Sexual dimorphism and ancestral variation in the pectoral and pelvic girdles of modern humans.

Discussions of the evolution of sexual dimorphism in torso shape and the pectoral region assume that this dimorphism exists independently of body size. We test this assumption in two human populations and further examine what is needed to understand sexual dimorphism in the pectoral region. Modern human males have broad shoulders and narrow hips relative to females, lending males a more triangular torso. The wider female pelvis is commonly attributed to obstetric pressures while the broader male pectoral girdle has been argued to be an adaptation that improves hunting or intrasexual competition. While sexual dimorphism in the pelvic girdle is known to exist after adjusting for body size across human populations, most studies of sexual dimorphism in the pectoral girdle have not adjusted the data to account for sexual size dimorphism or compared different ancestral groups. The aforementioned hypotheses explaining sexual dimorphism in the clavicle and scapula as products of natural selection are predicated on the untested assumption that sex differences do not scale with body size. This study tests this assumption by comparing various measurements of the pectoral girdle, the pelvic girdle, and six pectoral-pelvic indices of black and white South Africans of known sex and height to test whether the sexes and ancestral groups will differ in these values after adjusting for differences in body size. Comparisons of ancestral groups reveal that white South Africans have larger pectoral and pelvic dimensions than black South Africans, but that blacks have larger index values than whites. Regardless of differences in ancestry and body size, males have significantly broader pectoral regions as indicated by comparisons of both individual pectoral measurements and pectoral-pelvic indices. This pattern of sexual dimorphism is reversed in the pelvic region where females have larger skeletal elements. In addition to finding both absolute and relative differences in mean values for the pectoral and pelvic skeleton, females and males and blacks and whites differ in the scaling relationship of these traits, suggesting different allometric trajectories for these bones that may be explained by their distinct evolutionary functions, their adaptations to specific environments, or by changes in lengths due to age. These results suggest that sexual dimorphism in the pectoral region is not a product of scaling and that differences in this region reflect adaptive forces acting in unique ways on each sex, consistent with the assumptions of earlier evolutionary explanations.

Biomechanical Comparison of Ulnar Collateral Ligament Reconstruction With the Docking Technique Versus Repair With Internal Bracing.

BACKGROUND: The modified Jobe technique of ulnar collateral ligament (UCL) reconstruction has previously been biomechanically compared with primary repair augmented with internal bracing. However, the docking technique has not been compared with repair with internal bracing. HYPOTHESIS: Load to failure, gapping, and valgus opening angle are similar under valgus loading at 90° of flexion between repair with internal bracing and the docking technique for the UCL. STUDY DESIGN: Controlled laboratory study. METHODS: Nine matched pairs of fresh-frozen cadaveric elbows were potted with the forearm in neutral rotation. The palmaris longus tendon graft was harvested, and the bone was sectioned 14 cm proximal and distal to the elbow joint. First, native UCL testing was performed at 90° of flexion with 0.5 N·m preload, followed by a 5 N·m valgus moment to the elbow in cycles of 1, 10, 100, and 1000 at 1 Hz. The specimens were then loaded to failure at a rate of 0.2 mm/s. Next, the elbows were randomly divided into matched pairs to undergo either UCL reconstruction with docking technique or UCL repair augmented with internal bracing. Last, these specimens underwent testing as aforementioned. RESULTS: Load to failure, gapping, and valgus opening angle did not differ significantly between native ligaments that underwent reconstruction or repair with internal bracing, paired native ligaments and reconstructions, paired native ligaments and repairs augmented with internal bracing, or reconstructions and repairs augmented with internal bracing. CONCLUSION: UCL reconstruction with docking technique and repair augmented with internal bracing provides valgus stability to the medial elbow comparable to the native ligament at 90°. No significant differences were noted between docking reconstruction and repair techniques for load to failure, gapping, or valgus opening angle during cyclic loading at time zero. CLINICAL RELEVANCE: Our results suggest that UCL repair with internal bracing has a similar biomechanical profile at the time of initial fixation compared with the docking technique of UCL reconstruction.

