A preliminary study of contrast-enhanced ultrasound guided capsule-preserving hydrodilatation in shoulder adhesive capsulitis.

Background: Capsule-preserving hydrodilatation is a common treatment for adhesive capsulitis (AC), and ultrasound (US) has recently become the most popular adjuvant tool for image-guided glenohumeral joint injection. However, traditional US is hardly adequate to assess extracapsular fluid leakage, which may decide the treatment outcomes. In this study, we explored the value of contrast-enhanced ultrasound (CEUS) guided capsule-preserving hydrodilatation with steroids and ultrasonic contrast agents for treatment of AC. Methods: A total of 40 consecutive patients with AC were prospectively enrolled and received CEUS-guided capsule-preserving hydrodilatation. The number of injection attempts, injection volume, and fluid leakage were recorded, and the correlations with clinical features were analyzed by Pearson or Spearman correlation coefficients. Outcome measures including visual analog scale (VAS) score, passive range of motion (ROM), and shoulder pain and disability index (SPADI) score were evaluated at baseline and 4 weeks after treatment. Comparisons between patients with good and poor clinical outcomes were performed with independent t-test, Mann-Whitney U test, and chi-square test. Logistic regression was used to identify predictors of good clinical outcomes. A P value <0.05 defined significance. Results: Access to the glenohumeral joint was successful in 87.5% patients on the first attempt. The infused fluid volume was 21.0±3.40 mL. Longer symptom duration (r=-0.676, P<0.001), greater SPADI (r=-0.148, P=0.007), and decreased ROM in abduction (r=0.38, P=0.016) were associated with a decreased volume of infused fluid. CEUS detected massive fluid leakage in 5 (12.5%) patients, with 4 capsule ruptures confirmed by magnetic resonance imaging (MRI). Longer symptom duration (r=0.485, P=0.001), decreased ROM in the direction of abduction (r=-0.33, P=0.037), and external rotation (r=-0.34, P=0.032) were correlated with an increased incidence of massive fluid leakage. Moreover, patients with good outcomes had significantly shorter symptom duration (5.7±2.09 vs. 11.2±3.89 months, P=0.002) and greater initial VAS score (6.9±1.04 vs. 6.3±0.50, P=0.022) than those with poor outcomes. Absence of massive fluid leakage was an independent predictor of clinical good outcomes at 4 weeks after treatment [odd ratio (OR) =0.05, 95% confidential interval (CI): 0.003-0.882, P=0.041]. Conclusions: CEUS-guided capsule-preserving hydrodilatation allows real-time visualization of capsule dilatation, accurate detection of extracapsular fluid leakage, and identification of risks for capsule rupture. It provides an effective treatment for AC, and is useful to predict patients' clinical outcomes.

Changes in Shoulder Rotation Based on Elevation in Children With Brachial Plexus Birth Injury.

PURPOSE: Lack of shoulder external rotation is common in children with brachial plexus birth injuries. Development of glenohumeral (GH) dysplasia is associated with progressive loss of passive external rotation. Some authors recommend measuring external rotation with the arm adducted, whereas others recommend measurement with the arm in 90° of abduction. The purpose of this study was to compare active and passive external rotation and internal rotation measured in adduction versus abduction. METHODS: Fifteen children with brachial plexus birth injuries held their affected arms in maximal external and internal rotation with the arm adducted and the arm at approximately 90° of abduction. Active and passive rotations were measured with three-dimensional motion capture. Scapulothoracic (ST) internal/external rotation and GH internal/external rotation joint angles were calculated and compared using multivariable, one-way repeated measures analyses of variance. RESULTS: There were no significant differences for active or passive ST rotation in external rotation in adduction versus abduction. Glenohumeral external rotation was significantly increased with the arm in abduction compared with adduction both actively and passively. There were no differences in ST rotation in active versus passive conditions, but all GH rotations were significantly greater passively. CONCLUSIONS: Shoulder internal/external rotation in abduction and adduction is not interchangeable. Comprehensive assessment of shoulder external and internal rotation should include both adduction and abduction. CLINICAL RELEVANCE: For children with brachial plexus birth injuries, both active and passive GH external rotations were greater in abduction. Therefore, early GH joint dysplasia may be missed if GH external rotation is measured in abduction. Additionally, consistency in arm position is important for comparison over time. The entire ST rotation capacity was used to perform maximal internal and external rotation, but the entire passive GH range of motion was not actively used. This highlights an area for potential surgical intervention to improve motion.

