Shoulder Abduction Angle Research Articles

The Disease-Modifying Effects of a Single Intra-Articular Corticosteroid Injection during the Freezing Phase of Frozen Shoulder in an Animal Model.

Although frequently prescribed for frozen shoulder, it is not known if corticosteroid injections improve the course of frozen shoulder. This study aimed to assess the disease-modifying effects of an intra-articular corticosteroid administration at the freezing phase of frozen shoulder. Twenty-four Sprague-Dawley rats were divided into four groups. Their unilateral shoulders were immobilized for the first 3 days in all groups, followed by an intra-articular corticosteroid injection in Group A, an injection and the cessation of immobilization in Group B, no further intervention in Group C, and the cessation of immobilization in Group D. All rats were sacrificed in Week 3 of study, at which point the passive shoulder abduction angles were measured and the axillary recess tissues were retrieved for histological and Western blot analyses. The passive shoulder abduction angles at the time of sacrifice were 138° ± 8° (Group A), 146° ± 5° (Group B), 95° ± 11° (Group C), 132° ± 8° (Group D), and 158° ± 2° (Control). The histological assessments and Western blots showed greater fibrosis and inflammation in the groups that did not receive the corticosteroid injection (Groups C and D) compared to the corticosteroid-injected groups (Groups A and B). These findings demonstrate the anti-inflammatory and disease-modifying effects of corticosteroid injections during the freezing phase of frozen shoulder in an animal model.

Is the use of neuromonitoring necessary in Sprengel's deformity surgery?

This study aimed to emphasize the effectiveness of using intraoperative neuromonitoring (IONM) in preventing possible nerve damage in Sprengel's deformity surgery. Eighteen patients who underwent Woodward surgery accompanied by neuromonitoring due to Sprengel's deformity were included in the study. Demographic information of the patients and their clinical and cosmetic results before and after surgery were recorded. Complications that occurred during and after the surgery were recorded. Of the 18 patients who underwent surgery, 12 were female and 6 were male. The mean age of the patients was 4.4 (2-8). The mean shoulder abduction angle of the patients was 84.4 (65-105) degrees before the surgery and 151.1 (125-175) degrees in the first year after the surgery. The mean Cavendish score of the patients was 3.6 (3-4) before the surgery and 1.1 (1-2) in the first year after the surgery. In one patient, there was a decrease in IONM motor-evoked potency signals during the reduction of the intraoperative scapula. Considering some loss of correction in the deformity, the scapula was detected at the point where there was no loss of signals. No patients developed wound problems or infections. In this study, it was determined that the use of neuromonitoring was effective in preventing brachial plexus damage, even if this complication was minimal in patients operated on due to Sprengel's deformity.

Effects of Video-Based Exercises and Conventional Physiotherapy on Upper Extremity Functionality, Selective Motor Control, and Proprioception in Unilateral Cerebral Palsy: A Randomized Controlled Trial.

Objective: The present study was conducted to evaluate the effects of video-based exercises added to conventional physiotherapy (CPT) on upper extremity functionality, selective motor control, and proprioception in individuals with unilateral cerebral palsy (UCP). Materials and Methods: Thirty patients with UCP were randomized into two groups: the intervention group (15 individuals with a mean age of 9.2 ± 3.8 years) and the control group (15 individuals with a mean age of 8.3 ± 4.1 years). The intervention group received 8 weeks of video-based exercises, and the control group received 8 weeks of conventional physiotherapy. Upper extremity functional abilities, upper extremity selective motor control, proprioception, and entertainment levels were evaluated before and after the intervention for all groups. Results: While a significant change was observed in the mean scores of the ABILHAND-Kids, Selective Control of the Upper Extremity Scale right-left scores, shoulder flexion, shoulder abduction, and elbow flexion proprioception angles after the video-based exercises in the intervention group (P < 0.05), a significant change was observed only in the 60-degree flexion angle in the control group (P = 0.001). In the comparison between the groups, there were significant differences in post-intervention value only in shoulder flexion and abduction angles, whereas there was no difference between the groups in elbow flexion angles (P > 0.05). Conclusion: Incorporating video-based exercises into the upper extremity rehabilitation processes of individuals with UCP is beneficial in terms of upper extremity functionality, selective motor control, and proprioception.

