Anatomical basis of the suprascapular nerve entrapment, and clinical relevance of the supraspinatus fascia

Introduction  

The entrapment of the suprascapular nerve (SSN) is commonly considered at the level of the suprascapular notch and more rarely in the spinoglenoid notch. Recent per-operative findings showed a compression of the SSN along its course in the supraspinatus fossa. The removal of a fascia for releasing the nerve between the suprascapular notch and spinoglenoid notch led us to purchase an anatomical study.     

Sexual dimorphism of the suprascapular notch – morphometric study

Introduction

The concept of the study was to compare the morphometry of the suprascapular notch (SSN) in females and males because its size and shape may be a factor in suprascapular nerve entrapment.

Material and methods

The measurements of 81 scapulae included morphological length and width, maximal width and length projection of the scapular spine, and width and length of the glenoid cavity. The width-length scapular and glenoid cavity indices were calculated. In addition to standard anthropometric measurements three other dimensions were defined and collected for every SSN: maximal depth (MD), superior (STD) and middle (MTD) transverse diameters.

Results

The analysis of the measurements allowed us to distinguish five types of SSN. Type I (26%) had longer maximal depth than superior transverse diameter. Type II (3%) had equal MD, STD and MTD. In type III (57.6%) superior transverse diameter was longer than maximal depth. In type IV (7.4%) a bony foramen was present. Type V (6%) was without a discrete notch. Types I and III were divided into two subtypes: A (MTD was longer than STD) and B (MTD < STD). Distribution of the suprascapular notch types in both sexes was similar. However, MD, STD and MTD were significantly higher in males. The superior transverse suprascapular ligament was completely and partially ossified in 7.4% and 24.7% respectively.

Conclusions

The presented classification of the suprascapular notch is simple, easy to use, and based on specific geometric parameters which allow one to clearly distinguish five types of these structures. All dimensions of SSN were significantly higher in males than in females.     

Does the Suprascapular Nerve Move within the Suprascapular Notch? Biomechanical Perspective Using the Finite Element Method

PurposeWe aimed to analyze changes in suprascapular nerve (SSN) position within the suprascapular notch during in vivo shoulder abduction.Materials and MethodsThree-dimensional models of the shoulder complex were constructed based on magnetic resonance imaging of the brachial plexus (BP-MR) in a patient diagnosed with SSN dysfunction but normal scapular movement. Using BP-MR in neutral position and computed tomography data on shoulder abduction, shoulder abduction was simulated as the transition between two positions of the shoulder complex with overlapping of a neutral and abducted scapula. SSN movement during abduction was evaluated using the finite element method. Contact stress on the SSN was measured in the presence and absence of the transverse scapular ligament (TSL).ResultsIn the neutral position, the SSN ran almost parallel to the front of the TSL until entering the suprascapular notch and slightly contacted the anterior-inferior border of the TSL. As shoulder abduction progressed, contact stress decreased due to gradual loss of contact with the TSL. In the TSL-free scapula, there was no contact stress on the SSN in the neutral position. Towards the end of shoulder abduction, contact stress increased again as the SSN began to contact the base of the suprascapular notch in both TSL conditions.ConclusionWe identified changes in the position of the SSN path within the suprascapular notch during shoulder abduction. The SSN starts in contact with the TSL and moves toward the base of the suprascapular notch with secondary contact. These findings may provide rationale for TSL release in SSN entrapment.     

Anatomical considerations for safe scapular resection in snapping scapula syndrome

Background  

The resection of the superomedial angle of the scapula in snapping scapula syndrome is associated with potential risk of injury to the suprascapular nerve. The aim of the present study was to determine the distance of site of resection on the upper border of the scapula from the suprascapular notch during arthroscopic resection of the superomedial angle using standard superior Bell’s and medial portals at the middle of medial border.     

Anatomical basis of the vascular risk related to the circumflex scapular artery during posterior approach to the scapula

Purpose  

The vasculature and anastomosis around the scapula is extremely intricate making surgical treatment complicated. We aimed to determine the “at risk area” for the circumflex scapular artery and its anastomosis with the suprascapular artery during posterior approach to the scapula.     

