Shoulder Angle Research Articles

Does critical shoulder angle predict abduction motion and acromion-tuberosity impingement in reverse shoulder arthroplasty?

BackgroundVirtual planning software for reverse shoulder arthroplasty (RSA) has introduced the ability to optimize implant position in an effort to maximize bony impingement–free motion. Abduction impingement typically occurs between the glenoid and polyethylene or between the tuberosities and the acromion or coracoid. Acromion-tuberosity impingement has been considered less desirable, as it may create additional stress on the acromion. Patients with a large acromion overhang may have higher rates of acromion-tuberosity impingement. As the critical shoulder angle (CSA) represents a larger distance from the glenoid face to the acromion, the purpose of this study was to evaluate the impact of implant selection and position on abduction motion and acromion-tuberosity impingement, with a focus on the association to CSA. We hypothesize that a larger CSA will be associated with less abduction motion and an increase in acromion-tuberosity impingement. MethodsThis is a retrospective cohort case series of 85 consecutive patients who underwent RSA from June 2020 to January 2021. Humeral and glenoid components were implanted virtually (SurgiCase) using a standard protocol for a single implant system (DJO AltiVate Short Stem Reverse) with an inset humeral component. Implant variables analyzed included baseplate location (central vs. inferior glenoid), glenosphere lateralization (10 mm vs. 6 mm), and humeral shell (standard vs. semiconstrained). The maximal degree of abduction and location of impingement were recorded at external rotation of 0°, 45°, and 90°. Implant combinations that resulted in no impingement and no motion were recorded. ResultsIncrease in CSA was associated with acromion-tuberosity impingement for nearly every combination at 0° and 45° external rotation; however, there were no significant associations between CSA and maximum abduction motion. Acromion-tuberosity impingement was associated with central glenosphere placement in all degrees of external rotation (P < .001), use of a 10 mm lateralized glenosphere for 0° (P < .001) and 45° (P = .076), and using a standard polyethylene shell for 0° (P = .032) and 45° external rotation (P = .007). Maximal abduction motion was associated with inferior placement (P < .001), and use of a 10 mm lateralized glenosphere (P < .001) in all positions of external rotation but was not influenced by the polyethylene type. ConclusionIncreased CSA is associated with acromion-tuberosity impingement and can be used to screen for patients at risk for bony impingement in abduction. Placement of the glenosphere centrally and use of a 10 mm lateralized glenosphere were associated with higher rates of acromion-tuberosity impingement. Maximal abduction can be achieved using a 10 mm lateralized glenosphere and inferior placement.

The role of scapular morphology in traumatic rotator cuff tears and greater tuberosity fractures: A retrospective study

BackgroundTraumatic postero-superior Rotator Cuff Tears (RCT) and isolated Greater Tuberosity fractures (GTF) are equivalent injuries resulting in significant shoulder dysfunction if left retracted or displaced. The difference in morphometric aetiology is unclear. A raised critical shoulder angle (CSA) has been associated with rotator cuff degeneration. We hypothesised that traumatic RCT is associated with a raised CSA when compared to GTF. MethodsA retrospective study was conducted across the two trauma units in our institution. All patients between the period of 2010 and 2020 with Traumatic GTF or RCT assessed on cross-sectional imaging (CT or MRI) were identified. Patients were case-matched by age, gender, mechanism and laterality of injury. The primary outcome measurement was the Critical Shoulder Angle (CSA). Other radiographic features of subacromial degenerative change, mechanism of injury, association with shoulder dislocation and delay to diagnosis were also compared. ResultsEighty patients met the inclusion criteria(40 traumatic RCT and 40 GTF). The mean age was 61.8 years with 58(72.5%) left-sided injuries. Thirty-four (43%) were female.The mean CSA was 3.96° higher in the RCT group (95% CI 2.5 to 5.41, p < 0.05). A CSA of 33.73 gave a sensitivity of 0.68 and a specificity of 0.8 to differentiate between RCT and GTF. Patients with RCT were far more likely to display subacromial degenerate changes and experience a significant delay in diagnosis, whereas those with GTF were more likely to have suffered a shoulder dislocation. ConclusionsPatients with traumatic RCT have radiographic features and scapular morphology associated with degenerative rotator cuff disease compared to those with GTF. This supports the theory that tears occur on the background of pre-existing tendon degeneration. Careful assessment of these parameters, combined with clinical assessment, may help guide the provision of appropriate diagnostic imaging. Level of evidenceIII.