Effect of interactive scalp acupuncture on upper limb function in patients with hemiplegia after stroke

To explore the clinical effect of interactive scalp acupuncture combined with task-oriented mirror therapy on hemiplegia after stroke. A total of 86 patients with hemiplegia after stroke were randomly divided into an observation group (43 cases, 2 cases dropped out) and a control group (43 cases, 2 cases dropped out). Both groups received routine treatment and rehabilitation treatment for stroke. The control group was treated with task-oriented mirror therapy, 40 min each time, once a day, 6 days a week. The observation group was treated with interactive scalp acupuncture at ipsilateral upper 1/5 and 2/5 of the parietal and temporal anterior oblique line and upper 1/5 and 2/5 of the parietal and temporal posterior oblique line on the basis of the treatment as the control group, 45 min each time, once a day, 6 days a week. Both groups were treated for 4 weeks. Before and after treatment and in follow-up of 8 weeks after treatment completion, the Fugl-Meyer assessment (FMA) score, modified Ashworth scale (MAS) score, shoulder abduction angle, wrist dorsiflexion angle and N20 latency and amplitude of somatosensory evoked potential were compared between the two groups. After treatment and in follow-up, the FMA scores were increased (P<0.01), the MAS scores were decreased (P<0.01) compared with those before treatment in the two groups; the FMA scores in the observation group were higher than those in the control group (P<0.01), the MAS scores were lower than those in the control group (P<0.01). After treatment and in follow-up, the shoulder abduction angle and wrist dorsiflexion angle was increased (P<0.01), the N20 latency was shortened and amplitude was increased (P<0.01) compared with that before treatment in both groups; the shoulder abduction angle and wrist dorsiflexion angle in the observation group was greater than that in the control group (P<0.01), the N20 latency was shorter than that in the control group (P<0.01), and the N20 amplitude was higher than that in the control group (P<0.01). Interactive scalp acupuncture combined with task-oriented mirror therapy can improve upper limb function in patients with hemiplegia after stroke, and reduce the muscular tone of the affected limb.

Wearable Ultrasound Imaging Device for Dynamic Dual-Direction Shear Wave Elastography of Shoulder Muscle.

The shoulder is the most mobile joint in the human body, thus requiring intricate coordination of adjacent muscles. Patients suffered from rotator cuff muscle injuries have several typical symptoms including shoulder pain and difficulty raising the arm, thus reducing work efficiency and compromising the quality of life. Ultrasound has been used widely for shoulder soft tissue imaging as well as ultrasound elastography was introduced in shoulder examination for the dilemma of treating degenerative rotator cuff tears. However, most of the ultrasound examination was performed under a static condition. Providing dynamic information from shoulder muscle is important in clinical applications because the pains sometimes come from various positions of the shoulder during moving. In this study, a customized wearable T-shaped ultrasound transducer (128 + 128 elements) was proposed for shoulder dual-direction shear wave elastography (DDSWE), which provides the SWE for both longitudinal (SW along the muscle fiber) and transverse (SW cross the muscle fiber) directions dynamically. An optical tracking system was synchronized with an ultrasound imaging system to capture shoulder movements in 3-D space with their corresponding ultrasound images. The performance of DDSWE and the accuracy of optical tracking were verified by phantom experiments. Human studies were carried out by volunteers as they are moving their arms. The experimental results show that the bias and precision for the proposed DDSWE in elastic phantom were about 6% and 1.2% for both directions, respectively. A high accuracy of optical tracking was observed using a 3-D motor stage experimental setup. Human experiments show that the shear wave velocities (SWVs) were increased with the angles of shoulder abduction, and the average transverse and longitudinal SWVs were increased from 2.24 to 3.35 m/s and 2.95 to 5.95 m/s with abduction angle from 0° to 60°, respectively, which they are anisotropic-dependent. All the experimental results indicate that the proposed wearable ultrasound DDSWE can quantify the mechanical properties of shoulder muscles dynamically, thereby helping surgeons and physical therapists determine whether the intensity of rehabilitation shoulder be tuned down or escalated in the future.

