The 2D and 3D MR arthrographic description of aponeurotic expansion of supraspinatus tendon and biceps tendon anomaly in a large patient cohort.

OBJECTIVE: To describe the aponeurotic expansion of supraspinatus tendon (AEST) and biceps tendon abnormalities with magnetic resonance (MR) arthrographic examinations and determine their prevalence in patients, we performed a high-resolution 3D direct MR arthrography. MATERIALS AND METHODS: This was a retrospective study of 700 shoulder MR arthrograms performed between May 2010 and January 2022. Extension in the coronal plane of an AEST on 3D fat-suppressed T1-weighted volumetric interpolated breath-hold examination (VIBE) MR arthrography was identified. Based on its morphology, the AEST on MR arthrography was divided into four subtypes: absence of tendinous thickness in the bicipital synovial surface or intra-synovial tendon-like structure in the bicipital groove, thin and flat tendinous thickness ≥1 mm of bicipital synovium, oval tendinous structure less than half the size of the adjacent biceps tendon, oval tendinous structure more than half the size of the adjacent biceps tendon, and oval tendinous structure larger than the adjacent biceps tendon. Based on its origin and termination, aponeurotic expansions can be divided into three subtypes: proximal pulley zone, middle humeral neck zone, and distal myotendinous junction zone. Association with the biceps synovium of the AEST was categorized into three types: intra-synovial, extra-synovial, and trans-synovial. RESULTS: An AEST in the anterior shoulder joint in 3D VIBE MR arthrography images was identified in 63 (9%) of 700 arthrograms. The most common arthrographic type of AEST was type 1-this was detected in 39 of 63 patients. The most common course type of the AEST was anteriorly midline. The most common distal insertion type was at the tenosynovial sheath of the long head of the biceps tendon (LHBT) in the middle humeral neck zone-this was detected in 31 of 63 patients. There were only 10 MR arthrograms biceps tendon abnormality, including 4 biceps agenesis and 6 split ruptures. CONCLUSION: A 2D and high-resolution 3D MR arthrography can demonstrate the anatomical detail around the bicipital groove and facilitate the differentiation between a biceps tendon anomaly and an AEST. On high-resolution 3D MR arthrographic images, the AEST tends to be in the anterior midline and anteromedial portions of the biceps synovium with intra-synovial, extra-synovial, and trans-synovial courses and its three different insertion types.

How anatomic should anatomic total shoulder arthroplasty be? Evaluation of humeral head reconstruction with the best-fit circle.

BACKGROUND: Humeral implant designs for anatomic total shoulder arthroplasty (aTSA) focus on anatomic reconstruction of the articular segment. Likewise, the pathoanatomy of advanced glenohumeral osteoarthritis often results in humeral head deformity. We hypothesized the anatomic reconstruction of the humeral head in aTSA risks overstuffing the glenohumeral joint. METHODS: Ninety-seven cases (52 females) of primary glenohumeral osteoarthritis in patients treated with aTSA were evaluated. Preoperative computed tomography scans were used to classify glenoid morphology according to the Walch classification. Coronal plane images in the plane of the humerus were used to determine the anatomic best-fit circle as described by Youderian et al. Humeral head thinning was determined as the distance from the center of rotation of the best-fit circle to the nearest point along the humeral articular surface. aTSA was modeled with a predicted anatomic humeral head and a simulated 4-mm polyethylene glenoid component. The change in the position of the native humerus was determined. Wilcoxon Rank Sum tests were used to evaluate differences in humeral head thinning and humeral lateralization between monoconcave and biconcave glenoid morphologies. Spearman's rank correlation coefficients were used to assess the relationship between humeral head thinning with preoperative active forward elevation and external rotation. RESULTS: The mean radius of the best-fit circle was 25.0 ± 2.1 mm. There was a mean thinning of 2.4 ± 2.0 mm (range -1.7 to 8.3). The mean percent thinning of the humeral head was 9.4% ± 7.7%. The mean humeral lateralization was 6.4 ± 2.0 mm. Humeral head thinning was not significantly associated with active forward elevation (r = -0.15, P = .14) or active external rotation (r = -0.12, P = .25). There were no significant differences in the percentage of humeral head thinning (P = .324) or humeral lateralization (P = .350) between concentric and eccentric glenoid wear patterns. CONCLUSIONS: Utilization of the best-fit circle as a guide in aTSA may risk excessive lateralization of the humerus and overstuffing the glenohumeral joint. This may have implications for subscapularis repair and healing, as well as glenoid implant and rotator cuff longevity. These findings call into question whether recreation of normal glenohumeral anatomy in aTSA is appropriate for all patients. Humeral head reconstruction in aTSA should account for glenohumeral joint volume and soft tissue contracture.