Lineage-Specific Wnt Reporter Elucidates Mesenchymal Wnt Signaling during Bone Repair.

ß-Catenin-dependent Wnt signaling controls numerous aspects of skeletal development and postnatal bone repair. Currently available transgenic Wnt reporter mice allow for visualization of global canonical Wnt signaling activity within skeletal tissues, without delineation of cell type. This is particularly important in a bone repair context, in which the inflammatory phase can obscure the visualization of mesenchymal cell types of interest. To tackle the issue of tissue-specific Wnt signaling, we have generated and characterized a transgenic mouse strain [termed paired related homeobox 1 (Prx1)-Wnt-green fluorescent protein (GFP), by crossing a previously validated Prx1-Cre strain with a nuclear fluorescent reporter driven by T-cell factor/lymphoid enhancer factor activity (Rosa26-Tcf/Lef-LSL-H2B-GFP)]. Prx1-Wnt-GFP animals were subject to three models of long bone and membranous bone repair (displaced forelimb fracture, tibial cortical defect, and frontal bone defect). Results showed that, irrespective of bone type, locoregional mesenchymal cell activation of Wnt signaling occurs in a defined temporospatial pattern among Prx1-Wnt-GFP mice. In summary, Prx1-Wnt-GFP reporter animals allow for improved visualization, spatial discrimination, and facile quantification of Wnt-activated mesenchymal cells within models of adult bone repair.

Effect of shoulder model complexity in upper-body kinematics analysis of the golf swing.

The golf swing is a complex full body movement during which the spine and shoulders are highly involved. In order to determine shoulder kinematics during this movement, multibody kinematics optimization (MKO) can be recommended to limit the effect of the soft tissue artifact and to avoid joint dislocations or bone penetration in reconstructed kinematics. Classically, in golf biomechanics research, the shoulder is represented by a 3 degrees-of-freedom model representing the glenohumeral joint. More complex and physiological models are already provided in the scientific literature. Particularly, the model used in this study was a full body model and also described motions of clavicles and scapulae. This study aimed at quantifying the effect of utilizing a more complex and physiological shoulder model when studying the golf swing. Results obtained on 20 golfers showed that a more complex and physiologically-accurate model can more efficiently track experimental markers, which resulted in differences in joint kinematics. Hence, the model with 3 degrees-of-freedom between the humerus and the thorax may be inadequate when combined with MKO and a more physiological model would be beneficial. Finally, results would also be improved through a subject-specific approach for the determination of the segment lengths.

Resistance exercise and naproxen sodium: effects on a stable PGF2α metabolite and morphological adaptations of the upper body appendicular skeleton.

INTRODUCTION: Exercise-induced inflammation has been shown to be necessary for successful skeletal muscle regeneration post-injury. Accordingly, numerous investigations have demonstrated consequences of COX-inhibitors, anti-inflammatory drugs which prevent prostaglandin formation. In addition to its roles in inflammation, prostaglandin F2α (PGF2α) also mediates vital regenerative processes The majority of research to report consequences of suppressing inflammation has utilized acute injury models in combination with acute COX-inhibitor administration. To address the limited research investigating regular consumption of COX-inhibitors over time in exercising humans, the purpose of this study was to determine effects of a non-selective COX-inhibitor on a PGF2α metabolite and morphological adaptations of the upper body appendicular skeleton during periodized resistance training. Twenty-three (N = 23) recreationally trained college-aged males were randomly assigned to receive placebo (n = 11) or naproxen sodium (n = 12). Treatments were prophylactically administered in double-blind fashion with supervised upper body resistance exercise performed twice per week for 6 weeks. Venous blood was sampled pre- and post-exercise and analyzed for 13, 14-dihydro-15-keto PGF2α using enzyme immunoassay. Factorial mixed-design repeated-measures ANOVAs were utilized to examine relative changes in the plasma PGF2α metabolite and upper body appendicular morphology over the training period. RESULTS: Naproxen sodium significantly reduced the acute PGF2α metabolite response to exercise (p = 0.013); however, this effect diminished over time (p = 0.02), and both treatment groups exhibited significant increases in dominant arm skeletal muscle tissue (p = 0.037). CONCLUSION: Despite acute inhibition of the PGF2α metabolite at early time points, naproxen sodium did not hinder positive morphological adaptations of the upper body in response to resistance training.

