Morphology and Prevalence of the Inferior Transverse Scapular Ligament: Systematic Review, Meta-Analysis, and Proposal for Classification.

Background/Objectives: The suprascapular nerve is most vulnerable to entrapment at the suprascapular and spinoglenoid notches, causing neuropathy. Numerous studies have examined the suprascapular notch and ligament and its relationship with suprascapular nerve entrapment, but few have examined the spinoglenoid notch and the inferior transverse scapular ligament (ITSL). This study summarizes all existing ITSL morphology studies and presents a simple and comprehensive classification system for different ITSL subtypes. Methods: A systematic review of the literature was conducted according to the PRISMA guidelines, searching the online databases PubMed and Embase. The references of each relevant article were further screened to find more eligible studies. The Anatomical Quality Assessment tool was used in order to further evaluate the quality of the records extracted. STATA MP 14 was used for the analysis in this study. Results: In total, 14 studies (995 scapulae; minimum: 1 and maximum: 268) were included in the present study. The overall ITSL prevalence was 5.8 (95% CI: 4.5-7.1) and the estimated odds for ligamentous vs. membranous type was 0.5 (95% CI: 0.3-0.7). The basic different morphological subtypes of the ITSL reported in the included studies are the band-like ligament, the fan-shaped ligament, the membranous ITSL, and the perforated membranous types. Conclusions: The ITSL represents an anatomical structure of mostly ligamentous nature. A single ITSL definition and standardization of its basic morphological subtypes along with an easy-to-remember and thus widely used classification system could greatly facilitate the comprehensive description, identification, and proper handling of this element across many surgical procedures.

Sexual dimorphism and allometry in human scapula shape.

Scapula shape is highly variable across humans and appears to be sexually dimorphic-differing significantly between biological males and females. However, previous investigations of sexual dimorphism in scapula shape have not considered the effects of allometry (the relationship between size and shape). Disentangling allometry from sexual dimorphism is necessary because apparent sex-based differences in shape could be due to inherent differences in body size. This study aimed to investigate sexual dimorphism in scapula shape and examine the role of allometry in sex-based variation. We used three-dimensional geometric morphometrics with Procrustes ANOVA to quantify scapula shape variation associated with sex and size in 125 scapulae. Scapula shape significantly differed between males and females, and males tended to have larger scapulae than females for the same body height. We found that males and females exhibited distinct allometric relationships, and sexually dimorphic shape changes did not align with male- or female-specific allometry. A secondary test revealed that sexual dimorphism in scapula shape persisted between males and females of similar body heights. Overall, our findings indicate that there are sex-based differences in scapula shape that cannot be attributed to size-shape relationships. Our results shed light on the potential role of sexual selection in human shoulder evolution, present new hypotheses for biomechanical differences in shoulder function between sexes, and identify relevant traits for improving sex classification accuracy in forensic analyses.

Effect of Glenoid Bone Loss and Shoulder Position on Axillary Nerve Anatomy During the Latarjet Procedure.