Scapular morphology of great apes and humans: A three-dimensional computed tomography-based comparative study.

The primate scapula has been studied widely since its shape has been shown to correlate with how the forelimb is used in daily activities. In this study, we expand on the existing literature and use an image-based methodology that was originally developed for orthopaedic practice to quantify and compare the three-dimensional (3D) morphology of the scapula across humans and great apes. We expect that this image-based approach will allow us to identify differences between great apes and humans that can be related to differences in mobility and loading regime of the shoulder. We hypothesize that gorillas and chimpanzees will have a similar scapular morphology, geared towards stability and weight-bearing in knuckle-walking, whilst the scapular morphology of orangutans is expected to be more similar to that of humans given their high glenohumeral mobility associated with their suspensory lifestyle. We made 3D reconstructions of computed tomography scans of 69 scapulae from four hominid genera (Pongo, Gorilla, Pan and Homo). On these 3D bone meshes, the inferior glenoid plane was determined, and subsequently, a set of bony landmarks on the scapular body, coracoid, and acromion were defined. These landmarks allowed us to measure a set of functionally relevant angles which represent acromial overhang, subacromial space and coracoacromial space. The angles that were measured are: the delto-fulcral triangle (DFT), comprising the alpha, beta, and delta angle, the acromion-glenoid angle (AGA), the coracoid-glenoid centre-posterior acromial angle (CGA), the anterior tilt (TA CGA) and the posterior tilt of the CGA (PT CGA). Three observers placed the landmarks on the 3D bone meshes, allowing us to calculate the inter-observer error. The main differences in the DFT were found between humans and the great apes, with small differences between the great apes. The DFT of humans was significantly lower compared to that of the great apes, with the smallest alpha (32.7°), smallest delta (45.7°) and highest beta angle (101.6°) of all genera. The DFT of chimpanzees was significantly higher compared to that of humans (p < 0.01), with a larger alpha (37.6°) and delta angle (54.5°) and smaller beta angle (87.9°). The mean AGA of humans (59.1°) was significantly smaller (p < 0.001) than that of gorillas (68.8°). The mean CGA of humans (110.1°) was significantly higher (p < 0.001) than in orangutans (92.9°). Humans and gorillas showed mainly a posterior tilt of their coracoacromial complex whilst chimpanzees showed mainly an anterior tilt. The coracoacromial complex of the orangutans was not tilted anteriorly or posteriorly. With our image-based method, we were able to identify morphological features of the scapula that differed significantly between hominid genera. However, we did not find an overall dichotomy in scapular morphology geared towards high stability (Pan/Gorilla) or high mobility (Homo/Pongo). Further research is needed to investigate the functional implications of these differences in scapular morphology.

Evaluation of Preoperative Magnetic Resonance Imaging Parameters with Arthroscopic Validation of Subscapularis Tendon Abnormalities in 187 Patients at a Single Center in Turkey.

BACKGROUND This study from a single center in Turkey aimed to evaluate preoperative magnetic resonance imaging (MRI) parameters with arthroscopic validation of subscapularis (SS) tendon abnormalities in 187 patients. MATERIAL AND METHODS Preoperative MRI scans of 187 patients who had undergone arthroscopic shoulder surgery by the senior author (all in lateral decubitus position) were evaluated by 3 researchers. Patients with arthroscopically proven SS tendon rupture (n=69) and without rupture (n=118) were divided into 2 groups and compared with various distances and angles. The following parameters were measured: coracohumeral distance (CHD), coracoid morphology, coraco-glenoid angle (CGA), coracoid angle (CA), coraco-humeral angle (CHA), coracoid overlap (CO), coracoid body-glenoid angle (CBGA), coracoid tip-glenoid angle (CTGA), coracoid tip-body angle (CTBA), coraco-scapular angle (CSA), lesser tuberosity angle (LTA), and lesser tuberosity height (LTH). RESULTS CHD, CHA, CA, and LTA values decreased in the SS tendon rupture group; coracoid type grade and CO increased (all P<0.001, excluding LTA [P=0.022]). The cut-off values of these measurements were CHD=7.25 mm, CHA=107.25°, CA=111.5°, LTA=31.7°, and CO=16.5 mm. The differences in CGA and CBGA values were not statistically significant (P=0.11, 0.441, respectively). CTGA, CTBA, LTH, and CSA measurements were not included in the intergroup comparisons due to insufficient inter-observer reliability (kappa=0.478, 0.239, 0.496, 0.309, respectively). Power (1- b) in post hoc analysis was calculated as 0.941. CONCLUSIONS SS tendon rupture was associated with a reduction in the parameters of CHD, CHA, CA, and LTA and an increase in CO on MRI.