GIBPS technique-a novel sequential technique of performing shoulder corticosteroid injections.

The introduction of the xxxxxxxx (GIBPS) technique represents a patient-centric novel and innovative method of ultrasound guided corticosteroid injection targeting the Glenohumeral joint (GHJ) and the Subacromial-Subdeltoid (SASD) bursa in a sequential manner, in the same setting. By integrating the two different sites of injection into a single technique, the procedure has the potential of transforming musculoskeletal interventional radiology and maximising patient care in shoulder pathologies. This procedure aims to reduce patient discomfort, optimise procedural efficiency, and enhance treatment precision through ultrasound guidance and improve the overall patient experience.

Effects of bench press technique variations on musculoskeletal shoulder loads and potential injury risk.

While shoulder injuries resulting from the bench press exercise are commonly reported, no biomechanical evidence for lowering injury risk is currently available. Therefore, the aim of the present study was to compare musculoskeletal shoulder loads and potential injury risk during several bench press variations. Ten experienced strength athletes performed 21 technical variations of the barbell bench press, including variations in grip width of 1,1.5 and 2 bi-acromial widths (BAW), shoulder abduction angles of 45°, 70° and 90°, and scapula poses including neutral, retracted, and released conditions. Motions and forces were recorded by an opto-electronic measurement system and an instrumented barbell. An OpenSim musculoskeletal shoulder model was employed to estimate joint reaction forces in the glenohumeral and acromioclavicular joints. Time-series of joint reaction forces were compared between techniques by statistical non-parametric mapping. Results showed that narrower grip widths of < 1.5 BAW decreased acromioclavicular compression (p < 0.05), which may decrease the risk for distal clavicular osteolysis. Moreover, scapula retraction, as well as a grip width of < 1.5 BAW (p < 0.05), decreased glenohumeral posterior shear force components and rotator cuff activity and may decrease the risk for glenohumeral instability and rotator cuff injuries. Furthermore, results showed that mediolaterally exerted barbell force components varied considerably between athletes and largely affected shoulder reaction forces. It can be concluded that the grip width, scapula pose and mediolateral exerted barbell forces during the bench press influence musculoskeletal shoulder loads and the potential injury risk. Results of this study can contribute to safer bench press training guidelines.

Systematic Review of Shoulder Imaging Abnormalities in Asymptomatic Adult Shoulders (SCRUTINY): Abnormalities of the glenohumeral joint.

OBJECTIVE: The primary objective was to determine the population prevalence of glenohumeral joint imaging abnormalities in asymptomatic adults. METHOD: We systematically reviewed studies reporting the prevalence of X-ray, ultrasound (US), computed tomography, and magnetic resonance imaging (MRI) abnormalities in adults without shoulder symptoms (PROSPERO registration number CRD42018090041). This report presents the glenohumeral joint imaging findings. We searched Ovid MEDLINE, Embase, CINAHL and Web of Science from inception to June 2023 and assessed risk of bias using a tool designed for prevalence studies. The primary analysis was planned for the general population. The certainty of evidence was assessed using a modified Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) for prognostic studies. RESULTS: Thirty-five studies (4 X-ray, 10 US, 20 MRI, 1 X-ray and MRI) reported useable prevalence data. Two studies were population-based (846 shoulders), 15 studies included miscellaneous study populations (1715 shoulders) and 18 included athletes (727 shoulders). All were judged to be at high risk of bias. Clinical diversity precluded pooling. Population prevalence of glenohumeral osteoarthritis ranged from 15% to 75% (2 studies, 846 shoulders, 1 X-ray, 1 X-ray and MRI; low certainty evidence). Prevalence of labral abnormalities, humeral head cysts and long head of biceps tendon abnormalities were 20%, 5%, 30% respectively (1 study, 20 shoulders, X-ray and MRI; very low certainty evidence). CONCLUSION: The population-based prevalence of glenohumeral joint imaging abnormalities in asymptomatic individuals remains uncertain, but may range between 30% and 75%. Better estimates are needed to inform best evidence-based management of people with shoulder pain.