BACKGROUND: The Latarjet procedure is increasingly being utilized for the treatment of glenoid bone loss and has a relatively high neurological complication rate. Understanding the position-dependent anatomy of the axillary nerve (AN) is crucial to preventing injuries. PURPOSE: To quantify the effects of changes in the shoulder position and degree of glenoid bone loss during the Latarjet procedure on the position of the AN. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 10 cadaveric shoulders were dissected, leaving the tendons of the rotator cuff and deltoid for muscle loading. The 3-dimensional position of the AN was quantified relative to the inferior glenoid under 3 conditions: (1) intact shoulder, (2) Latarjet procedure with 15% bone loss, and (3) Latarjet procedure with 30% bone loss. Measurements were obtained at 0°, 30°, and 60° of glenohumeral abduction (equivalent to 0°, 45°, and 90° of shoulder abduction) and at 0°, 45°, and 90° of humeral external rotation (ER). RESULTS: Abduction of the shoulder to 60° resulted in a posterior (9.5 ± 1.1 mm; P < .001), superior (3.0 ± 1.2 mm; P = .013), and lateral (19.1 ± 2.3 mm; P < .001) shift of the AN, and ER to 90° resulted in anterior translation (10.0 ± 1.2 mm; P < .001). Overall, ER increased the minimum AN-glenoid distance at 30° of abduction (14.9 ± 1.3 mm [0° of ER] vs 17.3 ± 1.5 mm [90° of ER]; P = .045). The Latarjet procedure with both 15 and 30% glenoid bone loss resulted in a superior and medial shift of the AN relative to the intact state. A decreased minimum AN-glenoid distance was seen after the Latarjet procedure with 30% bone loss at 60° abduction and 90° ER (17.7 ± 1.6 mm [intact] vs 13.9 ± 1.6 mm [30% bone loss]; P = .007), but no significant differences were seen after the Latarjet procedure with 15% bone loss. CONCLUSION: Abduction of the shoulder induced a superior, lateral, and posterior shift of the AN, and ER caused anterior translation. Interestingly, the Latarjet procedure, when performed on shoulders with extensive glenoid bone loss, significantly reduced the minimum AN-glenoid distance during shoulder abduction and ER. These novel findings imply that patients with substantial glenoid bone loss may be at a higher risk of AN injuries during critical portions of the procedure. Consequently, it is imperative that surgeons account for alterations in nerve anatomy during revision procedures. CLINICAL RELEVANCE: This study attempts to improve understanding of the position-dependent effect of shoulder position and glenoid bone loss after the Latarjet procedure on AN anatomy. Improved knowledge of AN anatomy is crucial to preventing potentially devastating AN injuries during the Latarjet procedure.

Relationship between scapular body morphology and rotator cuff tears: a threedimensional computed tomography study.

The purpose of this study was to identify the relationship between scapula morphology and rotator cuff tears (RCT). Hundred seventeen shoulders with and 87 shoulders without RCTs were included in this retrospective study. The critical shoulder angle (CSA) and lateral acromion angle in the coronal view, and the acromial coverage angle (ACA) and coracoid and scapular spine angle (CSSA) in the sagittal view were evaluated using 3-dimensional computed tomography. The glenoid anterior tilt, anterior acromial projection angle (AAPA), coracoid process angle, scapular spine angle (SSA), and inferior angle angle (IAA) with respect to the scapular plane were measured in the sagittal view. In univariate logistic regression analysis, CSA, ACA, AAPA, SSA, and IAA were significantly greater in shoulders with RCTs, whereas CSSA was greater in shoulders without RCTs. In multivariate logistic regression analysis, CSA and IAA were greater in shoulders with RCT and were significantly associated with this condition (P=.00073, P=.0032). This study has shown us that RCTs were associated with a greater curvature of the scapular body and greater CSA and IAA.

The Foraminal Indices of the Rat Scapula.

The nutritive arteries of bones may be injured due to fracture or surgical procedures. Therefore, there are some studies focused on the location of the nutrient foramen (NF) of bones. Rats are the most preferred animals in experimental studies. The purpose of this study is to expose the locational variations of the NF on the rat (Sprague Dawley) scapula. A total of 60 adult rat scapulae (from 16 male and 14 female rats) were used. The diameters of NFs were measured. The length, width, and distances of the NF to the proximal and cranial edges were measured. Foraminal indices were also calculated. It was determined that the average number of NF per scapula was 1.8. The location of the NFs was 52% on the medial aspect and 48% on the lateral aspect. On the medial aspect of the scapula, NFs were frequently found ventrally, on the neck region of the scapula. Laterally, 40 NFs were found in the ventral region of the infraspinatus fossa and only 12 in the ventral region of the supraspinatus fossa. Longitudinal foraminal index 95% confidence intervals were 74.25-79.18 (lateral) and 71.70-75.97 (medial). Transversal foraminal index 95% confidence intervals were 40.98-45.02 (lateral) and 42.91-46.07 (medial). Diameter of the NF 95% confidence interval was 0.21-0.39 mm. The locational knowledge of the NF can be utilized in anatomical or experimental surgery studies. The cranial and proximal edges of the rat scapula may be palpable; surgeons may palpate these regions and easily evaluate the location of the NFs.

CT anatomical study of extreme lateral interbody fusion in thoracic spine.

