Spinoglenoid septum: a new anatomic finding

Morphology and Prevalence of the Inferior Transverse Scapular Ligament: Systematic Review, Meta-Analysis, and Proposal for Classification

Background/Objectives: The suprascapular nerve is most vulnerable to entrapment at the suprascapular and spinoglenoid notches, causing neuropathy. Numerous studies have examined the suprascapular notch and ligament and its relationship with suprascapular nerve entrapment, but few have examined the spinoglenoid notch and the inferior transverse scapular ligament (ITSL). This study summarizes all existing ITSL morphology studies and presents a simple and comprehensive classification system for different ITSL subtypes. Methods: A systematic review of the literature was conducted according to the PRISMA guidelines, searching the online databases PubMed and Embase. The references of each relevant article were further screened to find more eligible studies. The Anatomical Quality Assessment tool was used in order to further evaluate the quality of the records extracted. STATA MP 14 was used for the analysis in this study. Results: In total, 14 studies (995 scapulae; minimum: 1 and maximum: 268) were included in the present study. The overall ITSL prevalence was 5.8 (95% CI: 4.5-7.1) and the estimated odds for ligamentous vs. membranous type was 0.5 (95% CI: 0.3-0.7). The basic different morphological subtypes of the ITSL reported in the included studies are the band-like ligament, the fan-shaped ligament, the membranous ITSL, and the perforated membranous types. Conclusions: The ITSL represents an anatomical structure of mostly ligamentous nature. A single ITSL definition and standardization of its basic morphological subtypes along with an easy-to-remember and thus widely used classification system could greatly facilitate the comprehensive description, identification, and proper handling of this element across many surgical procedures.

Protective and Predisposing Morphological Factors in Suprascapular Nerve Entrapment Syndrome: A Fundamental Review Based on Recent Observations

Suprascapular nerve entrapment syndrome (SNES) is a neuropathy caused by compression of the nerve along its course. The most common compression sites include the suprascapular notch and the spinoglenoid notch. The aim of this article was to review the anatomical factors influencing the occurrence of SNES in the light of the newest reports. Potential predisposing morphological factors include a V-shaped, narrow, or "deep" suprascapular notch; a band-shaped, bifurcated, or completely ossified superior transverse scapular ligament (STSL); particular arrangements of the suprascapular nerve and vessels at the suprascapular notch. A very recent report indicates structures at the suprascapular notch region that may protect from SNES, such as the suprascapular notch veins (SNV). The role of the anterior coracoscapular ligament (ACSL) is still not clear. While some studies indicate that it may predispose for SNES, the newest study proposes a protective function. Knowledge of these variations is essential for arthroscopic and other surgical procedures of this area in order to avoid iatrogenic injury of the suprascapular nerve or unexpected bleeding from the suprascapular vessels running alongside the STSL.

Suprascapular nerve entrapment isolated to the spinoglenoid notch: surgical technique and results of open decompression

BACKGROUND

Entrapment of the suprascapular nerve (SSN) at the spinoglenoid notch (SGN) specifically affects the infraspinatus, and isolated external rotation (ER) weakness can result. We describe the technique of open SSN decompression at the SGN for infraspinatus involvement and report the results of a consecutive series.

MATERIALS AND METHODS

Twenty-nine shoulders underwent SSN decompression at the SGN. The mean age was 44 years (range, 15-69 years), and the mean follow-up was 4.3 years (range, 1-7 years). On manual muscle testing, ER strength was abnormal in all patients: 2/5 in 3, 3/5 in 21, and 4/5 in 5. The mean preoperative American Shoulder and Elbow Surgeons (ASES) score was 48 (range, 23-83). Atrophy of the infraspinatus was visible or palpable in 72% of shoulders. Magnetic resonance imaging showed ganglion cysts at the SGN in only 20.7% of shoulders.

RESULTS

Of the patients, 19 (66%) regained full ER strength, 9 (31%) improved to 4/5, and 1 (3%) had ER strength of 3/5. The mean ASES score improved to 75 (range, 60-100) (P < .05). Of 29 shoulders, 23 (79%) showed improved ER strength within 1 week of surgery. All ganglion cyst cases regained full ER strength within a mean of 6 weeks. In all cases, ER strength improved by at least 1 full strength grade.