Biomechanical Comparison Between Superior Capsular Reconstruction and Lower Trapezius Tendon Transfer in Irreparable Posterosuperior Rotator Cuff Tears

Background: Superior capsular reconstruction (SCR) and lower trapezius tendon transfer (LTT) have recently been used to manage irreparable posterosuperior rotator cuff tears (PSRCTs). There has been a paucity of comparative biomechanical considerations between the 2 procedures. Purpose: To compare the glenohumeral stability and biomechanical properties between SCR and LTT in PSRCTs involving the entire infraspinatus tendon region. Study Design: Controlled laboratory study. Methods: Eight fresh-frozen cadaveric shoulders were tested at 0°, 20°, and 40° of shoulder abduction. Maximum internal, external, and total humeral range of motion (ROM), superior translation of the humeral head, and subacromial contact characteristics were compared among 4 conditions: (1) intact rotator cuff, (2) PSRCTs involving the entire infraspinatus tendon region, (3) LTT using Achilles allograft (12 N and 24 N of loading), and (4) SCR using fascia lata allograft. Results: Although a decrease in total ROM was noted in LTT with 12 N compared with the tear condition, LTT with both 12 N and 24 N as well as SCR did not restrict total rotational ROM compared with the intact condition. LTT had decreased total ROM compared with tear condition at 20° of abduction (P = .042), while no significant decrease was confirmed at all abduction angles after SCR. SCR and LTT with 24 N decreased superior translation compared with the PSRCT condition at 0° and 20° of abduction (P < .037) but not significantly at 40° of abduction, whereas LTT with a 24-N load decreased glenohumeral superior translation at all abduction angles (P < .039). Both SCR and LTT decreased subacromial contact pressure compared with the tear condition (P < .014) at all abduction angles. SCR decreased subacromial contact pressure at 0° and 40° of abduction (P = .019 and P = .048, respectively) compared with LTT with 12 N of loading, while there was no difference between SCR and LTT with 24 N of loading in all abduction angles. SCR increased the contact area compared with the PSRCT condition at all abduction angles (P < .023), whereas LTT did not increase the contact area. Conclusion: SCR and LTT decreased glenohumeral superior translation and contact pressure compared with PSRCT conditions. The LTT was superior to SCR in terms of superior translation of the humeral head at a higher shoulder abduction angle, whereas the SCR showed more advantageous subacromial contact characteristics compared with LTT. Clinical Relevance: These biomechanical findings provide insights into these 2 fundamentally different procedures for the treatment of young and active patients with PSRCTs involving the entire infraspinatus tendon region.

Analysis of the stress-strain state of a three-dimensional model a shoulder hemiarthroplasty after changing the greater tubercle position on the shoulder

Background. The greater tubercle position change in shoulder hemiarthroplasty is of great importance for the shoulder joint contact surfaces’ stress-strain state (SТS). One of the important conditions for restoring a full range of motion in the shoulder joint after hemiarthroplasty and a longer service life of the endoprosthesis is the anatomical location of the greater tubercle. The purpose was to develop a three-dimensional model and study the STS of elements of the shoulder joint and implants of a hemiarthroplasty after changing the greater tubercle position on the shoulder. Materials and methods. The SolidWorks software package was used in order to construct a simulated 3D model of the shoulder joint, taking anatomical and anthropometric data into conside­ration to make the model as close to the real shoulder joint as possible. The ANSYS software package was used to calculate the shoulder joint models of the total load vector at different positions of the total load vector, depending on the greater tubercle of the humerus position. Results. The analysis of the shoulder joint mo­del elements’ STS with different greater tuberosity positioning and a shoulder abduction angle of 60° showed that the maximum increase in stress values is observed on the glenoid cavity subchondral bone when the greater tubercle of the humerus is transposed by 1 cm anterior — in 3.4 times, σmax up to 4.02 MPa. Moving the big tubercle by 1 cm distally is an optimal position in which the subchondral bone of the glenoid cavity undergoes minimum stress and deformation forces. Conclusions. The change in pressure on the contact surfaces is significant when changing the position of the greater tuberosity, which will undoubtedly affect the volume and range of motion in the postoperative period. Taking into account the data of the stress values on the contact surfaces obtained from our simula­ted 3D computer model of the shoulder joint allows improving the quality of preoperative planning and improving shoulder function and possible complications in the postoperative period.