Biomechanical Assessment of Throwing Gesture and Performance in Female Water-Polo Players

Water-polo is an aquatic sport based on the high level of coordination of several body movements, frequent changes in positions, speeds, and directions. Considering technical and tactical aspects, the power, the force, and the shot accuracy have been identified as important skills and specific training programs can be scheduled with the attempt to improve them. Moreover, the biomechanical investigation of kinematic parameters during the shot can contribute to the evaluation of player’s throwing performance and to the description of gesture. The principal aim of the current study is the comparative analysis of throwing kinematics in three different types of shots. Eleven female players were evaluated before and after 45 days of a specific water-polo training. In the experimental tests, three types of shots were performed, shoulder and elbow angles and throwing velocity were analyzed. In addition, power and precision parameters were estimated to describe players’ throwing performance. During the passing-feint shot, a significant lower maximum velocity (before: 14.7 m/s; after: 13.9 m/s; p-value = 0.005) and a higher shoulder angle (before: 56.7°; after: 63.9°; p-value = 0.003) were observed. During the passing-spontaneous shot, players’ precision showed a tendency to increase after the training (score before: 9.0; score after: 11.0 score; p-value = 0.05). This study proved the feasibility of an objective biomechanical assessment of the throwing kinematics and throwing performance of water-polo players, in ecological conditions.

A Training Method for a Sensor-Based Exercise Rehabilitation Robot

In order to solve the problem that the traditional mirror therapy did not take into account the real-time recovery of the affected limb and the training effect was limited, a training method of sports rehabilitation robot based on sensor was proposed. A mirror active rehabilitation training system was proposed, which was composed of four steps including trajectory acquisition of the limb inertial measurement unit (IMU), fuzzy adaptive proportion differentiation (PD) control in closed-loop variable domain, muscle force estimation of the surface electromyographic signal (sEMG) of the affected limb, and power compensation of the outer ring of the affected limb. The experimental results showed that the sagittal forward flexion angle of the healthy shoulder increased from 0° to 128° at a relatively uniform speed, and the sagittal forward flexion angle of the shoulder was basically consistent with that of the healthy limb after the adaptive power compensation of the affected limb. The calculated trajectory tracking error of the healthy limb controlled by the fuzzy adaptive PD controller in the variable domain was 0.21 ± 1.35 ° . The horizontal backward extension angle of the healthy shoulder joint increased from 0° to 43°, and the following trajectory of the affected limb was roughly consistent with the movement trajectory of the healthy limb. The calculated tracking error of the healthy limb trajectory was 0.39 ± 1.45 ° . It was concluded that the control system could provide the real-time power compensation according to the recovery of the affected limb, give full play to the training initiative of the affected limb, and make the affected limb achieve a better rehabilitation training effect.

Automatic recognition of the neck–shoulder shape based on 2D photos

To improve body type classification and automatic identification, this study adopted a method by combining three-dimensional (3D) point-cloud data with two-dimensional (2D) photos for the classification of young mens’ neck–shoulder shape. A total of 180 male college students were measured by photo and 3D body measuring methods to get the main body information. As for the 3D body cloud data, reverse engineering software was used to measure the parameters closely related to the neck–shoulder shape. Five important parameters, including the forward angle, back angle, shoulder angle, the ratio between neck and shoulder width, and the ratio between neck width and thickness were analyzed to divide young men’s neck–shoulder shape into three categories, namely round drop shoulder, forward round neck and wide straight neck, and the classification rules were established. As for the 2D photos (such as front and side photos), the human body contour was extracted to obtain the parameters required for neck–shoulder shape classification by identifying the feature points. The neck–shoulder shape could be automatically recognized, and the accuracy rate is 97.7% to verify that the neck–shoulder shape recognition system is effective. This study proposed a simple neck–shoulder shape automatic recognition method based on the 2D body photos, and provide reference for automatic neck–shoulder shape recognition, 3D modeling and virtual fitting of local features.

Optimization of the Grashey View Radiograph for Critical Shoulder Angle Measurement: A Reliability Assessment With Zero Echo Time MRI.

