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Measurements of acromial index (AI) and critical shoulder angle (CSA) on anteroposterior shoulder radiograph. The AI is the ratio of the distance between the glenoid plane and acromial plane (GA) to the distance between the glenoid plane and humeral plane (GH). The CSA is the angle formed by a line connecting the superior and inferior aspects of the glenoid and a line connecting the inferior aspect of the glenoid fossa to the lateral-most point of the acromion.
Source publication
Background:
The lateral extension of the acromion from the glenohumeral joint is the critical variable that both the acromial index and critical shoulder angle reflect. The purpose of this study was to establish a simple and reproducible method to directly measure the lateral extension of the acromion that will be independent of patient demographi...
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Background
A large critical shoulder angle (CSA) >35° is associated with the development of rotator cuff tearing. Lateral acromioplasty (AP) has the theoretical potential to prevent rotator cuff tearing and/ or to reduce the risk of re-tears after repair. It is, however unclear which part of the lateral acromion has to be reduced to obtain the desi...
Citations
... The acromial and coracoid processes have been the subject of multiple studies regarding the variations in their morphology and their association to shoulder pathology [24,28,31]. A high variability seems to predominate in some studies [1,9,10,20,31,37]. However, the prevalence of morphometric parameters in relation to age and gender in asymptomatic subjects have not been reported in our population. ...
... The AcT classification described by Bigliani et al. [8], although subjective, has been widely reported and used to compare variation between populations. Hence, the importance of analyzing images in a systematic and reproducible manner to avoid offset in measurements hypothesizing erroneous conclusions [10,11,37]. The modified Epstein classification was chosen, as it has better inter-observer reliability than the Bigliani and acromial angle classification when assessing the AcT [36]. ...
PurposeThe acromial and coracoid process morphology is of clinical relevance due to associations with functional limitations and shoulder pathology. Our objective was to describe the anatomical characteristics of the acromial and coracoid process using computed tomography (CT).Methods
Descriptive, observational, transversal and retrospective study. A total of 155 CT of patients without shoulder pathology, of both genders, and indistinct age were evaluated and grouped by age: Group 1 < 25 years; group 2 25–40 years; group 3 > 40 years. The following parameters were evaluated: Acromial type (AcT), vertical coracoid distance (VCD), acromial tilt (AT), acromial projection (AP), critical shoulder angle (CSA), type of the subcoracoid outlet (TSO), and the area of the subcoracoid outlet (ASO).ResultsStatistically significant differences were found between men and women for VCD (14.44 ± 4.79 vs. 11.76 ± 4.00 mm; p < 0.001) and AP (3.66 ± 4.71 vs. 1.62 ± 4.99 mm; p < 0.05) as well as between age groups 1 and 3 for AT (35.08 ± 11.53 vs. 28.41 ± 6.60; p < 0.05) and ASO (398.99 ± 153.91 vs. 255.56 ± 124.58 mm2; p < 0.001). An unexpected high ASO variation was identified with 11% of S-shaped acromion and 1.3% clock-shaped TSO.Conclusion
The age group between 25–40 years had the most uniform distribution of data. There is a high morphological variability present in an asymptomatic population, which should be considered in the clinical assessment such as shoulder impingement syndrome.
Objective
Morphological variation of the acromion and the lateral extension of the acromion (LEA) may contribute to the development of Rotator cuff tears. The aim of this study was to evaluate the effect of acromion morphology on the LEA by three-dimensional computed tomography (3D-CT) reconstruction.
Methods
A total of 120 patients with a bilateral shoulder in the radiology department of our affiliated hospital from January 2021 to May 2021 were collected. Mimics 21.0 software was used to construct the 3D model of the scapula. The morphological parameters of the LEA were measured. The correlation between LEA and acromial morphology was analyzed.
Results
There were two different types of LEA in the population, large acromial lateralization (31.43 ± 0.18 mm) and short acromial lateralization (27.48 ± 0.24 mm). There were no statistically significant differences in LEA among different ages and genders (P > 0.05). The average LEA measured on the right side (30.46 ± 0.25 mm) was significantly higher than that on the left side (28.81 ± 0.21 mm) (P < 0.05). It was a significant positive correlation between the left and the right side of the LEA in different acromial morphology (R = 0.904, P < 0.001). The LEA of the hooked acromion (32.81 ± 0.22 mm) was significantly higher than that of the flat acromion (26.38 ± 0.28 mm) and the curved acromion (29.74 ± 0.15 mm) (P < 0.05).
Conclusion
There were two types of LEA, large acromial lateralization and short acromial lateralization. The parameters of the large LEA are significantly related to the hooked acromion.
Background: Angular projection measurements have long been an established approach in anatomical morphometry. However, many described projection angles are in reference to inherently curved structures, often oversimplifying their topologies. Measuring the curvature of a structure allows for a more accurate description of the structure’s course and behavior in a given plane.
Purpose: Our goal was to develop a quick, quantitative method for determining structural curvature from digital images.
Materials and Methods/Design: Projection curvature was modeled on and assessed by the acromion of 50 dry scapulae. Digital images were taken at a known scale, perpendicular to the acromion, and then processed in ImageJ software where 7 markers were placed along the external and internal curvatures of the acromion. The marker positions were recorded as pixel coordinates and imported into Excel. Utilizing Excel’s Solver function, the coordinate points were passed through a rotation matrix and optimized for second order regression. Solver was instructed to minimize sum of squared error by manipulating angle of point rotation and regression coefficients. Outputted data reported 50 curvatures in mm-1 and R2. This method was subsequently tested on 15 radiographs and 1 CT reconstruction for in vivo assessment.
Results: Mean external acromion axial curvature was found to be 0.06 mm-1 ± 0.009 mm-1 at R2 = 0.99 ± 0.008. Mean internal acromion axial curvature was found to be 0.04 mm-1 ± 0.025 mm-1 at R2 = 0.98 ± 0.036. Sample set was lognormally distributed. Radiograph and CT analyses were successful in proof of concept.
Principle Findings: Solver allows for both researchers and clinicians to quickly characterize morphometric courses and properties of a given structure, even in vivo. Paired with other scalar measurements, curvature can complete the picture of an anatomical structure’s pattern.
Key words:
Curvature; angel; morphometry; scapula, anatomy; bioinformatics; method; acromion.