Patterns of morphological integration in the appendicular skeleton of mammalian carnivores.

We investigated patterns of evolutionary integration in the appendicular skeleton of mammalian carnivores. The findings are discussed in relation to performance selection in terms of organismal function as a potential mechanism underlying integration. Interspecific shape covariation was quantified by two-block partial least-squares (2B-PLS) analysis of 3D landmark data within a phylogenetic context. Specifically, we compared pairs of anatomically connected bones (within-limbs) and pairs of both serially homologous and functional equivalent bones (between-limbs). The statistical results of all the comparisons suggest that the carnivoran appendicular skeleton is highly integrated. Strikingly, the main shape covariation relates to bone robustness in all cases. A bootstrap test was used to compare the degree of integration between specialized cursorial taxa (i.e., those whose forelimbs are primarily involved in locomotion) and noncursorial species (i.e., those whose forelimbs are involved in more functions than their hindlimb) showed that cursors have a more integrated appendicular skeleton than noncursors. The findings demonstrate that natural selection can influence the pattern and degree of morphological integration by increasing the degree of bone shape covariation in parallel to ecological specialization.

Osteology of Pseudochampsa ischigualastensis gen. et comb. nov. (Archosauriformes: Proterochampsidae) from the early late triassic ischigualasto formation of Northwestern Argentina.

Proterochampsids are crocodile-like, probably semi-aquatic, quadrupedal archosauriforms characterized by an elongated and dorsoventrally low skull. The group is endemic from the Middle-Late Triassic of South America. The most recently erected proterochampsid species is "Chanaresuchus ischigualastensis", based on a single, fairly complete skeleton from the early Late Triassic Ischigualasto Formation of northwestern Argentina. We describe here in detail the non-braincase cranial and postcranial anatomy of this species and revisit its taxonomy and phylogenetic relationships. The phylogenetic analysis recovered 'Chanaresuchus ischigualastensis' as part of a trichotomy together with Gualosuchus reigi and Chanaresuchus bonapartei. Accordingly, "Chanaresuchus ischigualastensis" can be potentially more closely related to Gualosuchus reigi, or even Rhadinosuchus gracilis, than to Chanaresuchus bonapartei. In addition, after discussing previously claimed synapomorphies of Chanaresuchus, we could not find unambiguous support for the monophyly of the genus. As a result, we propose here the erection of the new genus Pseudochampsa for 'Chanaresuchus ischigualastensis', which results in the new combination Pseudochampsa ischigualastensis. The information provided here about the anatomy and taxonomy of Pseudochampsa ischiguaslastensis will be useful for future quantitative analyses focused on the biogeography and macroevolutionary history of proterochampsids.

A three-dimensional analysis of the morphological evolution and locomotor behaviour of the carnivoran hind limb.

