Systematic Review and Meta-analysis of Suprascapular Notch Morphological Variability: Do We Know Everything?

The suprascapular notch represents a depression on the lateral part of the superior border of the scapula, medially to the coracoid process. The current paper presents a systematic review with a meta-analysis of the suprascapular notch morphological variability. Related clinical implications were further discussed as well to emphasize the value of the topic. A total of 31 articles were included in the meta-analysis, which depicted great heterogeneity. Thus, due to the different classification systems, difficulties were faced in creating a complete and united classification. All the problems and pitfalls that arise from each classification system were discussed, and we concluded with the most complete one. The knowledge of the suprascapular notch morphological anatomy is of great importance, especially for orthopedic surgeons, due to its relationship with the suprascapular nerve. Thus, further research in this area is adequate.

Interobserver and Intraobserver Variability of Four Suprascapular Notch Classification Systems.

INTRODUCTION: Knowledge of the morphology of the suprascapular notch is clinically beneficial in patients with suspected suprascapular nerve compression or palsy. Several classification systems have been proposed for the morphological classification of the suprascapular notch and its several anatomical variations. The purpose of this study was to evaluate the inter- and intraobserver reliability of four different classification systems for suprascapular notch typing analysing shoulder computed tomography (CT) scans. METHODS: Shoulder CT scans from 109 subjects (71.5% males) were examined by three raters of various experience levels, one senior, one experienced, and one junior orthopaedic surgeon. The CT scans were evaluated quantitatively and qualitatively and the suprascapular notch was classified according to four classification systems at two separate timepoints, four weeks apart. To determine consistency among the same or different raters, the Kappa statistic was performed and intrarater reliability for each rater between the first and the second evaluation was assessed using Cohen's kappa. Reliability across all raters at each timepoint was assessed using the Fleiss kappa. RESULTS: Agreement was almost perfect for all the classification systems and amongst all raters, regardless of their experience level. There were no significant differences between the raters on any of the evaluations. The overall interobserver agreement for all classifications was almost perfect. CONCLUSION: The four suprascapular notch classification systems are reliable, and the rater's experience level has no impact on the evaluation.

Comparison of Spinoglenoid Versus Suprascapular Notch Approaches for Ultrasound-Guided Distal Suprascapular Nerve Blocks for Shoulder Pain: A Prospective Randomized Trial.

BACKGROUND: Distal suprascapular nerve blocks (SSNB) can be performed at the level of the suprascapular notch (the preferred site) or at the level of the spinoglenoid notch. OBJECTIVES: To compare the efficacy and safety of spinoglenoid versus suprascapular notch approaches for ultrasound (US)-guided distal SSNB in patients with chronic shoulder pain. STUDY DESIGN: Prospective randomized controlled trial. SETTING: Outpatient physical medicine and rehabilitation outpatient clinic of a tertiary center. METHODS: Eighty patients with chronic unilateral shoulder pain were included in this study. Patients were randomized into 2 groups: group 1 (SSNB at the level of the spinoglenoid notch) and group 2 (SSNB at the level of the suprascapular notch). The patients were evaluated for pain according to the Shoulder Pain and Disability Index (SPADI) and a secondary visual analog scale (VAS), as well as for the outcome measures of range of motion (ROM) and pain pressure threshold (PPT) at baseline and at one, 4, and 12 weeks after the injection. RESULTS: Statistically significant improvement was observed in the SPADI and VAS scores and ROM measurements, and the PPT measurements were similar at all post-injection follow-ups in both groups. Changes in outcome measures were similar between the groups, except for some ROM measurements at the post-injection follow-ups. LIMITATIONS: Heterogeneity of shoulder pain etiologies. CONCLUSION: Both distal SSNB approaches significantly improved pain and disability scores in patients with chronic shoulder pain, with no observable differences in the short-to-medium term. SSNB performed at the level of the spinoglenoid notch is therefore not inferior in efficacy and safety to SSNB performed at the level of the suprascapular notch.

Variability in the distance between the suprascapular notch with the spine of the scapulae and the acromion.