DISCUSSION

A ganglion cyst is not necessary to produce SSN compression at the SGN. SSN compression at the SGN can present as an isolated entity or can occur in conjunction with rotator cuff pathology or a ganglion cyst. An index of suspicion, physical examination, magnetic resonance imaging, and electromyography confirm the diagnosis. The described operative approach detaches no muscle and allows rapid recovery, and in all cases, ER strength improved to normal or by 1 full grade.

Morphological study of the inferior transverse scapular ligament

The suprascapular nerve can be compressed by the inferior transverse scapular ligament (ITSL), also known as the spinoglenoid ligament, and this entrapment results in dysfunction of the external rotation of the upper arm owing to isolated weakness of the infraspinatus muscle. The morphology of the ITSL has not been adequately characterized. The aim of this study was to clarify the morphological characteristics of the ITSL. In total, 110 shoulders from 72 cadavers were dissected in this study. The ITSL was present in 73 (66.4%) of the 110 specimens, and comprised membrane in 40 (36.4%), ligament in 25 (22.7%), and both membrane and ligament in eight (7.3%). This structure could be classified into three types on the basis of its shape: band-like (33.6%, type I), triangular (15.5%, type II), or irregular (17.3%, type III). In the spinoglenoid notch, the suprascapular nerve was always close to the lateral margin of the scapular spine. The length of the ligament between its origin and insertion sites ranged from 8.7 to 23.4 mm at its superior margin and from 8.9 to 17.5 mm at its inferior margin. The ligament width and thickness at its midportion ranged from 1.6 to 10.0 mm and from 0.1 to 1.2 mm, respectively. The results of this study improve understanding of the ITSL and will be helpful for successful diagnoses and treatments for selective suprascapular nerve entrapment.

Clinical outcomes of suprascapular nerve decompression

BACKGROUND

While the incidence and prevalence of suprascapular neuropathy (SSN) remains largely unknown, the evaluation and treatment of SSN appears to be increasing. Despite multiple technique articles demonstrating nerve decompression, there has been no clinical evidence to support the efficacy of SSN decompression in the absence of rotator cuff disease.

METHODS

Between October 2006 and February 2010, 27 patients underwent arthroscopic suprascapular nerve decompression at the suprascapular and/or spinoglenoid notch. Eighty-nine percent (24/27) of patients had preoperative positive electromyography and nerve conduction EMG/NCV studies documenting suprascapular nerve pathology. All patients had either a computed tomography (CT) arthrogram or magnetic resonance imaging (MRI) documenting rotator cuff integrity. All patients were evaluated with pre and postoperative subjective shoulder values (SSV) and American Shoulder and Elbow Society (ASES) self-assessment scores. Additionally, patients were questioned whether they would have the procedure again and approximately at what week they experienced noticeable pain relief.

RESULTS

The 27 patients were followed for an average of 22.5 months (range, 3-44). Three patients were lost to follow-up. Seventy-one percent (17/24) of patients reported pain relief (VAS [Visual Analogue Scales] pain scale) that was statistically significant (P = .0001) at an average of 9.4 weeks from surgery. Seventy-five percent (18/24) and 71% (17/24) had statistically significant improvement in ASES (P = .0001) and SSV scores (P = .0014), respectively. Seventy-one percent (17/24) would have the surgery again.

CONCLUSION

The present study demonstrates a large series of patients treated for SSN without rotator cuff pathology. Our results show statistically significant improvement in VAS, ASES, and SSV.

The suprascapular nerve and its articular branch to the acromioclavicular joint: an anatomic study

HYPOTHESIS

The suprascapular nerve and its articular branch innervate the acromioclavicular (AC) joint. Documenting the detailed anatomy of this innervation in the AC joint, including the pertinent surgical and anatomic relationships of the suprascapular nerve and its branches to the AC joint, will aid in the prevention of injury and the reduction of risk of denervation during shoulder surgery.

MATERIALS AND METHODS

Twelve shoulders from 6 embalmed human cadavers were bilaterally dissected to study the course of the suprascapular nerve and its motor and sensory branches.

