Search

Best practices for scapular motion tracking are still being determined. The repeatability of different scapular kinematic procedures needs to be evaluated. The purpose of this study was to assess the test-retest reliability of two scapular kinematic procedures: double calibration with AMC (D-AMC) and individualized linear modelling (LM). Ten healthy participants had their upper body movement tracked with optical motion capture in two identical sessions. Five scapular calibration poses were performed, and seven dynamic functional tasks were tested. Scapular angles were calculated from both procedures (D-AMC vs LM). The D-AMC approach uses two poses (neutral and maximum elevation) and tracks the scapula with a rigid cluster, while the LM approach predicts scapular positioning from humeral angles based on equations built from the calibration pose data. Angle waveforms and repeatability outcomes were compared. Internal and upward rotation angle waveforms were significantly different (p < 0.05) between kinematic procedures for some tasks, with maximum mean differences up to 17.3° and 23.2°, respectively. Overall, repeatability outcomes were similar between procedures, but the LM approach was slightly better for tilt and the D-AMC approach was notably improved for upward rotation in certain tasks. For example, minimal detectable changes during the Forward Transfer ranged from 6.9° to 11.9° for the D-AMC and 8.9° to 25.3° for the LM. Discrepancies between procedures may be a function of the calibration poses chosen. Additional calibration poses may improve the comparisons between procedures., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: This study validated the accuracy of the acromion marker cluster (AMC) and scapula spinal marker cluster (SSMC) methods compared with upright four-dimensional computed tomography (4DCT) analysis., Methods: Sixteen shoulders of eight healthy males underwent AMC and SSMC assessments. Active shoulder elevation was tracked using upright 4DCT and optical motion capture system. The scapulothoracic and glenohumeral rotation angles calculated from AMC and SSMC were compared with 4DCT. Additionally, the motion of these marker clusters on the skin with shoulder elevation was evaluated., Results: The average differences between AMC and 4DCT during 10°-140° of humerothoracic elevation were - 2.2° ± 7.5° in scapulothoracic upward rotation, 14.0° ± 7.4° in internal rotation, 6.5° ± 7.5° in posterior tilting, 3.7° ± 8.1° in glenohumeral elevation, - 8.3° ± 10.7° in external rotation, and - 8.6° ± 8.9° in anterior plane of elevation. The difference between AMC and 4DCT was significant at 120° of humerothoracic elevation in scapulothoracic upward rotation, 50° in internal rotation, 90° in posterior tilting, 120° in glenohumeral elevation, 100° in external rotation, and 100° in anterior plane of elevation. However, the average differences between SSMC and 4DCT were - 7.5 ± 7.7° in scapulothoracic upward rotation, 2.0° ± 7.0° in internal rotation, 2.3° ± 7.2° in posterior tilting, 8.8° ± 7.9° in glenohumeral elevation, 2.0° ± 9.1° in external rotation, and 1.9° ± 10.1° in anterior plane of elevation. The difference between SSMC and 4DCT was significant at 50° of humerothoracic elevation in scapulothoracic upward rotation and 60° in glenohumeral elevation, with no significant differences observed in other rotations. Skin motion was significantly smaller in AMC (28.7 ± 4.0 mm) than SSMC (38.6 ± 5.8 mm). Although there was smaller skin motion in AMC, SSMC exhibited smaller differences in scapulothoracic internal rotation, posterior tilting, glenohumeral external rotation, and anterior plane of elevation compared to 4DCT., Conclusion: This study demonstrates that AMC is more accurate for assessing scapulothoracic upward rotation and glenohumeral elevation, while SSMC is preferable for evaluating scapulothoracic internal rotation, posterior tilting, glenohumeral external rotation, and anterior plane of elevation, with smaller differences compared to 4DCT., (© 2024. The Author(s).)

Background: The shoulder complex relies on scapular movement controlled by periscapular muscles for optimal arm function. However, minimal research has explored scapular muscle activation ratios during functional tasks, nor how they might be influenced by biological sex. This investigation aims to characterize how sex impacts scapular muscle activation ratios during functional tasks., Methods: Twenty participants (ten females, ten males) were assessed with surface electromyography (EMG) and motion tracking during seven functional tasks. Activation ratios were calculated from normalized EMG for the three trapezius muscles and serratus anterior. Scapular angles were calculated using a YXZ Euler sequence. Two-way mixed methods ANOVAs ( p  < .05) were used to assess the effects of sex and humeral elevation level on ratios and angles., Results: Sex-based differences were present in the Tie Apron task, with males exhibiting higher upper trapezius/lower trapezius and upper trapezius/middle trapezius ratios than females. Males also demonstrated decreased internal rotation in this task. Other tasks showcased significant sex-based differences in scapular upward rotation but not in activation ratios. Humeral elevation generally demonstrated an inverse relationship with scapular muscle activation ratios., Conclusions: This study highlights sex-based differences in scapular muscle activation ratios during specific functional tasks, emphasizing the need to consider sex in analyses of shoulder movements. Normative activation ratios for functional tasks were provided, offering a foundation for future comparisons with non-normative groups. Further research is warranted to confirm and explore additional influencing factors, advancing our understanding of shoulder activation and movement in diverse populations., Competing Interests: The authors declare there are no competing interests., (©2024 Lang et al.)