INTRODUCTION: The suprascapular notch lies in the superior border of the scapula and is a passageway for the suprascapular nerve that is sensory to the shoulder joint. Suprascapular nerve block involves injection of local anaesthetic into the suprascapular notch, either ultrasound guided or blind, using the spine of scapula and/or the medial border of the acromion as surface landmarks. AIM: To investigate the anatomic variations that exist between the distance of the notch from the spine of scapula and acromion. METHOD: Ninety-two dry scapulae were measured with a digital calliper for their length of the spine, distance between the midpoint of the spine and base of the suprascapular notch and distance between the medial border of the acromion and the base of the suprascapular notch. These measurements were compared for variations in the scapular bony landmarks, the spine and the acromion to determine the site for the injection. RESULTS: Measurement reliability was assessed by intraclass correlation, Cronbach's alpha being 0.99, 0.97 and 0.91 for length of spine, distance from spine and distance from acromion respectively. The distance from the acromion had less variation in measurement (3.73 ± 0.42 cm) but a flatter distribution when compared to distance from the spine of the scapula (3.32 ± 0.39 cm). CONCLUSION: Length of the spine of the scapula appeared not to influence either distance from the acromion or distance from the spine of scapula. There is potential for greater variability in placement of nerve blocks that use acromion as the bony reference. Key Points • Dry scapular measurement using electronic Vernier callipers is accurate (0.91-0.97). • There is potential for greater variability in placement of blind nerve blocks that use acromion as the bony reference to locate the suprascapular notch.

Ultrasound-Guided Suprascapular Nerve Block at Suprascapular Notch-Do We Really Target Suprascapular Notch or Not? Where Is Our Real Target?

Ultrasound (US)-guided suprascapular nerve block (SSNB) is a widely used procedure and while describing the US-guided SSNB in the suprascapular notch, the suprascapular fossa is often visualized and injection is performed in that location. Although it can be done in both location, to inject the right area, the terminology should be settled and the visualization of these areas which are unclear and confusing in the literature should be clarified. In this sense, we showed the course of the nerve on a cadaver and briefly describe a protocol to correctly visualize the suprascapular notch with US.

Correlation of suprascapular notch morphology with suprascapular nerve palsy: a 3D-computed tomography study.

Background: The morphology of the suprascapular (SS) notch is a very important factor in treatment of suprascapular nerve (SSN) palsy. Several studies have reported SS notch morphology in cadavers or using a three-dimensional computed tomography (3D-CT); however, none has reported the distribution of SS notch morphology according to the age group. In addition, the correlation between SS notch morphology and SSN palsy remains unclear. The purposes of this study were to investigate the morphological distribution of the SS notch by age group in a large population and to assess the relationship between SS notch morphology and SSN palsy. Methods: We studied the 3D-CT images of 1063 shoulders in 1009 patients (mean age, 60.8 years; age range, 14-96 years). There were 53 shoulders with SSN palsy and 1010 shoulders without SSN palsy. Morphology of the SS notch was classified by Rengachary's classification (types I-VI). Shoulders with types I-IV were classified into the nonossified superior transverse scapular ligament (STSL) group (group N) and those with types V and VI into the ossified STSL group (group O). Results: The Rengachary's classifications of the 1063 shoulders were as follows: type I: n = 113, 10.6%; type II: n = 313, 29.4%; type III: n = 383, 36.0%; type IV: n = 109, 10.3%; type V: n = 107, 10.0%; and type VI: n = 38, 3.6%. Mean age was significantly older in the ossified STSL group, and the age was <40 years for only two shoulders in this group. The Rengachary's classifications of the SSN palsy cases were as follows: type I: 7.5%, II: 24.5%, III: 34.0%, IV: 15.1%, V: 13.2%, and VI: 5.7%. There was no statistical difference in age and sex, Rengachary type, or ossification between SSN palsy and non-SSN palsy cases. Conclusions: Ossification of the STSL was significantly more common in older patients, which suggests age-related change. In addition, no relation was identified between narrow notch or ossification of the STSL with the onset of SSN palsy.

