Ultrasound-Guided Versus Landmark-Based Approach to the Distal Suprascapular Nerve Block: A Comparative Cadaveric Study.

PURPOSE: To compare the accuracy of distal suprascapular nerve (dSSN) blockade performed with the use of ultrasound-guided regional anesthesia (USRA) versus with a landmark-based approach (LBA). A secondary aim was to describe the anatomic features of the sensory branches of the dSSN. METHODS: USRA and LBA were performed in 15 shoulders each from 15 cadavers (total of 30 shoulders). Then, 10 mL of methylene blue‒infused ropivacaine 0.75% was injected into the dSSN. Simultaneously, 2.5 mL of red latex solution was injected to identify the position of the needle tip. The division and distribution of the sensory branches originating from the SSN were described. RESULTS: The tip of the needle was identified at 1.3 cm (range, 0-5.2 cm) and 1.5 cm (range, 0-4.5 cm) with USRA and the LBA, respectively (P = .90). Staining diffused past the origin of the most proximal sensory branch in 27 cases. The most proximal sensory branch arose 2.5 cm from the suprascapular notch. Among the 3 failures that occurred in the USRA group, the sensory branches also failed to be marked. All 30 dSSNs gave off 3 sensory branches, which innervated the posterior glenohumeral capsule, the subacromial bursa, and the coracoclavicular and acromioclavicular ligaments. CONCLUSIONS: An LBA is as reliable and accurate as US guidance for anesthetic blockade of the dSSN. Marking of the suprascapular nerve must be proximal to the suprascapular notch to involve the 3 sensory branches in the anesthetic blockade. CLINICAL RELEVANCE: The present study demonstrates that a landmark-based approach to anesthetic blockade of the distal suprascapular nerve is accurate and can be performed by orthopaedic surgeons lacking experience in ultrasound-guided anesthetic techniques.

Sensory innervation of the subacromial bursa by the distal suprascapular nerve: a new description of its anatomic distribution.

BACKGROUND: Sensory innervation to the shoulder provided by the distal suprascapular nerve (dSSN) remains the subject of debate. The purpose of this study was to establish consensus with respect to the anatomic features of the sensory branches of the dSSN. The relevant hypothesis was that the dSSN would give off 3 sensory branches providing innervation to the posterior glenohumeral (PGH) capsule, the subacromial bursa, in addition to the coracoclavicular and acromioclavicular ligaments. METHODS: The division, course, and distribution of the sensory branches that originated from the dSSN and innervated structures around the shoulder joint were examined macroscopically by dissecting 37 shoulders of 19 fresh-frozen cadavers aged of 83.0 years (range, 74-98 years). RESULTS: The 37 dSSN provided 1 medial subacromial branch (MSAb), 1 lateral subacromial branch (LSAb), and 1 PGH branch (PGHb) to the shoulder joint. This arrangement allowed for bipolar-MSAb and LSAb-innervation of the subacromial bursa, acromioclavicular (MSAb and LSAb) and coracoclavicular (MSAb) ligaments, as well as the PGH capsule (PGHb). CONCLUSIONS: The dSSN provided 2 subacromial branches and 1 PGHb to the shoulder joint. This arrangement allowed for bipolar-MSAb and LSAb-innervation of the subacromial bursa, acromioclavicular and coracoclavicular ligaments, as well as the PGH capsule.

Distal suprascapular nerve block-do it yourself: cadaveric feasibility study.

BACKGROUND: A bone landmark-based approach (LBA) to the distal suprascapular nerve (dSSN) block is an attractive "low-tech" method available to physicians with no advanced training in regional anesthesia or ultrasound guidance. The primary aim of this study was to validate the feasibility of an LBA to blockade of the dSSN by orthopedic surgeons using anatomic analysis. The secondary aim was to describe the anatomic features of the sensory branches of the dSSN. MATERIALS AND METHODS: An LBA was performed in 15 cadaver shoulders by an orthopedic resident. Then, 10 mL of methylene blue-infused 0.75% ropivacaine was injected around the dSSN; 2.5mL of red latex solution was also injected to identify the position of the needle tip. The division and distribution of the sensory branches that originate from the suprascapular nerve were described. RESULTS: The median distance between the dSSN and the site of injection was 1.5 cm (0-4.5 cm). The most common injection site was at the proximal third of the scapular neck (n = 8). Fifteen dSSNs were stained proximal to the origin of the most proximal sensory branch. All 15 dSSNs gave off 3 sensory branches that innervated the posterior glenohumeral capsule, the subacromial bursa, and the coracoclavicular and acromioclavicular ligaments. CONCLUSIONS: An LBA for anesthetic blockade of the dSSN by an orthopedic surgeon is a simple, reliable, and accurate method. Injection close to the suprascapular notch is recommended to involve the dSSN proximally and its 3 sensory branches.

Anatomical Evaluation of the Proximity of Neurovascular Structures During Arthroscopically Assisted Acromioclavicular Joint Reconstruction: A Cadaveric Pilot Study.

