Function, strength, and muscle activation of the shoulder complex in Crossfit practitioners with and without pain: a cross-sectional observational study

Background The shoulder joint is the most commonly injured joint in CrossFit practitioners, because of the high intensity and loads associated with this sport. Despite the large number of clinical cases, there is a shortage of studies that investigate influence of biomechanical aspects of upper limbs' injuries on CrossFit practitioners. This study hypothesized that there would be a difference in function, strength, and muscle activation between Crossfit practitioners with and without shoulder pain. Methods We divided 79 Crossfit practitioners into two groups according to whether they reported pain (n = 29) or no pain (n = 50) in the shoulder during Crossfit training. Muscle function, strength, and activation were assessed using the Disability Arm, Shoulder and Hand function questionnaire, Upper Quarter Y Balance Test and Closed Kinetic Chain Upper Extremity Stability Test shoulder tests, isometric muscle strength assessment by manual dynamometry and muscle activation by surface electromyography and pain report. Results The function based on questionnaire was associated with pain (p = 0.004). We observed a statistically significant difference between the two groups only in the surface electromyography activity of the lower trapezius, and in the variables of shoulder pain and function (p = 0.038). Conclusion Crossfit practitioners with shoulder pain occurring during training showed good function and stability of the shoulder joint, but there was a reduction in the activation of stabilizing muscles, especially the lower trapezius. Trial registration Registro Brasileiro de Ensaios Clinico (Brasilian National Registry) with the ID: RBR-2gycyv.

Advanced Glycation End-products Are Associated With Limited Range of Motion of the Shoulder Joint Following Rotator Cuff Tears

Background: Most degenerative rotator cuff tears (RCTs) are associated with a limited range of motion (ROM) of the shoulder joint. Additionally, patients with diabetes mellitus (DM) show a higher frequency of limited ROM. Recently, advanced glycation end products (AGEs) of proteins have been observed to cause tissue fibrosis, primarily through abnormal collagen cross-linking and oxidative stress. In this study, we investigated the effect of AGEs on ROM limitation in the shoulder capsule and its relationship with DM.Methods: 16 patients (8 each in the DM and non-DM groups) who underwent arthroscopic surgery for RCT with limited shoulder ROM were included in this study. AGE-related pathologies in both groups were compared, and the relationship between AGE accumulation and shoulder joint ROM was evaluated. Shoulder capsule tissue was harvested and subjected to histological and in vitro evaluation. Results: The DM group displayed high levels of AGEs and reactive oxygen species (ROS), and reduced cell viability. There was a significant positive correlation between ROS expression, apoptosis, and preoperative hemoglobin A1c. ROS expression, apoptosis, and ROM of the shoulder joint showed a negative correlation. The NADPH oxidase (NOX) expression and collagen III/I ratio were significantly higher in the DM group than in the non-DM group.Conclusions: The DM group showed significant AGE deposition in the shoulder capsule. Additionally, there was a significant association between AGEs and ROM limitation. The oxidative stress induced by AGE deposition, which leads to fibrosis and local inflammation, might contribute to the limited ROM of the shoulder joint.

Morphology and morphometric study of dry scapula, with emphasis on the glenoid fossa and acromion process in Chennai city, South India

Background: The morphology and morphometry of the scapula and its glenoid fossa and acromion process play a significant role in the mechanics of shoulder joint. A variable morphology is found in glenoid fossa that has clinical implications. Aims and Objectives: The aim of the study was to evaluate the morphology and morphometry of dry scapula with emphasis on glenoid fossa and acromion process. Materials and Methods: A cross-sectional study was conducted at the department of anatomy, for a period of 6 months from January 2021 to June 2021. A total of 100 unpaired dry scapula were included in the study. The morphology and dimensions were measured. The dimensions were summarized as mean and standard deviation. Statistical analysis was done Chi-square test and student’s t-test based on the variable types. Results: Out of 100 scapulae studied, 48 were right sided and 52 were left sided. The mean of maximum length of the right scapula was 149.58±10.33 mm and the left side was 148.63±10.33 mm. Among the glenoid cavities, 54 were inverted comma shaped, 30 were pear shaped, and 16 were oval shaped. In one right-sided scapula Bony Spur Extends from Base of coracoid process to supra Scapular Notch. Conclusion: Size and shape of the glenoid cavity are directly related to the dislocation of shoulder joint and may affect the results of total shoulder arthroplasty and rotator cuff surgeries. The present study analyzed the morphological types and diameters of the glenoid cavity in adult scapulae to improve the efficacy and minimize the failure rates in shoulder arthroplasty particularly those involving the glenoid component of the shoulder joint.