Anatomy features of the shoulder joint in asymptomatic chinese Han adults.

BACKGROUND: To evaluate the shoulder anatomical characteristics in asymptomatic Chinese adults. METHODS: The prospective study enrolled individuals without shoulder pain at Beijing Tiantan Hospital Affiliated to Capital Medical University between January 2019 and January 2020. Six radiographic parameters were measured and analyzed, including glenoid plane to the acromion (GA), glenoid plane to the lateral aspect of the humeral head (GH), acromion index (AI), lateral acromial angle (LAA), acromion-humeral interval (AHI), and critical shoulder angle (CSA). RESULTS: 103 participants (51 males and 52 females) were enrolled. The mean values of GA, GH, AI, CSA, LAA, and AHI were 32.88 ± 5.68 mm, 47.16 ± 4.82 mm, 0.70 ± 0.11, 37.45 ± 6.00°, 6.32 ± 3.99°, and 9.611.86 mm, respectively. Females had lower GA (30.78 ± 5.06 vs. 35.01 ± 5.51 mm, P < 0.001) and GH (44.28 ± 3.67 vs. 50.11 ± 4.02 mm, P < 0.001) than males and LAA was significantly smaller in the Bigliani flat type compared with the curved type and the hooked type (5.07 ± 2.31° vs 12.33 ± 5.46°vs 10.00 ± 3.37, P = 0.001). CONCLUSIONS: Females had lower GA and GH than males in asymptomatic Chinese Han adults. Asymptomatic Chinese Han subjects with Bigliani flat type had lower LAA. CSA appears lager in Chinese Han individuals. Curve type of acromion performed lager LAA. The results may help establish an anatomical model of the shoulder joint and elucidate the anatomy features of the shoulder joint in asymptomatic Chinese Han adults.

A shallow morphology of the intertubercular groove is associated with medial and bilateral but not lateral pulley lesions.

PURPOSE: To investigate the influence of intertubercular groove (IG) morphology on the development of different types of biceps reflection pulley (BRP) injuries. METHODS: A consecutive cohort of 221 patients with ventral shoulder pain and a preoperative diagnosis suspecting BRP injury, who underwent arthroscopy, was retrospectively reviewed. The presence or absence as well as type of pulley injury (medial, lateral or bilateral) was confirmed arthroscopically. The intertubercular groove was evaluated on MRIs after triplanar reconstruction of the axial plane. IG depth, width, medial wall angle (MWA), lateral wall angle (LWA) and total opening angle (TOA) were measured. IG depth and width were expressed in relation to the humeral head diameter. Measurements were performed by two clinicians independently and averaged. RESULTS: Of 166 included patients 43 had bilateral, 65 medial and 38 lateral BRP lesions. 20 patients had intact BRPs and represented the control group. The intra-class correlation coefficient of measurements was 0.843-0.955. Patients with a medial or bilateral BRP injury had a flatter MWA (38.8° or 40.0° vs. 47.9°, p < 0.001), wider TOA (96.1° or 96.6° vs. 82.6°, p < 0.001), greater width (12.5 or 12.3 vs. 10.8 mm, p = 0.013) and shallower depth (5.5 or 5.4 vs. 6.2 mm, p < 0.001) than the control group. Conversely, the IG morphology of those with lateral BRP injuries did not differ significantly from the control group. The odds ratio for a medial or bilateral BRP injury when the TOA exceeded 95° was 6.8 (95% confidence interval 3.04-15.2). CONCLUSION: A dysplastic type of IG morphology with a wide TOA, flat MWA, decreased depth and increased width is associated with the presence of medial and bilateral BRP injuries. A TOA of > 95° increases the likelihood of a medial or bilateral BRP injury 6.8-fold. Lateral BRP injuries are not associated with dysplastic IG morphology. Concomitant LHBT surgery may, therefore, not always be necessary during isolated supraspinatus tendon repair. LEVEL OF EVIDENCE: Level III.

Anatomical, functional and biomechanical review of the glenoid labrum.