Muscle and joint function in the rotator cuff deficient shoulder.

Full-thickness rotator cuff tears can lead to poor coaptation of the humeral head to the glenoid, disrupting muscle forces required for glenohumeral joint stability, ultimately leading to joint subluxation. The aim of this study was to evaluate muscle forces and glenohumeral joint translations during elevation in the presence of isolated and combined full-thickness rotator cuff tears. Eight fresh-frozen upper limbs were mounted to a computer-controlled testing apparatus that simulated joint motion by simulated muscle force application. Scapular-plane abduction was performed, and glenohumeral joint translations were measured using an optoelectronic system. Testing was performed in the native shoulder, a following an isolated tear to the supraspinatus, as well as combined tears involving the supraspinatus and subscapularis, as well as supraspinatus, infraspinatus, and teres minor. Rotator cuff tears significantly increased middle deltoid force at 30°, 60°, and 90° of abduction relative to that in the native shoulder (p < 0.05). Significantly greater superior translations were observed relative to the intact shoulder due to combined tears to the supraspinatus and infraspinatus at 30° of abduction (mean increase: 1.6 mm, p = 0.020) and 60° of abduction (mean increase: 4.8 mm, p = 0.040). This study illustrates the infraspinatus-teres minor complex as a major humeral head depressor and contributor to glenohumeral joint stability. An increase in deltoid force during abduction occurs in the presence of rotator cuff tears, which exacerbates superior migration of the humeral head. The findings may help in the development of clinical tests in rotator cuff tear diagnostics, in surgical planning of rotator cuff repair, and in planning of targeted rehabilitation.

Maximum in-vivo joint contact forces double during active compared to assisted motion in the glenohumeral joint and decline long-term due to rotator cuff pathologies.

Rehabilitation programs advocate early passive and assisted motion after rotator cuff repair to induce healing und maintaining range of motion while avoiding excessive strain on the repaired tendons. In-vivo glenohumeral joint contact forces reflect the compressive forces generated by the rotator muscles. In the present study, maximum in-vivo joint contact forces (FresMax) were determined to compare active and assisted execution of a single movement and the long-term development of joint compression forces. FresMax were measured in six patients who received instrumented, telemetric modified anatomical hemi endoprostheses of the shoulder joint between 2006 and 2008. Data were gathered 23 months postoperatively (2006-2010), were analysed and compared with measurements 133 months postoperatively. Additional imaging was obtained as x-rays and ultrasound examination. Data analysis was conducted by synchronizing video tapes and measured force curves. New imaging showed a rupture of the M. supraspinatus and progressive joint degeneration. FresMax nearly doubled during active compared to assisted execution of each of the four chosen movements. Over the course of 133 months post-surgery, the studied movements showed a decrease of active compression force, probably due to a ruptured supraspinatus, resulting in a lower active/assisted ratio. A long term follow up after eleven years, eight out of ten measured movements showed a decrease of FresMax. These results support current rehabilitation protocols recommending early passive and assisted motion to limit activation of the rotator muscles generating compressive forces. Following degeneration of the rotator cuff, active joint contact forces decrease over time.Level of evidence: III.

Investigation of the limiting factors of shoulder joint complex motion in college baseball players: motion analysis of the humeral head and rotator cuff using ultrasound.

