrar la deformación de la forma del músculo durante el movimiento. Los modelos de superficie de las articulaciones de las manos se movieron mediante el control virtual de las articulaciones. Guardamos 87 modelos de superficies móviles de la mano, incluidos huesos, músculos y ejes articulares en formato de estereolitografía, y compilamos un archivo en formato de documento portátil (PDF). Usando el archivo PDF, los movimientos de las articulaciones en una mano se pueden observar considerando los ejes X, Y y Z junto con las formas estereoscópicas de los huesos y músculos. Estos modelos de superficie móvil de la mano mejorarán la comprensión de los estudiantes de medicina sobre los movimientos de la mano alrededor de las articulaciones.

Integrated linkage-driven dexterous anthropomorphic robotic hand.

Robotic hands perform several amazing functions similar to the human hands, thereby offering high flexibility in terms of the tasks performed. However, developing integrated hands without additional actuation parts while maintaining important functions such as human-level dexterity and grasping force is challenging. The actuation parts make it difficult to integrate these hands into existing robotic arms, thus limiting their applicability. Based on a linkage-driven mechanism, an integrated linkage-driven dexterous anthropomorphic robotic hand called ILDA hand, which integrates all the components required for actuation and sensing and possesses high dexterity, is developed. It has the following features: 15-degree-of-freedom (20 joints), a fingertip force of 34N, compact size (maximum length: 218 mm) without additional parts, low weight of 1.1 kg, and tactile sensing capabilities. Actual manipulation tasks involving tools used in everyday life are performed with the hand mounted on a commercial robot arm.

Hand Gesture Recognition and Finger Angle Estimation via Wrist-Worn Modified Barometric Pressure Sensing.

This paper presents a new approach to wearable hand gesture recognition and finger angle estimation based on the modified barometric pressure sensing. Barometric pressure sensors were encased and injected with VytaFlex rubber such that the rubber directly contacted the sensing element allowing pressure change detection when the encasing rubber was pressed. A wearable prototype consisting of an array of ten modified barometric pressure sensors around the wrist was developed and validated with experimental testing for three different hand gesture sets and finger flexion/extension trials for each of the five fingers. The overall hand gesture recognition classification accuracy was 94%. Further analysis revealed that the most important sensor location was the underside of the wrist and that when reducing the sensor number to only five optimally placed sensors, classification accuracy was still 90%. For continuous finger angle estimation, aggregate R2 values between actual and predicted angles were thumb: 0.81 ± 0.10, index finger: 0.85±0.06, middle finger: 0.77±0.08, ring finger: 0.77 ± 0.12, and pinkie finger: 0.75 ± 0.10, and the overall average was 0.79 ± 0.05. These results demonstrate that a modified barometric pressure wristband can be used to classify hand gestures and to estimate individual finger joint angles. This approach could serve to improve the clinical treatment for upper extremity deficiencies, such as for stroke rehabilitation, by providing objective patient motor control metrics to inform and aid physicians and therapists throughout the rehabilitation process.

Morphometric patterns among the 3D surface areas of human hand entheses.

OBJECTIVES: This study aimed to put forth a new and precise methodology for calculating the 3D areas of hand entheses. Furthermore, it investigated some of the factors affecting hand entheses development through an assessment of their correlations and morphometric patterns. MATERIALS AND METHODS: Fifty individuals from late-medieval San Pablo were studied. The sample consisted of high-definition 3D models of 17 entheses from the first, second, and fifth hand rays. A new methodology was introduced for quantifying their areas. Precision was verified using intraobserved and interobserver tests. Both raw and relative entheseal size (ratio of entheseal size to total bone surface size) were calculated. Bivariate analyses assessed the effect of age-group on entheses as well as the correlations across entheses of muscles that act synergistically, bone length, and articular surface size. The morphometric patterns among hand entheses were explored using a multivariate analysis. RESULTS: The methodology presented no significant error. Age-group variation does not seem to affect hand entheses. In relative size, only particular pairs presented significant association and the entheses involved were not correlated with bone length or articular surface size. The multivariate analysis demonstrated high sexual dimorphism in overall entheseal size as well as two morphometric trends among hand entheses. DISCUSSION: The proposed methodology can set the basis for further morphological 3D analysis of entheses. If biomechanical stress affects hand entheses, its impact would possibly be greater on their relative size. The morphometric patterns among entheses seem to reflect the performance of prehensile grips. Am J Phys Anthropol 160:694-707, 2016. © 2016 Wiley Periodicals, Inc.