Objective: Understanding how the main scapular muscles behave in overhead athletes with scapular dyskinesis (SD)., Design: Systematic Review., Setting: Electronic searches were performed in Pubmed (MedLine), Embase, CINAHL, and SPORTDiscus databases., Participants: Overhead athletes with SD., Main Outcome Measures: Electromyographic activity of the upper (UT), middle (MT), and lower (LT) trapezius, and serratus anterior (SA)., Results: Eight studies were included in this review. The UT activity showed a tended to increase its activity mainly during tasks over 90° compared to 45°. SA activity had similar behavior, mainly during isometric tasks. The MT also increased its activity mainly in tasks with overhead angulations when compared to lower angulations. The LT activation tended to decrease its EMG activity at angulations below 60° in overhead athletes with SD., Conclusions: The EMG behaviour of UT and SA for non-athletes appears to differ from what has already been described in the literature. The MT seems to be the most neglected muscle for scapular stabilization in overhead athletes with SD. The decrease in LT activity suggests that this may have implications for the performance of these athletes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Objective: To compare scapular kinematics and muscle activity among various scapular muscle exercises., Design: A cross-sectional study., Setting: A university research laboratory., Participants: Eighteen healthy men participated in this study., Main Outcome Measures: Three-dimensional scapular kinematics was measured with an electromagnetic motion capture system. Activities of the upper trapezius (UT), lower trapezius (LT), and serratus anterior (SA) were measured by using surface electromyography (EMG). In addition, the ratio of LT to the UT (LT/UT) and SA to the UT (SA/UT) was calculated. A repeated one-way analysis of variance and Shaffer's post-hoc analysis were used to detect the differences in each outcome during five exercises., Results: The scapula was rotated upwardly during all exercises except push-up plus. The LT/UT ratio during side-lying external rotation and side-lying flexion were significantly higher than that for scapular plane elevation (P < .05), although the highest activity of the lower trapezius was produced during scapular plane elevation. The activities of the serratus anterior and SA/UT ratio during horizontal adducted elevation and push-up plus were significantly higher than that during scapular plane elevation (P < .05)., Conclusion: Horizontal adducted elevation might be more appropriate for increasing scapular upward rotation with high serratus anterior activity and SA/UT ratio than push-up plus., Competing Interests: Declaration of competing interest There are no known conflicts of interest associated with this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Objective: Forward head posture (FHP) is a common postural disorder that alters shoulder function. This study examined the efficacy of a corrective program involving postural correction exercises (PCEs), scapular stabilization exercises (SSEs), and kinesiotaping (KT) on improving craniovertebral angle (CVA), scapular position, and dominant hand grip strength (HGS) in individuals with FHP., Methods: Sixty subjects (8 males and 52 females, 18-40 years old) were randomly allocated into four equal groups: Group A: received PCEs only, Group B: received PCEs and SSEs, Group C: received PCEs and KT, Group D: received PCEs, SSEs and KT. All subjects received treatment for 4 weeks (4 times/week) and postural advice. Outcome measures included cranio-vertebral angle (CVA), scapular position using Lateral Scapular Slide Test and dominant HGS using a CAMRY dynamometer that were assessed at baseline and 4 weeks post intervention., Results: Comparing all groups post training revealed that there were statistically significant increases (p < 0.05) in all measured variables (CVA, scapular position and dominant HGS) in favor of group (D)., Conclusion: Combination of PCEs, SSEs and KT interventions has achieved the best gains in terms of CVA, dominant HGS and regaining optimal scapular position in FHP subjects., (© 2024 John Wiley & Sons Ltd.)

Round-shoulder posture (RSP) is a common postural condition, characterized by protraction, downward rotation, anterior tilting and internal rotation of the scapula. RSP can lead to shoulder dysfunction. Different methods have been proposed for rehabilitating and correcting the altered posture in RSP including stretching, strengthening exercises, and shoulder brace or taping. However, the findings are controversial and studies are ongoing to develop more effective method. The present study is aimed at investigating the effects of scapular posterior tilting (SPT) exercise in different support positions on scapular muscle activities in men and women with RSP. In a prospective observational clinical study, we assessed demographic, basic clinical parameters and study variables of the subjects with RSP (n = 20) (men/women = 9/11) attending Daegu University in Gyeongsan, South Korea. To do so, we compared electromyographic (EMG) activities of lower trapezius and serratus anterior muscles between men and women with RSP during SPT exercise on four different support surfaces to determine any difference in the EMG activities. The results revealed that women showed significant differences in EMG activities in the lower and left upper trapezius and serratus anterior muscles, while men showed significant differences in EMG activity only in the lower trapezius muscle during SPT exercise on four different surfaces (P < 0.05). The post-hoc analysis revealed significantly greater EMG activity values in the lower trapezius and serratus anterior muscles during SPT exercise on the upper body unstable surface and whole-body unstable surface (p < 0.05). Independent t-tests after the Bonferroni correction showed no significant differences in muscle activities between men and women on the four different surfaces (p > 0.0125)., (© 2024. The Author(s).)