RESULTS

The sensory branch runs superiorly to the supraspinatus muscle towards the AC joint. The average distance from the supraglenoid tubercle to the nerve at the coracoid base was 15 mm. The average distance from the coracoclavicular ligaments to the nerve at the coracoid base was 6 mm. The average distance from the spinoglenoid notch to the sensory branch at the suprascapular notch was 22 mm. The average length of the sensory branch was 30 mm. In half of the specimen shoulders, the suprascapular artery accompanied the nerve at the suprascapular notch under the transverse scapular ligament.

DISCUSSION

The innervation of the AC joint by the suprascapular nerve has been described, along with pertinent distances to anatomic landmarks. The sensory branch of the suprascapular nerve, which passed through the scapular notch inferior to the transverse scapular ligament, was found in 100% of the study specimens.

CONCLUSION

The sensory branch of the suprascapular nerve runs superiorly to the supraspinatus muscle towards the AC joint. The detailed information can be used to help decrease the risk of nerve injury during shoulder surgery and to aid in effectively diagnosing and treating AC joint-related disorders.

Suprascapular nerve palsy secondary to spinoglenoid cysts: results of arthroscopic treatment

PURPOSE

The purpose of this study was to investigate the results of arthroscopic treatment in 14 patients with suprascapular nerve palsy secondary to spinoglenoid ganglion cysts.

METHODS

Fourteen patients underwent arthroscopic decompression of ganglion cysts associated with suprascapular neuropathy. The most common presenting symptoms were pain and weakness, which lasted an average of 7.5 months. Ten of 14 patients were noted on examination to have atrophy, and all 14 patients had weakness of the infraspinatus. Magnetic resonance imaging (MRI) showed spinoglenoid ganglion cysts in all 14 patients; average cyst size was 3 cm. MRI revealed labral pathology in 12 of 14 cases; labral pathology was identified intraoperatively in all 14 patients.

RESULTS

Postoperatively, the average Simple Shoulder Test (SST) score was 11.5 (12 maximum), which was improved from an estimated preoperative score of 4.3. Improvement in external rotation strength was seen in 100% of patients who were examined postoperatively. No patients were taking pain medicine at latest follow-up. No complications were reported, and there were no clinical or symptomatic recurrences at an average follow-up of 51 months.

CONCLUSIONS

Arthroscopic treatment of patients with spinoglenoid ganglion cysts is safe and effective, resulting in good clinical outcomes. In our study of 14 patients, no recurrences were seen at an average of 51 months of follow-up. Level of Evidence: Level IV, therapeutic case series.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Management and Outcomes of 42 Surgical Suprascapular Nerve Injuries and Entrapments

OBJECTIVE:

Retrospective chart reviews of 42 patients with surgical suprascapular nerve (SSN) injury/entrapment were performed. Presenting symptoms, findings, operative approach, and results are documented.

METHODS:

Forty-two patients with SSN injuries/entrapments underwent operations between 1970 and 2002. Charts were retrospectively reviewed for the presence of shoulder pain; spinati muscle function was evaluated with the Louisiana State University Health Sciences Center grading system. Side of lesion and sex were equally represented; mean follow-up was 18 months (range, 12–48 mo). SSN injuries/entrapments were associated with occupational overuse (19), sports-related injury (16), direct trauma (4) and ganglion cysts (3). Thirty-one (79%) of 39 patients with suprascapular notch SSN injuries/entrapments, excluding ganglion cysts, presented with mild to moderate shoulder pain and spinati weakness.

RESULTS:

Motor function for these 31 patients was graded on a scale of 0 to 5. Preoperatively, patients had supraspinatus function Grades 0 to 2 and infraspinatus function Grades 0 to 2. Supraspinatus function improved postoperatively to Grade 4 or better in 28 patients (90%) and to Grades 2 to 3 in 3 patients (10%). Infraspinatus function improved to better than Grade 3 in 10 patients (32%), to Grades 2 to 3 in 14 patients (45%), and to Grade 1 in 7 patients (23%). Preoperatively, eight (21%) of 39 patients presenting with persistent severe pain had Grade 3 spinati strength. Of these eight patients, seven (88%) had an improvement in pain postoperatively. Strength in this group remained the same or improved to Grade 4. Postoperatively, three patients with ganglion cysts had good improvement in spinati function.

CONCLUSION:

Although SSN injury/entrapment is rare, 42 patients are presented who responded well to SSN release. Supraspinatus muscle improvement was as good as or better than that achieved in the infraspinatus.