Scapula Dyskinesis

Scapular dyskinesis is any alteration of its static position or kinematics during movements in the shoulder joint. The correct scapula orientation is associated with the tone of the muscles attached to it. The prevalence of scapular dyskinesis is high among patients with subacromial impingement syndrome, partial rotator cuff tears, shoulder joint instability and SLAP injuries. Scapular dyskinesis can be caused by a whole range of factors, including upper cross syndrome and postural adaptations predisposing to it, neurological disorders. However, instrumental diagnosis of scapular dyskinesis is difficult, which makes the use of clinical tests the main method of its detection. In this lecture, the etiology of scapular dyskinesis, classification, diagnostic tests and treatment methods are analyzed in detail. The detection of scapular dyskinesis and its type determination in patients with shoulder joint pathologies allows us to form an optimal rehabilitation therapy protocol, including techniques of myofascial release, passive and active stretching of spasmodic and training of weak muscle groups aimed at correcting postural disorders, pathology of the scapulohumeral rhythm, restoration of the glenohumeral joint normal biomechanics.

Surgical treatment of the humeral head osteochondral defects in chronic shoulder dislocation: Literature review

Background. The shoulder joint is the one most amenable to dislocation. Dislocation of the humeral head is complicated by combined injuries of the shoulder joint, and if the patient does not seek treatment on the first day after the dislocation, irreversible changes in bone and soft tissue structures are formed.The aim of this review was to analyze modern methods of diagnosis and treatment of patients with defects in the articular surfaces of the scapula and humerus head with chronic shoulder dislocations.Material and methods. To search for literature data, we used the electronic databases MEDLINE, PudMed, eLIBRARY with a selection of sources published from 2000 to 2020. The analysis was carried out on works devoted to the diagnosis, surgical treatment and complications of traumatic shoulder dislocations.Results. When analyzing the literature on the surgical treatment of shoulder dislocations, we did not find clear criteria for planning the extent of surgery. The obtained results of surgical treatment testify to well-studied technologies for treating osteochondral defects of the humeral head up to 25 % of its total area. In the presence of a defect of 50 % of humeral head area or more, satisfactory results are shown when carrying out arthroplasty of the joint using a reverse endoprosthesis. However, the treatment of defects ranging in size from 25 to 50 % is still an unexplored problem. There are single techniques using allografts, mainly in English-speaking countries and, to a lesser extent, on the territory of the Russian Federation. Thus, the search for an algorithm for choosing a surgical treatment based on multi-layer spiral computed tomography and/or magnetic resonance imaging data, and the development of a new method of surgical treatment taking into account the obtained data are priority areas in modern traumatology and orthopedics.

Development and Multi-Site Assessment of a Novel Shoulder Motion Joint Simulator

Background: Multiple biomechanical shoulder simulators have been described in the literature, with a trend toward increasing complexity to better simulate clinical scenarios. Our objective was to develop an advanced, novel shoulder joint simulator and compare outcomes at two separate institutions, for a typical shoulder joint motion simulation. Methods: Identical shoulder simulators were developed & deployed at both institutions. Eight cadaveric upper extremities were tested by simulating actively controlled, arm elevation in the plane of the scapula for two sequential test conditions (intact and non-destructive simulated cuff-tear), each repeated for a total of five trials. Muscle forces and joint translations were recorded for both conditions. The intact condition was repeated following simulated cuff-tear to assess effect of testing order. Statistical analyses were aimed at assessing repeatability and reproducibility of results within specimens, between specimens, and between institutions. Results: The highest average forces were observed for the middle deltoid (233N or 32.5% body weight), followed by infraspinatus (99.0N), and posterior deltoid (93.7N) muscles. Differentiation between test conditions was unhindered by variability between repeated trials. Data from testing repeated over time, and between the two institutions were not significantly different. Conclusions: The novel shoulder simulator produced repeatable results with low trial-to-trial variation and outcomes were comparable between the two institutions. The results demonstrated a consistent response in muscle forces and humeral translation for the simulated rotator cuff tear condition. Such advanced shoulder simulators could thus be used for evaluating and optimizing surgical interventions and implant strategies.