The glenohumeral joint is the most mobile joint in the human skeleton, supported by both active and passive stabilisers. As one of the passive stabilisers, the glenoid labrum has increasingly been recognised to play an important role in stability of the glenohumeral joint, acting to maintain intraarticular pressure, centralise the humeral head and contribute to concavity-compression stability. Several studies have investigated the macro- and micro-anatomical features of the labrum as well as its biomechanical function. However, in order to better understand the role of the labrum and its mechanics, a comprehensive anatomical, functional and biomechanical review of these studies is needed. Therefore, this article reviews the current literature detailing anatomical descriptions of the glenoid labrum, with an emphasis on its function(s) and biomechanics, as well as its interaction with neighbouring structures. The intimate relationship between the labrum and the surrounding structures was found to be important in glenohumeral stability, which owes further investigation into the microanatomy of labrum to better understand this relationship.

The morphology of the subacromial and related shoulder bursae. An anatomical and histological study.

Shoulder bursae are essential for normal movement and are also implicated in the pathogenesis of shoulder pain and dysfunction. The subacromial bursa (SAB), within the subacromial space, is considered a primary source of shoulder pain. Several other bursae related to the subcoracoid space, including the coracobrachial (CBB), subcoracoid (SCB) and subtendinous bursa of subscapularis (SSB), are also clinically relevant. The detailed morphology and histological characteristics of these bursae are not well described. Sixteen embalmed cadaveric shoulders from eight individuals (five females, three males; mean age 78.6 ± 7.9 years) were investigated using macro-dissection and histological techniques to describe the locations, dimensions and attachments of the bursae, their relationship to surrounding structures and neurovascular supply. Bursal sections were stained with haematoxylin and eosin to examine the synovium and with antibodies against von Willebrand factor and neurofilament to identify blood vessels and neural structures respectively. Four separate bursae were related to the subacromial and subcoracoid spaces. The SAB was large, with a confluent subdeltoid portion in all except one specimen, which displayed a distinct subdeltoid bursa. The SAB roof attached to the lateral edge and deep surface of the acromion and coracoacromial ligament, and the subdeltoid fascia; its floor fused with the supraspinatus tendon and greater tubercle. The CBB (15/16 specimens) was deep to the conjoint tendon of coracobrachialis and short head of biceps brachii and the tip of the coracoid process, while the inconstant SCB (5/16 specimens) was deep to the coracoid process. Located deep to the subscapularis tendon, the SSB was a constant entity that commonly displayed a superior extension. Synovial tissue was predominantly areolar (SAB and SSB) or fibrous (CBB and SCB), with a higher proportion of areolar synovium in the bursal roofs compared to their floors. Blood vessels were consistently present in the subintima with a median density of 3% of the tissue surface area, being greatest in the SSB and SAB roofs (4.9% and 3.4% respectively) and least in the SAB floor (1.8%) and CBB roof and floor (both 1.6%). Nerve bundles and free nerve endings were identified in the subintima in approximately one-third of the samples, while encapsulated nerve endings were present in deeper tissue layers. The extensive expanse and attachments of the SAB support adoption of the term subacromial-subdeltoid bursa. Morphologically, the strong attachments of the bursal roofs and floors along with their free edges manifest as fixed and mobile portions, which enable movement in relation to surrounding structures. The presence of neurovascular structures demonstrates that these bursae potentially contribute blood supply to surrounding structures and are involved in mechanoreception. The anatomical details presented in this study clarify the morphology of the shoulder bursae, including histological findings that offer further insight into their potential function.

Assessing/Imaging the Subcoracoid Space: From Anatomy to Dynamic Sonography.

In the pertinent literature, standardized sonographic protocols have been widely described to evaluate the different compartments of the shoulder. However, the subcoracoid space is a complex anatomical region-usually not included/described in basic ultrasound approaches. Accordingly, starting from its anatomy, we describe a two-phase dynamic ultrasound protocol to scan the subcoracoid space. This way, we aim to optimize the diagnosis and management of patients with anterior shoulder pain and subcoracoid effusion.

MRI morphological evaluation of humeral head bone profile inside region of the biceps pulley reflection.