Ossification of Superior Transverse Scapular Ligament - Incidence, Embryology and Association with Suprascapular Neuropathy.

Introduction: Suprascapular notch is present at superior border of scapula just medial to coracoid process. This is covered by superior transverse scapular ligament (STSL). Suprascapular nerve passes below this ligament while suprascapular vessels pass above it. STSL ossification is a rare finding with variable incidences in different population groups. Materials and Methods: We observed 60 dry bony scapulae, 30 prosected formalin fixed upper limbs with scapula and 10 embalmed cadavers for the presence of ossified STSL. Results: There were complete ossification of STSL in two dried bony specimens of sacpula. Conclusion: Ossified STSL may be the causative factor for suprascapular neuropathy. The mainstay of management in cases of neuropathy or compression of suprascapular nerve is release of suprascapular ligament by either open or arthroscopic surgical approach. So, it is extremely important to know this type of variation to minimize any damage to related structure and plan the management accordingly.

Osseous suprascapular canal: rare variant that would hinder suprascapular nerve block and posterior surgical approach.

PURPOSE: To report atypical anatomical variation of an osseous suprascapular canal, and to elaborate on its clinical significance as a potential anatomical factor that could obscure a direct posterior surgical approach and suprascapular nerve block. METHODS: Osteological observational study of the scapula with emphasis on the suprascapular space. The pool of investigated sample size was collectively 768 specimens composed of 529 adult dry scapulae (240 paired, 289 un-paired), 54 children dry scapulae, 135 wet scapulae observed during cadaveric dissections, 47 retrospective 3D CT reconstructions, and 3 retrospective full sequence shoulder MRI. The two reported cases came from the 240 (120 skeleton) observed paired scapulae. Furthermore, the osseous suprascapular canal was examined by X-rays and its internal path was exposed by CT sections. A narrative review was conducted to investigate any relevant reports on the subject matter. RESULTS: Two left dry bone scapulae with unilateral osseous suprascapular canal were found. The incidence of this atypical morphology of an osseous canal is probably five cases reported in three studies including this cases study. CONCLUSIONS: The reported cases aid in explaining additional possible anatomical factors that could lead to below threshold anesthetic effect in posterior suprascapular nerve block procedures. Therefore, it is more practical to visualize the suprascapular canal by some imaging method before attempting to blindly access the suprascapular nerve in nerve block or posterior surgical approach due to the rare potential existence of an ossified barrier hindering the procedure. LEVEL OF EVIDENCE: V Basic Science Research.

An anatomical study for the location of suprascapular and spinoglenoid notches using three-dimensional computed tomography images of scapula.

Background: The optimal position for creating portals for arthroscopic suprascapular nerve decompression has not been sufficiently verified. Therefore, this study aimed to investigate the anatomical characteristics of the scapula for optimal portal creation using 3-dimensional computed tomography images. The posterolateral corner of the acromion was designated as the starting point for measurements because there is no secondary ossification center present. Methods: This study included 223 patients (females, 129; males, 94) who underwent computed tomography of the shoulder joint. Three-dimensional images of the scapula were created, and the distance from the posterolateral corner of the acromion to the suprascapular and spinoglenoid notches was measured. Additionally, the correlation coefficient with height and the differences between the female and male groups were investigated. Results: The distances from the posterolateral corner of the acromion to the suprascapular and spinoglenoid notches were 42.9 ± 4.6 and 31.5 ± 3.6 mm, respectively, and their correlation coefficients with height were 0.12 and 0.067, respectively. There was no significant difference in the distance from the posterolateral corner of the acromion to the suprascapular (42.5 ± 4.1 vs. 43.9 ± 5.1 mm, P = .098) and to the spinoglenoid (31.4 ± 3.3 mm vs. 32.0 ± 3.9 mm, P = .12) notches between the female and male groups. Conclusion: Regardless of height and sex, the distances from the posterolateral corner of the acromion to the suprascapular and spinoglenoid notches were approximately 43 and 32 mm, respectively. Therefore, creating portals at these locations may be effective for arthroscopic suprascapular nerve decompression.