Surgical exposures of the hand.

Surgical approaches to the hand are commonly executed in the treatment of fractures, ligament injuries, and less commonly in the resection of bony tumors. Careful design and execution of these surgical approaches translates into superior functional and aesthetic outcomes. We have provided a thorough review of commonly used approaches to the hand by evaluating each of these approaches in the context of core principles including safety, versatility, preservation of stability, and aesthetic outcomes.

Anatomical analysis of thumb opponency movement in the capuchin monkey (Sapajus sp).

Capuchin monkeys present a wide variety of manipulatory skills and make routine use of tools both in captivity and in the wild. Efficient handling of objects in this genus has led several investigators to assume near-human thumb movements despite the lack of anatomical studies. Here we perform an anatomical analysis of muscles and bones in the capuchin hand. Trapezo-metacarpal joint surfaces observed in capuchins indicate that medial rotation of metacarpal I is either absent or very limited. Overall, bone structural arrangement and thumb position relative to the other digits and the hand's palm suggest that capuchins are unable to perform any kind of thumb opponency, but rather a 'lateral pinch' movement. Although the capuchin hand apparatus bears other features necessary for complex tool use, the lack thumb opposition movements suggests that a developed cognitive and motor nervous system may be even more important for high manipulatory skills than traditionally held.

Trabecular bone structure correlates with hand posture and use in hominoids.

Bone is capable of adapting during life in response to stress. Therefore, variation in locomotor and manipulative behaviours across extant hominoids may be reflected in differences in trabecular bone structure. The hand is a promising region for trabecular analysis, as it is the direct contact between the individual and the environment and joint positions at peak loading vary amongst extant hominoids. Building upon traditional volume of interest-based analyses, we apply a whole-epiphysis analytical approach using high-resolution microtomographic scans of the hominoid third metacarpal to investigate whether trabecular structure reflects differences in hand posture and loading in knuckle-walking (Gorilla, Pan), suspensory (Pongo, Hylobates and Symphalangus) and manipulative (Homo) taxa. Additionally, a comparative phylogenetic method was used to analyse rates of evolutionary changes in trabecular parameters. Results demonstrate that trabecular bone volume distribution and regions of greatest stiffness (i.e., Young's modulus) correspond with predicted loading of the hand in each behavioural category. In suspensory and manipulative taxa, regions of high bone volume and greatest stiffness are concentrated on the palmar or distopalmar regions of the metacarpal head, whereas knuckle-walking taxa show greater bone volume and stiffness throughout the head, and particularly in the dorsal region; patterns that correspond with the highest predicted joint reaction forces. Trabecular structure in knuckle-walking taxa is characterised by high bone volume fraction and a high degree of anisotropy in contrast to the suspensory brachiators. Humans, in which the hand is used primarily for manipulation, have a low bone volume fraction and a variable degree of anisotropy. Finally, when trabecular parameters are mapped onto a molecular-based phylogeny, we show that the rates of change in trabecular structure vary across the hominoid clade. Our results support a link between inferred behaviour and trabecular structure in extant hominoids that can be informative for reconstructing behaviour in fossil primates.

Reproducible metacarpal joint space width measurements using 3D analysis of images acquired with high-resolution peripheral quantitative computed tomography.

OBJECTIVE: Joint space narrowing is an important feature of progressive joint damage and functional impairment in rheumatoid arthritis (RA). Methods to provide a continuous measurement of joint space width have not been adopted in research or clinical settings. High-resolution peripheral quantitative computed tomography (HR-pQCT) (Scanco Medical AG, Brüttisellen, Switzerland) accurately and reproducibly images bone microstructure at a nominal isotropic voxel dimension of 82 µm. Given the ability of HR-pQCT to detect bone margins with high precision, we developed methodology to measure a three-dimensional (3D) metacarpophalangeal (MCP) joint space width and tested the reproducibility of the scan protocol with hand repositioning. MATERIALS AND METHODS: Consecutive HR-pQCT scans of the 2nd and 3rd MCP joints of ten subjects with early RA (70% female, mean age 45 years), with repositioning between scans, were obtained. The periosteal edges of the metacarpal head and proximal phalanx base were detected using the µCT Evaluation Program V6.0 (Scanco Medical AG). Using the method of 'fitting maximal spheres', the joint space width and distribution of joint space thickness was estimated. RESULTS: The mean minimum joint space width of the 2nd MCP was 1.82 mm (SD 0.20) and of the 3rd MCP 1.84 mm (SD 0.23). Reproducibility with repositioning was reliable, with overlapping filtered histograms and a root square mean coefficient of variance of 4.8%. CONCLUSIONS: We provide reproducible methodology for evaluating the joint space width of the MCP joints. When combined with the assessment of erosions and periarticular bone density, HR-pQCT may be the ideal technology to assess disease activity and progression in RA.