Effect of stump-preserving repair on rotator cuff healing and shoulder function for degenerative total rotator cuff tears

To analyze the effect of stump-preserving repair on rotator cuff healing and shoulder function for degenerative total rotator cuff tears. A clinical data of 152 patients with degenerative total rotator cuff tears, who underwent arthroscopic repair between April 2019 and May 2022, was retrospectively analyzed. There were 76 males and 76 females with an average age of 55.4 years (range, 24-78 years). MRI was performed at 6 months postoperatively to evaluate the rotator cuff healing according to the Sugaya classification. Pre- and intra-operative related factors were included for univariate analysis, including age (≥60 years/<60 years), gender (male/female), passive activity disorder (yes/no), disease duration (≤3 months/>3 months), stump-preserving repair (yes/no), use of suture bridge technique (yes/no), shoulder joint abduction angle at knotting (<45°/≥45°), acromioplasty (yes/no), glucocorticoid injection (yes/no), time for patients to start postoperative passive exercise (≤2 weeks/>2 weeks), and time for patients to start postoperative active exercise (≤3 months/>3 months). The influencing factors of tendon healing were screened; further logistic regression was used to conduct multivariate analysis to screen for risk factors. Two sets of data were balanced by propensity score matching. The American Shoulder and Elbow Surgeons (ASES) score and Constant-Murley score of shoulder joint function at 6 and 12 months postoperatively, as well as rotator cuff healing rate at 6 months postoperatively, were compared between groups based on whether or not stump-preserving repair was used. All patients were followed up 12-33 months (mean, 23.8 months). MRI at 25-31 weeks postoperatively showed the 121 cases of rotator cuff healing and 31 cases of non healing. Univariate analysis showed that the disease duration, stump-preserving repair, shoulder joint abduction angle at knotting, and the time for patients to start postoperative active exercise were the influencing factors of rotator cuff healing ( P<0.05). Multivariate analysis showed that non-stump-preserving repair, shoulder abduction angle more than 45° at knotting, and the time to start active exercise within 3 months postoperatively were risk factors affecting rotator cuff healing ( P<0.05). A total of 51 pairs of cases were matched based on the grouping criteria of whether the disease duration exceeded 3 months, whether the shoulder abduction angle at knotting exceeded 45°, and whether the time to start postoperative active exercise exceeded 3 months. The rotator cuff healing rate, ASES score, and Constant-Murley score of the preserving repair group at 6 months postoperatively were superior to those of the non-preserving repair group, and the differences were significant ( P<0.05). There was no significant difference in ASES score and Constant-Murley score between the two groups at 12 months postoperatively ( P>0.05). For degenerative total rotator cuff tears, the stump-preserving repair can shorten the healing time and promote the shoulder function recovery, but has no significant effect on shoulder function at 1 year postoperatively.

Comparison of the Post Treatment Outcomes of a Conservative Physiotherapy Protocol for Subacromial Impingement Syndrome in Terms of Acromion Morphology

Objective: The present study aimed to compare the results of a conservative physiotherapy (CP) protocol for subacromial impingement syndrome (SIS) in terms of the morphological types of acromion. Methods: Fifty patients participated in the present study, and they were divided into 3 groups according to the acromion morphology types. A 8-week CP (4-week treatment period at the clinic and, in addition, an exercise program at home for 4 weeks) was applied to all patients. The patients were evaluated in terms of pain (at rest and activity) by the Visual Analog Scale, range of motion (ROM), joint position sense (laser pointer), muscle strength (digital dinamometer), and functionality (the Shoulder Pain and Disability Index, SPADI) before and after the treatment. Result: In the pre- and post-treatment changes (delta), the shoulder flexion angle increased less in the type 3 group than in the type 1 and type 2 groups (p&lt;0.05). In the shoulder abduction angle, there was a similar increase in the type 3 group compared to the type 2 group, while there was less increase in the type 1 group (p&lt;0.05). It was determined that there was more deviation in the change value of shoulder abduction position sense in the type 3 group compared to the other groups (p&lt;0.05). There was no difference between the groups in the change values of pain, muscle strength, or the SPADI score (p &gt; 0.05). Conclusion: Type 3 acromion may have a handicap in improving shoulder flexion and abduction ROM and shoulder abduction position compared to other types.