Background: The relationship between lower mobility, as measured by the elbow forward translation motion (T-motion) test, a new indicator of shoulder joint complex movement that measures elbow position when both dorsal hands are placed on the iliac crest while in a sitting position, and the parameters calculated by ultrasonography is unknown. The purpose of this study was to investigate the limiting factors of T-motion through motion analysis of the humeral head and rotator cuff muscles using ultrasonography in college baseball players. Methods: Thirteen college baseball players participated in this cross-sectional study. The shortest distance from the posterior edge of the glenoid to the humeral head was measured in the static and T-motion positions, and the difference was calculated as the humeral head translation. The velocity of the infraspinatus was calculated during shoulder internal/external rotation using the particle image velocimetry method. These parameters were compared between the throwing and nonthrowing sides to examine the limiting factors of T-motion. Results: This study indicated moderate-to-good reliability for the parameters calculated by ultrasonography. The mean anterior translation distance was significantly greater on the throwing side than on the nonthrowing side (r = 0.56, P = .015). The mean velocity of infraspinatus during internal rotation was significantly lower on the throwing side than on the nonthrowing side (r = 0.51, P = .028). Conclusion: Increased anterior translation of the humeral head and decreased the velocity of infraspinatus are likely correlated with reduced T-motion mobility in college baseball players. These methods showed potential for physical therapy assessment and intervention to prevent shoulder dysfunction.

Effect of patient-specific scapular morphology on the glenohumeral joint force and shoulder muscle force equilibrium: a study of rotator cuff tear and osteoarthritis patients.

Introduction: Osteoarthritis (OA) and rotator cuff tear (RCT) pathologies have distinct scapular morphologies that impact disease progression. Previous studies examined the correlation between scapular morphology and glenohumeral joint biomechanics through critical shoulder angle (CSA) variations. In abduction, higher CSAs, common in RCT patients, increase vertical shear force and rotator cuff activation, while lower CSAs, common in OA patients, are associated with higher compressive force. However, the impact of the complete patient-specific scapular morphology remains unexplored due to challenges in establishing personalized models. Methods: CT data of 48 OA patients and 55 RCT patients were collected. An automated pipeline customized the AnyBody™ model with patient-specific scapular morphology and glenohumeral joint geometry. Biomechanical simulations calculated glenohumeral joint forces and instability ratios (shear-to-compressive forces). Moment arms and torques of rotator cuff and deltoid muscles were analyzed for each patient-specific geometry. Results and discussion: This study confirms the increased instability ratio on the glenohumeral joint in RCT patients during abduction (mean maximum is 32.80% higher than that in OA), while OA patients exhibit a higher vertical instability ratio in flexion (mean maximum is 24.53% higher than that in RCT) due to the increased inferior vertical shear force. This study further shows lower total joint force in OA patients than that in RCT patients (mean maximum total force for the RCT group is 11.86% greater than that for the OA group), attributed to mechanically advantageous muscle moment arms. The findings highlight the significant impact of the glenohumeral joint center positioning on muscle moment arms and the total force generated. We propose that the RCT pathomechanism is related to force magnitude, while the OA pathomechanism is associated with the shear-to-compressive loading ratio. Overall, this research contributes to the understanding of the impact of the complete 3D scapular morphology of the individual on shoulder biomechanics.

Shoulder external rotation contracture following neonatal brachial plexus injury.