Background:Suboptimal positioning on Grashey view radiographs may limit the prognosticating potential of the critical shoulder angle (CSA) for shoulder disorders.Purpose:To investigate whether radiography optimized according to the latest research is reliable for measuring CSA in comparison with magnetic resonance imaging (MRI) featuring 3-dimensional (3D) zero echo time (ZTE) sequencing, which accentuates the contrast between cortical bone and surrounding soft tissue with high fidelity.Study Design:Cohort study (diagnosis); Level of evidence, 2.Methods:Patients with shoulder pain were prospectively and consecutively enrolled. All patients had Grashey view radiographs as well as 3.0-T MRI scans with isotropic 3D ZTE sequencing. Acceptable positioning on the radiographs was determined using the ratio of the transverse to longitudinal (RTL) diameter of the lateral glenoid outline; radiographs with an RTL ≥0.25 were repeated. Two observers independently measured the CSA on the radiographs and the coronal oblique reformatted ZTE images, the latter including verification of measurement points by cross-referencing against images from other planes. Reliability of measurements between observers and modalities was analyzed with the intraclass correlation coefficient (ICC). The paired-samples t test was used to compare the differences between imaging modalities.Results:Enrolled were 65 patients (35 female and 30 male; mean age, 40.2 years; range, 25-49 years). Radiographs with optimal positioning (RTL < 0.25) were attained after a mean of 1.6 exposures (range, 1-4); the mean RTL was 0.09 (range, 0-0.20). Interobserver agreement of CSA was excellent for radiographs (ICC = 0.91; 95% CI, 0.84-0.94) and good for ZTE MRI scans (ICC = 0.85; 95% CI, 0.71-0.92). Intermodality agreement of CSA between radiographs and ZTE MRI scans was moderate (ICC = 0.66; 95% CI, 0.48-0.73). The CSA was significantly different between an optimal radiograph (30.7° ± 4.3°) and ZTE MRI scan (31.8° ± 3.8) (P = .005). Subgroup analysis revealed no significant differences in CSA measurement between ZTE MRI scans and Grashey view radiographs with an RTL of <0.1 (P = .08).Conclusion:CSA measurement on ZTE MRI scans with anatomic point cross-referencing was significantly different from that on Grashey view radiographs, even with optimal positioning, and radiography may necessitate more than 1 exposure. An RTL of <0.1 ensured reliability of radiographs when other standards of sufficient x-ray exposure were met.

Positive Effect of Manipulated Virtual Kinematic Intervention in Individuals with Traumatic Stiff Shoulder: A Pilot Study.

Virtual reality enables the manipulation of a patient’s perception, providing additional motivation to real-time biofeedback exercises. We aimed to test the effect of manipulated virtual kinematic intervention on measures of active and passive range of motion (ROM), pain, and disability level in individuals with traumatic stiff shoulder. In a double-blinded study, patients with stiff shoulder following proximal humerus fracture and non-operative treatment were randomly divided into a non-manipulated feedback group (NM-group; n = 6) and a manipulated feedback group (M-group; n = 7). The shoulder ROM, pain, and disabilities of the arm, shoulder and hand (DASH) scores were tested at baseline and after 6 sessions, during which the subjects performed shoulder flexion and abduction in front of a graphic visualization of the shoulder angle. The biofeedback provided to the NM-group was the actual shoulder angle while the feedback provided to the M-group was manipulated so that 10° were constantly subtracted from the actual angle detected by the motion capture system. The M-group showed greater improvement in the active flexion ROM (p = 0.046) and DASH scores (p = 0.022). While both groups improved following the real-time virtual feedback intervention, the manipulated intervention provided to the M-group was more beneficial in individuals with traumatic stiff shoulder and should be further tested in other populations with orthopedic injuries.