BACKGROUND: The shape of the appendicular bones in mammals usually reflects adaptations towards different locomotor abilities. However, other aspects such as body size and phylogeny also play an important role in shaping bone design.We used 3D landmark-based geometric morphometrics to analyse the shape of the hind limb bones (i.e., femur, tibia, and pelvic girdle bones) of living and extinct terrestrial carnivorans (Mammalia, Carnivora) to quantitatively investigate the influence of body size, phylogeny, and locomotor behaviour in shaping the morphology of these bones. We also investigated the main patterns of morphological variation within a phylogenetic context. RESULTS: Size and phylogeny strongly influence the shape of the hind limb bones. In contrast, adaptations towards different modes of locomotion seem to have little influence. Principal Components Analysis and the study of phylomorphospaces suggest that the main source of variation in bone shape is a gradient of slenderness-robustness. CONCLUSION: The shape of the hind limb bones is strongly influenced by body size and phylogeny, but not to a similar degree by locomotor behaviour. The slender-robust "morphological bipolarity" found in bone shape variability is probably related to a trade-off between maintaining energetic efficiency and withstanding resistance to stresses. The balance involved in this trade-off impedes the evolution of high phenotypic variability. In fact, both morphological extremes (slender/robust) are adaptive in different selective contexts and lead to a convergence in shape among taxa with extremely different ecologies but with similar biomechanical demands. Strikingly, this "one-to-many mapping" pattern of evolution between morphology and ecology in hind limb bones is in complete contrast to the "many-to-one mapping" pattern found in the evolution of carnivoran skull shape. The results suggest that there are more constraints in the evolution of the shape of the appendicular skeleton than in that of skull shape because of the strong biomechanical constraints imposed by terrestrial locomotion.

Short-term exercise-induced improvements in bone properties are for the most part not maintained during aging in hamsters.

Physical exercise during growth affects composition, structure and mechanical properties of bone. In this study we investigated whether the beneficial effects of exercise during the early growth phase have long-lasting effects or not. Female Syrian golden hamsters (total n=152) were used in this study. Half of the hamsters had access to running wheels during their rapid growth phase (from 1 to 3months of age). The hamsters were sacrificed at the ages of 1, 3, 12, and 15months. The diaphysis of the mineralized humerus was analyzed with microCT and subjected to three-point-bending mechanical testing. The trabecular bone in the tibial metaphysis was also analyzed with microCT. The collagen matrix of the humerus bone was studied by tensile testing after decalcification. The weight of the hamsters as well as the length of the bone and the volumetric bone mineral density (BMDvol) of the humerus was higher in the running group at the early age (3months). Moreover, the mineralized bone showed improved mechanical properties in humerus and had greater trabecular thickness in the subchondral bone of tibia in the runners. However, by the age of 12 and 15months, these differences were equalized with the sedentary group. The tensile strength and Young's modulus of decalcified humerus were higher in the runners at early stage, indicating a stronger collagen network. In tibial metaphysis, trabecular thickness was significantly higher for the runners in the old age groups (12 and 15months). Our study demonstrates that physical exercise during growth improves either directly or indirectly through weight gain bone properties of the hamsters. However, the beneficial effects were for the most part not maintained during aging.

The upper limb of Australopithecus sediba.

The evolution of the human upper limb involved a change in function from its use for both locomotion and prehension (as in apes) to a predominantly prehensile and manipulative role. Well-preserved forelimb remains of 1.98-million-year-old Australopithecus sediba from Malapa, South Africa, contribute to our understanding of this evolutionary transition. Whereas other aspects of their postcranial anatomy evince mosaic combinations of primitive (australopith-like) and derived (Homo-like) features, the upper limbs (excluding the hand and wrist) of the Malapa hominins are predominantly primitive and suggest the retention of substantial climbing and suspensory ability. The use of the forelimb primarily for prehension and manipulation appears to arise later, likely with the emergence of Homo erectus.

Specialized connective tissue: bone, the structural framework of the upper extremity.

Bone is a connective tissue containing cells, fibers, and ground substance. There are many functions in the body in which the bone participates, such as storing minerals, providing internal support, protecting vital organs, enabling movement, and providing attachment sites for muscles and tendons. Bone is unique because its collagen framework absorbs energy, whereas the mineral encased within the matrix allows bone to resist deformation. This article provides an overview of the structure and function of bone tissue from a macroscopic to microscopic level and discusses the physiological processes contributing to upper extremity bone health. It concludes by discussing common conditions influencing upper extremity bone health.