BACKGROUND: Glenohumeral posterior external rotation contractures and scapular winging are frequently overlooked problems in residual neonatal brachial plexus injury (NBPI). Recent attention has emphasized their impact on vital functions such as feeding and hygiene. This study aims to present the epidemiology of posterior glenohumeral (GH) contractures in a significant pediatric NBPI population and explore contributing factors. METHODS: We conducted a retrospective analysis of data collected from January 2019 to November 2022, involving a case series of 262 children with residual NBPI. The data included demographics, palsy level, prior surgical history, and the modified Mallet scale. Glenohumeral passive internal rotation in abduction (IRABD) and cross-body adduction (CBADD) angles were measured bilaterally. Subjects were categorized into 'Belly-' (Mallet Hand-to-Belly <3) and 'Belly+' (Mallet Hand-to-Belly ≥3) groups. RESULTS: Median participant age was 7.9 years (range: 3.5 - 21 years). Extension injury patterns included Erb's palsy (56.5%), extended Erb's palsy (28.6%), and global palsy (14.9%). Contractures exceeding 10, 20, and 30 degrees were prevalent in both IRABD and CBADD angles. The 'Belly-' group (9.5%) demonstrated a significant reduction in both angles compared to the 'Belly+' group. Weak correlations were found between IRABD (r=0.390, p<0.0001) or CBADD (r=0.163, p=0.0083) angles and Mallet hand-to-abdomen item. Glenohumeral reduction and Hoffer procedures led to a notable decrease in CBADD angle, without affecting 'Belly-' prevalence. Global injuries exhibited decreased angles compared to Erb's group. CONCLUSIONS: External rotation glenohumeral contractures are prevalent in residual NBPI, impacting midline access. Surprisingly, history of glenohumeral procedures or extensive injuries did not increase the likelihood of losing the ability to reach the belly. ROC analysis suggests specific thresholds for maintaining this ability.

Glenohumeral Osteoarthritis: A Biological Advantage or a Missed Diagnosis?

(1) Background: Osteoarthritis is a degenerative joint disease that is commonly diagnosed in the aging population. Interestingly, the lower extremity joints have a higher published incidence of osteoarthritis than the upper extremity joints. Although much is known about the disease process, it remains unclear why some joints are more affected than others. (2) Methods: A comprehensive literature review was conducted utilizing the search engines PubMed, Google Scholar, and Elsevier from 2014 to 2024, directing our search to osteoarthritis of various joints, with the focus being on glenohumeral osteoarthritis. (3) Results and Discussion: The literature review revealed a publication difference, which may be explained by the inconsistency in classification systems utilized in the diagnosis of shoulder osteoarthritis. For instance, there are six classification systems employed in the diagnosis of glenohumeral osteoarthritis, making the true incidence and, therefore, the prevalence unobtainable. Furthermore, susceptibility to osteoarthritis in various joints is complicated by factors such as joint anatomy, weight-bearing status, and prior injuries to the joint. (4) Conclusions: This review reveals the lack of understanding of shoulder osteoarthritis's true incidence and prevalence while considering the anatomy and biomechanics of the glenohumeral joint. In addition, this is the first paper to suggest a single criterion for the diagnosis of glenohumeral osteoarthritis.

High accuracy of intra-articular needle position during anterior landmark guided glenohumeral injections.

OBJECTIVES: Image-guided ultrasound or fluoroscopic glenohumeral injections have high accuracy rates but require training, equipment, cost, and radiation exposure (fluoroscopy). In contrast, landmark-guided glenohumeral injections do not require additional subspecialist referrals or equipment. An optimal technique would be safe and accurate and have few barriers to implementation. The purpose of this study was to define the accuracy of glenohumeral needle placement via an anterior landmark-guided approach as assessed by direct arthroscopic visualization. METHODS: A consecutive series of adult patients undergoing shoulder arthroscopy in the beach chair position were included in this study. Demographic and procedural data were collected. The time required to perform the injection, the precise location of the needle tip, and factors that affected the accuracy of the injection were also assessed. RESULTS: A standardized anterior landmark-guided glenohumeral joint injection was performed in the operating room prior to surgery, and the location of the needle tip was documented by arthroscopic visualization with a low complication profile and few barriers to implementation. A total of 81 patients were enrolled. Successful intra-articular glenohumeral needle placement by sports medicine and shoulder/elbow fellowship-trained orthopedic surgeons was confirmed in 93.8% (76/81) of patients. The average time to complete the procedure was 24.8 â€‹s. There were no patient-related variables associated with nonintra-articular injections in the cohort. CONCLUSIONS: This study demonstrated that the technique of anterior landmark-guided glenohumeral injection has an accuracy of 93.8% and requires less than 30 â€‹s to perform. This method is safe, yields similar accuracy to image-guided procedures, has improved cost and time efficiency, and requires less radiation exposure. No patient-related factors were associated with inaccurate needle placement. Anterior landmark-guided glenohumeral injections may be utilized with confidence by providers in the clinical setting. LEVEL OF EVIDENCE: Level 5. IRB: Approved under Stanford IRB-56323.

