Scapular Fossa Research Articles

A case of progressive ossifying myositis caused by ACVR1 gene mutation

A 2-year-and-10-month-old boy presented with multiple masses in the neck and chest for over 3 months. The child had a history of unstable walking, with hard lumps visible at the injury sites after falls, which would resolve on their own. Following a recent injury, a mass was discovered in the posterior neck, protruding above the skin surface and accompanied by limited joint movement. Gradually, new masses were found on the left side of the neck, back near the scapular lower angle, in the scapular fossa, and along the left axillary midline. Magnetic resonance imaging examination showed diffuse low signal on T1-weighted images and high signal on T2-weighted images in the bilateral posterior neck and back muscles two months ago. A CT scan revealed muscle swelling, with areas of patchy low density and multiple nodular high-density ossifications within some muscles. Genetic testing results indicated a mutation in the ACVR1 gene, leading to the final diagnosis of progressive ossifying myositis in this patient. This article summarizes the etiology, diagnosis, and treatment of one case of progressive ossifying myositis, providing a reference for clinicians.

Accessory subscapularis muscle – A forgotten variation?

The quadrangular space is a space in the axilla bounded by the inferior margin of the teres minor muscle, the superior margin of the teres major muscle, the lateral margin of the long head of the triceps brachii muscle and the surgical neck of the humerus, medially. The axillary nerve (C5-C6) and the posterior circumflex humeral artery and veins pass through this space in order to supply their territories. The subscapularis muscle is situated into the scapular fossa and inserts itself into the lesser tubercle of the humerus, thus helping stabilize the shoulder joint. A supernumerary muscle known as accessory subscapularis muscle originates from the anterior surface of the muscle and usually inserts itself into the shoulder joint. It is a rare variation with few reports of its existence and incidence. We present a case of the accessory subscapularis muscle in a male cadaver fixated with a 10% formalin solution. The muscle passed anteriorly to the axillary nerve, thus, predisposing an individual to quadrangular space compression syndrome. We perform a review of the literature and address its clinical, anthropological and anatomical significance.

Rotator cuff muscle size and the interpretation of scapular shape in primates

Scapular shape variation among primates is widely viewed as being strongly related to locomotor differences. The relative importance of overhead forelimb elevation in the locomotor repertoire of a species, as reflected in muscular leverage for scapular rotation or in the sizes of attachment areas for muscles involved in glenohumeral elevation, has proven to be a useful organizing principle for understanding this variation. While generally successful in sorting primate scapulae into functional groups, the scapulae of some species do not entirely match predictions based on the perceived importance of forelimb elevation. A recent study has shown that scapular fossa sizes in apes are not as accurate predictors of the sizes of the muscles arising from them as has been assumed. To further explore the degree of correspondence between actual and predicted muscle size based on the perceived importance of forelimb elevation, the current study examines the relative sizes of the rotator cuff muscles in a wider sample of primate taxa using published data on muscle mass and cross-sectional area. The results do not support some of the accepted generalizations about the relative sizes of members of the rotator cuff based on measurements of the sizes of scapular fossae. For example, orthograde apes do not display enlarged supraspinatus muscles compared to pronograde monkeys. Differences in assessments of relative muscle size based on mass compared to those based on cross-sectional area suggest that poor correspondence between muscle size predicted from scapular fossa size and actual muscle size may be related to constraints on scapular form associated with muscular leverage for scapular rotation and with scapular position on the thorax.

Quantifying rotator cuff atrophy and fatty degeneration at the supraspinatus origin in the scapular fossa.

The aim of this study was to evaluate the location difference (distance) between the conventional Y-view (CYV) and the bony origin of the supraspinatus, and therefore, to suggest hypotrophy measurement in the CYV could be highly influenced by retraction of a torn tendon. Ninety five arthroscopically repaired rotator cuff tears were retrospectively enrolled in this study. The most lateral portion of the osseous origin of the supraspinatus muscle [the Y-view at the level was newly defined as the supraspinatus origin-view (SOV)] and the CYV were determined on the MRI, and location discrepancy between the two levels was measured. Fatty degeneration and cross-sectional areas of rotator cuff muscles were measured on both views. Subgroup analyses were performed in partial-thickness tears and full-thickness tears with tendon retraction. Distance between the SOV and CYV was 11.2 ± 3.7 mm. Discrepancy of the supraspinatus areas at the two views was greater in full-thickness tears than it was in partial-thickness tears without retraction. In the full-thickness tear group, correlation analysis between retraction and cross-sectional areas of the supraspinatus in both views exhibited statistical significance [Pearson's correlation coefficients = 0.500 (P < 0.001) in the CYV and 0.283 (P = 0.017) in the SOV]; however, the correlation was stronger in the CYV. Ratings of fatty degeneration were similar in both views. There is considerable location discrepancy between the osseous origin of the supraspinatus at the suprascapular fossa and the CYV in which fatty degeneration and hypotrophy are routinely measured. Case series, Level IV.