OBJECTIVE: Evaluating humeral head bone profile inside biceps reflection pulley area in order to identify possible anatomical variants and any causes predisposing to tendon's instability of the long head of the biceps. MATERIALS AND METHODS: This retrospective study analyzed 326 patients, 183 males and 143 females (age 15-88 years; average 51.5 years), who underwent MRI examination between 2013 and 2019. Biceps pulley reflection area morphology of 192 right shoulders and 134 left shoulders was assessed analyzing 309 MRI and 17 MR arthrography (MRA) shoulder exams. We investigated age and gender and the frequency of morphological variants among the patient groups. RESULTS: Four possible morphological variants were identified: 95 with convex shape; 127 with flat shape; 77 with spiculated shape; and 12 with mixed morphology. Fifteen humeral bone profiles were not classifiable. CONCLUSIONS: MRI was effective in defining humeral head anatomic variants inside the biceps pulley reflection area. The most frequent variants were flat or convex types.

A prospective observational case control study investigating the coronal plane scapular morphological differences in full-thickness posterosuperior cuff tears and primary glenohumeral osteoarthritis.

INTRODUCTION: The critical shoulder angle (CSA) is a surrogate marker of the coronal plane morphology of the scapula. CSA differences between scapulae could be due to differences in glenoid inclination (GI) or the location of the most lateral part of the acromion relative to the inferior glenoid, or both. An understanding of the hierarchy of the scapular morphological changes associated with glenohumeral osteoarthritis (GHOA) and rotator cuff (RC) tears would allow accurate biomechanical modeling. METHODS: A prospective observational case control study was undertaken in which the GI, "nonglenoid"-CSA, acromial vertical offset index, acromial horizontal offset index, acromial horizontal-vertical offset index, and coronal plane angulation of the acromion (CPAA-m) were measured on high-quality radiographs to compare coronal plane scapular anatomy in: (1) patients with asymptomatic atraumatic full-thickness RC tears, (2) patients with symptomatic primary GHOA, and (3) a control group with no RC tear or GHOA treated for glenohumeral instability or symptomatic labral pathology. Intraobserver reliability of the measurements was performed. RESULTS: In the GHOA group, the GI was lower (less superiorly inclined) than the RC tear group (difference between the means: -4.8°, 95% confidence interval [CI] [-8.8°, -0.9°], P = .014) and the control group (difference between the means: -7.9°, 95% CI [-11.8°, -3.9°], P = .000); there was no difference in the acromial measurements. In the RC tear group, the nonglenoid-CSA was higher (difference between the means: 7.7°, 95% CI [3.0°, 12.3°], P = .001), the acromial vertical offset index was lower (difference between the means: -0.13, 95% CI [-0.24, -0.01], P = .026), and the acromial horizontal-vertical offset index was higher (difference between the means: 0.15, 95% CI [0.01, 0.28], P = .030) than the control group; there was no difference in the acromial horizontal offset index or the GI. The CPAA-m was lower (greater coronal plane downslope of the acromion) in both GHOA (difference between the means: -9.6°, 95% CI [-18.6°, -0.5°], P = .036) and RC tears (difference between the means: -9.9°, 95% CI [-19.0°, -0.9°], P = .029) compared with the control group. The intraclass correlation coefficients for intraobserver reliability demonstrated excellent reliability for the measurements (all >0.900). DISCUSSION: Scapulae associated with GHOA have lower GI, but no spatial differences in the location of the lateral acromion compared with a normal population. Scapulae associated with RC tears have a lower vertical offset of the lateral acromion, but no difference in horizontal offset or GI compared with a normal population. The downslope of the acromion in the coronal plane is greater (lower CPAA-m) in both RC tears and GHOA than the normal population.

Subscapularis minor-does it exist?

INTRODUCTION: It has been well established that the subscapularis is divided in two different parts with a tendinous insertion at its superior two-thirds and a muscular attachment on its inferior third. The objective of this cadaveric study was to follow the muscular insertion of the subscapularis medially in order to determine the origin of this inferior muscle insertion and whether a subscapularis minor can be individualized MATERIALS AND METHODS: Twenty-six shoulders from thirteen fresh-frozen cadaveric specimens (5 males and 8 females; mean age, 74.4 years) were dissected in our anatomy lab. The humeral insertion of the subscapularis was then analyzed, and the inferior muscular part of the insertion was identified. The muscle fibers were followed medially until their scapular origin which was recorded as line drawings and photographs. We measured the dimensions of both the humeral insertion and of the scapular origin of the fibers going to the muscular portion. RESULTS: In all cases, the fibres going to the tendinous portion and those going to the muscular portion of the insertion had a different orientation. The fibres going to the muscular portion of the humeral insertion did not originate from the subscapularis fossa but on the glenoid neck and in a depression at the infero-lateral part of the scapular pillar. The mean length of the superior tendinous portion of the humeral insertion was 3.42 cm (± 0.43 cm); the mean length of the inferior muscular portion of the humeral insertion was 1.88 cm (± 0.80 cm). The mean length of the scapular origin in the depression at the infero-lateral part of the scapular pillar of the fibres going to the muscular portion of the humeral insertion was 3.7 cm (± 0.17 cm). CONCLUSION: The fibres of the subscapularis do not all originate from the subscapularis fossa. An additional origin exists at the inferior part of the glenoid neck and in a depression at the infero-lateral part of the scapular pillar. The fibers which originate at this location all insert on the humerus at the muscular portion of the subscapularis humeral insertion. This portion however does not seem to correspond to the so-called subscapularis minor which has been previously described.