Morphometric study of the suprascapular notch and scapular dimensions in adult Malawian cadavers and implications of completely ossified superior transverse scapular ligament.

Introduction: the anatomy of the suprascapular notch and its relationship to scapular dimensions are critical in the management of suprascapular neuropathies. Individuals show considerable differences in the dimensions of the suprascapular notch across populations. The purpose of this study was to determine the morphology and morphometric dimensions of the suprascapular notch in adult Malawian cadavers and to suggest clinical implications associated with complete ossification of the suprascapular ligament. Methods: adult dry scapulae from undetermined sex specimens (n=125) obtained from the skeletal collection at Kamuzu University of Health Sciences were classified according to the Rengachary categorization method to assess the suprascapular notch superior transverse distance, mid transverse distance, depth, scapula length and width using a standard Vernier caliper. Results: the most prevalent suprascapular notch class was type I, which was found in 46 (36.8%) of all scapulae. Type VI was the least common, found in only 1 (0.8%) of the scapulae. The mean notch superior transverse distance was 1.3 ± 0.6 cm, while the mean maximum depth was 0.6 ± 0.3 cm. Only the differences in depth, however, were statistically significant (p=0.001). Conclusion: the current study has described the morphology and morphometry of the suprascapular notch in relation to the risk of suprascapular nerve entrapment associated with complete ossification of the suprascapular ligament. Our sample population generally showed smaller suprascapular notch and scapular dimensions than other populations. This should be considered during the management of suprascapular neuropathy and preoperative planning of surgical operations of the shoulder region.

Morphometry and Contents of the Suprascapular Notch with Potential Clinical Implications: Α Cadaveric Study.

Background The suprascapular notch (SN) represents the point along the route of the suprascapular nerve (SSN) with the greatest potential risk for injury and compression. Thus, factors reducing the area of the notch have been postulated for suprascapular neuropathy development. Methods Thirty-one fresh-frozen shoulders were dissected. The contents of the SN were described according to four types as classified by Polguj et al and the middle-transverse diameter of the notch was measured. Also, the presence of an ossified superior transverse scapular ligament (STSL) was identified. Results The ligament was partially ossified in 8 specimens (25.8%), fully ossified in 6 (19.35%), and not ossified in the remaining 17 (54.85%). The mean middle-transverse diameter of the SN was 9.06 mm (standard deviation [SD] = 3.45). The corresponding for type-I notches was 8.64 mm (SD = 3.34), 8.86 mm (SD = 3.12) was for type-II, and 14.5 mm (SD = 1.02) was for type III. Middle-transverse diameter was shorter when an ossified ligament was present (mean = 5.10 mm, SD = 0.88 mm), comparing with a partially ossified ligament (mean =7.67 mm, SD = 2.24 mm) and a nonossified one (mean = 11.12 mm, SD = 2.92 mm). No statistically significant evidence was found that the middle-transverse diameter depends on the number of the elements, passing below the STSL. Conclusion Our results suggest that SSN compression could be more likely to occur when both suprascapular vessels pass through the notch. Compression of the nerve may also occur when an ossified transverse scapular ligament is present, resulting to significant reduction of the notch's area.

Bilateral suprascapular notches are asymmetrically shaped in a third of the Asian population.

PURPOSE: The side-to-side differences within an individual's suprascapular notch (SSN) and the clinical characteristics of an ossified superior transverse scapular ligament are unclear. Therefore, the morphological asymmetry of the SSN was investigated, and the factors associated with the ossification of the superior transverse scapular ligament were analyzed. METHODS: Two hundred and seventy-six computed tomography images were retrospectively analyzed, which included those of both scapulae of Asian patients (mean age, 62.1 ± 19.1 years; males, 197) with high-energy injuries or respiratory diseases. Variations in the SSN were classified into six types based on Rengachary's classification using reconstructed three-dimensional computed tomography. The group with a type VI SSN (completely ossified superior transverse scapular ligament) in at least one scapula was compared with the other group for age, sex, and chronic comorbidities. RESULTS: Among 276 patients, 95 (34.4%) had asymmetric SSNs and 15 (5.4%) had type VI SSNs. There were no significant differences in age, sex, or comorbidities between both the groups. However, on comparing age groups, the prevalence of type VI SSN was higher in patients aged > 70 years than in those aged < 70 years. Fifteen patients had type VI SSNs, which were unilateral in 10 patients. CONCLUSION: Asymmetric SSNs were observed in a third of the Asian patients. There were variations in SSNs between individuals and also within an individual. In the cases with suprascapular nerve paralysis, the difference in SSN morphology compared to a healthy side should be considered. LEVEL OF EVIDENCE: III.