The Effect of a Selected Corrective Program on Upper Crossed Syndromein Men With Depression

Purpose: Most studies have examined the effect of aerobic exercises on improving depression and performance. However, due to the importance of the relationship between corrective exercise and spine alignment, especially in depressed men, this study aimed to investigate the effect of a selected corrective program on the upper crossed syndrome in men with depression. Methods: The present study was a randomized controlled trial conducted in Shahrekord City, Iran. To perform this research, 30 depressed people with the upper crossed syndrome were purposefully selected and divided into experimental and control groups. The Beck depression inventory was used to measure their depression. The amount of forward head and shoulder angles were determined by the photogrammetry method, and a flexible ruler was used to measure the dorsal curvature of the spine. After evaluating the variables in the pre-test, the experimental group received the selected corrective exercise program for 8 weeks, 3 days a week. During this period, the control group did not do any exercises. Finally, after executing the selected protocol, the mentioned variables were measured again in the post-test. In inferential statistics, an analysis of covariance was used to compare inter-group differences. Results: After performing corrective exercises, the results showed a significant difference between the groups (P&lt;0.05). The change in the corrective exercises group was significantly greater in the angles of kyphosis (P=0.001), forward head (P=0.001), forward shoulder (P=0.001), and level of depression (P=0.001) than those in the control group. Conclusion: The results revealed that 8 weeks of selected corrective exercises positively affect depression. According to the results, 8 weeks of corrective exercises can significantly reduce the angle of the head forward, round shoulder, and hyperkyphosis in depressed men with the upper crossed syndrome. So, these corrective exercises can be recommended to specialists as a treatment.

Ultrasound Assessment of Anterior Humeral Head Translation in Patients With Anterior Shoulder Instability: Correlation With Demographic, Radiographic, and Clinical Data.

Background:Ultrasonography can be used to quantitatively assess anterior humeral head translation (AHHT) at different degrees of shoulder abduction. Risk factors for recurrent shoulder instability have been identified.Hypothesis:It was hypothesized that the number of dislocations or glenoid or humeral bone loss would be associated with more AHHT as measured using ultrasound.Study Design:Cross-sectional study; Level of evidence, 3.Methods:A total of 39 patients who underwent surgery for anterior shoulder instability were prospectively studied. Ultrasound assessment of AHHT was performed immediately after general anesthesia was induced. The upper arm was placed at 0°, 45°, and 90° of abduction, and a 40-N anterior force was applied to the proximal third of the arm. The distance from the posterior edge of the glenoid to that of the humeral head was measured at each abduction angle using ultrasound with and without a 40-N anterior force, and the AHHT was calculated. The differences in translation at each shoulder angle were compared. Additionally, the authors investigated the association between AHHT and demographic, radiographic, and clinical data.Results:Compared with the AHHT at 0° of abduction (5.29 mm), translation was significantly larger at 45° of abduction (8.90 mm; P < .01) and 90° of abduction (9.46 mm; P < .01). The mean translation was significantly larger in female patients than in male patients at all degrees of abduction (P ≤ .036 for all). There was no correlation between AHHT at any abduction angle and number of dislocations, clinical data, or radiographic data (including bone loss).Conclusion:Ultrasound assessment of AHHT showed larger amounts of laxity at 45° and 90° than at 0° of abduction. Anterior glenohumeral laxity was greater in female than male patients. Glenoid or humeral bone loss did not correlate with AHHT, thereby clarifying that bone loss has no direct effect on measurements of capsular laxity in neutral rotation.

The Critical Shoulder Angle in a Middle Eastern Cohort: is There an Association with Rotator Cuff Tear?

The Critical Shoulder Angle in a Middle Eastern Cohort: is There an Association with Rotator Cuff Tear?

Acromial and humeral head osteolysis following superior capsular reconstruction using autologous tensor fascia lata graft.