Extreme Lateral Interbody Fusion (XLIF) is currently used in the clinical treatment of thoracic spine disorders and has achieved desirable results. In this study, we selected CT images of the thoracic spine from 54 patients and divided the intervertebral spaces into six regions (A, I, II, III, IV, P) using the Moro method. We observed the adjacent relationships between the thoracic spine and surrounding tissues such as the scapula, esophagus, thoracic aorta, and superior vena cava. We made four main findings: firstly, when the scapulae were symmetrical on both sides, over 80% of patients had the T1-4 II-III region obstructed by the scapulae; secondly, when the esophagus was located on the left side of the vertebral body, 3.7% to 24.1% of patients had the T4-9 region located in the II-III zone; furthermore, when the thoracic aorta was on the left side of the vertebral body, over 80% of individuals in the T4-9 segment occupied the II-III region, with the values being 55.5% and 20.4% for T9/10 and T10/11, respectively; finally, the superior vena cava was located on the right side of the T4/5 vertebra, with 3.7% of individuals having it in the II-III region, while on the left side of T5-9, 3.7% to 18.5% of individuals had it in the II-III region. Based on these findings, we suggest that XLIF should not be performed on the T1-4 vertebrae due to scapular obstruction. Selecting the left-sided approach for XLIF in the T4-11 segments may risk injuring the thoracic aorta, esophagus, and superior vena cava, while the T11/12 segment is considered safe and feasible. Choosing the right-sided approach for XLIF may pose a risk of injuring the superior vena cava in the T4/5 segment, but it is safe and feasible in the T5-12 segments.

Anthropometric study of the scapula in a contemporary population from granada. Sex estimation and glenohumeral osteoarthritis prevalence.

Anthropometric studies of the scapula have been rare in Spanish populations, nevertheless they are of current interest in forensic anthropology for estimation of sex. Although the estimation of sex is usually carried out on the pelvis and skull, other measurements related to the scapula can be helpful when the skeletal remains are incomplete. Glenohumeral osteoarthritis development is influenced, among others, by the morphology of the scapula, which is one of the less studied aspects. We carried out a descriptive study of anthropometric parameters in a series of 157 scapulae (82 individuals) on bone remains dated to the 20th century from a population of Granada (Southern Spain). Seventy seven (49%) were right-side and 80 (51%) left-side; 72 (45.9%) were from males and 85 (54.1%) from females, and the mean age at death was 70.76±11.7 years. The objective was to develop a discrimination function for sex estimation based on anthropometric parameters of the scapula other than those considered to date, and to analyze the prevalence of glenohumeral osteoarthritis in relation to selected anthropometric parameters. A logistic regression model based on parameters of the upper-external segment of the scapula was done. The obtained formula: 1/1+e^ (- (-57.911 + 0.350*B + 0283*C + 0.249*b + 0.166*a +-0.100*ß) classifies male sex with 98.3% accuracy and female sex with 92.1%. Glenohumeral osteoarthritis was detected in 16.6% of individuals and was related to age (p<0.05), scapular length (p<0.05), glenoid width (p<0.05), glenopolar angle (p<0.05), and α angle (p<0.05) in bivariate analyses but showed no significant associations in multivariate analyses. This approach can be useful for anthropological-forensic identification when scapula remains are incomplete. Glenohumeral osteoarthritis is significantly associated with a smaller α angle.

Surface anatomy and levator scapulae muscle injection: A cadaveric investigation.

Accurate detection of the levator scapulae muscle is critical for effective diagnostic and therapeutic interventions. The commonly used surface anatomy approach has not been validated and is less accurate than ultrasound-guided techniques. Therefore, we determined the needle insertion point for the levator scapulae using a new technique based on the anatomy of the scapula. This investigation used 15 fresh-frozen cadavers to explore the relationship between the acromial angle and medial tip of the scapular spine (O) of the scapular spine. Based on the x-axis (the distance [L] from Point O to point acromial angle) and the y-axis perpendicular to the x-axis passing through Point O, the barycentric coordinates were determined through the intersections of each axis and the superior angle of the scapula with the levator scapulae. Various ratios involving the established distance L) were ascertained, we compared the measurements and ratios between the male and female groups, and the accuracy of the new technique was compared with the conventional technique. The optimal site of the new technique was within 6 to 7% of distance L on the x-axis and 42 to 44% of distance L on the y-axis. This technique was significantly more accurate than the conventional technique (P = .006). Although ultrasound allows for accurate injections via real-time visualization, its unavailability in some cases highlights the importance of understanding surface anatomy landmarks. Our new technique, based on the anatomy of the scapula and relative measurements, is more accurate than the conventional technique. This should enable more precise detection of the levator scapulae for accurate and efficient diagnostic and therapeutic procedures.

