Morpho-Functional Analysis Using Procrustes Superimposition by Static Reference

In conventional geometric morphometric analyses of limb long bones, differences in the evolutionary capacity of articular surfaces and non-articular structures often remain unrecognised. It can be shown that areas of high spatial variance dominate shape data, which is problematic for the functional interpretation of limb long bone shape. We herein introduce Procrustes superimposition by static reference (PSSR), a novel analysis strategy that aims to facilitate morpho-functional inference. This procedure exploits the spatial constraint of some reference structures (in our case, articular surfaces) for the superimposition of other subareas (e.g. muscle attachment sites) in relation to that static reference. PSSR allows for the transformation of raw scan data, enabling researchers to extract geometric models of two- and three-dimensional substructures that cannot effectively be integrated with landmarks. As we demonstrate by a simple model analysis for one muscle attachment site, this procedure can yield measures of direct functional relevance. Multivariate analysis of an extensive set of subareas indicates how this type of data relates to conventional shape coordinates. The shape evolution of xenarthran humeri, which has previously been subject to a detailed study (Milne et al., J Zool 278(1):48–56, 2009), serves as a test case. The concept of a variance-based separation of landmark subsets expands mathematical methods by incorporating knowledge about evolutionary constraints. PSSR could therefore find application far beyond the intuitive case study of long bone shape.     

Tracking the scapula using the scapula locator with and without feedback from pressure-sensors: A comparative study

BackgroundThe scapula locator method has associated intra-observer and inter-observer errors caused by the dependency on the observer to locate the scapular landmarks. The potential effect of the pressures applied by the observer on the measured scapular kinematics when this method is used has also been overlooked so far. The aim of this study was to investigate the effect of using feedback on the pressures applied on the scapula using the locator on the intra-observer and inter-observer reliabilities of the method as well as on the kinematics obtained using this method.MethodsThree observers tracked the scapular motion of the dominant shoulder of each subject using the locator with no reference to pressure-feedback for three trials of bilateral elevation in the scapular plane and using the locator with pressure-feedback for three other trials. Variations between the measurements obtained were used to calculate the intra-observer errors and variations between the measurements obtained by the three observers for the same subject were used to calculate inter-observer errors. Repeated-measures ANOVA tests were used to look at differences between the two methods in terms of intra-observer and inter-observer errors and scapular kinematics.FindingsUsing pressure-feedback reduced the intra-observer errors but had no effect on the inter-observer errors. Different scapular kinematics was measured using the two methods.InterpretationsPressure-feedback improves the reliability of the scapula locator method. Differences in the scapular kinematics suggest that unregulated pressures have an effect on the physiological scapular motion.     

Variations in muscle activation levels during traditional latissimus dorsi weight training exercises: An experimental study.

BACKGROUND: Exercise beliefs abound regarding variations in strength training techniques on muscle activation levels yet little research has validated these ideas. The purpose of the study is to determine muscle activation level, expressed as a percent of a normalization contraction, of the latissimus dorsi, biceps brachii and middle trapezius/rhomboids muscle groups during a series of different exercise tasks. METHODS: The average muscle activity during four tasks; wide grip pulldown, reverse grip pull down [RGP], seated row with retracted scapula, and seated rows with non-retracted scapulae was quantified during two 10 second isometric portions of the four exercises. A repeated measures ANOVA with post-hoc Tukey test was used to determine the influence of exercise type on muscle activity for each muscle. RESULTS & DISCUSSION: No exercise type influenced biceps brachii activity. The highest latissimus dorsi to biceps ratio of activation occurred during the wide grip pulldown and the seated row. Highest levels of myoelectric activity in the middle trapezius/rhomboid muscle group occurred during the seated row. Actively retracting the scapula did not influence middle trapezius/rhomboid activity. CONCLUSION: Variations in latissimus dorsi exercises are capable of producing small changes in the myoelectric activity of the primary movers.     