Dependence of Rotator Cuff Muscle Thickness and Stiffness on Low-Level Contractions: Metrology of the Contraction Level Using Shear-Wave Imaging.

The study aimed to investigate the effects of the level of contraction during isometric shoulder abduction at different abduction angles on muscle thickness and stiffness of the shoulder girdle in asymptomatic individuals. Measurement properties study. Biomechanics and motion analysis lab. Twenty individuals volunteered to participate in this study. The subjects were tested for morphological and mechanical properties, expressed by thickness and stiffness of the supraspinatus tendon and muscle, and upper trapezius muscle. Moreover, acromiohumeral distance was also evaluated using B-mode ultrasound and shear-wave elastography. The thickness and stiffness of the supraspinatus and upper trapezius muscle were assessed at 3 angles of abduction (0°, 60°, and 90°) and 3 levels of contraction (0%, 10%, and 20% of the maximal voluntary isometric contraction) using ultrasonography with shear-wave imaging. Moreover, the acromiohumeral distance was measured to establish the occupation ratio during passive movement. The supraspinatus and upper trapezius muscle thickness and stiffness were significantly greater at 60° shoulder abduction compared with 0°, and 90° compared with 60°, as well as significantly greater at 20% maximal voluntary isometric contraction compared with 0% and 10% maximal voluntary isometric contraction. Thickness and stiffness were significantly greater in the supraspinatus compared with the upper trapezius muscle at all 3 angles of shoulder abduction for all 3 level of contractions. The acromiohumeral distance decreased significantly from 0° to 60° and from 60° to 90°. Morphological and mechanical properties of the supraspinatus and upper trapezius muscles depended on the relative level of muscle contraction and the angle of shoulder abduction.

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 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 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.

Analysis of in vivo humeral rotation of reverse total shoulder arthroplasty patients during shoulder abduction on the scapular plane with a load

BackgroundFew studies have investigated the kinematics after reverse total shoulder arthroplasty (RTSA). This study aimed to compare the shoulder kinematics in RTSA patients during shoulder abduction on the scapular plane with and without a load and yield information regarding the function of stabilizing the joints against gravity for the functional assessment of the shoulder after RTSA, which could lead to changes in postoperative rehabilitation treatment.MethodsTwenty RTSA patients (7 men, 13 women; mean age: 78.1 [64–90] years) were examined. First, active shoulder abduction in the scapular plane was captured using single-plane fluoroscopic X-ray images. Imaging was performed by stipulating that one shoulder abduction cycle should be completed in 6 s. Two trials were conducted: one under a load equivalent to 2% of body weight and one without a load. Next, a three-dimensional (3D) model of each humeral and scapular component was matched to the silhouette of the fluoroscopic image to estimate the 3D dynamics. By using the 3D dynamic model obtained, the kinematics of the glenosphere and humeral implant were calculated relative to the shoulder abduction angle on the scapular plane and were compared between groups with and without a load. A one-way analysis of variance and a post hoc paired t-test with a statistical significance level of 0.05 were performed.ResultsThe humeral internal rotation decreased with a load at shoulder abduction between 40° and 90° on the scapular plane (P < 0.01, effect size: 0.15). No significant differences in scapular upward rotation (P = 0.57, effect size: 0.022), external rotation (P = 0.83, effect size: 0.0083) and posterior tilting (P = 0.74, effect size: 0.013) were observed between groups with and without a load. The main effect was not observed with and without a load (P = 0.86, effect size: 0.0072). However, the scapulohumeral rhythm was significantly greater without a load during shoulder joint abduction between 40° and 60° on the scapular plane.ConclusionIn RTSA patients, the glenohumeral joint was less internally rotated, and the scapulohumeral rhythm decreased under loaded conditions. It was stabilized against the load through the mechanical advantage of the deltoid muscle and other muscles.

