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.

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.

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.

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.

Morphological Aspects in Ultrasound Visualisation of the Suprascapular Notch Region: A Study Based on a New Four-Step Protocol

Background: Sonographic evaluation of the suprascapular notch (SSN) region is clinically important, because it is the most common location for performing suprascapular nerve block. The aim of the study was to describe the morphology of the SSN region based on ultrasound examination and in accordance with the patients’ body mass index (BMI). Material and Methods: The SSN region was sonographically examined in 120 healthy volunteers according to our new four-step protocol. The morphometry of the SSN and the neurovascular bundle was assessed, and patients’ BMI were calculated. The shape of the suprascapular notch was classified based on its superior transverse diameter (STD) and maximal depth (MD). Result: The type III scapular notch was the most prevalent (64%). The BMI was higher in type IV/V (27.38 ± 3.76) than in type I (24.77 ± 3.49). However, no significant differences were observed in the distribution of SSN notch types with regard to BMI (p = 0.0536). The suprascapular artery was visualised in all of the recognised SSNs, while the suprascapular vein and nerve were visualised only in 74.9% and 48.1% of the SSNs, respectively. The suprascapular nerve was significantly thicker on the right side (3.5 ± 1.1 mm) than on the left (1.3 ± 0.4 mm) (p = 0.001). In contrast, the suprascapular vein (1.5 ± 0.9 mm) was found to be a significantly wider on the left side than the right (1.2 ± 0.7 mm) (p = 0.001). Conclusion: Our original four-step sonographic protocol enabled characterising the morphology of the SSN region, despite the SSN notch types. The suprascapular artery is the best sonographic landmark for the suprascapular notch region. No significant differences were found between sides regarding the thickness of the soft tissue above the suprascapular nerve and vessels. Recognition of the SSN morphology is not affected by the BMI.

The prevalence and morphometric analysis of ossified superior transverse scapular ligaments in patients with rotator cuff tears

BACKGROUND

The prevalence of ossified superior transverse scapular ligaments (OSTSLs) in rotator cuff tears (RCTs) has not yet been determined. The purposes of this study were to evaluate the prevalence of OSTSLs in RCTs and to investigate the correlation between OSTSL morphology and supraspinatus muscle atrophy.

METHODS

We analyzed a total of 213 patients with RCTs for whom 3-dimensional (3D) computed tomography (CT) and magnetic resonance imaging were performed prior to arthroscopic procedures. The mean age of the patients was 59.73 ± 8.43 years, and 103 patients were men. OSTSLs were identified based on 3D CT findings. The correlations between OSTSLs and age, sex, and RCT size were analyzed. The horizontal and vertical diameters, area, and circumference of the suprascapular foramen were measured. By use of the occupation ratio calculated from magnetic resonance imaging results, supraspinatus muscle atrophy was evaluated.

RESULTS

Of 213 patients with RCTs, 22 (10.3%) had OSTSLs. OSTSLs were found at a rate of 15.5% (16 of 103) in men, higher than that in women (P = .016). The rate of OSTSLs increased with age (P = .003). RCT size was not correlated with the prevalence of OSTSLs. As the horizontal diameter and circumference of the suprascapular foramen increased, muscle atrophy progressed (P = .001 and P = .046, respectively).

CONCLUSION

One of ten patients with RCTs had OSTSLs; the rate of OSTSLs was higher among men and increased with age. For patients with RCTs preparing to undergo arthroscopic superior transverse ligament resection, preoperatively identifying OSTSLs through 3D CT would be useful for the resection.

Variations in the origin and course of the suprascapular artery: case report and literature review

The suprascapular artery is normally a branch of the thyrocervical trunk of the subclavian artery. During dissection of the left upper limb of a female cadaver, aged 70 years and fixed in 10% formalin solution, the suprascapular artery was observed aberrantly arising from the first part of the axillary artery. Later, it coursed obliquely behind the clavicle bone and brachial plexus to reach the suprascapular notch, where it was accompanied by the suprascapular nerve. Then, both suprascapular nerve and artery anomalously traversed beneath the transverse scapular ligament. It then irrigated the supraspinatus muscles and took part in the anastomosis around the scapula. On the contralateral side there was no abnormality. Variations in the origin and course of suprascapular artery are of immense value to orthopedic and vascular surgeons, angiographists, and anatomists.

Clinical outcomes of suprascapular nerve decompression: a systematic review

BACKGROUND

Suprascapular neuropathy is an uncommon clinical diagnosis. Although there have been a number of case series reporting on this pathologic process, to date there has been no systematic review of these studies. This study aimed to synthesize the literature on suprascapular neuropathy with regard to clinical outcomes. The secondary objective was to detail the diagnosis and treatment of suprascapular neuropathy and any associated complications.

METHODS

A systematic review was performed to identify studies that reported the results or clinical outcomes of suprascapular nerve decompression. The searches were performed using MEDLINE through PubMed and Cochrane Database of Systematic Reviews.