Objective: The aim of the study is to compare the surface electromyographic amplitude, activation ratio, and onset latency of the main scapular stabilizing muscles between five typical rehabilitative exercises., Design: Twenty-seven healthy participants performed five scapular exercises (wall slide, wall push-up plus, prone horizontal abduction with external rotation, external rotation in side lying, and low row) while simultaneously recording surface electromyographic of serratus anterior, middle trapezius, lower trapezius, and upper trapezius. Surface electromyographic amplitudes, onset latencies, and activation ratios were calculated., Results: Prone horizontal abduction with external rotation showed an excellent upper trapezius/middle trapezius (0.43) and upper trapezius/lower trapezius (0.30) muscle balance with high (>50% maximum voluntary isometric contraction) middle trapezius and lower trapezius amplitudes, a low (<20% maximum voluntary isometric contraction) upper trapezius amplitude, and an early activation of the scapular stabilizing muscles (-474.7 to 89.9 ms) relative to upper trapezius. External rotation in side lying showed excellent upper trapezius/serratus anterior (0.26), upper trapezius/middle trapezius (0.32), and upper trapezius/lower trapezius (0.21) activation ratios and, along with low row and wall slide, showed early activation of the scapular stabilizing muscles (-378.1 to -26.6 ms)., Conclusions: Prone horizontal abduction with external rotation presented optimal scapular neuromuscular control. Although external rotation in side lying, low row, and wall slide did not meet all the criteria associated with optimal scapular neuromuscular control, these exercises could be used in early stages of shoulder rehabilitation because they favor early activation of the scapular stabilizing muscles., Competing Interests: Financial disclosure statements have been obtained, and no conflicts of interest have been reported by the authors or by any individuals in control of the content of this article., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Context: Individuals with shoulder impingement syndrome (SIS) exhibit changes in corticospinal excitability, scapular kinematics, and scapular muscle-activation patterns. To restore the scapular kinematics and muscle-activation patterns in individuals with SIS, treatment protocols usually include scapula-focused exercises, such as scapular-orientation and strength training., Objective: To investigate whether scapular-orientation and strength training can reverse the altered corticospinal excitability of recreational overhead athletes with SIS., Design: Randomized controlled clinical trial., Setting: University laboratory., Patients or Other Participants: Forty-one recreational overhead athletes with SIS: 20 in the scapular-orientation group (age = 26.45 ± 4.13 years, height = 171.85 ± 7.88 cm, mass = 66.70 ± 10.68 kg) and 21 in the strengthening group (age = 26.43 ± 5.55 years, height = 171.62 ± 5.87 cm, mass = 68.67 ± 10.18 kg)., Intervention(s): Both groups performed a 30-minute training protocol consisting of 3 exercises to strengthen the lower trapezius (LT) and serratus anterior muscles without overactivating the upper trapezius muscles. Participants in the scapular-orientation group were instructed to consciously activate their scapular muscles with electromyographic biofeedback and cues, whereas the strengthening group did not receive biofeedback or cues for scapular motion., Main Outcome Measure(s): Corticospinal excitability was assessed using transcranial magnetic stimulation. Scapular kinematics and muscle activation during arm elevation were also measured., Results: After training, both groups demonstrated an increase in motor-evoked potentials in the LT (P = .004) and increases in scapular upward rotation (P = .03), LT activation (P < .001), and serratus anterior activation (P < .001) during arm elevation. Moreover, the scapular-orientation group showed higher LT activation levels during arm elevation after training than the strengthening group (P = .03)., Conclusions: With or without biofeedback and cues, scapula-focused exercises improved scapular control and increased corticospinal excitability. Adding biofeedback and cues for scapular control during exercise helped facilitate greater LT activation, so feedback and cues are recommended during scapula-focused training., (© by the National Athletic Trainers' Association, Inc.)

Clinical Scenario: The fascial relationship between scapular muscles and abdominal muscles has been documented from previous studies. However, it is not yet clear whether voluntary abdominal contraction has a beneficial effect on scapular muscle activity during shoulder exercises., Clinical Question: Do scapulothoracic muscle activation levels increase if shoulder exercises are performed with voluntary abdominal activation? Summary of Key Finding: After the literature review, 4 cross-sectional studies met the inclusion criteria and were included in this critically appraised topic., Clinical Bottom Line: There is moderate evidence to support dynamic shoulder exercises with voluntary abdominal contraction can increase trapezius and serratus anterior muscle activation level in asymptomatic shoulders. Strength and Recommendation: Findings from 4 cross-sectional trials indicate that there is moderate evidence supporting that dynamic shoulder exercises performed with voluntary abdominal contraction can increase scapular muscle activity.

Introduction: Low back pain (LBP) is an economic and physically disabling burden on individuals and society. With 70% of cases classed as non-specific, there is a need for further research into the causes and consequences associated. The involvement of postural balance in musculoskeletal conditions is gaining increasing interest in research and health practice. However, there is a lack of literature surrounding LBP and posture in distal segments of the body., Objective: The current study investigated scapula positioning in those with non-specific LBP., Methods: Scapula angle of rotation, scapula protraction, and scapula elevation were assessed in nine participants with chronic non-specific LBP and compared with that of nine asymptomatic controls (aged 18-60 years). The degree of pelvic tilt was assessed across both groups as a secondary outcome measure., Results: No difference was identified between the two sample groups for scapula angle of rotation (p = 0.707), protraction (p = 0.755), or elevation (p = 0.691). Anterior pelvic tilt was greater in those with LBP (p = 0.046), supporting previous literature., Conclusion: The findings for the scapula position are novel, given that research in this field is limited. It is concluded that there is no change in scapula positioning in those with non-specific LBP, but there is an increased anterior pelvic tilt., Competing Interests: Declaration of competing interest There is no conflict of interest., (Crown Copyright © 2024. Published by Elsevier Ltd. All rights reserved.)