Sex differences regarding the effects of arm swing on ground reaction force and trunk movements between track and field athletes

The purpose of this study was to clarify the sex difference in the effects of arm swing movements of track and field athletes on ground reaction force and trunk movement. Seven male and nine female athletes belonging to a university track and field team were asked to perform arm swings for 10 seconds each under three different conditions (longitudinal, lateral, and original) while in the standing position. Three-dimensional coordinate data for each experimental trial was collected using an automatic optical motion analyser, and ground reaction forces were measured using a force plate. Under the longitudinal condition, the mean acceleration force was greater for males than for females (p &lt; .05), and the operating range of trunk twist angle was significantly greater for females than for males (p &lt; .05). However, under the original condition, there were no significant differences between the sexes in mean acceleration force, but there were significant differences in maximum twist angle and minimum and maximum shoulder abduction angles (p &lt; .05). These results indicate that there are sex differences in trunk movement and ground reaction force depending on the direction of arm swing.

Feasibility and Efficacy of the Newly Developed Robotic Hybrid Assistive Limb Shoulder Exercises in Patients with C5 Palsy during the Acute Postoperative Phase.

Background and Objectives: Although postoperative C5 palsy is a frequent complication of cervical spine surgery, no effective therapeutic rehabilitation approach has been established for postoperative C5 palsy. The purpose of this study was to find evidence confirming the effectiveness and feasibility of robotic Hybrid Assistive Limb (HAL) shoulder exercises for C5 palsy. Materials and Methods: In this before-after, uncontrolled case series clinical study, we performed a mean of 11.7 shoulder training sessions using a shoulder HAL immediately after the onset of C5 palsy in seven shoulders of six patients who developed postoperative C5 palsy and had difficulty raising their shoulder during the acute postoperative phase of cervical spine surgery. Shoulder HAL training was introduced as early as possible after evaluating the general condition of all inpatients who developed C5 palsy. Patients underwent shoulder abduction training using shoulder HAL on an inpatient and outpatient basis at 2-week or 1-month intervals. Adverse events associated with shoulder HAL training were investigated. The shoulder abduction angle and power without the shoulder HAL were evaluated before shoulder HAL usage, at every subsequent session, and upon completion of all sessions. Results: Severe adverse events due to shoulder HAL training were not reported. After completion of all shoulder HAL sessions, all patients showed improved shoulder elevation, while shoulder abduction angle and power improved over time. Conclusions: Shoulder elevation training with HAL in patients in the acute stage of postoperative C5 palsy has the potential to demonstrate improvement in shoulder joint function with a low risk of developing severe adverse events.

Efficacy of Intra-articular Triamcinolone and Hyaluronic Acid in a Frozen Shoulder Rat Model.