Isokinetic Shoulder Strength and its Associations to Injury in Tactical Populations: A Critical Review.

The aim of this review is to evaluate existing isokinetic testing protocols for the shoulder in tactical occupations, document their shoulder strength profiles, and determine any associations to shoulder injury. Four electronic databases were searched (Medline/Pubmed, Ovid/Emcare, CINAHL/Ebsco and Embase) using the keywords police OR law enforcement, firefighter, military, AND isokinetic. Articles were eligible if they had at least one cohort of a tactical population and included isokinetic testing of the glenohumeral joint. The search yielded 275 articles. After screening for duplicates and inclusion criteria, 19 articles remained for review, six of which assessed injury correlation. 17 articles evaluated military personnel and two examined firefighters. Articles were categorized by study design, population, isokinetic protocols, strength outcome measures and statistical measures. Concentric internal rotation (IR) and external rotation (ER) strength at 60 degrees/second were reported most frequently (84% of cases). There was a paucity of testing speeds, repetition ranges and contraction types evaluated when compared to existing literature in other populations with high shoulder injury occurrence such as overhead and collision athletes. Outside of military cohorts, there is limited data available to characterise the isokinetic strength profile of the shoulder in tactical occupations. Meta-analysis for injury association was unable to be performed due to independent variable and statistical heterogeneity. However, a best evidence synthesis suggested conflicting evidence to support the association of injury with isokinetic strength testing in tactical populations. Future studies should prioritise prospective designs utilising variable speeds, repetition schemes and contraction types to better capture the dynamic occupational demands in tactical groups.

Neglected Superior Dislocation of the Shoulder Joint: A Case Report.

The anterior subtype of shoulder dislocations constitutes the vast majority that either reduces instantly or is reduced at the point of care with no serious complexities. The posterior ones are infrequent and inferior and superior dislocations are even more rare. Rupture of the deltoid is considered to be linked with superior dislocation; regardless, very few articles are available pertaining to the mechanism of onset and the management of a superior shoulder dislocation. In the line of traumatic shoulder dislocations, we present a one-year-old neglected case of a 23-year-old male who sustained an open injury over the right outstretched upper arm, abducted at an angle of approximately 45° due to a fall from a height of approximately 18 feet. This unique report outlines the various surgical modalities available, given the patient's late presentation due to neglect.

Developing a Rehabilitation Guideline (REGUIDE) for Patients Undergoing an Arthroscopic Bankart Repair After Traumatic Anterior Shoulder Dislocation, Focusing on Managing Apprehension: An International Delphi-Based Consensus Study.

OBJECTIVE: We aimed to develop a consensus-based rehabilitation guideline specifically designed to reduce apprehension following arthroscopic Bankart repair after traumatic anterior shoulder dislocation. DESIGN: Delphi-based consensus. METHOD: A comprehensive list of interventions for potential inclusion in a postoperative rehabilitation guideline was developed. American and European physiotherapists and orthopedic surgeons were invited to participate in a Delphi panel, engaging in 3 survey rounds. The health professionals were surveyed about their level of agreement on both initially listed and newly suggested interventions. Consensus was established when a "critical-to-include" rating was given in ≥70% of all responses. Ten former patients were consulted to identify the intervention during standard care rehabilitation that had the most impact on reducing postoperative apprehension following ABR. Any interventions not initially listed in the first round were added to the second survey round of the Delphi process. RESULTS: Forty-four health professionals reached consensus on a set of 27 interventions for managing apprehension after arthroscopic Bankart repair. New interventions included gradual exposure to shoulder positions eliciting apprehension, training in anterior stability-provoking positions, and education addressing the impact of psychosocial factors. Former patients identified specific interventions that were effective in reducing postoperative apprehension following ABR. These interventions encompassed medicine ball throws, active-assisted wall slides, and kinetic chain exercises in anterior stability-provoking positions. CONCLUSION: Our Delphi process informed expert recommendations for various interventions aimed at addressing apprehension associated with ABR. The recommendations were the foundation for developing a rehabilitation guideline (REGUIDE). The REGUIDE integrates principles from cognitive-behavioral therapy to improve rehabilitation and mitigate apprehension. J Orthop Sports Phys Ther 2024;54(5):1-13. Epub 20 March 2024. doi:10.2519/jospt.2024.12106.