Early-to-mid gestation fetal testosterone increases right hand 2D:4D finger length ratio in polycystic ovary syndrome-like monkeys.

A smaller length ratio for the second relative to the fourth finger (2D:4D) is repeatedly associated with fetal male-typical testosterone (T) and is implicated as a biomarker for a variety of traits and susceptibility to a number of diseases, but no experimental human studies have been performed. The present study utilizes the rhesus monkey, a close relative of humans, and employs discrete gestational exposure of female monkeys to fetal male-typical T levels for 15-35 days during early-to-mid (40-76 days; n = 7) or late (94-139 days; n = 7) gestation (term: 165 days) by daily subcutaneous injection of their dams with 10 mg T propionate. Such gestational exposures are known to enhance male-typical behavior. In this study, compared to control females (n = 19), only early-to-mid gestation T exposure virilizes female external genitalia while increasing 2D:4D ratio in the right hand (RH) by male-like elongation of RH2D. RH2D length and 2D:4D positively correlate with androgen-dependent anogenital distance (AG), and RH2D and AG positively correlate with duration of early-to-mid gestation T exposure. Male monkeys (n = 9) exhibit a sexually dimorphic 2D:4D in the right foot, but this trait is not emulated by early-to-mid or late gestation T exposed females. X-ray determined phalanx measurements indicate elongated finger and toe phalanx length in males, but no other phalanx-related differences. Discrete T exposure during early-to-mid gestation in female rhesus monkeys thus appears to increase RH2D:4D through right-side biased, non-skeletal tissue growth. As variation in timing and duration of gestational T exposure alter male-like dimensions of RH2D independently of RH4D, postnatal RH2D:4D provides a complex biomarker for fetal T exposure.

Proportions of hand segments / Proporciones de los segmentos de la mano

The analysis of proportions of hand segments has been carried out on the basis of X-ray films of 66 adult patients without developmental abnormalities. There were hand joint topographies determined proceeding from the data obtained. There were suggested methods of practical utilization of the obtained data in the field of medicine.

Se analizaron en radiografías de 66 pacientes sin anomalías del desarrollo las proporciones de los diferentes segmentos de la mano. De acuerdo a los datos obtenidos se determinó una topografía de las articulaciones. Se proponen modos de empleo en la medicina de los datos obtenidos en este estudio.

[Tenodesis in hand surgery]. / Les ténodèses en chirurgie de la main.

Joining tendon's inextensibility with joint's mobility, a tenodesis fixes on the bones the two ends of a tendon on both sides of one or several joints. A "simple" tenodesis overrides only one joint, whereas a "dynamic" tenodesis crosses two or more joints. A "crossed" dynamic tenodesis crosses the line which joins rotation axes. A "direct" dynamic tenodesis is located on the same side of this line. The "tenodesis effect" is normally produced by the movements of the joint on the neighbouring tendons. Anatomical examples are given by the oblique retinacular ligaments (crossed dynamic tenodesis), and by the tenodesis effects linked to the flexion-extension of the wrist on the extrinsic tendons of the fingers (direct tenodesis effect), or to the flexion-extension of the PIP joints on the intrinsic tendons of the fingers (crossed tenodesis effect). Main tenodesis techniques are used for palliative surgery in paralysis of EDC, intrinsic muscles of the fingers, or extrinsic muscles of the thumb (EPL, FPL, APL and EPB).

Comparative 3D quantitative analyses of trapeziometacarpal joint surface curvatures among living catarrhines and fossil hominins.

