Applied anatomy of the suprascapular nerve: a cadaveric study

The suprascapular nerve plays a very important role in the shoulder. Characterization of anatomy is essential to assist surgeons in shoulder surgery. Objectives: This study is to determine further the anatomical characteristics of the SSN regarding origin, pathway, branching and correlations of SSN with some neighboring structures. Thirty specimens taken from 15 fresh cadavers (9 males and 6 females) were dissected and data were recorded. The presences of the motor branches, sensitive branches, some neighboring structures and the correlation between them and the SSN were de-scribed. The distances from the SSN at the suprascapular notch and spinoglenoid notch to some neighboring structures were measured. The SSN arises from the upper trunk of the brachial plexus. The nerve has two motor branches for supraspinatus and infraspinatus muscles and two sensory branches, the superior articular branch for acromioclavicular joint and coracohumeral ligament about 73.3%, the inferior articular branch for the posterior joint capsule about 100%. The average distance from the nerve at the suprascapular notch to the acromion lateral border is 61.4 mm, to the tip of coracoid is 49.5 mm, and to the superior rim of the glenoid is 31.7 mm. The average distance from the nerve at the spinoglenoid notch to the posterior rim of the glenoid is 19.9 mm. This circles the safe distances for shoulder surgeries. This study deter-mines the anatomical characteristics of the SSN and defines the safe zone on the shoulder. It al-lows surgeons to avoid causing the nerve injury and to approach it easily

No disponible

Revisiting the Anterior Glenoid: An Analysis of the Calcified Cartilage Layer, Capsulolabral Complex, and Glenoid Bone Density.

PURPOSE: In this cadaveric study, we aim to define the basic anatomy of the anterior glenoid with attention to the relationships of calcified cartilage, capsulolabral complex, and osseous morphology of the anterior glenoid. METHODS: Seventeen cadaveric glenoid specimens (14 male, 3 female, mean age 53.9 ± 10) were imaged with micro-computed tomography (CT) and embedded in poly-methyl-methacrylate. Specimens were included for final analysis only if the entire glenoid articular cartilage, labrum, capsule, and biceps insertion were pristine and without evidence of injury, degeneration, or damage during the preparation process. Group 1 members (n = 9) were axially sectioned through 3 to 9 o'clock and 4 to 8 o'clock; group 2 members (n = 8) were radially sectioned through 3, 4, 5, and 9 o'clock. A scanning electron microscope (SEM) analysis quantified the percentage of bone within a 5 × 2.5 mm region at the glenoid rim. Micro-CT, SEM, and light microscopy evaluated the capsulolabral complex and calcified fibrocartilage. RESULTS: A 7 ± 2.1 mm region of calcified fibrocartilage at 4 o'clock was identified from the articular face to the medial glenoid neck supporting the overlying capsulolabral footprint and was >3× thicker at the articular attachment (316 ± 153 µm) versus the glenoid neck (92 ± 66 µm). At 3 to 9 o'clock and 4 to 8 o'clock 79.2% ± 5.4% and 75.2% ± 7.8% of the glenoid osseous width was covered with articular cartilage. The labrum accounted for 13.1% ± 3.4% of the glenoid width at 4 o'clock. SEM analysis demonstrated decreased glenoid bone density at 3, 4, and 5 o'clock (P ≤ .015) and no difference (P = .448) at 9 o'clock versus central subchondral bone. CONCLUSIONS: The capsulolabral footprint contributes significantly to the glenoid face, inserts directly adjacent to the articular cartilage, and extends medially along the glenoid neck. A layer of calcified fibrocartilage lies immediately beneath the capsulolabral footprint and is 3× thicker at the articular insertion compared with the glenoid neck. Lastly, there is a bone density gradient at the anterior-inferior rim versus the central subchondral bone. CLINICAL RELEVANCE: Arthroscopic Bankart repair has been reported to have a significant failure rate in many settings. It is felt that reproducing anatomy with the repair could help improve outcomes. Based on this study's findings, an arthroscopic Bankart technique that most closely reproduces native anatomy and potentially optimizes soft-tissue healing could be performed. This includes removal of 1 to 2 mm of articular cartilage from the glenoid face with anchor placement at this location to appropriately reposition the capsulolabral complex.