Rotator cuff muscle function and its relation to scapular morphology in apes

It is widely held that many differences among primate species in scapular morphology can be functionally related to differing demands on the shoulder associated with particular locomotor habits. This perspective is largely based on broad scale studies, while more narrow comparisons of scapular form often fail to follow predictions based on inferred differences in shoulder function. For example, the ratio of supraspinous fossa/infraspinous fossa size in apes is commonly viewed as an indicator of the importance of overhead use of the forelimb, yet paradoxically, the African apes, the most terrestrial of the great apes, have higher scapular fossa ratios than the more suspensory orangutan. The recent discovery of several nearly complete early hominin scapular specimens, and their apparent morphological affinities to scapulae of orangutans and gorillas rather than chimpanzees, has led to renewed interest in the comparative analysis of human and extant ape scapular form. To facilitate the functional interpretation of differences in ape scapulae, particularly in regard to relative scapular fossa size, we used electromyography (EMG) to document the activity patterns in all four rotator cuff muscles in orangutans and gibbons, comparing the results with previously published data for chimpanzees.The EMG results indicate that the distinctive contributions of each cuff muscle to locomotion are the same in the three ape species, failing to support inferences of differences in rotator cuff function based on relative scapular fossa size comparisons. It is also shown that relative scapular fossa size is not in fact a good predictor of either the relative masses or cross-sectional areas of the rotator cuff muscles in apes, and relative fossa size gives a false impression of the importance of individual cuff muscles to locomotor differences among apes. A possible explanation for the disparity between fossa and muscle size relates to the underappreciated role of the scapular spine in structural reinforcement of the blade.

3D Morphometric and Posture Study of Felid Scapulae Using Statistical Shape Modelling

We present a three dimensional (3D) morphometric modelling study of the scapulae of Felidae, with a focus on the correlations between forelimb postures and extracted scapular shape variations. Our shape modelling results indicate that the scapular infraspinous fossa becomes larger and relatively broader along the craniocaudal axis in larger felids. We infer that this enlargement of the scapular fossa may be a size-related specialization for postural support of the shoulder joint.

The effects of hypermuscularity on shoulder morphology in myostatin-deficient mice

Mechanical loads, particularly those generated by skeletal muscle, play a significant role in determining long-bone shape and strength, but it is less clear how these loads influence the morphology of flat bones like the scapula. While scapular morphology has been shown to vary with locomotor mode in mammals, this study seeks to better understand whether genetically modified muscle size can influence scapular shape in the absence of significant locomotor differences. The soft- and hard-tissue morphological characteristics were examined in 11 hypermuscular, mutant (myostatin-deficient), 20 heterozygote, and 15 wild-type mouse shoulders. Body mass did not significantly differ among the genotype groups, but homozygous mutant and heterozygote mice had significantly larger shoulder muscles than wild-type mice. Mutant mice also differed significantly from the wild-type controls in several aspects of scapular size and shape, including glenohumeral joint orientation, total scapular length, superior border length, and supraspinous and infraspinous fossa length. Conversely, several traits describing superoinferior scapular breadth measures (e.g. total breadth and dorsal scapular fossa breadth) did not significantly differ between mutant and wild-type mice. Since the intrinsic musculature of the scapula is oriented in a mediolateral fashion, it follows that mediolaterally configured hard-tissue features like scapular length were most distinct among genotype groups. As had been noted previously with long bones, this study demonstrates that genetically enhanced muscle size has marked effects on the morphological characteristics of the shoulder.

Arthroscopic rotator cuff repair: analysis of technique and results at 2- and 3-year follow-up

We present 53 patients who underwent arthroscopic rotator cuff repair and had a minimum of 2-year follow-up. Most tears were avulsions of the supraspinatus from the greater tuberosity, some with associated longitudinal tears. Longitudinal tears were repaired with a side-to-side suturing technique. Avulsion tears from the tuberosity were repaired using nonretrievable suture anchors. Traditional open-mobilization techniques, such as elevating the cuff off the glenoid neck and scapular fossa, and cutting the coraco-humeral ligament, were performed arthroscopically as needed. All repairs were performed using O-PDS or 1-PDS suture and a 7-mm suture punch for suture delivery. Both simple and mattress suture configurations were used. An anterolateral operative portal was used in most cases. A modified UCLA rating system that included additional points for abduction range of motion and strength was adapted for clinical evaluation in this study (maximum score, 45 points). The average preoperative rating was 17 (range, 9 to 26). The average postoperative rating was 41 (range, 16 to 45). There were 36 excellent (41 to 45 points), 13 good (36 to 40 points), 1 fair (30 to 35 points), and 3 poor (< 30 points) results. We have seen intraoperative but no cases of postoperative anchor pullout. The simple sutures performed as well as, and in some ways better than, mattress configurations. All fair and good results were with O-PDS. To perform an arthroscopic repair, the tear must be well visualized and mobilizable back to the tuberosity with only moderate tension. The anterolateral operative portal has been very useful because it allows better angle of entry for instruments and anchors and improved visualization in the subacromial space. The use of PDS and simple suture configurations has made the repair technically easier to perform with the instruments that are currently available. We do recommend 1- PDS suture because it breaks less easily even though it is slightly more difficult to deliver and tie. Arthroscopic cuff mobilization is relatively simple and has allowed us to repair larger tears. Based on our experience, arthroscopic rotator cuff repair is technically achievable and a superior alternative in selected cases for an experienced shoulder arthroscopist. Patients who underwent arthroscopic repairs had less scarring and shorter hospital stays and, we believe, less postoperative pain and easier rehabilitation compared with open repairs. Arthroscopy 1998 Jan-Feb;14(1):45-51