A meta-analysis of bone mineral density in collegiate female athletes.

PURPOSE: In a number of small studies focused on one or two sports, exercise and competitive level has been observed to favor attainment of higher bone mineral density (BMD) in otherwise healthy athletes. We analyzed merged data from 10 studies to determine the effects of competitive level on upper extremity BMD in female athletes across multiple sports. METHODS: This study is a meta-analysis of 10 articles reporting results of similar case-control and cross-sectional studies of BMD in female athletes and nonathletes reporting an effect of athletic participation level. Upper extremity BMD was modeled as an outcome of the level of athleticism using a categorical weighted least squares model and controlling for upper-body impact, age, and body mass index. RESULTS: Upper extremity BMD significantly increased for each level of participation (ß = 0.140; 95% CI, 0.047-0.234), Age and body mass index approached significance but the level of upper extremity impact was not significant in the final model. CONCLUSIONS: Clinicians may see iteratively greater BMD in female patients who compete at increasingly intense athletic levels, with elite athletes having much higher BMD than other patients who are either active or not. Further research is needed to identify direction and causality of the relationship between competitive level and BMD.

Enthesopathies as occupational stress markers: evidence from the upper limb.

Enthesopathies--that is, "musculo-skeletal stress markers"--are frequently used to reconstruct past lifestyles and activity patterns. Relatively little attention has been paid in physical anthropology to methodological gaps implicit in this approach: almost all methods previously employed neglect current medical insights into enthesopathies and the distinction between healthy and pathological aspects has been arbitrary. This study presents a new visual method of studying fibrocartilaginous enthesopathies of the upper limb (modified from Villotte: Bull Mém Soc Anthropol Paris n.s. 18 (2006) 65-85), and application of this method to 367 males who died between the 18th and 20th centuries, from four European identified skeletal collections: the Christ Church Spitalfields Collection, the identified skeletal collection of the anthropological museum of the University of Coimbra, and the Sassari and Bologna collections of the museum of Anthropology, University of Bologna. The analysis, using generalized estimating equations to model repeated binary outcome variables, has established a strong link between enthesopathies and physical activity: men with occupations involving heavy manual tasks have significantly (P-value < 0.001) more lesions of the upper limbs than nonmanual and light manual workers. Probability of the presence of an enthesopathy also increases with age and is higher for the right side compared with the left. Our study failed to distinguish significant differences between the collections when adjusted for the other effects. It appears that enthesopathies can be used to reconstruct past lifestyles of populations if physical anthropologists: 1) pay attention to the choice of entheses in their studies and 2) use appropriate methods.

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 11.1mm, 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.

Complete 3D kinematics of upper extremity functional tasks.

Upper extremity (UX) movement analysis by means of 3D kinematics has the potential to become an important clinical evaluation method. However, no standardized protocol for clinical application has yet been developed, that includes the whole upper limb. Standardization problems include the lack of a single representative function, the wide range of motion of joints and the complexity of the anatomical structures. A useful protocol would focus on the functional status of the arm and particularly the orientation of the hand. The aim of this work was to develop a standardized measurement method for unconstrained movement analysis of the UX that includes hand orientation, for a set of functional tasks for the UX and obtain normative values. Ten healthy subjects performed four representative activities of daily living (ADL). In addition, six standard active range of motion (ROM) tasks were executed. Joint angles of the wrist, elbow, shoulder and scapula were analyzed throughout each ADL task and minimum/maximum angles were determined from the ROM tasks. Characteristic trajectories were found for the ADL tasks, standard deviations were generally small and ROM results were consistent with the literature. The results of this study could form the normative basis for the development of a 'UX analysis report' equivalent to the 'gait analysis report' and would allow for future comparisons with pediatric and/or pathologic movement patterns.

Shoulder motion analysis using simultaneous skin shape registration.