Graft tear is a critical complication following superior capsular reconstruction (SCR) as it directly links with clinical outcomes. No previous reports have described acromial and humeral head osteolysis following SCR. Acromial and humeral head osteolysis may incidentally occur after SCR using autologous tensor fascia lata graft. This study aimed to demonstrate the incidence of osteolysis following SCR using autologous tensor fascia lata graft and investigate the factors that affect osteolysis. This retrospective cohort study included patients who underwent SCR for irreparable rotator cuff tears between June 2014 and June 2019. The patients were divided into 2 groups-those with no osteolysis and those with osteolysis-and were compared. For subanalysis, patients in the osteolysis group were further divided into 3 groups according to the location of the osteolysis-acromial osteolysis, humeral head osteolysis, and acromial and humeral head osteolysis-to clarify the factors determining the location of osteolyses. The shoulder range of motion was evaluated preoperatively and 24 months postoperatively. Additionally, the following items were evaluated: condition of the subscapularis tendon, Hamada classification (grade 2 or 3), critical shoulder angle, acromiohumeral distance measured preoperatively and 24 months postoperatively, graft size, and graft thickness. In addition, the graft condition was evaluated using magnetic resonance imaging 12 months postoperatively. In total, 57 patients were enrolled and followed up for a minimum of 2 years (follow-up rate, 92% [57 of 62 cases]). Overall, the incidence of osteolysis following SCR was 35.1% (20 of 57 cases; acromial osteolysis in 7, humeral head osteolysis in 3, and acromial and humeral head osteolysis in 10). Compared with the group with no osteolysis, the osteolysis group had no inferior clinical outcomes or higher graft tear rates. The proportions of Hamada grade 3 (P=.041) and involvement of the subscapularis tendon (P=.020) were significantly higher in the osteolysis group. The relative risks of subscapularis involvement and Hamada grade 3 for osteolysis were 2.9 and 5.1, respectively. In the subanalysis, the factors determining the location of the osteolysis could not be clarified. This study suggested that the progression of the Hamada classification and condition of the subscapularis tendon affect the occurrence of osteolyses. However, these osteolyses were not associated with clinical outcomes, including graft tear rate and shoulder range of motion.

A biomechanical analysis of differences between natural and clinical angle degrees and correlations to performance in road cycling

Background and Study Aim. The study aims to determine differences between natural and clinical angle degrees in hips and shoulders, and determination of the correlations between angle degrees and functional threshold power (FTP) in road cycling athletes.&#x0D; Material and Methods. The study includes 11 male road cycling athletes aged 14-16 years old. The volunteer's body weight average was determined as 68.5±14.58, body height average was 175.4±6.98, and body mass index average 21.8±3.87. Volunteers are active athletes in “Büyükçekmece Road Cycling Team”. To measure the performance of the cyclists clinical hip angle, clinical shoulder angle, hip angle degree, shoulder angle, functional threshold power (FTP) tests were used. The Kinovea 0.8.15 program was used in the data analysis of the variables in the study. Analyzes were performed using SPSS 26 analysis program. The analyses of the Shapiro Wilks test resulted in the normal distribution of the variables included in the study. Correlations between FTP test parameters and angle degrees, the correlation of a continued variable were calculated with Pearson correlation.&#x0D; Results. A statistically significant correlation between functional threshold power parameters such as distance, power avarege, total energy, cadance avarege, speed avarege, functional threshold power, and hip angle degree parameter (p&lt;0.05). Similarly, correlations between functional threshold power, parameters such as power avarege and back curve resulted to be statistically significant (p&lt;0.05). Also, like an functional threshold power parameter, speed avarege resulted to be in a significant correlation with the clinical shoulders angle degree.&#x0D; Conclusions. Based on these results, increases in the FTP parameters may affect positively the cyclist’s performance helping to avoid undesirable hip angles, which may lead to back pain. Similarly, power average and back curve degree resulted to be in a correlation. Therefore, the back curve degree may be increased or decreased by the changes in the power average parameter. In addition, during the high intensity of training and fatigue levels increased, the clinical hip and shoulder angles were also increased.

초음파용 프로브 설계의 인간공학적 분석

Objective: The present study is intended to analyze the design characteristics of ultrasonic probes in different sizes and shapes and identify the preferred design characteristics by ergonomic evaluation.<BR><BR>Background: The use of an ultrasound probe among sonographers in improper postures with high repetitions for long periods of time has resulted in a high incidence of musculoskeletal symptoms and/or disorders.<BR><BR>Method: While sonographers (n = 12) simulated ultrasound scanning tasks with two linear array probes (small-flat, SF; large-curved, LC) in different sizes and shapes by applying forces of 20±4N, EMG activities, body motions, and grip postures were measured. After completing the ultrasound simulation tasks, a comparative evaluation of subjective satisfaction with the two probe designs was conducted.<BR><BR>Results: The SF probe required a larger range of motion at the elbow (up to 9.9° on average), higher RMS EMG levels (-1.8~48.4%) during the probe rotation task at the shoulder (pectoralis and infraspinatus), neck (right/left sterno-cleido-mastoid and trapezius), and upper-arm (biceps), and larger finger joint angles (-6.3~15.8°) than the LC probe.<BR><BR>Conclusion: The SF probe was preferred to the LC probe in terms of grip fit, the opposite was found in terms of the efficiency of force transfer.<BR><BR>Application: The analysis and evaluation methods of ultrasound probe design and the identification of the preferred design characteristics of linear array probe will be of use to develop ergonomic probe designs that can reduce musculoskeletal symptoms and disorders among sonographers.