Growth of the brachial nerve plexus with reference to topographical relation of the medianus nerve ansa with the thoracic wall and shoulder: a histologic study using human embryos and fetuses.

BACKGROUND: There is currently no information on positional changes in the brachial nerve plexus during prenatal growth. The subclavian-axillary artery passing through the medianus nerve ansa is considered a good landmark for evaluating the height of the plexus. MATERIALS AND METHODS: We used histologic sections from 9 embryos and 17 fetuses (approximately 6-15 weeks of gestational age) to identify the height of the ansa by referring to the level of the rib and the glenohumeral joint. RESULTS: The nerve ansa was usually (23 plexuses) observed at the level of the first and/or second ribs. However, it was sometimes observed above the first rib, at a distance equal to or more than an intercostal width (7 plexuses). In the latter group, the ansa was usually located below the glenohumeral joint. Thus, the joint was located higher than the first rib, although the upper extremities were in the anatomic position for all specimens. The left-right difference in the height of the plexus corresponded to or was less than the width of the first intercostal space. Despite the synchronized growth between the thorax and shoulder girdle, the brachial plexus showed a considerable variation in comparative height; the range corresponded to twice of an intercostal width. Whether the nerve plexus is located high or low is determined at an early developmental stage and is maintained during the later growth stages. CONCLUSION: The high-positioned plexus might cause nerve injury at delivery, followed by a glenohumeral joint deformity because of the fragility without fixation in the thorax.

Finite Element Model of the Shoulder with Active Rotator Cuff Muscles: Application to Wheelchair Propulsion.

The rotator cuff is prone to injury, remarkably so for manual wheelchair users. To understand its pathomechanisms, finite element models incorporating three-dimensional activated muscles are needed to predict soft tissue strains during given tasks. This study aimed to develop such a model to understand pathomechanisms associated with wheelchair propulsion. We developed an active muscle model associating a passive fiber-reinforced isotropic matrix with an activation law linking calcium ion concentration to tissue tension. This model was first evaluated against known physiological muscle behavior; then used to activate the rotator cuff during a wheelchair propulsion cycle. Here, experimental kinematics and electromyography data was used to drive a shoulder finite element model. Finally, we evaluated the importance of muscle activation by comparing the results of activated and non-activated rotator cuff muscles during both propulsion and isometric contractions. Qualitatively, the muscle constitutive law reasonably reproduced the classical Hill model force-length curve and the behavior of a transversally loaded muscle. During wheelchair propulsion, the deformation and fiber stretch of the supraspinatus muscle-tendon unit pointed towards the possibility for this tendon to develop tendinosis due to the multiaxial loading imposed by the kinematics of propulsion. Finally, differences in local stretch and positions of the lines of action between activated and non-activated models were only observed at activation levels higher than 30%. Our novel finite element model with active muscles is a promising tool for understanding the pathomechanisms of the rotator cuff for various dynamic tasks, especially those with high muscle activation levels.

The comparative effectiveness of combined hydrodilatation/corticosteroid procedure with two different quantities for adhesive capsulitis.