The effectiveness of ultrasonography-guided suprascapular nerve block for perishoulder pain.

This study analyzed the effectiveness of suprascapular nerve block under ultrasonographic guidance in patients with perishoulder pain. Patients with perishoulder pain were enrolled in the study and were randomly divided into 2 groups. In the first group of 25 patients (12 men and 13 women), nerve block was applied under ultrasonographic guidance. Mean patient age in this group was 55.1 years. In the control group, 25 patients (11 men and 14 women) underwent nerve block without ultrasonographic guidance; mean patient age was 51.6 years. Degree of pain was assessed using a visual analog scale (VAS) and shoulder function was evaluated using the Constant shoulder score (CSS) before the nerve block, immediately following the procedure, and 1 month after the procedure. There was no statistically significant difference between the 2 groups in VAS score and CSS before the procedure (P>.05). Immediately after the procedure, both the study and control groups revealed significantly improved VAS and CSS patterns (P<.05). However, the study group showed better VAS and CSS patterns than the control group at 1-month follow-up (P<.05). No complications occurred in the study group. In the control group, there were 2 cases of arterial punctures and 3 cases of direct nerve injury with neurological deficit for 2 months. Ultrasonography-guided suprascapular nerve injection is a safe, accurate, and useful procedure compared to the blind technique.

Músculo elevador de la escápula: caracterización macroscópica / Levator scapulae muscle: macroscopic characterization

RESUMEN: Nuevas técnicas y aplicaciones quirúrgicas han impulsado un mayor estudio anatómico del músculo elevador de la escápula. Sin embargo, persisten interrogantes sobre su morfología, las que son de importancia al considerarlo como una herramienta reconstructiva. Se trabajó con 11 cadáveres (ocho masculinos y tres femeninos) con edad promedio de 70 años. Se realizó una disección bilateral por planos de las regiones cervical y escapular en 9 preparados, en 2 casos fue unilateral. Fueron analizadas variables macroscópicas como: conformación general, ubicación, origen e inserción, relaciones directas y variaciones. Ubicado en las regiones cervicales posterior y lateral, y escapular, su forma asemeja una cincha, conformado por fascículos musculares hacia su origen y una masa muscular común en su inserción. Observamos un promedio de fascículos por músculo de 3.95 (D.E. ±0.85), con longitudes totales entre 18.3 cm como máximo y 14.9 cm como mínimo. Los fascículos se originaron mediante elementos tendinosos, en promedio 3.9 (D.E. ±0.78), desde las primeras vértebras cervicales. Se comprobó la inserción muscular directa en varios puntos a nivel de la escápula y fascia del músculo serrato anterior. Destacamos además, la presencia de un desdoblamiento de la masa muscular común previo a su inserción escapular. Fueron identificadas, además, relaciones directas con elementos musculares, vasculares, nerviosos y linfáticos en las regiones estudiadas. Finalmente, encontramos variaciones respecto al origen de los fascículos, trayecto de las fibras musculares e inserción. La anatomía del desarrollo del músculo ayuda a entender y explicar varias de las observaciones macroscópicas. Si bien algunas de las características morfológicas (relaciones directas y variaciones) desincentivan su uso, otras (longitud de los fascículos musculares y ubicación topográfica) lo señalan como una buena alternativa en la cirugía reconstructiva de cabeza y cuello.

Glenoid bone architecture.

This article describes regional variations in trabecular bone architecture in terms of density and orientation within six glenoid specimens. The mean donor age was 56 years and ranged from 31 to 72 years. An automated imaging technique based on 3-dimensional serial sectioning was used for the direct examination of the glenoid cancellous bone structures. Subchondral plate thickness was on average 1.9 mm and ranged from 1.2 mm to 2.9 mm. The volume fraction of trabecular bone varied from 11% to 45% with peak values at the posterior glenoid vault. On graphic 3-dimensional reconstructions, the glenoid appeared as platelike trabeculae, radially oriented perpendicular to the subchondral plate and interconnected by thin rods. These views also displayed regional variations throughout the glenoid, reflecting differences in the macroscopic appearance. Quantitative structural analysis revealed different degrees of anisotropy at the glenoid cancellous region, predominantly transverse isotropy. Resemblance to direct weight-bearing cancellous bone such as the proximal tibia was evident.