Estimating muscle attachment contours by transforming geometrical bone models

For individualization of a biomechanical model, it is necessary to estimate the muscle attachments of the person to whom it is to be adapted. One of the methods to estimate muscle attachments is to use model transformations to transform a model with known muscle attachments to the bones of a person. We hypothesize that the location and shape of muscle attachment sites correlate with the shape of the bones they are attached to. If this hypothesis holds, it is possible to predict the location of muscle attachments when the shape of the bones is known. To validate this hypothesis, geometric models of three sets of shoulder bones were built. These models consist of 3-D surface models of the scapula, clavicle, and humerus, with the muscle attachment contours connected to them. By means of geometric transformations, the models were transformed, so the muscle attachments of the different data sets could be compared. Using these techniques, 50 per cent of the muscle attachment contours could be predicted with high accuracy. The muscle attachment contours that could not be predicted were all influenced by measurement errors. For 30 per cent of the muscle attachment contours, it was not possible to distinguish the interindividual differences from the inaccuracies of the method used. From this study, we concluded that most muscle attachment contours can be predicted by means of geometric models of the bones.     

Role of development in the evolution of the scapula of the giant sthenurine kangaroos (Macropodidae: Sthenurinae)

Extinct giant sthenurine kangaroos possessed scapulae morphologically distinct from those of all other extant and extinct adult macropodids, but qualitatively resembling those of newborn macropodids. The similarity between adult sthenurine and neonatal macropodid scapulae suggests that a developmental process, such as heterochrony, might have been behind the evolution of the unique sthenurine scapular morphology. By incorporating adult and ontogenetic data, this study examines the evolution and development of the sthenurine scapula. This study quantitatively upholds the previous qualitative morphological observations of macropodid scapulae and finds that ontogenetic and evolutionary morphological changes are correlated in macropodids. The similarity of scapula morphology in sthenurines and newborn macropodids, the correlation between ontogenetic and evolutionary morphological change, and information from other sources (i.e., sthenurine evolutionary history) suggests that pedomorphic shifts in morphology, most likely due to neotenic processes, occurred within the development of the scapula of giant sthenurines.     

New characters for the functional interpretation of primate scapulae and proximal humeri

The study of muscle function in nonhuman primates through the technique of electromyography (EMG) has facilitated the identification of specific functional roles for muscles in particular behaviors. This has led to a more complete understanding of the biomechanics of certain regions of the musculoskeletal system, and should facilitate our ability to identify morphological features useful in the functional interpretation of fossil material. The current paper represents one such investigation of a new set of morphometric characters of the scapula and proximal humerus suggested by EMG analyses of shoulder muscle function. A set of new metric variables were examined on the scapulae and proximal humeri of 25 species of extant anthropoid primates, as well as on casts of scapulae and humeri of three fossil primate taxa. The variables are primarily related to the line of action and attachments of the rotator cuff muscles. The position of the scapular spine, the degree of lateral expansion of the subscapular fossa, the size and shape of the subscapularis insertion facet on the lesser tubercle, and the orientation of the infraspinatus insertion facet on the greater tubercle all appear to successfully sort the extant taxa into locomotor groups. Their appearance on the fossil specimens generally supports previous functional interpretations of each taxon's locomotor abilities based on a variety of other characters, suggesting that these traits are equally applicable to fossil material. © Wiley-Liss, Inc.     

Scapula Skin-Dressing And Fiber-Processing Tools

Abstract

Information from ethnographic and archaeological literature supports the interpretation that some bison scapula tools were used for dressing skins. Sim!lar scapula artifacts may have been used for processing bark fiber used in making cordage or weaving. References to possible scapula processing tools from the Plains Northwest Coast, Great Lakes Riverine Area, and the Southeast are summarized. Specimens made of deer and elk scapulae probably represent functionally similar tool types. These artifacts may be more common than the available reports on Plains sites indicate, and archaeologists should exercise care when identifying scapula tools. We cannot assume that all scapula artifacts represent hoes or hoe fragments.     