A scapular statistical shape model can reliably predict premorbid glenoid morphology in conditions of severe glenoid bone loss.

BACKGROUND: Knowledge of premorbid glenoid parameters at the time of shoulder arthroplasty, such as inclination, version, joint line position, height, and width, can assist with implant selection, implant positioning, metal augment sizing, and/or bone graft dimensions. The objective of this study was to validate a scapular statistical shape model (SSM) in predicting patient-specific glenoid morphology in scapulae with clinically relevant glenoid erosion patterns. METHODS: Computed tomography scans of 30 healthy scapulae were obtained and used as the control group. Each scapula was then virtually eroded to create 7 erosion patterns (Walch A1, A2, B2, B3, D, Favard E2, and E3). This resulted in 210 uniquely eroded glenoid models, forming the eroded glenoid group. A scapular SSM, created from a different database of 85 healthy scapulae, was then applied to each eroded scapula to predict the premorbid glenoid morphology. The premorbid glenoid inclination, version, height, width, radius of best-fit sphere, and glenoid joint line position were automatically calculated for each of the 210 eroded glenoids. The mean values for all outcome variables were compared across all erosion types between the healthy, eroded, and SSM-predicted groups using a 2-way repeated measures analysis of variance. RESULTS: The SSM was able to predict the mean premorbid glenoid parameters of the eroded glenoids with a mean absolute difference of 3° ± 2° for inclination, 3° ± 2° for version, 2 ± 1 mm for glenoid height, 2 ± 1 mm for glenoid width, 5 ± 4 mm for radius of best-fit sphere, and 1 ± 1 mm for glenoid joint line. The mean SSM-predicted values for inclination, version, height, width, and radius were not significantly different than the control group (P > .05). DISCUSSION: An SSM has been developed that can reliably predict premorbid glenoid morphology and glenoid indices in patients with common glenoid erosion patterns. This technology can serve as a useful template to visually represent the premorbid healthy glenoid in patients with severe glenoid bony erosions. Knowledge of the premorbid glenoid preoperatively can assist with implant selection, positioning, and sizing.

Variations in the Anatomic Morphology of the Scapular Spine and Implications on Fracture After Reverse Shoulder Arthroplasty.

INTRODUCTION: This study evaluates the role of anatomic scapular morphology in acromion and scapular spine fracture (SSAF) risk after reverse shoulder arthroplasty (RSA). METHODS: Twelve scapular measurements were captured based on pilot study data, including scapular width measurements at the acromion (Z1), middle of the scapular spine (Z2), and medial to the first major angulation (Z3). Measurements were applied to 3D-CT scans from patients who sustained SSAF after RSA (SSAF group) and compared with those who did not (control group). Measurements were done by four investigators, and the intraclass correlation coefficient was calculated. Regression analysis determined trends in fracture incidence. RESULTS: One hundred forty-nine patients from two separate surgeons (J.L., A.M.) were matched by age and surgical indication of whom 51 sustained SSAF after reverse shoulder arthroplasty. Average ages for the SSAF and control cohorts were 78.6 and 72.1 years, respectively. Among the SSAF group, 15 were Levy type I, 26 Levy type II, and 10 Levy type 3 fractures. The intraclass correlation coefficient of Z1, Z2, and Z3 measurements was excellent (0.92, 0.92, and 0.94, respectively). Zone 1 and 3 measurements for the control group were 18.6 ± 3.7 mm and 3.2 ± 1.0 mm, respectively, compared with 22.5 ± 5.9 mm and 2.0 ± 0.70 mm in the SSAF group, respectively. The fracture group trended toward larger Z1 and smaller Z3 measurements. The average scapular spine proportion (SSP), Z1/Z3, was significantly greater in the control 6.20 ± 1.80 versus (12.60 ± 6.30; P < 0.05). Regression analysis showed a scapular spine proportion of ≤5 was associated with a fracture risk <5%, whereas an SSP of 9.2 correlated with a 50% fracture risk. DISCUSSION: Patients with a thicker acromions (Z1) and thinner medial scapular spines (Z3) have increased fracture risk. Understanding anatomic scapular morphology may allow for better identification of high-risk patients preoperatively.