Glenoid bony morphology along long diameter is associated with the occurrence of recurrent anterior shoulder dislocation: a case-control study based on three-dimensional CT measurements.

PURPOSE: The purpose of our study is to compare the anatomic parameters of proximal humerus, glenoid, and glenohumeral joint between patients with recurrent anterior shoulder dislocation (RASD) and patients without RASD with the assistance of three-dimensional (3D) CT scans. METHODS: Sixty patients were included in the study and divided into group RASD and group control. 3D-CT models of shoulder joint for each included patient were reconstructed and multiple anatomic parameters were measured. RESULTS: There were no statistically significant differences between the two groups in morphological parameters of humerus and glenohumeral joints. Long diameter of glenoid was 3.50 ± 0.34 cm for patients in group RASD and 3.31 ± 0.32 cm in group control (p = 0.039). There was a statistically significant difference in the ratio of long to short diameter of glenoid (p < 0.001). Ratio of humeral head height to glenoid long diameter (Hhh/Gld) was 1.02 ± 0.07 in group RASD, significantly lower than 1.09 ± 0.08 in group control (p = 0.001). Longitudinal depth of glenoid was significantly higher in group RASD (p = 0.013). CONCLUSION: The glenoid morphology along long diameter is closely correlated with the stability of glenohumeral joint, including glenoid long diameter and glenoid longitudinal depth. It is especially noteworthy that the value of Hhh/Gld decreases in patients with RASD. The difference of Hhh/Gld between the two groups reminds us that the correlation of bony structure along long diameter between glenoid and humeral head plays an important role in RASD.

A newly reported muscle: an accessory infraspinatus or a deep layer of the latissimus dorsi?

The infraspinatus muscle is a component of the rotator cuff; the latissimus dorsi muscle is the largest muscle of the back. These muscles are not considered very morphologically variable. However, the latissimus dorsi has more frequent variations than the infraspinatus. During anatomical dissection, an additional muscle structure was found. It originated on the medial border of the scapula, ran under the scapular spine, and ended on the greater tubercle next to the infraspinatus attachment. We will discuss the anatomical and physiological relationships of this muscle. We believe that our finding underlines the importance of different muscle variants in the rotator cuff region. Level of evidence: II basic science research.

A proposal for a new classification of the long head of the biceps brachii.

INTRODUCTION: The anterior compartment of the arm consists of three muscles: the biceps brachii, brachialis and coracobrachialis. The aim of the present study was to characterize possible variations in the morphology of the proximal attachments of the long head of the biceps brachii and to propose an accurate classification of the area which can be useful for planning surgical procedures and planning rehabilitation in the region. MATERIALS AND METHODS: Eighty (40 left and 40 right, 40 female, 40 male) upper limbs fixed in 10% formalin solution were examined. RESULTS: The main tendon of the long head of the biceps brachii demonstrated three types of attachment. The most common type, Type I (53.75%), was characterized by a single attachment only for the supraglenoid tubercle. Type III (33.75%) was characterized by a single attachment to the glenoid labrum. Type II (12.5%) was characterized by a double attachment to the glenoid labrum and the supraglenoid tubercle. Additionally, two types of the accessory tendon of the long head of the biceps brachii were identified (Type A-B). Type A (14 cases) was attached to the capsule of the humeral joint, and Type B (six cases) was attached to the greater tubercle of the humerus. CONCLUSION: The long head of the biceps brachii is characterized by high morphological variability. The new classification proposes three types of proximal attachment (I-III), with two types of accessory long head of the biceps brachii (A-B) tendon. A thorough understanding of the morphological variability of the long head of the biceps brachii is necessary when planning arthroscopic procedures or even planning rehabilitation procedures.