Effects of Muscle Energy Technique with and without Bowen Therapy in Text Neck Syndrome

Aim: To determine the effects of Muscle energy technique with and without Bowen therapy on pain, function, range of movement, and posture in Text neck syndrome. Methods: A randomized clinical trial was conducted in Fatima Hospital Sargodha. A total of 22 patients with text neck syndrome were included and randomly allocated to two groups. Assessment of pain, function, Cervical ROM, Craniovertebral angle, and Rounded shoulder angle was taken using a Numeric pain rating scale (NPRS), Neck disability index (NDI), Goniometer, and photogrammetry. Group A received treatment with hot packs and METs. Group B received a hot pack, Muscle energy technique (METs) and Bowen therapy. A total of 18 sessions were given in 6 weeks with 3 sessions per week. Both groups were reassessed after 3 weeks and 6 weeks of treatment with follow-up after 3 weeks of treatment completion. Data were analyzed by using SPSS 21. Results: Findings revealed that a statistically significant difference (p&lt;0.05) was observed for both within a group and between-group analysis in NPRS, NDI, cervical range of motion (CROM), Craniovertebral angle (CVA), and Rounded shoulder angle (RSA). However, the Bowen group showed more improvement in terms of all outcome measures based on their mean differences. Conclusion: The combination of METs and Bowen therapy was more effective in decreasing pain, improving movement, regaining functional status, and correcting posture in individuals with Text neck syndrome rather than using METs alone. Keywords: Text neck, Muscle energy technique, Bowen technique, Pain, Range of motion

Anterolateral Acromioplasty Does Not Change the Critical Shoulder Angle and Acromion Index in a Clinically Relevant Amount

Assessment on whether radiographic parameters of the acromion measured in radiographs change significantly after anterolateral acromioplasty. This retrospective study included patients that underwent an arthroscopic anterolateral acromioplasty between January 2014 and September 2020. n= 435 subjects with high-quality preoperative and postoperative radiographs according to Suter-Henninger criteria were included in the final assessment. All measurements were independently performed by the first and second author in a blinded fashion using dicomPACS software: acromion index (AI), critical shoulder angle (CSA), lateral acromial angle (LAA), beta angle, acromio-humeral distance (AHD), Aoki angle, frontal supraspinatus outlet angle (FSOW), and acromion type, according to Bigliani. SPSS software was used for statistical analysis. The beta angle and the CSA did not significantly change after operation (alpha power 0.32 and 0.11, respectively). In a subgroup analysis of patients with a pathological CSA >35° (n= 194), the CSA changed from 38.62 (range: 35.08-47.52, SD 2.83) to 38.04 (range: 29.18-48.12, SD 3.77) postoperatively (P= .028) (Fig 8). All other parameters changed significantly after operation (AI, AHD, FSOW, and Aoki; P= .001, LAA; P= .039) (Fig.9). The interobserver and intraobserver reliability was good to excellent in the majority of measured values. Mean patient age was 59.2 years (range: 18.1-87.1; SD 11.3), mean height was 1.73 meters (range: 1,50-1.98, SD 0.09), mean weight was 80.2 kg (range: 37.0-133.0, SD 16.68), and mean body mass index was 26.6 (range: 0.0-46.1, SD 4.73). Anterolateral acromioplasty producing a flat acromion undersurface did not result in a significant change of the CSA in the study population. Pathological preoperative CSA values of >35° were significantly reduced but not to normal values, but only by a small amount that puts the clinical relevance into question. IV, diagnostic study, case series.