Background: Cranio-cervico-mandibular (CCM) malalignment is associated with forward head posture (FHP) and temporomandibular joint (TMJ) disorders and affects masticatory muscles., Objective: This randomized, double-blind controlled trial aimed to compare the efficacy of scapula-thoracic (ST) exercises on temporomandibular and cervical joint position sense and postural stability in individuals with CCM malalignment., Methods: Fourty-nine participants with CCM malalignment were randomly assigned to the ST exercise group (STEG, n= 24) or the control group (CG, n= 25). STEG included progressive strengthening, proprioceptive, and stabilization exercises. All participants were assessed before treatment, at the end of the 8th week treatment period and at the 12th week post-treatment follow-up. Cranio-vertebral angle measurement, Fonseca's Questionnaire, Helkimo Clinical Dysfunction Index, TMJ position test, cervical joint position error test and postural stability assessment were used., Results: The TMJ and cervical joint position sense, total sway degree, area gap percentage, sway velocity and antero-posterior body sway results showed significant improvement in the STEG compared to the CG (p< 0.05), however medio-lateral body sway did not differ between groups (p> 0.05)., Conclusions: Postural stability, TMJ and cervical joint position sense appear to be affected in individuals with CCM malalignment. Our results showed that an exercise program including ST stabilization, proprioception and strengthening of the scapular muscles may be effective in the management of CCM malalignment and will allow clinicians to plan holistic treatment.

Background: An evaluation of scapula position is important to predict spine curvature and shoulder function in patients with adolescent idiopathic scoliosis (AIS). Therefore, a reliable scapula position is required to assess posture in patients with AIS., Objective: This study investigated the reliabilities of scapula position tests and differences in scapula position and shoulder function between individuals with and without AIS., Methods: The study compared 18 patients with AIS and 18 healthy controls to identify differences in scapula position and shoulder function. The acromion-table distance, lateral displacement of the scapula, acromion depression, winged scapula, upward rotation of the scapula, and anterior tilt of the scapula were measured. Scapula position test reliabilities were assessed using the intraclass correlation coefficient (ICC), standard error of measurement (SEM), and minimum clinically important difference (MCID). Shoulder function was measured using the Shoulder Pain and Disability Index., Results: The reliabilities of scapula position tests (ICC 0.85-0.93, SEM 0.1-1.2, and MCID 0.2-2.5) were good. There were significant differences in scapula position and shoulder function between patients with AIS and healthy controls (p< 0.05)., Conclusion: Scapula position tests were highly reliable in patients with AIS; they can be used to evaluate scapula position during clinical assessment of posture in patients with AIS.

A comprehensive review of scapular pathologies and their effect on shoulder function is necessary to determine the best treatment options. The coordinated motion between the scapulothoracic and glenohumeral joints is essential for shoulder motion and depends on the balanced activity of the periscapular muscles. Disruption in these muscles can cause abnormal scapular motion and compensatory glenohumeral movements, leading to misdiagnosis or delayed diagnosis. Scapular pathologies can arise from muscle overactivity or underactivity/paralysis, resulting in a range of scapulothoracic abnormal motion (STAM). STAM can lead to various glenohumeral pathologies, including instability, impingement, or nerve compression. It is important to highlight the critical periscapular muscles involved in scapulohumeral rhythm (such as the upper, middle, and lower trapezius; rhomboid major and minor; serratus anterior; levator scapulae; and pectoralis minor). A discussion of the different etiologies of STAM should include examples of muscle dysfunction, such as overactivity of the pectoralis minor, underactivity or paralysis of the serratus anterior or trapezius muscles, and dyskinesis resulting from compensatory mechanisms in patients with recurrent glenohumeral instability due to Ehlers-Danlos syndrome. The evaluation and workup of STAM has shown that patients typically present with radiating shoulder pain, especially in the posterior aspect of the shoulder and scapula, and limitations in active shoulder overhead motion associated with glenohumeral pain, instability, or rotator cuff pathologies.

Background: Sufficient shoulder flexor strength is necessary for accurate movement of the shoulder joint because several factors can cause compensatory movements of the scapula., Objective: We investigated the influence of external fixation on the isometric shoulder flexors strength (ISFS) in individuals with and without scapular elevation (SE) during shoulder flexion., Methods: The healthy and SE groups included 29 individuals. The ISFS was measured using a tensiometer (kg) under conditions of with and without external fixation, in a random order. The change in the ISFS (the strength difference with and without external fixation) was compared between the healthy and SE groups using an independent t-test., Results: The change in the ISFS differed significantly between the healthy and SE groups (3.5% and 32.3%, respectively; p= 0.001)., Conclusion: These findings suggest that external fixation should be considered during shoulder flexion to determine the ISFS accurately in individuals with compensated SE.