Comparisons of joint surface curvature at the base of the thumb have long been made to discern differences among living and fossil primates in functional capabilities of the hand. However, the complex shape of this joint makes it difficult to quantify differences among taxa. The purpose of this study is to determine whether significant differences in curvature exist among selected catarrhine genera and to compare these genera with hominin fossils in trapeziometacarpal curvature. Two 3D approaches are used to quantify curvatures of the trapezial and metacarpal joint surfaces: (1) stereophotogrammetry with nonuniform rational B-spline (NURBS) calculation of joint curvature to compare modern humans with captive chimpanzees and (2) laser scanning with a quadric-based calculation of curvature to compare modern humans and wild-caught Pan, Gorilla, Pongo, and Papio. Both approaches show that Homo has significantly lower curvature of the joint surfaces than does Pan. The second approach shows that Gorilla has significantly more curvature than modern humans, while Pongo overlaps with humans and African apes. The surfaces in Papio are more cylindrical and flatter than in Homo. Australopithecus afarensis resembles African apes more than modern humans in curvatures, whereas the Homo habilis trapezial metacarpal surface is flatter than in all genera except Papio. Neandertals fall at one end of the modern human range of variation, with smaller dorsovolar curvature. Modern human topography appears to be derived relative to great apes and Australopithecus and contributes to the distinctive human morphology that facilitates forceful precision and power gripping, fundamental to human manipulative activities.

Careful climbing in the Miocene: the forelimbs of Ardipithecus ramidus and humans are primitive.

The Ardipithecus ramidus hand and wrist exhibit none of the derived mechanisms that restrict motion in extant great apes and are reminiscent of those of Miocene apes, such as Proconsul. The capitate head is more palmar than in all other known hominoids, permitting extreme midcarpal dorsiflexion. Ar. ramidus and all later hominids lack the carpometacarpal articular and ligamentous specializations of extant apes. Manual proportions are unlike those of any extant ape. Metacarpals 2 through 5 are relatively short, lacking any morphological traits associable with knuckle-walking. Humeral and ulnar characters are primitive and like those of later hominids. The Ar. ramidus forelimb complex implies palmigrady during bridging and careful climbing and exhibits none of the adaptations to vertical climbing, forelimb suspension, and knuckle-walking that are seen in extant African apes.

[Trapezio second metacarpal joint: anatomical study and clinical matters]. / Articulation du trapèze avec le second métacarpien: étude anatomique et intérêts cliniques.

INTRODUCTION: An unusual dislocation of the column of the thumb associated with a fracture of the base of the second metacarpal inspired an anatomical study of the trapeziosecond metacarpal joint. MATERIALS AND METHODS: Forty-five dissections of the palmar aspect of trapeziometacarpal joint aimed at focusing on palmar ligaments and tendons reinforcing the joints. RESULTS: Trapeziosecond metacarpal joint is a constant little diarthrosis reinforced by a palmar ligament stressed between the crest of the trapezium and the base of the second metacarpal. The tendon of flexor radialis carpi muscle is an active link due to strong vinculae to trapezium bone and distal attachment to the bases of both second and third metacarpals. CONCLUSION: The connections between the trapezium and the base of the second metacarpal bone play a role in the treatment of thumb instability and their mechanical importance is illustrated in our original clinical observation.

[Hands and feet of prosimians primates. Attempts of morphologic characterization]. / Mains et pieds des primates prosimiens. Essai de caractérisation morphologique.

The length of the carpus and tarsus, the metacarpus and metatarsus, the fingers and toes of 142 prosimian apes was measured. The relationship expressed as a percentage was drawn up for each individual between the length of each osseous part and that of its third metacarpal in order to eliminate the differences related to the size of the rest of the body. This ratio was compared with that of man. The characteristic variations appeared at the level of the subfamilies. CONCERNING THE HAND: The carpus presented the same values as that of man except for that of the indris, which was shorter. The thumb had proportionally the same length as that of man, sometimes longer and sometimes smaller as in the Eulemurs, Hapalidea, Megalapidea, Indrises, Daubentonia and Perodictus. The different metacarpals, including the fourth, were a little shorter than the third. In these subfamilies, the second ray was also often shorter and even much shorter in the Megalapidea and the Perodictus. The other rays were a little longer, in particular the fourth which could exceed the third in rather many subfamilies. CONCERNING THE FOOT: The length of the tarsus was extremely variable. It was twice larger in the Galagoidae, definitely larger in the tarsius and discreetly in the Hapalidae, a little smaller in the other Lemurs and much smaller in the other Prosimian apes, joining in that the near totality of the simians. The hallux was proportionally as long as that of man and sometimes even longer. The metatarsals were sometimes a little longer, sometimes less long, but always appreciably of the same length between them. The other toes were short at the aye aye (daubentonia), of which the foot appeared even smaller than that of man. The toes of the other prosimious resembled much to the fingers and in the propithecus and the perodictus, the fourth took gigantic proportions. There has been establishment of an anatomical relation and functional calculus between the length of the last three rays of the hands and the feet of prosimian apes and the biomechanics of their trapezometacarpal and their first cuneometacarpal joints.