Clinical evaluation of the shape of the suprascapular notch—an ultrasonographic and computed tomography comparative study: Application to shoulder pain syndromes

The most common site of suprascapular nerve compression and injury is the suprascapular notch. The aim of this study was to assess the sensitivity and specificity of sonography in determining the type of suprascapular notch (SSN). Thirty randomized patients (60 upper extremities) underwent USG examination of the shoulder area. The results were further compared with three‐dimensional reconstructions of the scapulae obtained through CT examination to place the SSNs within a fivefold classification. For identification of type I, the sensitivity was 73.3% and the specificity 97.8%. For identification of type III, the values was 96.9% and 85.7%, respectively. Type II was not found in USG examination. Discrimination between type IV and V was not possible. The mean distance between the line connecting the edges of the SSN and the skin was 38 mm in right‐handed patients and 34 mm in ambidextrous subjects. Ultrasonographic examination of the SSN is characterized by high specificity for type I, and high sensitivity for type III SSN. Discrimination between type IV and V of the SSN is not recommended based on sonographic evaluation. Clin. Anat. 28:774–779, 2015. © 2015 Wiley Periodicals, Inc.     

Proposed surgical technique to facilitate targeted reinnervation of the infraspinatus: A cadaveric feasibility study

Restoration of shoulder lateral rotation remains a significant challenge following brachial plexus injury. Transfer of the accessory nerve to suprascapular nerve (SSN) has been widely performed, although with generally poor outcomes for lateral rotation. A recent report suggested a selective infraspinatus reinnervation technique using a radial nerve branch for SSN transfer. This cadaveric study was performed in 7 specimens (14 shoulders). We present technical modifications to achieve additional length to the recipient nerve (suprascapular) that would facilitate direct repair. Key elements of the technique are (1) isolation of the SSN immediately distal to its motor branch to supraspinatus near the superior transverse scapular ligament; and (2) delivery of the transected SSN through the spinoglenoid notch and deep to the infraspinatus for emergence in the infraspinatus‐teres minor interval. Nerve overlap of at least 21 mm was observed in all 14 dissected shoulders between the harvested SSN and radial nerve branches. The mean nerve overlap between harvested branches was 26 mm (range 21–32 mm). The mean harvested SSN length was 59 mm (range 46–80 mm). The mean length of the harvested radial nerve branch was 72 mm (range 65–85 mm). No measurements were significantly different between left and right shoulders or between males and females (smallest P value = 0.1249). Nerve diameter of the two harvested branches was judged to be appropriately compatible for surgical coaptation in all 14 dissected shoulders. We present a variation on a described technique to increase recipient suprascapular nerve length. Additional length of the recipient nerve is achieved through utilization of a more proximal dissection of the suprascapular nerve near the level of the superior transverse scapular ligament and delivering the nerve through the teres minor‐infraspinatus interval. These surgical modifications are of clinical interest when selective reinnervation of the infraspinatus muscle is considered. We believe such a targeted approach can potentially increase shoulder lateral rotation function. Clin. Anat. 32:131–136, 2019. © 2018 Wiley Periodicals, Inc.     

Proposal for classification of the suprascapular notch: a study on 423 dried scapulas

The present study proposes a simple and reproducible method to classify the morphology of the suprascapular notch (SSN), on the basis of specific geometrical parameters that clearly distinguish one type from another. Four hundred twenty-three dried scapulas from the Department of Anatomy in the University of Cologne, Germany, were examined. Five types of SSN were observed: type I, without a discrete notch, 35 (8.3%); type II, a notch that was longest in its transverse diameter, 177 (41.85%); type III, a notch that was longest in its vertical diameter, 177 (41.85%); type IV, a bony foramen, 31 (7.3%); type V, a notch and a bony foramen, 3 (0.7%). For the vertical diameter, we took the maximal diameter of the notch perpendicular to the imaginary line that joins the two superior corners of the notch. For the transverse diameter, we took the diameter perpendicular to the midpoint of the vertical diameter. This classification based on the vertical and the transverse diameters of the SSN suggested a clear distinction of the notch types. This simple classification included all the anatomical variations of the SSN. Using this method, the clinician will be able to define easily and quickly the notch type on a plain radiograph, and perhaps be able to correlate suprascapular nerve entrapment with a specific type of SSN.     

Variable morphology of the suprascapular notch: an investigation and quantitative measurements in Chinese population

Although several morphological variations and classification of the suprascapular notch (SSN) were reported in western populations, little attention has been paid to this anatomic issue in the Chinese population. In this research of SSN morphology in Chinese people, 295 specimens of intact dry Chinese adult scapulas were investigated and measured thoroughly and systematically. Morphological features of SSN variations were observed by visual inspection, and correlation parameters of variability and classification were measured in digital images with image processing software and bones with a vernier caliper, respectively. The incidence of different subtypes of SSN classification and comparative analysis of correlation parameters were calculated. It was interesting that a new variable morphology of SSN with a double suprascapular foramen had been found. We found the most prevalent groups were Type II (an incisura that was longer in its transverse diameter) and Type III (an incisura that was longer in its vertical diameter) which accounted for 58.16 and 28.23%, respectively. The circumference and area of Type II and Type III was larger than those of Type IV. The thickness of 1 mm below the lowest point of the SSN ranges from 0.55 to 3.00 mm. Eight cases with a narrow groove on the lowest point of SSN and four cases with bony canals formed by the ossified superior transverse scapular ligament were found. Further, the distance between the SSN and bony landmarks were varied. For AD (the distance between the lowest point of the SSN and the supraglenoid tubercle), Type I was largest, followed by the Type II, Type III, and Type IV. For AE (the distance between the lowest point of the SSN and the base of the spinoglenoid notch), Type IV was the shortest and there was no statistical difference between other types. This study reveals that SSN variations are common in Chinese population. This anatomic information is important in the management of entrapment neuropathy or interventional procedure of the SSN.     