Functional and morphological divergence in the forelimb musculoskeletal system of scratch-digging subterranean mammals (Rodentia: Bathyergidae).

Whether the forelimb-digging apparatus of tooth-digging subterranean mammals has similar levels of specialization as compared to scratch-diggers is still unknown. We assessed the scapular morphology and forelimb musculature of all four solitary African mole rats (Bathyergidae): two scratch-diggers, Bathyergus suillus and Bathyergus janetta, and two chisel-tooth diggers, Heliophobius argenteocinereus and Georychus capensis. Remarkable differences were detected: Bathyergus have more robust neck, shoulder, and forearm muscles as compared to the other genera. Some muscles in Bathyergus were also fused and often showing wider attachment areas to bones, which correlate well with its more robust and larger scapula, and its wider and medially oriented olecranon. This suggests that shoulder, elbow, and wrist work in synergy in Bathyergus for generating greater out-forces and that the scapula and proximal ulna play fundamental roles as pivots to maximize and accommodate specialized muscles for better (i) glenohumeral and scapular stabilization, (ii) powerful shoulder flexion, (iii) extension of the elbow and (iv) flexion of the manus and digits. Moreover, although all bathyergids showed a similar set of muscles, Heliophobius lacked the m. tensor fasciae antebrachii (aiding with elbow extension and humeral retraction), and Heliophobius and Georychus lacked the m. articularis humeri (aiding with humeral adduction), indicating deeper morphogenetic differences among digging groups and suggesting a relatively less specialized scratch-digging ability. Nevertheless, Heliophobius and Bathyergus shared some similar adaptations allowing scratch-digging. Our results provide new information about the morphological divergence within this family associated with the specialization to distinct functions and digging behaviors, thus contributing to understand the mosaic of adaptations emerging in phylogenetically and ecologically closer subterranean taxa. This and previous anatomical studies on the Bathyergidae will provide researchers with a substantial basis on the form and function of the musculoskeletal system for future kinematic investigations of digging behavior, as well as to define potential indicators of scratch-digging ability.

Age Estimation Based on Computed Tomography Analysis of the Scapula.

Background and Objectives: Age estimation from skeletal remains and in living individuals is an important issue for human identification, and also plays a critical role in judicial proceedings for migrants. Forensic analysis of ossification centers is the main evaluation method for age estimation, and ossification degree can be determined using computed tomography analysis. The purpose of this study is to investigate the applicability of CT (computed tomography) in the analysis of left scapula ossification centers, for forensic age estimation in Turkish society. Materials and Methods: We analyzed six ossification centers of the left scapula and these ossification centers are the coracoid, subcoracoid, coracoid apex, acromial, glenoid, and inferior angle ossification centers. A pediatric radiologist analyzed these six ossification centers of the scapula by using a staging method defined by Schmeling et al. in 2004. Two months after the first assessment, 20 randomly selected cases was reanalyzed by the first observer and by another pediatric radiologist. Correlation between the age and ossification stage was assessed using Spearman's nonparametric correlation test. Linear regression analysis was performed using a backwards model. Cohen's kappa coefficient was used for evaluating interobserver and intraobserver variability. Results: In this retrospective study, 397 (248 male and 149 female) cases were evaluated. Ages ranged between 7.1 and 30.9. The mean age was 19.83 ± 6.49. We determined a positive significant correlation between the age and the ossification stages of ossification centers analyzed in both sexes. In each ossification center, except inferior angle, all of the stage 1 and 2 cases in both sexes were under 18 years old. Intraobserver and interobserver evaluations showed that reproducibility and consistency of the method was relatively good. Conclusions: The present study indicated that CT analysis of scapula ossification centers might be helpful in forensic age assessment of living individuals and dry bones.

A Morphometric Study of Glenoid Cavity of Scapula in Bangladeshi Population.