Sex-specific effects of localized muscle fatigue on upper body kinematics during a repetitive pointing task

BackgroundFemales are reported to have a higher risk of musculoskeletal disorders than males. Repetitive motions can lead to muscle fatigue, which may play a mediator role in the development of musculoskeletal disorders. However, sex differences in adaptations to localized fatigue at different joints are poorly understood. We examined the sex-specific effects of fatigue location on shoulder, elbow and spinal joint angles, and angular variabilities during a repetitive pointing task.MethodsSeven males and ten females performed a 30-s standing repetitive pointing task with their right upper limb when they were non-fatigued (NF), elbow-fatigued (EF), shoulder-fatigued (SF) and trunk-fatigued (TF), while trunk and upper body tridimensional kinematic data was recorded. Joint angles and angular variabilities of shoulder, elbow, upper thoracic spine, lower thoracic spine, and lumbar spine were calculated.ResultsResults showed that shoulder angles changed the most after EF in males, but after SF in females. The similarities between sexes were that SF increased the variabilities at upper (lateral flexion: 0.15° greater than NF, rotation: 0.26° greater than all other conditions) and lower thoracic spine (lateral flexion: 0.13° greater than NF, rotation: averagely 0.1° greater than all other condition) in both sexes. TF altered upper thoracic spine variability (0.36° smaller than SF), lower thoracic spine angle (lateral flexion: 3.00° greater than NF, rotation: 1.68° greater than SF), and lumbar angle (averagely 1.8° smaller than all other conditions) in both sexes. However, females had greater lower thoracic spine angle (lateral flexion: 8.3° greater, p = 0.005) as well as greater upper (rotation: 0.53° greater, p = 0.006) and lower thoracic spine (rotation: 0.5° greater, p = 0.007; flexion: 0.6° greater, p = 0.014) angular variabilities than males.ConclusionsResults suggest that females’ fatigue responses focused on the trunk and spine. Results highlight a few sex differences in adapting to localized muscle fatigue, which may help explain how sex differences in repetitive motion-related injuries differ between joints.

The functional role of the supraspinatus and infraspinatus muscle subregions during forward flexion: a shear wave elastography study.

BackgroundKnowledge of the morphological and functional differences in the anatomic subregions of the supraspinatus (SSP) and infraspinatus (ISP) muscles during forward flexion will provide useful information in the management of shoulder joint disorders. The purpose of this study was to investigate whether the SSP and ISP muscle subregions exhibit independent roles during forward flexion of the shoulder joint.MethodsEight healthy male volunteers without any restriction in their shoulder joints were recruited for this study. Participants were instructed to sit on a chair with their back against the backrest. Shear modulus (kPa) was measured as a surrogate for muscle stiffness using shear wave elastography on the SSP and ISP muscle subregions. Active measurements of the nondominant arm were obtained during isometric contraction at a neutral position and every 15° intervals from 30° to 150° during forward flexion. Friedman test and Dunn's post hoc test were used to evaluate differences in measurement outcomes among angles during forward flexion in each muscle subregion.ResultsActive stiffness outcomes of the anterior-middle subregion of the SSP muscle during forward flexion increased from 30° up to 45°, reaching a value of 182.4 ± 32.1 kPa (P < .001). Stiffness of the anterior-superficial subregion of the SSP muscle was highest at 30° (125.0 ± 20.6 kPa; P < .019) and linearly decreased up to 105° with increasing shoulder angle position. Stiffness of the superior, middle, and inferior subregions of ISP muscle presented a mountain-shaped trend, with peaks of 99.9 ± 23.5 kPa at 90° (P < .013), 144.2 ± 11.2 kPa at 90° (P < .013), and 122.9 ± 27.9 kPa at 105° (P < .007), respectively. Finally, the stiffness outcomes of the pectoralis major and anterior region of the deltoid muscles showed a mountain-shaped trend with peaks of 89.4 ± 23.5 kPa at 60° (P < .007) and 176.7 ± 22.9 kPa at 90° (P < .026), respectively.ConclusionsThe SSP and ISP muscle subregions play a significant role during active forward flexion motion. While closely overlapped, the activity of the muscle subregions changed during the forward flexion motion range, starting with an active anterior-superficial subregion of the SSP muscle at the initial range of motion and an active inferior subregion of the ISP muscle toward midrange of motion. The SSP and ISP subregions did not demonstrate independent functional behavior during forward flexion.