Innervation pattern of the suprascapular nerve within supraspinatus: A three‐dimensional computer modeling study

The relationship between the innervation pattern of the suprascapular nerve (SSN) and the muscle architecture of supraspinatus has not been thoroughly investigated. The supraspinatus is composed of two architecturally distinct regions: anterior and posterior. Each of these regions is further subdivided into three parts: superficial, middle and deep. The purpose of this study was to investigate the course of the SSN throughout the volume of supraspinatus and to relate the intramuscular branches to the distinct regions and parts of the supraspinatus. The SSN was dissected in thirty formalin embalmed cadaveric specimens and digitized throughout the muscle volume in six of those specimens. The digitized data were modeled using Autodesk^® Maya^® 2011. The three‐dimensional (3D) models were used to relate the intramuscular innervation pattern to the muscle and tendon architecture defined by Kim et al. (2007, Clin Anat 20:648–655). The SSN bifurcated into two main trunks: medial and lateral. All parts of the anterior region were predominantly innervated by the medial trunk and its proximal and medial branches, whereas all parts of the posterior region predominantly by the lateral trunk and its posterolateral and/or posteromedial branches. The posterior region also received innervation from the proximal branch of the medial trunk in half of the specimens. These findings provide evidence that the anterior and posterior regions are distinct with respect to their innervation. The 3D map of the innervation pattern will aid in planning future clinical studies investigating muscle activation patterns and provide insight into possible injury of the nerve with supraspinatus pathology and surgical techniques. Clin. Anat. 622–630, 2014. © 2013 Wiley Periodicals, Inc.     

An anatomic study of the spinal accessory nerve: extended harvest permits direct nerve transfer to distal plexus targets

An anatomic study of the distal spinal accessory nerve (SAN) to determine the number of myelinated axons and feasibility of posterior harvest for direct neurotization of distal targets was performed. Ten fresh human cadavers were studied. A supraclavicular approach was performed followed by a posterior approach. The relationship of the SAN to bony landmarks (T1 spinous process, acromioclavicular joint, posterolateral corner of the acromium, and angle at the superior medial border of the scapula) as well as maximal harvestable length was recorded. After posterior dissection, the SAN was mobilized and the ability to reach both anterior infraclavicular and posterior targets was assessed. Axon counts were also performed at the proximal, mid, and distal points along the course of the nerve. The posteriorly harvested SAN was identified reliably with respect to bony landmarks. When harvested posteriorly, the SAN could reach the infraclavicular part of the brachial plexus (i.e., terminal branches), and posteriorly, the suprascapular nerve (SSN) both proximal and distal to the suprascapular ligament, the latter for selective reinnervation of the infraspinatus branch. The average number of myelinated fibers at the proximal end of the nerve was 1,328 axons, at the mid-way point was 1,021 axons, and at terminal end of the nerve was 817 axons. Harvest of the SAN from a posterior approach based on these landmarks is feasible, allowing direct transfer of the nerve to the infraclavicular brachial plexus and to the SSN both proximal and distal to the suprascapular ligament, without the use of interposition nerve grafts.     

Ultrasonographic evaluation and morphometric measurements of the suprascapular notch

Background:  The aim of this study was to define the sonographic evaluation and morphometric measurements of the suprascapular notch. Methods  The suprascapular notch was evaluated by ultrasound on both sides in 50 volunteers (25 males, 25 females). By means of ultrasound, the notch width, the notch depth and the distance between the skin and the notch base (skin–notch base interval) were measured and imaging of the superior transverse scapular ligament was attempted. Furthermore, imaging of the suprascapular artery and vein was performed by Doppler ultrasound. Results  On the measurements performed, the notch was found to be deeper in men than in women on both the right (P = 0.022) and the left (P = 0.011) sides. Taking all volunteers into account without grouping sex, no differences were detected between the two sides with respect to the measurements of the notch width, notch depth and distance between the skin and the notch base. The superior transverse scapular ligament was demonstrated in 48 (96%) of 50 volunteers. On color Doppler ultrasound, the artery–vein complex was visualized in a total of 43 (86%) volunteers. Conclusions  Suprascapular notch measurements and the visualization of the anatomical neighborhood, which may be beneficial for the suprascapular nerve blockade procedure, can be successfully performed by the use of high-frequency ultrasound imaging.     