OBJECTIVE: To assess the efficacy of injecting various amounts of fluid into the shoulder joints for capsule distension in patients with adhesive capsulitis. DESIGN: A randomized controlled trial. SETTING: Outpatient clinic of a tertiary care centre. PARTICIPANTS: Eighty-four patients with adhesive capsulitis underwent a baseline (time0), 6 weeks (time1), and 12 weeks (time2) follow-up after hydrodilitation. INTERVENTION: Group 1 (n = 42) received 20 ml of lidocaine, steroid, and saline hydrodilatation via posterior glenohumeral recess, while Group 2 (n = 42) received 10 ml of lidocaine, steroid, and saline hydrodilitation. MAIN MEASURES: The primary outcome was the visual analogue scale for pain. The secondary outcomes were shoulder pain and disability index (SPADI) and ROM of the shoulder. RESULTS: There was a significant reduce in VAS scores for pain, SPADI scores, and increased shoulder ROM in both groups over time; however, the group-by-time interactions for any of the outcomes between groups were not significant except VAS pain in motion. Post-hoc pairwise analysis of the marginal effect of time and group showed that the significant difference of VAS in motion is due to time effect: time1 vs time0 (95% CI -4.09 to -2.68), time2 vs time0 (-4.21 to -2.77), and time2 vs time1 (-0.83 to 0.63), without between-group difference: group 1 vs group 2 (-0.38 to 0.59). CONCLUSION: Our study suggests hydrodilatation achieved an optimal effect at time1 for patients with adhesive capsulitis in both groups, and adding more saline offers additional benefits in flexion and external roatation until time2.

Improved joint function when reaching behind the back is associated with patient reported outcomes in individuals with rotator cuff tears following exercise therapy.

BACKGROUND: Reaching behind the back is painful for individuals with rotator cuff tears. The objectives of the study were to determine changes in glenohumeral kinematics when reaching behind the back, passive range of motion (RoM), patient reported outcomes and the relationships between kinematics and patient reported outcomes following exercise therapy. METHODS: Eighty-four individuals with symptomatic isolated supraspinatus tears were recruited for this prospective observational study. Glenohumeral kinematics were measured using biplane radiography during a reaching behind the back movement. Passive glenohumeral internal rotation and patient reported outcome measures were collected. Depending on data normality, appropriate tests were utilized to determine changes in variables. Spearman's correlations were utilized for associations, and Stuart-Maxwell tests for changes in distributions. FINDINGS: Maximum active glenohumeral internal rotation increased by 3.2° (P = 0.001), contact path length decreased by 5.5% glenoid size (P = 0.022), passive glenohumeral internal rotation RoM increased by 4.9° (P = 0.001), and Western Ontario Rotator Cuff Index and American Shoulder and Elbow Surgeons scores increased by 29.8 and 21.1 (P = 0.001), respectively. Changes in Western Ontario Rotator Cuff Index scores positively associated with changes in maximum active glenohumeral internal rotation and negatively associated with changes in contact path lengths (P = 0.008 and P = 0.006, respectively). INTERPRETATION: The reaching behind the back movement was useful in elucidating in-vivo mechanistic changes associated with patient reported outcomes. Glenohumeral joint function and patient reported outcomes improved, where changes in Western Ontario Rotator Cuff Index scores were associated with kinematics. These findings inform clinicians of functional changes following exercise therapy and new targetable treatment factors.

Glenohumeral joint force prediction with deep learning.

Deep learning models (DLM) are efficient replacements for computationally intensive optimization techniques. Musculoskeletal models (MSM) typically involve resource-intensive optimization processes for determining joint and muscle forces. Consequently, DLM could predict MSM results and reduce computational costs. Within the total shoulder arthroplasty (TSA) domain, the glenohumeral joint force represents a critical MSM outcome as it can influence joint function, joint stability, and implant durability. Here, we aimed to employ deep learning techniques to predict both the magnitude and direction of the glenohumeral joint force. To achieve this, 959 virtual subjects were generated using the Markov-Chain Monte-Carlo method, providing patient-specific parameters from an existing clinical registry. A DLM was constructed to predict the glenohumeral joint force components within the scapula coordinate system for the generated subjects with a coefficient of determination of 0.97, 0.98, and 0.98 for the three components of the glenohumeral joint force. The corresponding mean absolute errors were 11.1, 12.2, and 15.0 N, which were about 2% of the maximum glenohumeral joint force. In conclusion, DLM maintains a comparable level of reliability in glenohumeral joint force estimation with MSM, while drastically reducing the computational costs.