Intra-articular corticosteroid or hyaluronic acid (HA) is commonly prescribed for frozen shoulder. However, few studies have investigated histological and molecular changes after injection. To compare the effectiveness of intra-articular injections of triamcinolone and HA in a frozen shoulder rat model and verify a greater effect of triamcinolone in passive shoulder abduction compared with HA. Controlled laboratory study. Twenty male Sprague-Dawley rats were randomly allocated into 4 groups (n = 5 in each): control group, which did not receive cast immobilization or injection, and 3 experimental groups, which received 3 weeks of unilateral shoulder immobilization followed by intra-articular injections (normal saline, triamcinolone, or HA) at the immobilized shoulder. Passive shoulder abduction angle, histological and immunohistochemical staining, and Western blotting results were assessed 2 weeks after injection. The intensity and extent of staining were converted to semiquantitative scores for further analysis. Shoulder abduction angles before sacrifice were 153.0°± 2.7° (control group), 107.0°± 5.7° (saline group), 139.0°± 9.6° (triamcinoline group), and 110.0°± 10.6° (HA group), showing significant differences between control and saline groups, control and HA groups, saline and triamcinoline groups, and triamcinoline and HA groups (P < .001) but not between control and triamcinoline groups (P = .053). Histologic evaluation revealed an increase in synovial folds and thickening of the capsular membrane in the saline and HA groups; this change was not evident in the triamcinolone group. A comparison of semiquantitative scores revealed greater expression levels of proteins involved in fibrosis and angiogenesis in the saline and HA groups compared with the control and triamcinolone groups. In Western blotting, the expression of inflammatory cytokines and the receptor for advanced glycation end products was significantly lower in the triamcinolone and HA groups than in the saline group. Triamcinolone injection was more effective than normal saline or HA injection in improving range of motion and reversing fibrotic and angiogenic features of frozen shoulder. Both triamcinolone and HA injections elicited anti-inflammatory effects. The antifibrotic and antiangiogenic properties of triamcinolone and the anti-inflammatory properties of both triamcinolone and HA should be considered when performing injections in clinical settings.

Effects of error rates and target sizes on neck and shoulder biomechanical loads during augmented reality interactions

Augmented reality (AR) interactions have been associated with increased biomechanical loads on the neck and shoulders. To provide a better understanding of the factors that may impact such biomechanical loads, this repeated-measures laboratory study evaluated the effects of error rates and target sizes on neck and shoulder biomechanical loads during two standardized AR tasks (omni-directional pointing and cube placing). Twenty participants performed the two AR tasks with different error rates and target sizes. During the tasks, angles, moments, and muscle activity in the neck and shoulders were measured. The results showed that the target sizes and error rates significantly affected angles, moments, and muscle activity in the neck and shoulder regions. Specifically, the presence of errors increased neck extension, shoulder flexion angles and associated moments. Muscle activity in the neck (splenius capitis) and shoulder (anterior and medial deltoids) also increased when the errors were introduced. Moreover, interacting with larger targets resulted in greater neck extension moments and shoulder abduction angles along with higher muscle activity in the splenius capitis and upper trapezius muscles. These findings indicate the importance of reducing errors and incorporating appropriate target sizes in the AR interfaces to minimize risks of musculoskeletal discomfort and injuries in the neck and shoulders.

Measurement of Shoulder Abduction Angle with Posture Estimation Artificial Intelligence Model.

Substantial advancements in markerless motion capture accuracy exist, but discrepancies persist when measuring joint angles compared to those taken with a goniometer. This study integrates machine learning techniques with markerless motion capture, with an aim to enhance this accuracy. Two artificial intelligence-based libraries-MediaPipe and LightGBM-were employed in executing markerless motion capture and shoulder abduction angle estimation. The motion of ten healthy volunteers was captured using smartphone cameras with right shoulder abduction angles ranging from 10° to 160°. The cameras were set diagonally at 45°, 30°, 15°, 0°, -15°, or -30° relative to the participant situated at a distance of 3 m. To estimate the abduction angle, machine learning models were developed considering the angle data from the goniometer as the ground truth. The model performance was evaluated using the coefficient of determination R2 and mean absolute percentage error, which were 0.988 and 1.539%, respectively, for the trained model. This approach could estimate the shoulder abduction angle, even if the camera was positioned diagonally with respect to the object. Thus, the proposed models can be utilized for the real-time estimation of shoulder motion during rehabilitation or sports motion.

A comparison of functional vestibulo-ocular reflex and proprioception in athletes of combat sports and ball sports