The prevalence, electrophysiologic feature, and outcome of obstetric brachial plexus injury in East Azerbaijan province, Iran

Background. Obstetric brachial plexus injury (OBPI) occurs as a result of excessive stretching of the baby's neck and an increase in cervical and shoulder angle during the second stage of labor. This study aimed to investigate the prevalence, electrophysiological panel, and motor outcome of cervical paralysis in East Azerbaijan province, Iran during 2008-2018. Methods. The total number of deliveries was obtained by census method. The annual relative frequency of OBPI was calculated using the medical records of children with this injury. Then, the electrophysiological findings and Modified Mallet Classification System (MMCS) were extracted. Results. The prevalence of OBPI during 2008-2018 was 0.026% in East Azerbaijan province. The involved nerve roots were C5 and C6 in 59.6% of cases, C5, C6, and C7 in 28.4% of cases, and wider injuries were observed in 12% following C5 to T1 involvement. No significant association was found between electrophysiological findings and MMCS in children with OBPI (P&gt;0.05). Conclusion. Due to the sudden increase in OBPI since 2017, it seems necessary to pay special attention and take preventive measures in this regard. Practical Implications. Due to the increasing prevalence of OBPI compared to previous years, it is necessary to take the necessary measures to prevent this injury in vaginal delivery.

Testing protocol for evaluating underhand serve-reception biomechanics in volleyball

A testing protocol for conducting biomechanical underhand serve-reception evaluation in volleyball in match-like conditions is presented. A launcher sends a ball over the net toward the reception zone for the player to pass it to the setter; the ball is tracked with video cameras and the player’s articular information is captured by inertial sensors, force plates, and video cameras. Test-retest reliability and, known-groups and concurrent validity of the test are evaluated. Left knee, right knee, left shoulder, and right shoulder angles were highly reliable (ICC &gt; 0.88), with low standard errors of measurement (%SEM &lt; 13.07). Resultant normalized ground reaction forces were also reliable (ICC: 0.76, %SEM: 9.14). Professional and amateur athletes’ comparisons were statistically significant and non-trivial ( p &lt; 0.05, Cohen’s d &gt; 0.49), with professionals’ body movements presenting small variance and symmetry between left and right limb variables, and amateurs’ presenting higher variance and greater asymmetry. Finally, each athlete’s left limb angles were compared against their corresponding sagittal Kinovea measurements for concurrent validity, obtaining acceptable correlation scores for amateur athletes (PCC &gt; 0.79) and good correlation scores (PCC &gt; 0.83) for professional athletes. The test offers a reliable and valid method for evaluating underhand serve-reception biomechanics in volleyball players.

Critical shoulder angle and failure of conservative treatment in patients with atraumatic full thickness rotator cuff tears

BackgroundAtraumatic full thickness rotator cuff tears (AFTRCT) are common lesions whose incidence increases with age. Physical therapy is an effective conservative treatment in these patients with a reported success rate near 85% within 12 weeks of treatment. The critical shoulder angle (CSA) is a radiographic metric that relates the glenoid inclination with the lateral extension of the acromion in the coronal plane. A larger CSA has been associated with higher incidence of AFTRCT and a higher re-tear rate after surgical treatment. However, no study has yet described an association between a larger CSA and failure of conservatory treatment in ARCT. The main objective of this study is to determine whether there is an association between CSA and failure of physical therapy in patients with AFTRCT.MethodsWe reviewed the imaging and clinical records of 48 patients (53 shoulders), 60% female, with a mean age of 63.2 years (95% CI ± 10.4 years); treated for AFTRCT who also underwent a true anteroposterior radiograph of the shoulder within a year of diagnosis of the tear. We recorded demographic (age, sex, type of work), clinical (comorbidities), and imaging data (CSA, size and location of the tear). We divided the patients into two groups according to success or failure of conservative treatment (indication for surgery), so 21 shoulders (39.6%) required surgery and were classified as failure of conservative treatment.Univariate and multivariate analysis was performed to detect predictors of failure of conservative treatment.ResultsThe median CSA was 35.5º with no differences between those with failure (median 35.5º, range 29º to 48.2º) and success of conservative treatment (median 35.45º, range 30.2º to 40.3º), p = 0.978.The multivariate analysis showed a younger age in patients with failure of conservative treatment (56.14 ± 9.2 vs 67.8 ± 8.4, p < 0.001) and that male gender was also associated with failure of conservative treatment (57% of men required surgery vs 28% of women, p = 0.035).ConclusionsIt is still unclear if CSA does predict failure of conservative treatment. A lower age and male gender both could predicted failure of conservative treatment in AFTRCT. Further research is needed to better address this subject.