SEM corrosion-casts study of the microcirculation of the flat bones in the rat.

BACKGROUND: Little is known about the organization of microcirculation in flat bones in comparison with long bones. This study, therefore, helps us to determine the design of this vascular system in flat bones in relation to their structure and function. METHODS: The organization of microvasculature in parietal, scapula, and ileum bones of 15 young sexually mature rats, aged 6-7 weeks, was studied by light and scanning electron microscopy (SEM) from vascular corrosion cast (vcc), a resin-cast obtained material. RESULTS: Our observations show that the pattern of the microcirculation in flat bones is different in the thick and thin parts of such bones. Where the bone is thinner than 0.4 mm, only periosteal and dural network exist. Larger vessels which do not form a real network connect the two tables of the bones in these regions. In thicker areas, the organization of the microvasculature is similar to that in long bones, with distinct periosteal, cortical and bone marrow networks. Moreover, in different bones, outer networks show slightly different characteristics according to the different adjacent structures (dura mater, muscles etc.). Different types of vessels were recognized by comparing their different diameter, course and endothelial imprints. CONCLUSIONS: The microvascular patterns of the flat bones are strongly influenced by the bone thickness. The different microvascular systems can interact both with the bone modelling and remodeling and with the variable metabolic needs, modifying the microvascular pattern and the blood flow. This is even more important in view of the reciprocal influence of the different networks within the same bone.

Histogenesis of unique elastinophilic fibers of elastofibroma: ultrastructural and immunohistochemical studies.

Electron microscopy and both light and electron microscopic immunohistochemical tests for elastin were employed to study the morphogenesis of the unique elastinophilic fibers of an elastofibroma removed from the subscapular region of a 62-year-old woman. Ultrastructurally, as shown by tannic acid stain, elastinophilic fibers of the elastofibroma consisted of central cores and outer zones. The latter were composed of various sizes of vaguely demarcated, irregularly shaped amorphous components and compactly and randomly arranged large amounts of microfibrils. The electron microscopic immunohistochemical results showed that the small-sized amorphous components and microfibrils in the outer zones of the elastinophilic fibers were stained evenly and of granular texture, but the vaguely outlined large amorphous components were not stained. These findings were interpreted as indicating that the amorphous components of the outer zones of elastinophilic fibers were less compact and allowed the penetration of antielastin antibody. The unique elastinophilic fibers of elastofibromas appear not to be formed by the degeneration of the fibers but by abnormal elastogenesis, including an abnormal arrangement of microfibrils.

Pre-elastofibroma and elastofibroma (the continuum of elastic-producing fibrous tumors). A light and ultrastructural study.

A fibroproliferative lesion arising anterior to the lower end of the scapula and containing polymorphic often fiberlike deposits of weakly elastinophilic fibrillary material is described. It is compared on the light and ultrastructural level to a typical elastofibroma. The fibrillary material seen in this tumor strongly resembles that which surrounds the strongly elastinophilic deposits in the typical elastofibroma and from which the elastin is thought to be derived. It is concluded that elastin-producing tumors form a continuum; at one end of which lies the tumor we have designated pre-elastofibroma and at the other, the typical elastofibroma.

Stress distribution in the scapula studied by neutron diffraction.

High intensity neutron beams provide a method of measuring the preferred orientation of apatite crystals in bulk samples of bone. Measurements at seven different sites on the scapula show that the c axes of the crystals lie preferentially along the directions of pull of the attached muscles. The highest orientation is found at positions under the influence of only a single group of muscles, such as M. teres major or M. infraspinatus. In intermediate regions a multiple distribution of crystals is found, able to withstand stresses in more than one direction. The technique provides a method of assessing the distribution of stress in bones.