Anatomy and pathomechanics of the thumb.

The prehensile thumb provides the human mind an outlet for coordinated activity through its fine motions of prehension, opposition, and circumduction. A comprehensive understanding of the anatomy and biomechanics of the thumb provides a foundation on which functional disorders may be recognized and effectively treated.

The mend of the bend-flexor pollicis longus tendon has an additional pulley distal to its point of angulation.

The tendon of flexor pollicis longus angulates at the trapezio-metacarpal joint level. The degree of angulation varies with extent of radial/ulnar deviation (Rack and Ross [1984] J. Physiol. 351:99-110). We report a fibrous pulley at this level that helps stabilize the tendon and facilitates its action. The morphology of the pulley is described. We believe that it has an important role to play in the unique function of the tendon facilitating the movement of the thumb perpendicular to the plane of the thumbnail.

Articular constraint, handedness, and directional asymmetry in the human second metacarpal.

The hypothesis that functional adaptation of joint surfaces to mechanical loading occurs primarily through change in mass, density, and structure of subarticular trabeculae (the "articular constraint" model) is investigated through an analysis of directional asymmetry among three separate bone compartments in the human second metacarpal. Measures of midshaft cross-sectional geometry, osteometry of the distal epiphysis, and subarticular trabecular microarchitecture of the distal epiphysis (assessed by high-resolution microcomputed tomography) were determined for 29 paired male and female metacarpals from a well-preserved nineteenth-century Euro-Canadian historic cemetery sample. For each measure, asymmetry was quantified using both mean-difference and confidence-interval methods. Both methods found a significant right-hand bias for measures of structural strength in midshaft geometry, as has been previously noted for this sample. Articular size, however, exhibits a right-hand bias only with regard to mediolateral, and not dorsopalmar, dimensions, a result that may reflect directional asymmetry in hand breadth at the distal palmar arch. The most striking asymmetries occur for subarticular trabecular microarchitecture. The right metacarpal head exhibits greater bone volume fraction, bone surface density, trabecular number, connectivity, and a more platelike rather than rodlike structure. These outcomes confer greater resistance to both axial compressive and shear strains for the metacarpal head at the metacarpophalangeal arthrosis. In all, these results confirm and extend previous research documenting structural asymmetries and limb dominance and are consistent with the concept of articular constraint. They also suggest a morphological signal through which functional asymmetry associated with handedness in fossil hominins may be investigated.

Anatomic variation of the 5th extensor tendon compartment and extensor digiti minimi tendon.

Anatomic variation within the 5th extensor compartment may contribute to the development of tenosynovitis and limit the usefulness of the extensor digiti minimi (EDM) for tendon transfer. The purpose of this study was to assess the anatomic variation of the EDM tendon and its surrounding retinaculum, with particular attention to anatomical variation between specimens. Forty-one fresh cadaver hands were dissected. The length of the 5th compartment retinaculum was noted. The incidence of an intercompartmental septum was noted in each specimen as well as the type of tendinous attachments present between the EDM and extensor digitorum communis (EDC) tendons. The presence and length of any accessory retinacular bands distal to the edge of proper extensor retinaculum was also noted. Only one specimen contained a single EDM tendon, while 71% (n = 29) of specimens contained two slips and 23% (n = 9) had three slips; 24% (n = 10) of EDC tendons had no slip to the small finger, while 61% (n = 25) of specimens had a single slip to the small finger. The EDC's contribution to the small finger was found to be an independent tendon in 42% of cases (n = 17), while 34% (n = 14) of specimens were found to have a common EDC slip, which branched to both the ring and small finger. Three EDM tendons divided distal to the extensor retinaculum, while the remaining EDM tendons divided beneath or proximal to the extensor retinaculum. Seventy-three percent (n = 30) of the specimens had an accessory retinacular band surrounding the EDM tendon identified at the base of the 5th metacarpal. Eighty-eight percent (n = 36) of hands had a septum between the EDM slips. The surgeon should be aware of variability within the 5th dorsal compartment in cases of trauma and in cases of tendon transfer. In our series 30 of 41 specimens were noted to contain an accessory dorsal retinacular band surrounding the EDM and 36 specimens were noted to contain a septum within the 5th compartment. The presence of an accessory retinacular band surrounding the EDM at the level of the 5th metacarpal base is an anatomic finding that requires further investigation.