It is important to discuss the importance of synchronous balance between periscapular muscles for scapulothoracic motion and resultant scapulohumeral rhythm. Abnormalities in this balance can lead to scapular dyskinesia and winging, affecting shoulder motion and leading to impingement. Strategies exist to diagnose and differentiate between pathologies such as muscle paralysis (eg, trapezius or serratus anterior) or overactivity (eg, pectoralis minor). The physician should be aware of the role of diagnostic imaging, as well as the unique considerations for patients with Ehlers-Danlos syndrome. Overall, a comprehensive physical examination to accurately diagnose and treat scapular pathologies is particularly important.

Background: The normal value of the scapular muscle activity ratio during arm elevation is not clear., Objective: To obtain normal values of the scapular muscle activity ratio during arm elevation in healthy individuals., Methods: This cross-sectional study enrolled 47 healthy people. The participants performed shoulder flexion and lowered task with 90-degree movements every 2 seconds. Muscle activities of scapular muscles were measured. For normalization, the maximum isometric contraction of the shoulder flexion was measured at 90∘ (reference contraction). The integrated electromyographic value (IEMG) obtained during the task was normalized by IEMG during the reference contraction and the relative IEMG value was calculated. Then, the scapular muscle activity ratio was computed. The relationship between muscle strength and other factors was also investigated., Results: The median values for upper trapezius/serratus anterior and upper trapezius/lower trapezius were often approximately 1, and that for upper trapezius/middle trapezius was often between 1 and 2. The shoulder flexion isometric strength and scapular muscle activity ratio showed significant negative correlations in multiple phases., Conclusion: Normal values for upper trapezius/serratus anterior and upper trapezius/lower trapezius during arm elevation and lowering were generally 1. Low muscle strength may contribute to an abnormal scapular muscle activity balance.

Objectives. This study aimed to investigate the presence of scapular dyskinesis (SD) in office workers with neck and scapular complaints. The postural malalignment and related muscle adaptations were also explored. Methods . SD and its subtypes were determined. Postural deviations and the length of commonly reported muscle tightness were evaluated. Results . Among 99 participants, 90% of them had SD. Considering both sides or 198 scapula, 90.4% were identified as having painful scapula and 19% as having painless scapula. There was a difference in the proportion of SD on painful (93%) and painless (69%) sides. Postural deviations including rounded shoulder (100%), forward head (43.3%) and thoracic hyperkyphosis (54.5%) were prevalent. Persons with type III SD had a higher percentage of forward head than other types. There was also tightness of the pectoralis minor (100%), levator scapulae (93.0%) and upper trapezius (98.3%) muscles without different proportions among types of SD. The greatest proportion of persons with SD had tightness of the levator scapulae. Conclusions . There was a high prevalence of SD among office workers with neck and scapular complaints. SD was also associated with abnormal posture and muscle tightness. The proper management of SD and working posture is warranted.

The passive stiffness and strength of periscapular muscles may affect scapulohumeral control, especially in overhead athletes due to sports-specific training. This study tried to assess the relationship between the passive stiffness and strength of periscapular muscles, scapulohumeral kinematics and neuromuscular control during scaption in swimmers. Ten male adolescent competitive front-crawl swimmers were recruited. The passive stiffness and strength of periscapular muscles were measured in standard postures by a hand-held myotonometer and dynamometer, respectively. Surface electromyography and electromagnetic tracking systems were synchronized to record the muscle activities and scapulohumeral kinematics during scaption. Correlations between the passive stiffness or strength of periscapular muscles and the kinematics or muscle activity were examined by Spearman's rank correlation coefficient. The maximal strength of periscapular muscles correlated positively with the ranges of upward and external rotation of the scapula and negatively with muscle activity during scaption. Passive stiffness of periscapular muscles was associated with the downward rotation of the scapula and triggered an increase in muscle activity. Increased passive stiffness or decreased strength in the periscapular muscles may affect their role in controlling the scapular rotation and contribute to compensation from adjacent muscles. Our findings suggest that when attempting to evaluate scapular behavior, it may be beneficial to examine muscle strength and passive stiffness of periscapular muscles., (© 2023. The Author(s).)