RESULTS

Twenty-one studies comprising 275 patients and 276 shoulders met inclusion criteria. The mean age was 41.9 years, and mean follow-up was 32.5 months. The most common symptom was deep, posterior shoulder pain (97.8%), with a mean duration of symptoms before decompression of 19.0 months; 94% of patients underwent electrodiagnostic testing before decompression, and 85% of patients had results consistent with suprascapular neuropathy. The most common outcome reported was the visual analog scale score, followed by the Constant-Murley score. The mean postoperative Constant-Murley score obtained was 89% of ideal maximum. Ninety-two percent of athletes were able to return to sport. Only 2 (0.74%) complications were reported in the included studies.

CONCLUSIONS

Surgical decompression in the setting of suprascapular neuropathy leads to satisfactory outcomes as evidenced by the patient-reported outcomes and return to sport rate. Furthermore, the rate of complications appears to be low.

Unusual morphology of scapulae: incidence and dimensions of ossified ligaments and supraspinous bony tunnels for clinical consideration

INTRODUCTION

Knowledge of morphological variations of the suprascapular region is important in the management of entrapment neuropathy and interventional procedures. The objective of this study was to collect data on the morphological features and dimensions of ossified ligaments and unusual bony tunnels of scapulae from a North Indian population.

METHODS

A total of 268 adult human scapulae of unknown gender were obtained from the bone bank of the Department of Anatomy, Dayanand Medical College and Hospital, Ludhiana, Punjab, India. The scapulae were evaluated for the incidence of ossified superior transverse scapular ligaments (STSLs), ossified inferior transverse scapular ligaments (ITSLs) and bony tunnels (i.e. the bony canal between the suprascapular notch and spinoglenoid notch), found along the course of the suprascapular nerve (SSN). The dimensions of these structures were measured and noted down. Ossified STSLs were classified based on their shape (i.e. fan- or band-shaped) and the dimensions of the ossified suprascapular openings (SSOs) were measured.

RESULTS

Ossified STSLs were present in 26 (9.7%) scapulae. Among the 26 scapulae, 16 (61.5%) were fan-shaped (mean area of SSO 16.6 mm(2)) and 10 (38.5%) were band-shaped (mean area of SSO 34.2 mm(2)). Bony tunnels were observed in 2 (0.75%) specimens, while an ossified ITSL was observed in 1 (0.37%) specimen.

CONCLUSION

The data obtained in the present study augments the reference literature for SSN decompression and the existing anatomical databases, especially those on Indian populations. This data is useful to clinicians, radiologists and orthopaedic surgeons.

Treatment of Combined Injuries of the Axillary and Suprascapular Nerves with Scapulothoracic Dissociation

A 20-year-old man suffered the combined axillary and suprascapular nerve palsies associated with scapulothoracic dissociation by motorcycle accident. The dislocated shoulder girdle was reduced and stabilized with osteosynthesis of the fractured clavicle and reattachment of the trapezius avulsed from the scapular spine for removal of continuous traction force to these damaged nerves. Because of no evidence of recovery on manual muscle test and electromyogram, exploration for these nerves was administered 6 weeks after injury. Although neurolysis of both nerves revealed neural continuity, excessive tension still existed on the suprascapular nerve. It was thought that previous operation in which the shoulder girdle had been reduced and stabilized as much as possible could not achieve complete anatomical reduction of the scapula. As an additional treatment, medial walls of the suprascapular and spinoglenoid notches were shaven to relax the suprascapular nerve. After a year, complete recovery of both the axillary and suprascapular nerve was identified. Although scapulothoracic dissociation is commonly recognized as massive injury of the shoulder girdle with poor prognosis because of existence of accompanied severe neurovascular injuries, there are more than a few cases in which partial damage on the infraclavicular brachial plexus is only accompanied. In case of them, there is the possibility of lesions in continuity of the nerves in which good prognosis might be expected with surgical intervention including early reduction of the shoulder girdle for removal of excessive tension to the damaged nerve.

Suprascapular foramen: a rare variation caused by ossified suprascapular ligaments

BACKGROUND

The aim of this study was to investigate the incidence of the suprascapular foramen in West Anatolian population.

MATERIALS AND METHODS

Eighty-one dried human scapulae of West Anatolian people of unknown ages and gender belonging to the Anatomy Department Laboratory of Dokuz Eylul University Medical School were examined macroscopically. The vertical and transverse diameters of the suprascapular foramen and central thickness of the ossified ligaments were measured with calliper in millimetres and digital calliper, respectively.

RESULTS

We observed the suprascapular foramen due to ossification of the suprascapular ligament only in 2 of 81 (2.47%) scapulae. The vertical and transverse diameters of the suprascapular foramen and central thickness of the ossified ligaments (No. 1 and No. 2) were measured as 8.0 mm vs. 4.0 mm, 3.6 mm vs. 2.0 mm and 4.0 mm vs. 1.4 mm, respectively.

CONCLUSIONS

The suprascapular foramen caused by ossified suprascapular ligament is rarely observed variation in West Anatolian population.