Use of uncalibrated biplanar radiography for the measurement of skeletal coordinates around the shoulder girdle

Mechanical modelling of the musculoskeletal system is dependent upon information regarding the bony attachments of the relevant muscles; in order to study the biomechanics of the shoulder girdle the authors have identified the muscle attachments in three embalmed cadavers. A simple biplanar radiographic technique was then used to determine the attachment coordinates using frames of reference defined for each bone. This technique, using hand positioning without special fixtures was believed to be sufficiently accurate, bearing in mind the likely degree of biological variation. In order to test this assumption, the accuracy of the technique has been studied by measuring the agreement between the two measurements of the common coordinate in the pairs of radiographs. it was found that for the trunk, the errors in the common coordinate were always less than the natural variation; for the scapula they were of a similar magnitude but, for the humerus, the measurement errors frequently exceeded the variation in the coordinates of muscle attachments. It was concluded that, in general, uncalibrated biplanar radiography was sufficiently accurate for the determination of the spatial coordinates of muscle attachments.     

Enhancing Agrobacterium tumefaciens-mediated transformation efficiency of perennial ryegrass and rice using heat and high maltose treatments during bacterial infection

Perennial ryegrass is one of the most widely cultivated grasses in temperate regions. However, it is recalcitrant for in vitro manipulation. In this study, various parameters affecting Agrobacterium tumefaciens-mediated infection were tested to optimize transformation efficiency in perennial ryegrass. The effects of heat shock and maltose concentration during Agrobacterium infection were evaluated along with variations in callus induction medium, bacterial infection media and callus age. Our results suggest that Agrobacterium infection at 42 °C for 3 min and co-cultivation of Agrobacterium-infected callus on a high maltose medium (6 %) significantly enhances the transformation efficiency in perennial ryegrass. The most optimal conditions proved to be use of four-month-old embryogenic callus induced on a modified N6 medium, infected with Agrobacterium grown on a modified Murashige and Skoog (MSM) medium, and a 42 °C heat shock treatment followed by the co-cultivation of the Agrobacterium and the callus on medium containing 6 % maltose (instead of 3 %). Using this optimized protocol, we were able to increase the transformation efficiencies for regenerated plants from approximately 1 % to over 20 %. Significant improvement in rice stable transformation efficiency was also observed when the optimized conditions were applied to this important cereal, indicating the method described here may apply to other monocots as well.     

Scapula form and locomotion in chimpanzee evolution

A number of primatologists have followed Coolidge (Am. J. Phys. Anthropol. 18:1–57, 1933) in suggesting that 1) there are significant shape differences in scapula form between pygmy and common chimpanzees, 2) scapulae of P. paniscus resemble those of hylobatids more than do those of P. troglodytes, and 3) therefore pygmy chimpanzees may exhibit a greater component of arm-swinging and other arboreal behaviors than common chimpanzees. In this paper I utilize a comparative analysis of ontogenetic allometries of linear dimensions to determine shape differences in the scapulae of adult pygmy and common chimpanzees and to clarify size-related changes in shape resulting from ontogenetic scaling, i.e., the differential extension of common patterns of growth allometry. Results demonstrate that the scapulae of adult P. paniscus are relatively narrower (in a direction approximately perpendicular to the scapula spine) than those of P. troglodytes, supporting Coolidge's original claim. The allometric analysis further demonstrates, however, that the two chimpanzee species exhibit ontogenetic scaling for all proportions of the scapula examined. Thus, adult pygmy chimpanzees have the scapula proportions observed in small adult and subadult P. troglodytes of comparable scapula size. The implications of this finding for past claims concerning differences in locomotor behavior between the species are discussed. This work lends additional support to previous studies that have demonstrated a high frequency of ontogenetic scaling within the genus Pan and a pedomorphic or juvenilized morphology in the pygmy chimpanzee.     

Modeling the effects of musculoskeletal geometry on scapulohumeral muscle moment arms and lines of action

