Acromion-axillary Nerve Distance and Its Relation to the Humeral Length in the Prediction of the Axillary Nerve Position During the Anterolateral Deltoid-splitting Approach in the Treatment of Proximal Humerus Fractures: a Clinical Study

Background Because of the broad anatomical variation in the course of the axillary nerve, several cadaveric studies have investigated the acromion-axillary nerve distance and its association with the humeral length to predict the axillary nerve location. This study aimed to analyze the acromion-axillary nerve distance (AAND) and its relation to the arm length (AL) in patients who underwent internal plate fixation for proximal humerus fractures.Methods The present prospective study involved 37 patients (15 female, 22 male; the mean age = 51 years, age range = 19 to 76) with displaced proximal humerus fractures who were treated by open reduction and internal fixation. After anatomic reduction and fixation was achieved, the following parameters were measured in each patient before wound closure without making an extra incision or dissection: (1) the distance from the anterolateral edge of the acromion to the course of axillary nerve was recorded as the acromion-axillary nerve distance and (2) the distance from the anterolateral edge of the acromion to the lateral epicondyle of the humerus was recorded as arm length. The ratio of AAND to AL was then calculated and recorded as the axillary nerve index.Results The mean AAND was 6 ± 0.36 cm (range = 5.5–6.6), and the mean arm length was 32.91 ± 2.9 cm (range = 24–38). The mean axillary nerve ratio was 0.18 ± 0.02 (range = 0.16 to 0.23). There was a significant moderate positive correlation between AL and AAND (p = 0.006; r = 0.447). The axillary nerve location was predictable in only 18% of the patients.Conclusion During the anterolateral deltoid-splitting approach to the shoulder joint, 5.5 cm from the anterolateral edge of the acromion could be considered as a safe zone for the prevention of possible axillary nerve injury.

The Structure of the Brachial Plexus of the Djungarian Hamster (Phodopus sungorus)

Hamsters are often chosen as companion animals but are also a group of animals frequently subjected to laboratory tests. As there are no scientific publications providing information on the anatomical architecture of the brachial plexus of the Djungarian hamster, this study analyses the structure of this part of the nervous system of this species. It is important to know the details of this structure not only for cognitive reasons, but also due to the increasing clinical significance of rodents, which are often used in scientific research. The study was conducted on 55 specimens. Like in humans, the brachial plexus of the Djungarian hamster has three trunks. The following individual nerves innervating the thoracic limb of the Djungarian hamster: the radial nerve, median nerve, ulnar nerve, musculocutaneous nerve, axillary nerve, suprascapular nerve, thoracodorsal nerve, cranial pectoral nerves, caudal pectoral nerve, lateral thoracic nerve, long thoracic nerve, and subscapular nerves. Similarly to other mammals of this order, the brachial plexus of the Djungarian hamster ranges widely (C5-T1). However, its nerves are formed from different ventral branches of the spinal nerves than in other mammals.

Application of Dexmedetomidine Sedation Combined With Suprascapular Nerve Block and Axillary Nerve Block in Shoulder Arthroscopy, A Randomized Single-Blind Study

Objective: The aim of the present study was to evaluate the anesthetic and analgesic effects of dexmedetomidine combined with suprascapular nerve block and axillary nerve block in shoulder arthroscopy.Methods: A total of 60 patients were randomly divided into the experimental group (DEX group) and the control group (GA group) via a random number table method. Dexmedetomidine sedation combined with suprascapular nerve block and axillary nerve block was used in the DEX group, while general anesthesia with tracheal intubation combined with interscalene brachial plexus block was used in the GA group. The perioperative indexes, intraoperative hemodynamics, cerebral oxygen saturation, and postoperative pain score, as well as any complications, were compared between the two groups.Results: The anesthesia duration (p < 0.05) and postoperative monitoring time (p < 0.05) in the DEX group were significantly shorter than those in the GA group. At most time points during the anesthesia, the cerebral oxygen saturation (p < 0.05) and mean arterial pressure (p < 0.05) in the DEX group were significantly higher than those in the GA group. Additionally, the decrease in the cerebral oxygen saturation and mean arterial pressure in the GA group was significantly higher than that in the DEX group (p < 0.05). The pain score of DEX group 12 h after operation significantly lower than that in the GA group (p < 0.05), and the incidence of postoperative hypoxemia along with nausea and vomiting in the GA group was significantly higher than that in the DEX group (p < 0.05).Conclusion: Dexmedetomidine combined with suprascapular nerve block and axillary nerve block could reduce the incidence of hypoxemia, while the approach demonstrated better hemodynamic stability, fully ensured the cerebral blood perfusion, and exhibited better anesthetic and analgesic effects, meaning it could be safely and effectively applied in shoulder arthroscopy procedures.