BackgroundThe contribution and role of sensory systems in providing postural control may vary depending on the condition or activity. Vestibulo-ocular reflex (VOR) and proprioception might be affected by the type of sport. ObjectiveThis study aimed to compare athletes engaged in combat sports and ball sports in terms of functional VOR and proprioception. DesignThis study is a cross-sectional, comperative research. MethodTwenty-four athletes engaged in combat sports and 20 in ball sports were included in the study. Functional examination of VOR in athletes was performed with a novel Functional Head Impulse Test (fHIT). Proprioception analysis was evaluated using Laser Pointer Assisted Angle Reproduction Test (LPA-ART) in 90° shoulder flexion and abduction. ResultsfHIT lateral and posterior % Correct Answer (CA) values and anterior SCC 6000°/s2 values of athletes engaged in ball sports were found to be statistically significantly higher than athletes in combat sports (p < 0.05). Except for anterior SCC 4000°/s2 value, scores of the ball players in all accelerations and directions were higher than combat sports athletes, although it was not statistically significant. The 90° shoulder flexion and abduction angle deviation values obtained from the LI-ATT were statistically lower in those who played ball sports (p < 0.05). ConclusionsParticipation in sports branches played with the ball is expected to provide gains for athletes who want to reach high-level performance in proprioceptive and vestibular functioning and those with vestibular/proprioceptive pathology. Maintaining clear vision in dynamic sports branches can be improved by training VOR function.

The effect of pathological shoulder rhythm on muscle and joint forces after reverse shoulder arthroplasty, a numerical analysis

BackgroundCompromised abduction ability after reverse shoulder arthroplasty is primarily linked to limited glenohumeral range of motion while scapulothoracic mobility can typically be maintained. Glenohumeral joint forces strongly depend on the resulting scapulohumeral rhythm, however, an association between the acting muscle and joint forces and the subject-specific scapulohumeral rhythm after reverse shoulder arthroplasty has not been established. MethodsEleven reverse shoulder arthroplasty patients were divided into groups of poor and excellent abduction ability. Subject-specific models were developed and scaled for each patient using existing motion capture data in AnyBody™. Shoulder muscle and joint forces were obtained using inverse dynamics calculations during shoulder abduction to 100° in the scapula plane. The scapulohumeral rhythm, the resting abduction angle and internal body forces between the outcome groups were compared using a Mann Whitney U test. FindingsThe mean glenohumeral and scapulothoracic contribution to overall shoulder abduction for the excellent group was on average 9.7% higher and 21.4% lower, respectively, compared to the mean of the poor group. For shoulder abduction angles between 30° and 60°, the excellent group demonstrated on average 25% higher muscle forces in the anterior deltoid which was significantly higher compared to the poor outcome patients. Scapulothoracic muscle activity did not differ significantly between the two functional groups. InterpretationAccordingly, rehabilitation strategies focusing on strengthening the anterior part of the deltoid in particular may improve clinical outcomes.

Effect Of Different Grip Position And Shoulder- Abduction Angle On Muscle Strength And Activation During The Seated Cable Row

The purpose of this study was to compare the peak force and electromyographic activation in different techniques of the seated row. Eleven recreationally trained male (28±5 years, 176±5 cm, 94±16 kg) and ten female (27±5 years, 168±8 cm, 65±11 kg ) performed an isometric and a dynamic assessment of the seated cable row and the preacher curl: pronated grip (PRO), supinated grip (SUP), neutral grip (NEU), 30° (30°), 60° (60°), 90° (90°) of shoulder abduction, and cable preacher curl (PC). Peak force and muscle activation of upper trapezius, middle trapezius, upper latissimus, lower latissimus, posterior deltoid, and biceps bracii were recorded during the isometric and dynamic assessment of the exercises. p values&lt;0.05 were considered statistically significant. The peak force was greater when shoulder abduction angle was closer to 0° (PRO, SUP, and NEU) and decreased as abduction angle increased (60° and 90°). Muscle activation of the upper back (upper trapezius, middle trapezius) and posterior deltoid increased as abduction angle increased (60° and 90°) on both isometric and dynamic analysis. Muscle activation of the upper and lower latissimus increased as abduction angle was closer to 0° (PRO, SUP, and NEU) on both isometric and dynamic analysis. Biceps brachii activation on both isometric and dynamic analysis during the PC was greater than all other rowing conditions; among the rowing techniques, BB activation was greater during SUP, NEU, and 90° techniques. In conclusion, the closer to 90° shoulder abduction the greater UT, MT, and PD activity, on the other hand, the closer to 0° shoulder abduction the greater peak force, UL, and LL activity during the variations of the rowing exercise.