Abstract

Biomechanical investigations examining shoulder function commonly observe a high degree of inter-individual variability in muscle activity and kinematic patterns during static and dynamic upper extremity exertions. Substantial differences in musculoskeletal geometry between individuals can alter muscle moment arms and lines of action that, theoretically, alter muscle activity and shoulder kinematics. The purposes of this research were to: (i) quantify model-predicted functional roles (moment arms, lines of action) of the scapulohumeral muscles, (ii) compare model predictions to experimental data in the literature, and (iii) evaluate sensitivity of muscle functional roles due to changes in muscle attachment locations using probabilistic modeling. Monte Carlo simulations were performed to iteratively adjust muscle attachment locations at the clavicle, scapula, and humerus of the Delft Shoulder and Elbow Model in OpenSim. Muscle moment arms and lines of action were quantified throughout arm elevation in the scapular plane. In general, model-predicted moment arms agreed well with the reviewed literature; however, notable inconsistencies were observed when comparing lines of action. Variability in moment arms and lines of action were muscle-specific, with 2 standard deviations in moment arm and line of actions as high as 25.8?mm and 18.8° for some muscles, respectively. Moment arms were particularly sensitive to changes in attachment site closest to the joint centre. Variations in muscle functional roles due to differences in musculoskeletal geometry are expected to require different muscle activity and movement patterns for upper extremity exertions.     

A transformation method to estimate muscle attachments based on three bony landmarks

In order to create musculoskeletal models that can be scalable to different subject specificities the calculation of the exact locations of muscle attachment is required. For this purpose, a scaling method is presented that estimates muscle attachment locations in homologous segments using three bony landmarks per segment.A data-set of 17 muscles’ attachment lines from the shoulders of seven cadavers was used to assess the estimation quality of the scaling method. By knowing from the cadaver data the measured location of the muscles’ attachment lines it is possible to assess the quality of the estimated ones. The scaling results showed an overall mean RMSE for the scapula and humerus muscles of 7.6 and 11.1 mm, respectively. These results were then analyzed with an upper extremity model, in order to compute the influence of the RMSE in glenohumeral elevation muscle moment arms in the scapular plane.The results presented were considered to be satisfactory. Among other error contributors, the inter- and intra-subject variability should be further investigated, along with the sensitivity of a biomechanical model to these error variations.     

The function of the coracoacromial ligament

The function of the coracoacromial ligament was investigated in 8 dissecting-room scapulae. Strain gauges were attached around the coracoid process and the acromion, and tension (50 or 100 N) applied through the remaining muscle stumps. The results showed that, after division of the ligament, significantly more distortion could be measured in the acromion than in the coracoid process, which suggests that the 'stay' effect of the coracoacromial ligament is stronger for the former. Since the degree of distortion is largely dependent on the direction of pull, the ligament is interpreted as a dynamic brace between the two processes of the scapula.     

Outcomes of scapula stabilization in obstetrical brachial plexus palsy: a novel dynamic procedure for correction of the winged scapula

Among the late consequences of obstetrical brachial plexus palsy is winging of the scapula, a functional and aesthetic deformity. This article introduces a novel surgical procedure for the dynamic correction of this clinical entity that involves the dynamic transfer of the contralateral trapezius muscle and/or rhomboid muscles and anchoring to the affected scapula. In more severe cases of scapula winging, the contralateral latissimus dorsi muscle may also need to be transferred to achieve dynamic scapula stabilization. The outcomes of this novel surgical procedure were analyzed in relation to the effect on abduction, external rotation, growth of the scapula, and distance of the scapula from the posterior midline. The results were analyzed in 26 patients who underwent this procedure and had adequate follow-up. The mean patient age was 6.39 years. Fourteen (54 percent) had a diagnosis of Erb palsy, and 12 (46 percent) had a diagnosis of global paralysis. All 26 patients had an additional secondary procedure performed prior to or simultaneously with the scapula stabilization procedure. In 19 patients, the contralateral trapezius was transferred and anchored to the medial border of the winged scapula alone, but in seven cases the underlying rhomboid major was transferred along with the trapezius muscle to provide sufficient scapula stabilization. In five cases in which the scapula winging was severe, the contralateral latissimus dorsi muscle was transferred at a second stage. After this procedure, all patients demonstrated improved scapula symmetry. The mean increase in abduction was 18 degrees (p < 0.001), the mean increase in external rotation was 19 degrees (p < 0.001), and the mean increase in anterior flexion was 12 degrees (p = 0.015). The improvement of the relative position of the winged scapula on the posterior thorax was analyzed by measuring the distance of the inferior angle of both scapulae from the midline, then calculating the difference between normal and affected sides and comparing this value before and after the scapula stabilization procedure. This value preoperatively was 3.24 cm; postoperatively it decreased to 0.36 cm (p < 0.001), demonstrating a statistically significant improvement.     