This cross-sectional descriptive purposive study was conducted among 150 (70 right and 80 left) fully ossified dry human scapulae of Bangladeshi people from January 2019 to December 2019 in the Department of Anatomy, Mymensingh Medical College, Mymensingh. Shape of the glenoid cavity was observed as pear, oval or inverted comma shape. Morphometric parameters such as length and breadth of glenoid cavity were measured by digital Vernier slide calipers. In this study, 19.13% cases were found inverted comma shaped, 35.65% cases were oval and 45.22% cases were pear shaped. The mean±SD length of glenoid cavity was 37.5±3.61 mm and 36.19±3.68 mm on right and left sided scapulae respectively and mean±SD breadth was 23.6±2.73 mm on right and 23.42±2.75 mm on left side respectively. Mean±SD glenoid cavity index was 62.89±4.39 on right and 64.61±4.74 on left sided scapulae. Morphometric analysis of glenoid fossa of scapula might help clinicians in shoulder and its associated diseases.

Scapulohumeral Spaces: Concordance and Proposal for Terminologia Anatomica / Espacios Escapulohumerales: Concordancia y Propuesta a la Terminologia Anatomica

SUMMARY: The updating of anatomical terms is essential to facilitate teaching and learning as well as international communication through publications and presentations at scientific events. In the posterior wall of the axilla, the teres major, teres minor and triceps brachii muscles form three spaces through which neurovascular structures of clinical significance run. The current study seeks to define and propose terms for these spaces which have been omitted by Terminologia Anatomica. The definition of the Latin term 'Spatium' was investigated using A Latin Dicionary, while the term 'Espacio' was analyzed using Diccionario panhispánico de términos médicos (Real Academia Nacional de Medicina de España, 2023), as well as the lexemes of the words 'scapula' and 'humerus', for which the Diccionario Médico-Biológico, Histórico y Etimológico de la Universidad de Salamanca was consulted. The presence of the term 'Spatium' in the Terminologia Anatomica was also investigated. Finally, 10 anatomy textbooks in Spanish were reviewed to identify the terms used for these spaces. In reviewing the latest edition of Terminologia Anatomica, it was found that the term 'Spatium' appears 25 times in different chapters and it was evident that no terms for scapulohumeral spaces appear in the chapters on upper limb structures. Moreover, in 100 % of the anatomy textbooks reviewed, at least one term is used to describe the scapulohumeral spaces. We believe that the proposed terms: 'Spatium humerotricipitale', 'Spatium scapulotricipitale' and 'Spatium teretricipitale' more accurately describe both the location and their association with the bone/muscle structures that form them. We therefore suggest that these terms be revised for inclusion in future editions of Terminologia Anatomica.

La actualización de términos anatómicos es esencial para facilitar la enseñanza-aprendizaje y comunicación internacional a través de publicaciones y presentaciones en eventos científicos. En la pared posterior de la axila, los músculos redondo mayor, redondo menor y tríceps braquial, forman tres espacios por donde discurren estructuras neurovasculares relevantes en la clínica. El estudio tuvo como objetivo definir y proponer términos para estos espacios omitidos por Terminologia Anatomica. En el diccionario A Latin Dictionary se investigó la definición en latín del término 'Spatium' y 'Espacio' en el Diccionario panhispánico de términos médicos (Real Academia Nacional de Medicina de España, 2023), además de los lexemas de las palabras 'escápula' y 'húmero' en el Diccionario Médico-Biológico, Histórico y Etimológico de la Universidad de Salamanca. También se investigó la presencia del término 'Spatium' en la Terminologia Anatomica. Por último, se revisaron 10 libros-textos de anatomía en español para identificar los términos utilizados para estos espacios y su relevancia clínica. Al revisar la última edición de Terminologia Anatomica, se observó que el término 'Spatium' aparece 25 veces en distintos capítulos y se evidenció que no aparecen términos para los espacios escapulohumerales en los capítulos de miembro superior. Además, en el 100 % de los libros-textos de anatomía revisados, se utiliza al menos un término para describir a los espacios escapulohumerales. Consideramos que los términos propuestos: 'Spatium humerotricipitale', 'Spatium scapulotricipitale' y 'Spatium teretricipitale' aluden con mayor precisión a la ubicación, ya que relaciona a las estructuras óseas y/ o musculares que lo forman. Por lo que sugerimos que estos términos sean revisados para incluirlos en futuras ediciones de Terminologia Anatomica.