Arthroscopic release of proximal supra-scapular nerve entrapment: Medium-term results. / Liberación artroscópica del atrapamiento proximal del nervio supraescapular: resultados a medio plazo.

OBJECTIVE: To evaluate the clinical and electrophysiological results in the medium term of the arthroscopic release of the proximal entrapment of the suprascapular nerve. MATERIAL AND METHOD: It is a retrospective study that includes 75 patients with idiopathic entrapment of the suprascapular nerve in the suprascapular notch in whom conservative treatment has failed. All patients underwent electrophysiological tests (EMG) as well as clinical test (Constant and DASH test) preoperatively and during follow-up. RESULTS: 75 patients (53 women and 22 men) with a mean age of 44.1 ± 10.7 years met study criteria with a mean follow-up of 63.7 ± 29.1 months. Preoperatively the DASH value was 78,6 ± 10,2, the Constant test value was 37.1 ±8.8 and the EVA value was 8.8 ± 1.1 while the values in the last revision were 19.4 ± 15.8 for DASH, 80.2 ± 9.6 (for the CS and 2 ±1.3 for the EVA scale; the differences were significant in all cases (P<.001). Regarding the results of the electrophysiological test, preoperatively there were 21 very severe grades (28%), 32 severe (42.6%), 17 moderate (22.6%) and 5 mild (6.6%). While in the last review there were 3 severe degrees (4%), 6 moderate (8%), 40 mild (53.3%) and 26 normal (34.6%). There was no very severe grade (0%); 3 patients (4%) had to be reoperated due to persistent symptons. CONCLUSIONS: The arthroscopic release of idiopathic entrapment of the suprascapular nerve in the superior scapular notch achieved good clinical and electrophysiological results in the medium term. LEVEL OF EVIDENCE: iv; case series; treatment study.

"Suprascapular canal": Anatomical and topographical description and its clinical implication in entrapment syndrome.

BACKGROUND: Suprascapular nerve (SN) entrapment syndrome accounts for 1-2% of all shoulder pain. The SN travels within a space between the suprascapular notch (SSN) and the spinoglenoid notch (SGN). PURPOSE: To report a detailed topographical study of the suprascapular canal (SSC) and ultimately sort the different types of SN entrapment by its anatomical localization within the canal. BASIC PROCEDURES: Observational study on 30 free dissected limbs of formaldehyde-fixed cadavers. The SN and vessels were traced as they passed through the SSC and the boundaries of the SSC were observed and documented. The SSC was then exposed by reflecting away the bordering muscles. Dimensions of the SSC as well as parameters of the SSN and SGN were measured using a digital caliper. Finally, a thorough literature review was made to survey the SN entrapment occurrence by site. MAIN FINDINGS: The SSC is situated in the spinoglenoid fossa, has an average width of 13 mm, and runs underneath the supraspinatus muscle with an average distance of 25 mm between the SSN and SGN sloping in an infero-postero-lateral direction. The first segment represents the SSC entrance site and is composed of two spaces: osteofibrous and musculofibrous. The second segment is bordered by the supraspinatus muscle fascia, lateral margin of the supraspinous fossa, glenohumeral joint capsule, and the bony surface of the scapula (spinoglenoid fossa). This represents the SSC passage site. The third segment represents the SSC exit site around the spinoacromial arch at the SGN. PRINCIPAL CONCLUSIONS: The SSC is defined as an osteofibrous canal running between the SSN and SGN enclosed by the supraspinatus fascia. It is anatomically composed of three segments: an entrance, a passage, and an exit. The distal SN passes through the SSC via five intervals that correspond to five potential sites of anatomical nerve entrapment: at the pre-entrance site, entrance site, passage site, exit site, and post-exit site. Each of those sites was found to be associated with specific causes and forms of entrapment.