Effects of attachment position and shoulder orientation during calibration on the accuracy of the acromial tracker

The acromial tracker is used to measure scapular rotations during dynamic movements. The method has low accuracy in high elevations and is sensitive to its attachment location on the acromion. The aim of this study was to investigate the effect of the attachment position and shoulder orientation during calibration on the tracker accuracy. The tracker was attached to one of three positions: near the anterior edge of the acromion process, just above the acromial angle and the meeting point between the acromion and the scapular spine. The scapula locator was used to track the scapula during bilateral abduction simultaneously. The locator was used to calibrate the tracker at: no abduction, 30°, 60°, 90° and 120° humerothoracic abduction. ANOVA tests compared RMS errors for different attachment positions and calibration angles. The results showed that attaching the device at the meeting point between the acromion and the scapular spine gave the smallest errors and it was best to calibrate the device at 60° for elevations ≤90°, at 120° for elevations >90° and at 90°or 120° for the full range of abduction. The accuracy of the tracker is significantly improved if attached appropriately and calibrated for the range of movement being measured.     

3-D finite element modelling of facial soft tissue and preliminary application in orthodontics

Prediction of soft tissue aesthetics is important for achieving an optimal outcome in orthodontic treatment planning. Previously, applicable procedures were mainly restricted to 2-D profile prediction. In this study, a generic 3-D finite element (FE) model of the craniofacial soft and hard tissue was constructed, and individualisation of the generic model based on cone beam CT data and mathematical transformation was investigated. The result indicated that patient-specific 3-D facial FE model including different layers of soft tissue could be obtained through mathematical model transformation. Average deviation between the transformed model and the real reconstructed one was 0.47 ± 0.77 mm and 0.75 ± 0.84 mm in soft and hard tissue, respectively. With boundary condition defined according to treatment plan, such FE model could be used to predict the result of orthodontic treatment on facial soft tissue.     

Dielectric Properties Based Detection of Heavy Metal Contaminated Soil in the Frequency Range from 10 MHz to 1 GHz

Physical parameters based electromagnetic methods are promising technologies to detect contaminated sites. In these methods, the dielectric property is a key parameter. In this paper, we studied the dielectric characteristics of heavy metal contaminated soil. The chromium contaminated soil was made into samples, and the open-ended coaxial line was adopted as the measurement method. Experiments were conducted in the frequency band between 10 MHz and 1 GHz. The results showed that the complex permittivity, including the real part and the imaginary part, changes as the ionic content changes. Especially, at low frequencies (<50 MHz), the complex permittivity increases significantly with the increase of ionic content. In addition, it also could be seen that the water content of the soil also affects the complex permittivity. We proposed to adopt the drying method or the Time Domain Reflection method to determine the water content. The dielectric parameters are most affected by the ionic content after knowing the water content. Therefore, it is feasible to detect heavy metal contaminated sites based on dielectric properties.     

Evaluation of a morphing based method to estimate muscle attachment sites of the lower extremity

To generate subject-specific musculoskeletal models for clinical use, the location of muscle attachment sites needs to be estimated with accurate, fast and preferably automated tools. For this purpose, an automatic method was used to estimate the muscle attachment sites of the lower extremity, based on the assumption of a relation between the bone geometry and the location of muscle attachment sites. The aim of this study was to evaluate the accuracy of this morphing based method. Two cadaver dissections were performed to measure the contours of 72 muscle attachment sites on the pelvis, femur, tibia and calcaneus. The geometry of the bones including the muscle attachment sites was morphed from one cadaver to the other and vice versa. For 69% of the muscle attachment sites, the mean distance between the measured and morphed muscle attachment sites was smaller than 15 mm. Furthermore, the muscle attachment sites that had relatively large distances had shown low sensitivity to these deviations. Therefore, this morphing based method is a promising tool for estimating subject-specific muscle attachment sites in the lower extremity in a fast and automated manner.