The role of nitric oxide during healing of trauma to the skeletal muscle

Introduction  

The role of NO in muscle injury is not clear.     

A single bout of breast milk expression does not increase resting metabolic rate

Introduction

Breastfeeding women have elevated resting metabolic rate (RMR); however, whether a single bout of lactation increases RMR is unknown. This study aimed to determine if a single bout of lactation acutely increased RMR.

Methods

Twenty-two lactating women (age: 31 ± 0.9 year, body mass index: 27.3 ± 1.2 kg/m²) were recruited. RMR was assessed at baseline and at 1- and 2-h following breast milk expression.

Results

RMR was unchanged in lactating women following a single bout of lactation (baseline: 1437 ± 39; 1 h: 1425 ± 37 2 h: 1440 ± 31 kcal/day) (p > .05). RMR was not correlated to daily milk produced (r = 0.05, p > .05), but was correlated to body mass (r = 0.74, p < .001), fat-free mass (kg) (r = 0.61, p < .01), and fat mass (kg) (r = 0.71, p < .01).

Conclusion

RMR in lactating women appears to be more related to body mass or composition in the postpartum period rather than lactation.     

The suprascapular notch narrows with aging: a preliminary solution of the old conjecture based on a 3D-CT evaluation

Purpose

The purpose of this study was to describe the morphology of the suprascapular notch in terms of age distribution. We hypothesized that the notch narrows with aging.

Methods

Seven hundred and sixty consecutive patients (465 men and 295 women) scheduled for a shoulder surgery were retrospectively reviewed. A 3D-CT of the shoulder was taken to evaluate the shape of the notch according to the Rengachary classification. The six types of Rengachary classification were arranged into three major categories according to transverse scapular ligament ossification and notch size as follows: the wide notch (type 1 and type 2); the narrow notch (type 3 and type 4); and the ossified notch (type 5 and type 6). Comparisons between categories were done with a one-way analysis of variance.

Results

There was a statistically significant difference among the three categories (P < .01): the narrow notch group (n = 442, 63.4 ± 12.8 years) and the ossified notch group (n = 66, 65.9 ± 10.6 years) were significantly older than the wide notch group (n = 252, 57.5 ± 17.8 years), respectively. In patients with Rengachary type 5 shoulders, ossification was dominant on the medial side of the notch in 37 of 39 shoulders (92.3 %).

Conclusion

The current study showed that morphological changes of the scapular notch are related to aging. The narrow notch and the ossified notch are seemed to be developed from the wide notch in terms of the ossification starting from the medial side.

     

The retinacula of Weitbrecht in the adult hip

Purpose  

The aim of the study was to describe the retinacula of Weitbrecht in the adult hip.     

An experimental COVID-19 messaging study in a representative sample of the Scottish population: Increasing physical distancing intentions through self-efficacy

Objectives

Self-efficacy is important for adherence to transmission-reducing behaviours (e.g., physical distancing) as also shown in the CHARIS project. We aimed to show that a theory-based short message can increase physical distancing self-efficacy and intentions to keep physical distance.

Design

Structured telephone surveys with a randomly selected nationally representative sample of adults in Scotland (N = 497).

Methods

Participants were randomly assigned to one of two experimental conditions: message condition (short message to increase self-efficacy via vicarious experiences, verbal persuasion and emotional arousal) or control condition (no message). Followed by measures for self-efficacy and intention for physical distancing on 4-point scales. Adherence to physical distancing was assessed on a 5-point frequency scale (never – always).

Results

Using mediation analyses with bootstrapping procedures, we first confirmed that self-efficacy was associated indirectly with adherence, via higher intentions in a partial mediation (unstandardized indirect effect .21, 95% CI .18–.25). The message increased self-efficacy; participants receiving the message reported higher self-efficacy (M = 4.23, SD = .80) compared to participants in the control condition (M = 4.08, SD = .77; standardized regression coefficient = .19, p < .05) and self-efficacy affected intention (.48, p < .001). There was a small significant indirect effect of the message on intention via self-efficacy (unstandardized indirect effect .07, CI .01–.14).

Conclusions

Increasing self-efficacy for physical distancing with a short message can successfully increase intention to physical distance via increased self-efficacy. As both self-efficacy and intentions are important predictors of adherence to transmission-reducing behaviours short messages have potential to limit the spread of COVID-19.