PURPOSE: The purpose of this study was to examine the safety of an arthroscopic technique for acromioclavicular joint (ACJ) reconstruction by investigating its proximity to important neurovascular structures. METHODS: Six shoulders from 4 cadaveric specimens were used for ACJ reconstruction in this study. The procedure consists of performing an arthroscopic acromioclavicular (AC) reduction with a double button construct, followed by coracoclavicular ligament reconstruction without drilling clavicular tunnels. Shoulders were subsequently dissected in order to identify and measure distances to adjacent neurovascular structures. RESULTS: The suprascapular artery and nerve were the closest neurovascular structures to implanted materials. The mean distances were 8.2 (standard deviation [SD] = 3.6) mm to the suprascapular nerve and 5.6 (SD = 4.2) mm to the suprascapular artery. The mean distance of the suprascapular nerve from implants was found to be greater than 5 mm (P = .040), while the distance to the suprascapular artery was not (P > .5). Neither difference was statistically significant (P = .80 for artery; P = .08 for nerve). CONCLUSIONS: Mini-open, arthroscopically assisted ACJ reconstruction safely avoids the surrounding nerves, with no observed damage to any neurovascular structures including the suprascapular nerve and artery, and may be a viable alternative to open techniques. However, surgeons must remain cognizant of possible close proximity to the suprascapular artery. CLINICAL RELEVANCE: This study represents an evaluation of the safety and feasibility of a minimally invasive ACJ reconstruction as it relates to the proximity of neurovascular structures.

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.

Safe drilling angles and depths for plate-screw fixation of the clavicle: avoidance of inadvertent iatrogenic subclavian neurovascular bundle injury.

BACKGROUND: Plate fixation is frequently used to repair clavicle fractures, but over drilling can cause subclavian neurovascular bundle damage. The aims of this study were to investigate the anatomic relationship between the clavicle and subclavian neurovascular bundle and to determine safe drilling angles and depths. METHODS: Twenty-six healthy subjects underwent magnetic resonance imaging. Coronal and sagittal images of the periclavicular region including the whole clavicle and nearby vital anatomic structures were obtained. The clavicle was divided into three sections: section I: between the sternoclavicular joint and point N (where the subclavian neurovascular bundle coursed below the midaxial level of the clavicle); section II: from N to the projection point of the coracoid process to the clavicle (CP'); and section III: from CP' to the acromioclavicular joint. Dangerous drilling depths and angles were determined for each section. RESULTS: In section I, the safe drilling angle was >59.7 degrees cephalad and >95.3 degrees caudad, while safe drilling depth was <17.0 +/- 2.4 mm. Corresponding values in section II were <1.2 degrees caudad and >142.4 degrees caudad. Safe drilling depth was no more than 36.2 mm +/- 12.4 mm. Depth and direction limitations were not assessed for section III, because the neurovascular bundle coursed well below the level of the coracoid process. CONCLUSIONS: We have used magnetic resonance imaging to determine safe drilling directions and depth for plate-screw fixation of the clavicle. On confirmation, these findings could be used in the clinical setting to reduce the risk of inadvertent iatrogenic subclavian neurovascular bundle injury during surgical clavicle fracture repair.

The brachial plexus in the chacma baboon (Papio ursinus).

The brachial plexus in each of ten embalmed, mature chacma baboons was dissected to document the structure and branching pattern of this nerve plexus in this increasingly used research animal. In general, the brachial plexus in the chacma baboon was similar to the plexuses in the vervet and other Old World monkeys. However, several aspects were comparable to those observed in domestic animals. Thus the bipedal and quadrupedal abilities of the chacma baboon were reflected in the structure of its brachial plexus.

Inserçäo clavicular do ligamento coracoacromial. Uma variaçäo com potencial para causar maus resultados nas cirurgias para descompressäo subacromial / Clavicular isnsertion of the coracoacromial ligament. A variation that may cause poor results in surgery for subacromial decompression

Os autores removeram randomicamente o ligamento coracoacromial de 37 ombros de 20 cadáveres frescos na sala de autópsia. Ao exame macroscópico, encontraram um feixe medial de ligamentos inserido na parte lateral da clavícula em 16(43,2 por cento) dos ombros examinados. Essa variaçäo anatömica que ainda näo havia sido descrita só era observada quando uma pequena porçäo do músculo deltóide era removida da clavícula, o que os levou a especular sobre a possibilidade da ocorrência de uma descompressäo subacromial incompleta quando o feixe clavicular näo é detectado durante a acromioplastia executada sem visualizaçäo dos 2cm laterais da clavícula. O ligamento coracoacromial foi classificado como tipo I quando tinha a única inserçäo proximal conhecida e como tipo II quando a porçäo clavicular estava presente

[Conduction blocks in the complex treatment of humeroscapular periarthritis]. / Provodnikovye blokady v kompleksnom lechenii plechelopatochnogo periartrita.

The authors propose a method of treatment of humeroscapular periarthritis by high conduction blocks of the brachial plexus by supraclavicular approach. The influence of high conduction blocks of the brachial plexus on the peripheral circulation in the upper extremities has been studied. The results of the treatment of 192 patients with humeroscapular periarthritis (mostly) with neglected forms of the disease) are presented.