An unreported infraspinatus muscle variation-two-headed infraspinatus minor muscle and three-headed fusion with the teres minor muscle.

The infraspinatus muscle is situated under the scapular spine in the infraspinous fossa and inserts into the greater tuberosity of the humerus. It is a component of a crucial shoulder muscle group, the rotator cuff. There are a few interesting additional muscles in the infraspinal region. In the literature they are called the infraspinatus superficialis, infraspinatus minor and infraspinatus accessory muscles. The infraspinatus minor muscle is described as a superficial muscle bundle running under the scapular spine. During routine anatomical dissection, an unreported variation of the infraspinatus minor muscle was found. It derived from the inferior surface of the scapular spine and the infraspinous fossa. It had two heads. The superior head inserted on the greater tuberosity of the humerus. The inferior head inserted on the tendinous part of the infraspinatus muscle. There was also an unusual fusion of the infraspinatus muscle with the teres minor muscle. In this paper we will discuss the anatomical and physiological relationships of this morphological variation.

Exploring the functional morphology of the Gorilla shoulder through musculoskeletal modelling.

Musculoskeletal computer models allow us to quantitatively relate morphological features to biomechanical performance. In non-human apes, certain morphological features have long been linked to greater arm abduction potential and increased arm-raising performance, compared to humans. Here, we present the first musculoskeletal model of a western lowland gorilla shoulder to test some of these long-standing proposals. Estimates of moment arms and moments of the glenohumeral abductors (deltoid, supraspinatus and infraspinatus muscles) over arm abduction were conducted for the gorilla model and a previously published human shoulder model. Contrary to previous assumptions, we found that overall glenohumeral abduction potential is similar between Gorilla and Homo. However, gorillas differ by maintaining high abduction moment capacity with the arm raised above horizontal. This difference is linked to a disparity in soft tissue properties, indicating that scapular morphological features like a cranially oriented scapular spine and glenoid do not enhance the abductor function of the gorilla glenohumeral muscles. A functional enhancement due to differences in skeletal morphology was only demonstrated in the gorilla supraspinatus muscle. Contrary to earlier ideas linking a more obliquely oriented scapular spine to greater supraspinatus leverage, our results suggest that increased lateral projection of the greater tubercle of the humerus accounts for the greater biomechanical performance in Gorilla. This study enhances our understanding of the evolution of gorilla locomotion, as well as providing greater insight into the general interaction between anatomy, function and locomotor biomechanics.

Anatomy and Correlation of the Coracoid Process and Coracoclavicular Ligament Based on Three-Dimensional Computed Tomography Reconstruction and Magnetic Resonance Imaging.

BACKGROUND The anatomy of the coracoid process and coracoclavicular (CC) ligament have been described and the correlation between them has been assessed based on 3-dimensional computed tomography (CT) reconstruction and magnetic resonance imaging (MRI), which provide a guide for coracoclavicular ligament reconstruction. MATERIAL AND METHODS Data were collected from 300 patients who underwent both CT and MRI of the shoulder joint from January 2017 to January 2019 at the Jiang'an Hospital of Traditional Chinese Medicine. The coracoid process was observed and classified and parameters of the CC ligament were measured according to different corneal types. All of the statistics were collected and classified by 2 radiologists, and average values were determined.Measurements of segments were taken as follows: ab - In the coronal plane, the length of the CC ligament from the central point of the CC ligament at the clavicular attachment to the CC ligament at the center of the CC attachment); ac - The distance from the center point of the CC ligament at the supraclavicular attachment to the acromioclavicular joint; de - In the sagittal plane, the length of the CC ligament from the center of the clavicular attachment to the coracoid attachment point; fg - The maximum diameter of the CC ligament at the anterior and posterior margins of the clavicle attachment; hi - The largest diameter of the CC ligament at the anterior and posterior edge of the coracoid process attachment; dj - The distance of the coracoclavicular ligament from the center point of the coracoid process attachment to the coracoid process tip; kl - The distance in the supraclavicular plane from the coracoclavicular ligament to the subcoracoid process. RESULTS The analysis showed that there are 5 types of coracoid process: gourd (31%), short rod (20%), long rod (22.3%), wedge (10.3%), and water drop (6.3%). There were statistically significant differences between the lengths of the ac and hi segments in the among the wedge and gourd-type and the short rod and water drop-type coracoid processes. There were statistically significant differences between the lengths of the ab, de, and fg segments in the short rod, gourd, and long rod-type coracoid processes. There were statistically significant differences between the lengths of the ac, fg, hi, dj, and kl segments in the water drop, gourd, and long rod-type coracoid processes. CONCLUSIONS The present study indicated that measurement of the CC ligament and the different shapes of the coracoid process provide an anatomical basis for the diagnosis and treatment of shoulder diseases and the data can be used to improve the safety of CC ligament reconstruction.