Background: Clavicular and scapular orientations vary between neck pain patients as do clinical features and responses (changes in pain and rotation range) to scapular repositioning. Associations between these factors are unknown., Objectives: To identify subgroups of neck pain patients based on three-dimensional (3D) measures of clavicular and scapular orientations and differences between subgroups in clinical characteristics and responses to scapular repositioning., Design: Cross-sectional study., Methods: Eligible participants were recruited as part of a larger study. The 3D clavicular and scapular orientations were analyzed on the more painful side of the neck using a hierarchical cluster analysis. Clinical characteristics were neck pain location, intensity, duration, disability and presence of headache. Responses to scapular repositioning were classified as "yes and no"., Results: Fifty-eight participants (29 responsive; 29 non-responsive to scapular repositioning) participated in the study. Analysis identified two distinct subgroups: subgroup1 had greater clavicular retraction and scapular downward rotation (n = 26) and subgroup2 had greater clavicular elevation and scapular internal rotation and anterior tilt (n = 32). Headache and dominant pain in the upper neck were more frequent in subgroup 1 while dominant pain in the lower neck was frequent in subgroup 2 (p < 0.01). Most participants who responded positively to scapular repositioning (88.5%) were in subgroup1 and most non-responsive participants (81.2%) in subgroup2., Conclusions: The 3D clavicular and scapular orientations identified two subgroups of neck pain patients. Participants with predominantly downward scapular rotation were distinguished by pain in the upper neck, presence of headache and a positive response to scapular repositioning., Competing Interests: Declaration of competing interest None., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The glenoid track geometry and the contact forces acting on the glenohumeral joint at static positions of 30°, 60°, 90° and 120° of abduction with 90° of external rotation were evaluated using a finite element model of the shoulder that, differently from most usual approximations, accounts the humeral head translations and the deformable-to-deformable non-spherical joint contact. The model was based on data acquired from clinical exams of a single subject, including the proximal humerus, scapula, their respective cartilages concerning the glenohumeral joint, and the rotator cuff and deltoid muscles. The forces acting on the glenohumeral joint were estimated using a simulation framework consisting of an optimization procedure allied with finite element analysis that seeks the minimum muscle forces that stabilize the joint. The joint reaction force magnitude increases up to 680.25 N at 90° of abduction and decreases at further positions. From 60° onward the articular contact remains at the anterior region of the glenoid cartilage and follows an inferior to superior path at the posterior region of the humeral head cartilage. The maximum contact pressure of 3.104 MPa occurs at 90° abduction. Although translating inferiorly throughout the movement, the projection of the humeral head center at the glenoid plane remains at the central region of the glenoid surface. The model results qualitatively matched the trends observed in the literature and supports the consideration of the translational degrees of freedom to evaluate the joint contact mechanics., Competing Interests: Declaration of Competing Interest The authors have no conflicts of interest to disclose., (Copyright © 2022. Published by Elsevier Ltd.)

Background: Rounded shoulder (RS) posture causes neck and shoulder pathologies. Mechanical correction taping (MCT) is often incorporated into postural corrective therapies; however, its effects on muscle stiffness are unclear., Objective: We investigated the effect of MCT with different tape fabrics, along with exercise, on upper trapezius and pectoralis minor muscle stiffness and the posture of sedentary workers., Design and Setting: A randomized controlled study was performed at Aydın Adnan Menderes University, Aydın, Turkey., Methods: The study included 39 workers with RS posture. Two intervention groups (performance tape: PT and classic tape: CT) were taped twice a week and administered a home exercise program for 4 weeks. The control (C) group performed only home exercises. RS was measured using an acromion-testing table (AT), stiffness using shear wave elastography ultrasound, and shoulder angle (SA) using a smartphone application at baseline and 4 weeks. Time and group interactions were determined using 3 × 2 mixed analysis of variance., Results: Intragroup analyses revealed a significant main effect of time on AT distance (η2 = 0.445) and SA (η2 = 0.325) in the PT and C groups (P < 0.05) and left upper trapezius stiffness (η2 = 0.287) in the CT and C groups (P < 0.05). In the post hoc analyses, no difference was noted between the groups from baseline to 4 weeks (P > 0.05)., Conclusion: Scapular MCT added to postural exercises did not show any difference between the intervention groups and controls in terms of muscle stiffness and posture in sedentary workers.

Context: The wall-slide exercise is commonly used in clinic and research settings. Theraband positioning variations for hip exercises have been investigated and used, but Theraband positioning variations for upper extremity wall-slide exercises, although not commonly used, have not been examined., Objective: To evaluate the effect of different Theraband positions (elbow and wrist) on the activation of the scapular and shoulder muscles in wall-slide exercises and compare these variations with each other and with regular wall-slide exercises for the upper limbs., Design: Descriptive laboratory study., Setting: University laboratory., Patients or Other Participants: A total of 20 participants (age = 23.8 ± 3 years, height = 176.5 ± 8.14 cm, mass = 75.3 ± 12.03 kg, body mass index = 24.23 ± 4.03) with healthy shoulders., Intervention(s): Participants performed wall-slide exercises (regular and 2 variations: Theraband at the elbow and Theraband at the wrist) in randomized order., Main Outcome Measure(s): Surface electromyographic activity of the trapezius (upper trapezius [UT], middle trapezius [MT], and lower trapezius [LT]), infraspinatus, middle deltoid (MD), and serratus anterior (SA) muscles., Results: Regular wall-slide exercises elicited low activity in the MD and moderate activity in the SA muscles (32% of maximal voluntary isometric contraction [MVIC] in the SA), whereas the Theraband-at-elbow and Theraband-at-wrist variations elicited low activity in the MT, LT, infraspinatus, and MD muscles and moderate activity in the SA muscle (46% and 34% of MVIC in the SA, respectively). The UT activation was absent to minimal (classified as 0% to 15% of MVIC) in all wall-slide exercise variations. The Theraband-at-wrist variation produced lower UT:MT, UT:LT, and UT:SA levels compared with the regular wall-slide exercise and Theraband-at-elbow variation., Conclusions: In shoulder rehabilitation, clinicians desiring to activate the scapular stabilization muscles should consider using the Theraband-at-wrist variation. Those seeking more shoulder-abduction activation and less scapular stabilization should consider using the Theraband-at-elbow variation of the upper extremity wall-slide exercise., (© by the National Athletic Trainers' Association, Inc.)