A new non-invasive approach is proposed to study joint motions. It is based on dynamic tracking of the skin shape. A robust simultaneous registration algorithm (Iterative Median Closest Point) is used to follow the evolving shape and compute the rigid motion of the underlying bone structures. This new method relies on the differentiation of the rigid and elastic parts of the shape motion. A skin marker network is tracked by a set of infrared cameras. Unlike usual techniques, the algorithm tracks the instantaneous polyhedral shape embedding this network. This innovating approach is expected to minimize bias effect of skin sweeps and give some new information about the underlying soft tissue activities. Current application addresses the motion of the shoulder complex (humerus, clavicle and scapula). It is compared with two marker-based methods published in the literature. Preliminary results show significant differences between these three approaches. The new approach measurements give rise to greater rotations.

Age estimation in the Mediterranean bottlenose dolphin Tursiops truncatus (Montagu 1821) by bone density of the thoracic limb.

The determination of age is an important step in defining the life history traits of individuals and populations. Age determination of odontocetes is mainly based on counting annual growth layer groups in the teeth. However, this useful method is always invasive, requiring the cutting of at least one tooth, and sometimes the results are difficult to interpret. Based on the concept that bone matrix is constantly deposited throughout life, we analysed the bone mineral density of the arm and forearm of a series of bottlenose dolphins (Tursiops truncatus, Montagu 1821) stranded along the Italian coast of the Adriatic Sea or maintained in confined waters. The bone mineral density values we obtained were evaluated as possible age predictors of the Mediterranean population of this species, considering age as determined by counting growth layer groups in sections of the teeth and the total body length of the animal as references. Comparisons between left and right flipper showed no difference. Our results show that bone mineral density values of the thoracic limb are indeed reliable age predictors in Tursiops truncatus. Further investigations in additional odontocete species are necessary to provide strong evidence of the reliability of bone mineral density as an indicator of growth and chronological wear and tear in toothed-whales.

Use of the rat forelimb compression model to create discrete levels of bone damage in vivo.

Skeletal responses to damage are significant for understanding the etiology of stress fractures and possibly osteoporotic fractures. We refined the rat forelimb-loading model to produce a range of sub-fracture damage levels during in vivo cyclic loading. A total of 98 right forelimbs of anesthetized, male, 5-month old Fischer rats were loaded cyclically (2 Hz) in axial compression. Rats were killed immediately after loading. In the first experiment, forelimbs were loaded to fracture, which occurred after an increase in peak displacement of 2.0+/-0.2 mm, independent of peak force or cycle number. In the next experiment, we loaded forelimbs at a constant peak force until the peak displacement increased by 0.6-1.8 mm (30-90% of fracture displacement). Mechanical properties of the loaded (right) and contralateral control (left) ulnae were determined ex vivo using three-point bending, and cracks were analyzed using micro-computed tomography. Results demonstrated a dose-response between increased forelimb displacement and increased ulnar damage, with four discrete damage levels. "Low" damage was produced by cyclic loading to 30% of fracture displacement, with no visible cracks and a 10% strength loss. "Mild" damage was produced by loading to 45% of fracture displacement, with variable linear cracks and 20% strength loss. "Moderate" damage was produced by loading to 60-75% of fracture displacement, with consistent linear cracks and 40% strength loss. "High" damage was produced by loading to 85-90% of fracture displacement, with branching cracks and 60% strength loss. This loading model will be useful for examining biological responses to a range of sub-fracture damage levels in future experiments.

Desenvolvimento e validacao de versao brasileira do questionario de avaliacao funcional dos membros superiores DASH - disabilities of the Arm, Shoulder and Hand / Development and validation of Brazilian version of the questionnaire for assessing performance of senior members DASH - disabilities of the arm, shoulder and hand

O questionario DASH e uma escala de avaliação funcional dos membros superiores, descrito na lingua inglesa em 1996. Tem hoje vinte e cinco versões ingluindo uma brasileira elaborada na Escola Paulista de Medicina (EPM). (AL)

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.