Is the Anterior Injection Approach Without Ultrasound Guidance Superior to the Posterior Approach for Adhesive Capsulitis of the Shoulder? A Sequential, Prospective Trial.

BACKGROUND: Shoulder injections for conditions such as adhesive capsulitis are commonly performed and can be administered through image-based or landmark-based injection approaches. Ultrasound-guided injections are widely used and accurate because ultrasound allows real-time visualization of the needle and injected contrast. Landmark-based injections would be advantageous, if they were accurate, because they would save the time and expense associated with ultrasound. However, few prospective studies have compared well-described landmark-based shoulder injection techniques without ultrasound. QUESTION/PURPOSE: Using anatomic landmarks, and without using ultrasound, is the accuracy of glenohumeral injection for adhesive capsulitis greater via the posterior approach or via a new anterior approach? METHODS: Between 2018 and 2020, we treated 108 patients potentially eligible for adhesive capsulitis treatment. These patients had clinical symptoms of aggravating shoulder pain with a duration of less than 4 months and passively impaired, painful glenohumeral ROM. Due to the exclusion of patients with other shoulder conditions (full-thickness rotator cuff ruptures and posttraumatic stiffness), 95 patients received an injection in this sequential, prospective, comparative study. Between 2018 and 2019, 41 patients (17 males and 24 females; mean age 52 ± 5 years; mean BMI 24 ± 3 kg/m2) were injected through the posterior approach, with the acromion as the anatomical landmark, during the first part of the study period. After that, between 2019 and 2020, 54 patients (20 males and 34 females; mean age 54 ± 4 years; mean BMI 23 ± 3 kg/m2) received an injection through a new anterior approach, with the acromioclavicular joint as the anatomic landmark, during the second part of the study period. Injections via both approaches were administered by two experienced shoulder specialists (both with more than 10 years of experience). Both specialists had experience with the posterior approach before this study, and neither had previous training with the new anterior approach. Injections contained a corticosteroid, local anaesthetic, and contrast medium. Radiographs were taken within 20 minutes after the injection, and a radiologist blinded to the technique determined accuracy. Accurate injections were defined as having contrast fluid limited to the glenohumeral joint, while inaccurate injections displayed leakage of contrast fluid into the soft tissue or subacromial space. All of the enrolled patients were analyzed. RESULTS: In the group with the posterior approach, the accuracy was 78% (32 of 41) in contrast to 94% (51 of 54, odds ratio 0.21 [95% CI 0.05 to 0.83]; p = 0.03) in patients with the new anterior approach. CONCLUSION: The new anterior approach without the use of ultrasound was more accurate than the posterior approach. In fact, it was nearly as accurate as previously published ultrasound-guided approaches. We recommend using the new anterior approach for intraarticular glenohumeral injections instead of ultrasound-guided injections because it will save time and costs associated with ultrasound. Still, the clinical effects (anxiety, pain, functional outcome, and adverse events) of the new anterior approach should be compared with ultrasound-guided injections in a randomized study. LEVEL OF EVIDENCE: Level II, therapeutic study.

The glenoid and humeral head in shoulder osteoarthritis: A comprehensive review.

The key management of glenohumeral osteoarthritis is shoulder arthroplasty which aims to reduce pain and restore full shoulder function: it has increased in recent years. A detailed understanding of the anatomy of the glenoid and humeral head, as well as morphological changes of the glenoid in osteoarthritis, are important factors to consider when deciding on replacement components. This review begins with a brief introduction of the glenohumeral joint itself, and then considers the detailed anatomy of the glenoid fossa and humeral head, both of which are reported to have variable morphology. Several studies have been undertaken to assess various parameters, especially of the glenoid fossa including its shape, height, width, and articular surface area, version and inclination, in an attempt to define a standard classification that can be applied to surgical intervention. Nevertheless, no definitive consensus concerning the classification of these morphologies has been forthcoming, hence the need for this review. Following a consideration of these morphologies, the current state of knowledge regarding glenoid deformity in osteoarthritis, as well as its surgical management, is considered.