Background: Scapular rehabilitation exercises should target appropriate muscles. Recently, adding external rotation resistance to scapular exercises has gained interest. Moreover, clinical experts advise kinetic chain integration into shoulder rehabilitation exercises., Objective: To investigate scapular muscle activity during kinetic chain variations of a prone elevation exercise., Methods: Activity of the upper (UT), middle (MT), and lower (LT) trapezius and serratus anterior (SA) muscles was determined with surface electromyography (EMG) in 31 asymptomatic participants during six prone elevation exercise variations. Variation was created by adding external rotation resistance, adding trunk extension, or changing exercise position (prone on a Swiss ball with knees or feet supported, or prone on a physiotable). All data were normalized as a percentage of maximal voluntary isometric contraction (% MVIC). For each muscle, a Friedman's ANOVA was conducted to analyse statistical differences in EMG signal intensity between exercises., Results: The LT was moderately (42 - 48% MVIC) and MT highly (63 - 66% MVIC) activated during all exercise variations. No significant differences between exercises for these muscles could be detected. Adding external rotation to a prone elevation exercise decreased UT activity while adding trunk extension increased UT activity. Altering exercise position had no influence on scapular muscle activity except increased UT activity when lying prone on a physiotable with trunk extension., Conclusion: Prone elevation exercises are appropriate for facilitating LT and MT activity. Adding external rotation inhibits UT activity while UT facilitation could be achieved when adding trunk extension., Competing Interests: Conflicts of interest This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors., (Copyright © 2022 Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia. Publicado por Elsevier España, S.L.U. All rights reserved.)

Context: The purpose of this study was to determine test-retest reliability of upper-extremity muscle activity and kinematics during submaximal adapted rowing., Design: A repeated-measures design was used., Methods: Data were collected on 10 individuals (7 male and 3 female) with mobility impairment. Surface electromyography of muscles of the dominant arm (upper, middle, and lower trapezius, anterior and posterior deltoid, latissimus dorsi, and infraspinatus) was acquired. Muscle activity was analyzed using the area under the curve, peak amplitude, and mean amplitude. Kinematic analysis determined joint motions for shoulder plane and angle of elevation, and trunk flexion/extension, and rotation at the catch (0%) and finish (100%) of the stroke. Three submaximal rowing trials (20 strokes each) were completed with the middle 10 strokes of each trial averaged for analysis., Results: An interclass correlation coefficient (3, 10) determined test-retest reliability across trials (interclass correlation coefficient defined as poor < .5; moderate .5-.75; and good .75-.9). Moderate to excellent reliability existed across all muscles for the area under the curve, peak amplitude, and mean amplitude. Excellent reliability was seen for all kinematic measures., Conclusion: Results indicate upper-extremity muscle activity and kinematics of the adapted rowing stroke are reliable in a diverse group of individuals with mobility impairment.

Background: Scapular dyskinesis has been associated with shoulder dysfunctions, and changes in electromyographic (EMG) activity have been reported during the execution of some exercises., Objective: To compare upper limb muscles EMG of asymptomatic subjects with and without scapular dyskinesis during bench-press and dumbbell fly exercise performed on different surface stability conditions., Methods: Twenty-eight physically active men were allocated into two groups: Control group (n= 14) and Dyskinesis group (n= 14). The participants performed six repetitions lasting three seconds of the bench press and dumbbell fly exercises with 50% of one-repetition maximum (1RM) on a bench and a Swiss ball. The EMG activity of the pectoralis major, serratus anterior, upper and lower trapezius, anterior deltoid, biceps and triceps muscles were recorded., Results: No differences were found between groups, regardless of exercise or surface type. Inserting the unstable surface in the supine exercise promoted a slight increase in upper trapezius EMG activity for the control [4.32 (95% CI: 1.04 to 7.60)] and dyskinesis [3.30 (95% CI: 0.34 to 6.27)] groups., Conclusions: There is no difference in upper limb muscle EMG activity between subjects with and without scapular dyskinesis. In addition, inserting unstable surfaces did not modify EMG activity.

Background: Many researchers have questioned whether shoulder kinematics such as the glenohumeral position and scapular kinematics would be different in different age groups. However, studies comparing shoulder kinematics between different age groups have been rare. The aim of this study was to analyze and compare the three-dimensional (3D) glenohumeral position, scapular kinematics, and scapulohumeral rhythm (SHR) during scapular plane arm abduction between a normal young male group and a normal older male group., Methods: Twenty normal men (10 young and 10 older) were enrolled in this controlled laboratory study. Fluoroscopic images were obtained using a single plane X-ray system. Bilateral computed tomography scans were taken to create a 3D model. A 3D-2D registration technique was used to determine the 3D position and orientation of the bones of the shoulder., Results: During scapular plane arm abduction, there were significant differences in scapular kinematics between the groups. The older male group showed more upward rotation, posterior tilt, and external rotation than the young male group. On the other hand, the glenohumeral position such as superior inferior translation, anterior posterior translation, and external rotation of the humeral head did not show significant difference between the groups. The mean value of SHR for the overall arm elevation range from start to maximum elevation angle for the older group and young group was 2.298 ± 0.964 and 2.622 ± 0.931, respectively, showing a significant difference between the two groups ( p = 0.035)., Conclusions: Scapular kinematics and SHR were significantly different between the older male group and the young male group. Our study could provide reference values of shoulder kinematics for older men aged 55-65 years., Competing Interests: CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported., (Copyright © 2021 by The Korean Orthopaedic Association.)