Morphological variation, modularity and integration in the scapula and humerus of Lissotriton newts.

The modular organization of tetrapod paired limbs and girdles, influenced by the expression of Hox genes is one of the primary driving forces of the evolution of animal locomotion. The increased morphological diversification of the paired limbs is correlated with reduced between-limb covariation, while correlation within the elements is usually higher than between the elements. The tailed amphibians, such as Lissotriton newts, have a biphasic lifestyle with aquatic and terrestrial environments imposing different constraints on limb skeleton. By employing the methods of computerized microtomography and 3D geometric morphometrics, we explored the pattern of morphological variation, disparity, modularity and morphological integration in the proximal parts of the anterior limbs of six species of Eurasian small bodied newts. Although the species significantly differ in limb shape, there is a great overlap in morphology of scapula and humerus, and there are no differences in morphological disparity. For the scapula, the shape differences related to the duration of the aquatic period are in length, depth and curvature. The shape of the humerus is not affected by the length of aquatic period, and shape differences between the species are related to robustness of the body. The length of aquatic period has statistically supported phylogenetic signal. The scapula and humerus are structures of varying modularity. For the humerus, the strongest support on the phylogenetic level was for the capitulum/shaft hypothesis, which can also be interpreted as functional modularity. For the scapula, the greatest support was for the antero-posterior hypothesis of modularity in case of Lissotriton vulgaris, which can be explained by different functional roles and muscle insertion patterns, while there was no phylogenetic modularity. The modularity patterns seem to correspond with the general tetrapod pattern, with modularity being more pronounced in the distal structure. The future research should include more salamandrid taxa with different habitat preferences and both adult and larval stages, in order to explore how size, phylogeny and ecology affect the morphology and covariation patterns of limbs.

Scapular morphology variation affects reverse total shoulder arthroplasty biomechanics. A predictive simulation study using statistical and musculoskeletal shoulder models.

Reverse total shoulder arthroplasty (RTSA) accounts for over half of shoulder replacement surgeries. At present, the optimal position of RTSA components is unknown. Previous biomechanical studies have investigated the effect of construct placement to quantify mobility, stability and functionality postoperatively. While studies have provided valuable information on construct design and surgical placement, they have not systematically evaluated the importance of scapular morphology on biomechanical outcomes. The aim of this study was to assess the influence of scapular morphology variation on RTSA biomechanics using statistical models, musculoskeletal modeling and predictive simulation. The scapular geometry of a musculoskeletal model was altered across six modes of variation at four levels (±1 and ±3 SD) from a clinically derived statistical shape model. For each model, a standardized virtual surgery was performed to place RTSA components in the same relative position on each model then implemented in 50 predictive simulations of upward and lateral reaching tasks. Results showed morphology affected functional changes in the deltoid moment arms and recruitment for the two tasks. Variation of the anatomy that reduced the efficiency of the deltoids showed increased levels of muscle force production, joint load magnitude and shear. These findings suggest that scapular morphology plays an important role in postoperative biomechanical function of the shoulder with an implanted RTSA. Furthermore a "one-size-fits-all" approach for construct surgical placement may lead to suboptimal patient outcomes across a clinical population. Patient glenoid as well as scapular anatomy may need to be carefully considered when planning RTSA to optimize postoperative success.

Validation of age estimation methods through the scapula in a Mediterranean non-adult population.

Age estimation methods through the metric study of bones in non-adult individuals are a frequently used tool in Biological and Forensic Anthropology; however, few methodological validation studies are available, given the limited number of adequate samples for their study. In this context, the aim of this work is to test the effectiveness of the methods of Fazekas and Kósa (1978), Saunders et al. (1993), Rissech and Black (2007) and Cardoso et al. (2017), for age estimation through the measurements of the scapula, in the non-adult osteological collection of the Anthropology Laboratory of the University of Granada (Spain), one of the most representative identified non-adult collections internationally. For this purpose, nine different measurements of the scapula were taken from a total of 149 non-adult individuals, applying the regression formulae proposed by the different authors and verifying their accuracy. Results have shown the existence of significant differences between the real age and the estimated age in almost all the tested methods, with degrees of error that differ from those obtained in the original study populations. Based on the obtained results, it is recommended to use the method of Cardoso et al. in postnatal individuals, always adjusting the degrees of error with those obtained in this work.