The morphological stenosis pattern of the suprascapular notch is revealed yielding higher incidence in the discrete type and elucidating the inevitability of osteoplasty in horizontally oriented stenosis.

PURPOSE: To identify the morphological patterns of suprascapular notch stenosis. METHODS: Suprascapular notch space capacity was assessed by morphometric analysis of 333 dry scapulae. Suprascapular notch parameters-superior transverse distance, middle width, depth, medial border length and lateral border length-were measured. The probable suprascapular notch stenosis was referenced by (1) comparing each obtained parameter measurement to the range of the suprascapular nerve diameter, and (2) quantifying the reduced parameters. Finally, the morphological pattern was determined based on the collective reduction of the parameters and their alignments. RESULTS: Five types of suprascapular notch based on depth to superior transverse distance ratio were identified and assessed. Type-I showed low incidence of stenosis (6/333) and low frequency within type (6/28) with potential risk of horizontal compression. Type-II showed relatively low incidence of stenosis (9/333) and low frequency within type (9/50) with undetermined pattern. Type-III showed relatively higher incidence of stenosis (47/333) but low frequency within type (47/158) with potential risk of vertical compression. Type-IV (foramen) showed low incidence of stenosis (6/333) and relatively lower frequency within type (6/26) with potential risk of encircled compression. Finally, type-V (discrete) showed relatively high incidence of stenosis (40/333) and high frequency within type (40/71) with potential risk of vertical compression. The suprascapular notch was found to be stenosed beyond its capacity to accommodate the suprascapular nerve in 49/333. Type-V is at most risk followed by Type-III. CONCLUSIONS: Suprascapular notch stenosis takes three morphological patterns: horizontal, vertical or mixed. An osteoplasty of suprascapular notch margins may be required beside the common surgical approach of the superior transverse scapular ligamentectomy.

Morphometric study of suprascapular notch and scapular dimensions in Ugandan dry scapulae with specific reference to the incidence of completely ossified superior transverse scapular ligament.

BACKGROUND: Understanding of suprascapular notch (SSN) anatomy and relationship with scapular dimensions are vital in diagnosis, prevention, and assessment of suprascapular nerve entrapment syndrome. The study aimed to assess morphometry of suprascapular notch and scapular dimensions in Ugandan dry scapulae with specific reference to scapulae with completely ossified superior transverse scapular ligaments. METHODS: This was a cross-sectional analytical study conducted on 50 Ugandan dry scapulae. SSN types and prevalence of completely ossified superior transverse scapular ligament among dry scapulae were quantified and compared with previous data. Scapular dimensions were assessed by measuring scapular length (A), scapular width (B), glenoid length (C), and glenoid width (D). One-way ANOVA was used to compare scapular dimensions of scapulae with different SSN types, and Spearman's correlation coefficient was used to evaluate the correlation coefficient of scapular dimensions amongst groups. RESULTS: Superior transverse scapular ligament (STSL) was completely ossified in 8% of cases. There was no significant (P > 0.05) difference between scapular dimensions of scapulae with completely ossified STSL compared to scapulae with other SSN types. Scapulae with completely ossified STSL showed strong negative (r = - 0.89137, r = - 0.877) correlations for its A, B respectively compared against D, this finding was not true to scapulae of other SSN types. Also, there were strong positive or negative (r > 0.7, r > - 0.7) correlations: for A, types I and III compared to type VI; for B, types I, III compared to VI; for C, type IV and VI; and for D, type III and VI. CONCLUSIONS: The prevalence of completely ossified STSL is moderately high in the Ugandan population. Characteristics of the scapula (scapular dimensions) are not 'vital' but rather important or relevant for shoulder pathology with specific reference to suprascapular nerve entrapment syndrome due to completely ossified superior transverse scapular ligaments. Further correlation analyses of scapular dimensions of different SSN types in different populations are important.