A computed tomography study on the correlation between the morphometry of the suprascapular notch and anthropometric measurements of the scapula

BACKGROUND

The suprascapular notch is a clinically important site because it is the main site of injury and compression of the suprascapular nerve. Its shape and size are the most important factors in the aetiopathology of suprascapular nerve neuropathy. This article reports the first computed topography (CT) study on the correlation between the diameters of the suprascapular notch and anthropometric measurements of the human scapula.

MATERIALS AND METHODS

A total of 130 scans of shoulders by a helical 32-row multidetector CT scanner were retrospectively analysed. The following scapular measurements were performed: morphological length, morphological width, projection length of the scapular spine, maximal width of the scapular spine, length of the acromion, maximal length of the coracoid process, length of the superior border of the scapula, morphological height of the supraspinous fossa, length of the lateral border of the scapula, and morphological height of infraspinous fossa. The following suprascapular notch dimensions were measured: maximal depth, superior transverse diameter, middle transverse diameter.

RESULTS

The maximum depth of the suprascapular notch correlates with the morphological length of the scapula, the length of the lateral border of the scapula and the morphological width of the scapula. The superior transverse diameter of the suprascapular notch correlates with the length of the superior border of the scapula and negatively with the length of the lateral border of the scapula. In addition it has been shown that the length of the superior border of the scapula correlates more closely with the superior transverse diameter of the suprascapular notch than the middle transverse diameter of the suprascapular notch.

CONCLUSIONS

It could be supposed that humans with longer scapulae have deeper notches. It may be also concluded that scapulae with a wider superior border have a shallower suprascapular notch.

Arthroscopic decompression at the suprascapular notch: a radiographic and anatomic roadmap

BACKGROUND

Arthroscopic decompression of the suprascapular nerve (SSN) at the suprascapular notch is a technically demanding procedure. Additional preoperative and intraoperative information may assist surgeons. The purpose of this study was to (1) identify which imaging modality most accurately represents the anatomic distance to the notch and (2) quantify the mean intraoperative distances from routine arthroscopic portals to the notch.

METHODS

Ten matched pairs of fresh cadaveric shoulders were imaged by roentgenogram, computed tomography (CT), magnetic resonance imaging, and 3-dimensional (3D) CT, followed by arthroscopic SSN decompression at the notch and anatomic dissection. Measurements obtained included the distances from the anterolateral, posterior, and SSN portal sites to the notch in addition to the distance from the anterolateral acromion to the notch. Statistical analysis with Spearman correlation coefficients and Bland-Altman plots were used to determine the correlation and agreement between measurements.

RESULTS

The preoperative imaging modality with the highest correlation to anatomic distances from the anterolateral acromion to the notch was 3D CT (Rs = 0.90, P < .0001). The mean intraoperative distances to the notch from the anterolateral, posterior, and SSN arthroscopic portals were 89 mm, 88 mm, and 49 mm, respectively. The mean anatomic distance from the anterolateral acromion to the notch was 64 mm.

CONCLUSIONS

Preoperative imaging with 3D CT may assist surgeons in performing arthroscopic SSN decompression. Understanding of the mean distances from the portal sites to the suprascapular notch and being cautious of arthroscopic instruments placed beyond 9 cm from laterally based portals may result in safer intraoperative medial dissection.

New parameters describing morphological variations in the suprascapular notch region as potential predictors of suprascapular nerve entrapment

BACKGROUND

The suprascapular notch (SSN), bridged by the superior transverse scapular ligament (STSL), creates a pathway for the suprascapular nerve (SN). Morphological variations in the SSN region are common and can increase the risk of neuropathy by constricting the space for the nerve. The aim of this study was to establish new objective parameters that take this complex morphology into account.

METHODS

The SSN region of 100 formalin-fixed cadaveric shoulders was dissected. The dimensions of the SSN, the STSL and the anterior coracoscapular ligament (ACSL), as well as diameters of the SN, associated vessels and SN passage area, were measured by means of quantitative visual data analysis software to assign those structures to present classifications. The area reduction coefficient (ARC) and the ambit occupation coefficient (AOC) were defined and calculated for each shoulder.

RESULTS

The mean ARC and AOC for ligaments in the suprascapular region were: ARCSTSL = 71.6%, ARCACSL = 9.6%, AOCSTSL = 56.8% and AOCACSL = 9.1%. The SN passage area, ARC and AOC did not differ significantly between SSN types. The SN passage area and ARC differed significantly between band- and fan-shaped types of STSL. A significant relationship was observed between ARC and AOC (R=0.6855; p<0.0001). The SN passage area correlated significantly with ARC (R=-0.7555; p<0.0001) and AOC (R=-0.5609; p<0.0001).

CONCLUSIONS

The proposed parameters convey the complex morphology of the SSN region in a quantitative manner. The area reduction coefficient seems to be a more relevant indicator than the AOC as it better correlates with the SN passage area. Contrary to the SSN type, the STSL type significantly influences SN passage area and ARC.

Suprascapular nerve entrapment due to a stenotic foramen: a variant of the suprascapular notch

Suprascapular nerve (SSN) entrapment is an uncommon cause of posterior shoulder pain. Entrapment can be relieved arthroscopically in some cases.

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.