Variation of Acromiocoracoid and Acromioglenoid Distance in Bangladeshi People.

This cross-sectional descriptive purposive study was done on 150 (70 right and 80 left) fully ossified dry human scapulae of Bangladeshi people to find out the variation in length of acromiocoracoid and acromioglenoid distance. Sample collection was carried out in the Department of Anatomy, Mymensingh Medical College, Bangladesh from January to December 2019. Any kind of damaged or broken scapulae were excluded to maintain standard measurement. Length of these distances was measured with the help of digital Vernier slide calipers. The mean±SD acromiocoracoid distance were 35.8±4.64 mm and 36.32±5.55 mm on right and left sided scapulae respectively and the mean±SD acromioglenoid distance were 27.69±3.43 mm on right sided scapulae and 28.18±3.26 mm on left sided scapulae. These data are important to compare Bangladeshi scapulae to those from various other races that could contribute to demographic studies of shoulder disease probability and management in Bangladeshi population.

Does Morphology of the Shoulder Joint Play a Role in the Etiology of Rotator Cuff Tear?

BACKGROUND: The etiology of rotator cuff tears (RCTs) have been investigated for years and many underlying causes have been identified. Shoulder joint morphology is one of the extrinsic causes of RCTs. AIM: Morphometric measurements on MRI sections determined which parameters are an important indicator of RCT in patients with shoulder pain. The aim of this study was to determine the risk factors in the etiology of RCTs by evaluating the shoulder joint morphology with the help of previously defined radiological parameters. METHOD: Between January 2019-December 2020, 408 patients (40-70 years old) who underwent shoulder MRI and met the criteria were included in the study. There were 202 patients in the RCT group and 206 patients in the control group. Acromion type, acromial index (AI), critical shoulder angle (CSA), acromiohumeral distance (AHD), lateral acromial angle (LAA), acromial angulation (AA), acromion-greater tuberosity impingement index (ATI), and glenoid version angle (GVA) were measured from the MRI images of the patients. RESULTS: AI (0.64 vs. 0.60, p = 0.003) CSA (35.3° vs. 32.4°, p = 0.004), ATI (0.91 vs. 0.83, P < 0.001), and AA (13.6° vs. 11.9°, p = 0.011) values were higher in the RCT group than in the control group and the difference was significant. AHD (8.1 mm vs. 9.9 mm, P < 0.001), LAA (77.2° vs. 80.9°, p = 0.004) and GVA (-3.9° vs. -2.5°, P < 0.001) values were lower in the RCT group than in the control group, and again the difference was significant. According to the receiver operating characteristic curve analysis, the cutoff values were 0.623 for AI and 0.860 for ATI. CONCLUSION: Acromion type, AI, CSA, AHD, LAA, AA, ATI, and GVA are suitable radiological parameters to evaluate shoulder joint morphology. High AI, CSA, AA, ATI, GVA and low AHD and LAA are risk factors for RCT.

Assigned sex estimation with the clavicle and scapula: A study in a Portuguese reference sample.

The estimation of biological sex is a critical step in the assessment of the biological profile of an anonymous skeletonized individual. In certain recovery circumstances, the most dimorphic skeletal areas, such as the pelvis, are absent or fragmented; in that case, other bones of the skeleton, including the clavicle and scapula, can be used to predict sex. The purpose of this research is to generate new models for the estimation of sex with clavicular and scapular measurements using a study-sample of 129 individuals with clavicle (65 males and 64 females) and 112 individuals with scapula (50 males and 62 females) from the Lisbon Identified Skeletal Collection (Portugal). A decision tree classifier (C4.5) and logistic regression (LR) were employed to create univariable and multivariable sex prediction models. Accuracy under cross-validation of the classification models is high (up to 93.8%), with minimal bias (<5%), particularly in the multivariable models. The proposed LR models facilitate the probabilistic estimation of biological sex, accounting for the significant overlap in the expression of sexual dimorphism.