Suprascapular Neuropathy around the Shoulder: A Current Concept Review.

Suprascapular neuropathy is an uncommon but increasingly recognized cause of shoulder pain and dysfunction due to nerve entrapment. The aim of this review is to summarize some important aspects of this shoulder pathology. An extensive research was performed on PubMed and Clinical Key. The goal was to collect all the anatomical, biomechanical and clinical studies to conduct an extensive overview of the issue. Attention was focused on researching the state of art of the diagnosis and treatment. A total of 59 studies were found suitable and included. This condition is more frequently diagnosed in over-head athletes or patients with massive rotator cuff tears. Diagnosis may be complex, whereas its treatment is safe, and it has a great success rate. Prompt diagnosis is crucial as chronic conditions have worse outcomes compared to acute lesions. Proper instrumental evaluation and imaging are essential. Dynamic compression must initially be treated non-operatively. If there is no improvement, surgical release should be considered. On the other hand, soft tissue lesions may first be treated non-operatively. However, surgical treatment by arthroscopic means is advisable when possible as it represents the gold standard therapy. Other concomitant shoulder lesions must be recognized and treated accordingly.

Ultrasound-Guided Proximal and Distal Suprascapular Nerve Blocks: A Comparative Cadaveric Study.

OBJECTIVES: The primary aim of our study was to evaluate and compare the accuracy of ultrasound (US)-guided distal suprascapular nerve (dSSN) and proximal SSN (pSSN) blocks. Secondary aims were to compare the phrenic nerve involvement between groups and to describe the anatomical features of the sensory branches of the dSSN. METHODS: pSSN and dSSN blocks were performed in 14 cadavers (28 shoulders). Ten mL of 0.2% ropivacaine colored with methylene blue was injected under US guidance. Accuracy was determined using SSN staining and the distance between predefined anatomical landmarks and the targeted SSN. The phrenic nerve (PN) was judged to be colored or not. The distribution of the sensory branches that originate from the 14 dSSNs is described. Quantitative data are expressed as median (range). RESULTS: The pSSN was dyed more frequently than the dSSN (13 vs 11, P = 0.59). The targeted SSN was close to the suprascapular notch (1.3 [0-5.2] cm) and the origin of the SSN (1.4 [0.2-4.5] cm) for dSSN and pSSN blocks, respectively (P = 0.62). For dSSN blocks, the most frequent injection site was the supraspinous fossa. Three PNs were marked in pSSN blocks, compared with none in dSSN blocks (P = 0.22). Three sensory branches were identified for all 14 dSSNs: the medial subacromial branch, the lateral subacromial branch, and the posterior glenohumeral branch. CONCLUSIONS: US-guided pSSN and dSSN blocks can be realized with accuracy. A distal approach to the SSN could be an alternative to interscalene brachial plexus block for the management of postoperative pain after shoulder surgery in high-respiratory risk patients.

The Incidence of Ossified Superior Transverse Scapular Ligament during Nerve Transfer through Posterior Shoulder Approach.

BACKGROUND: The purpose of this study was to assess the incidence and importance of bony bridge that covers the supra scapular notch during posterior approach to transfer accessory nerve to suprascapular nerve. METHODS: Between 2010 and 2015, the frequency and importance of suprascapular bony bridge instead of transverse ligament was assessed among patients with brachial plexus injury candidate to shoulder function restoration by accessory to suprascapular nerve transfer through posterior approach. RESULTS: Forty three patients, 41 male and 2 female, (mean age: 32.5 years, range 14 to 36) were included in this study. Five male patients (11.6%) had a complete bony rim on the superior scapular notch. Suprascapular nerve release needed osteotomy of the bony bridge and related equipment. CONCLUSION: Although all previous cadaveric studies among different ethnic groups had reported the prevalence between 0.3 to 30% of suprascapular canal, this in vivo study showed the incidence of 11.6%. Preoperative alertness about this variation could make the exploration and release of the suprascapular nerve easier and reduce the risk of nerve injury or failing to anatomize it. LEVEL OF EVIDENCE: IV.