The anatomy of the anconeus nerve redefined

The anconeus nerve is the longest branch of the radial nerve and suitable as a donor for the neurotization of the axillary nerve. The aim of this study was to map its topographical course with reference to palpable, anatomical landmarks. The anconeus nerve was followed in 15 cadaveric specimens from its origin to its entry to the anconeus. It runs between the lateral and the medial head of the triceps before entering the medial head and running intramuscularly further distal. Exiting the muscle, it lies on the periosteum and the articular capsule of the elbow, before entering the anconeus muscle. Two types of anconeus nerve in relation to branches innervating triceps were found: nine nerves also innervated the lateral triceps head, while the other six only contributed two branches to its innervation. The course of the anconeus nerve is important for harvesting as a donor nerve and to protect the nerve in surgical elbow approaches.

«Terrible triad» of the shoulder. Biomechanicalsemi-natural modeling andjustificationto rotator cuff restoration

The aim of this study: was determine the force of tension and deformation of axillary nerve in rupture rotator cuff and paresis of deltoid muscle of the shoulder joint. Material and methods: Semi-natural modelling based on the axial scans spiral computed tomography of the intact shoulder joint was performed to determine the degree of traction load on the axillary nerve with distal displacement shoulder head and tendon rupture which paresis of the deltoid muscle. Result: The values of deformations for axillary nerve being at the limit of tissue strength at distal displacement of humeral head of the model by 50 %, progressively increased with increasing distal displacement of humeral head to 100 % of its diameter, reaching values 1.7 times higher than the strength nervous tissue. Conclusion: The progressive changes occurring in the axillary nerve under the action of traction loads, and as a consequence of its ischemia, over time can lead not only to demyelination, but also to the defeat of the axons themselves atrophy of its fibers. In turn, deltoid muscle atrophy increases the traction load on the affected axillary nerve, which forms a vicious circle. The only possible option to "break" the vicious circle is restore the stabilizing structures damaged during the injury, among which one of the most important is the tendons of the rotator cuff of the shoulder. Surgical restoration of the integrity rotator cuff of the shoulder reduces the traction load acting on the axillary nerve, which in turn significantly improves the conditions for reinnervation of the deltoid muscle.

Digital analysis of external fixation area of proximal humerus fractures in elderly patients

Introduction The purpose is based on anatomical basis, combined with three-dimensional measurement, to guide the clinical repositioning of proximal humeral fractures, select the appropriate pin entry point and angle, and simulate surgery. Methods 11 fresh cadaveric specimens were collected, the distance of the marked points around the shoulder joint was measured anatomically, and the vertical distance between the inferior border of the acromion and the superior border of the axillary nerve, the vertical distance between the apex of the humeral head and the superior border of the axillary nerve, the vertical distance between the inferior border of the acromion and the superior border of the anterior rotator humeral artery, and the vertical distance between the apex of the humeral head and the superior border of the anterior rotator humeral artery were marked on the 3D model based on the anatomical data to find the relative safety zone for pin placement. Results Contralateral data can be used to guide the repositioning and fixation of that side of the proximal humerus fracture, and uniform data cannot be used between male and female patients. For lateral pining, the distance of the inferior border of the acromion from the axillary nerve (5.90 ± 0.43) cm, range (5.3-6.9) cm, was selected for pining along the medial axis of the humeral head, close to the medial cervical cortex, and the pining angle was measured in the coronal plane (42.84 ± 2.45)°, range (37.02° ~ 46.31°), and in the sagittal plane (28.24 ± 2.25)°, range (19.22° ~ 28.51°). The pin was advanced laterally in front of the same level of the lateral approach point to form a cross-fixed support with the lateral pin, and the pin angle was measured in the coronal plane (36.14 ± 1.75)°, range (30.32° ~ 39.61°), and in the sagittal plane (28.64 ± 1.37)°, range (22.82° ~ 32.11°). Two pins were taken at the greater humeral tuberosity for fixation, with the proximal pin at an angle (159.26 ± 1.98) to the coronal surface of the humeral stem, range (155.79° ~ 165.08°), and the sagittal angle (161.76 ± 2.15)°, with the pin end between the superior surface of the humeral talus and the inferior surface of the humeral talus. The distal needle of the greater humeral tuberosity was parallel to the proximal approach trajectory, and the needle end was on the inferior surface of the humeral talus. Conclusion Based on the anatomical data, we can accurately identify the corresponding bony structures of the proximal humerus and mark the location of the pin on the 3D model for pin placement, which is simple and practical to meet the relevant individual parameters.

An unusual case of anteroinferior paralabral cyst with axillary nerve compression: A case report

Paralabral cysts are an uncommon cause of shoulder pain in young adults. Their association with neurological symptoms is seldom reported in the literature. The cysts are believed to develop when there is a labral tear allowing synovial fluid entry into tissues causing one-way valve effect. This case report describes a case of anteroinferior paralabral cyst in a painful shoulder associated with axillary nerve palsy. MRI revealed an anteroinferior labral cyst. Electromyography revealed denervation of deltoid and teres minor muscles. Shoulder arthroscopy was performed with cyst decompression and labral repair. Shoulder function improved gradually and by the end of 1 year, power was back to pre-injury status. Paralabral cysts are a rare entity. When associated with nerve injury, prompt decompression is necessary to prevent irreversible nerve and muscle damage.