Context: A single clinical assessment device that can be used to objectively measure scapular motion in each anatomical plane is not currently available. The development of a novel electric goniometer would allow scapular motion in all 3 anatomical planes to be quantified., Objective: To investigate the reliability and validity of an electric goniometer for measuring scapular motion in each anatomical plane during upper extremity elevation., Design: Cross-sectional study., Setting: Laboratory., Patients or Other Participants: Sixty participants (29 women, 31 men; age = 30 ± 14 years, height = 1.73 ± 0.10 m, mass = 75.32 ± 16.90 kg) recruited from the general population., Intervention(s): An electric goniometer was used to record clinical measurements of scapular position at rest and total arc of motion (excursion) during active upper extremity elevation in 2 testing sessions separated by several days. Measurements were recorded independently by 2 examiners. In 1 session, scapular motion was recorded simultaneously using a 14-camera, 3-dimensional optical motion-capture system., Main Outcome Measure(s): Reliability analysis included examination of clinical measurements for scapular position at rest and excursion during each condition. Both the intrarater reliability between testing sessions and the interrater reliability recorded in the same session were assessed using intraclass correlation coefficients (ICCs [2,3]). The criterion validity was examined by comparing the mean excursion values of each condition recorded using the electric goniometer and the 3-dimensional optical motion-capture system. Validity was assessed by evaluating the average difference and root mean square error., Results: The between-sessions intrarater reliability was moderate to good (ICC [2,3] range = 0.628-0.874). The within-session interrater reliability was moderate to excellent (ICC [2,3] range = 0.545-0.912). The average difference between total excursion values recorded using the electric goniometer and the 3-dimensional optical motion-capture system ranged from -7° to 4°, and the root mean square error ranged from 7° to 10°., Conclusions: The reliability of scapular measurements was best when a standard operating procedure was used. The electric goniometer provided an accurate measurement of scapular excursions in all 3 anatomical planes during upper extremity elevation., (© by the National Athletic Trainers' Association, Inc.)

Purpose: The purpose of this study was to investigate if the three partitions (superior, middle, and inferior partitions) of the infraspinatus muscle previously described in anatomical studies will present different behavior during scapular plane abduction (scaption) as described using shear-wave elastography, especially during initial range of motion., Methods: Eight volunteers held their arm against gravity 15° intervals from 30° to 150° in scaption. Shear-wave elastography was implemented at each position to measure shear modulus at rest and during muscle contraction, as a surrogate for muscle stiffness, of each partition. Muscle activity was defined as the difference in stiffness values between the resting positions and those during muscle contraction (ΔE = stiffness at contraction-stiffness at rest)., Results: The activity value for the middle partition was 25.1 ± 10.8 kPa at 30° and increased up to 105° (52.2 ± 10.8 kPa), with a subsequent decrease at larger angle positions (p < .001). The superior partition showed a flatter and constant behavior with smaller activity values except at higher angles (p < .001). Peak activity values for the superior partition were observed at 135° (23.0 ± 12.0 kPa). Increase activity for inferior partition began at 60° and showed a peak at 135° (p < .001; 32.9 ± 13.8 kPa)., Conclusion: Stiffness measured using shear-wave elastography in each partition of the infraspinatus muscle demonstrated different behavior between these partitions during scaption. The middle partition generated force throughout scaption, while the superior and inferior partitions exerted force at end range.

Characterization of scapular kinematics under demanding load conditions might aid to distinguish between physiological and clinically relevant alterations. Previous investigations focused only on submaximal external load situations. How scapular movement changes with maximal load remains unclear. Therefore, the present study aimed to evaluate 3D scapular kinematics during unloaded and maximal loaded shoulder flexion and extension. Twelve asymptomatic individuals performed shoulder flexion and extension movements under unloaded and maximal concentric and eccentric loaded isokinetic conditions. 3D scapular kinematics assessed with a motion capture system was analyzed for 20° intervals of humeral positions from 20° to 120° flexion. Repeated measures ANOVAs were used to evaluate kinematic differences between load conditions for scapular position angles, scapulohumeral rhythm and scapular motion extent. Increased scapular upward rotation was seen during shoulder flexion and extension as well as decreased posterior tilt and external rotation during eccentric and concentric arm descents of maximal loaded compared to unloaded conditions. Load effects were further seen for the scapulohumeral rhythm with greater scapular involvement at lower humeral positions and increased scapular motion extent under maximal loaded shoulder movements. With maximal load applied to the arm physiological scapular movement pattern are induced that may imply both impingement sparing and causing mechanisms., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Background: Scapular focused exercise interventions are frequently used to treat individuals with shoulder pain. However, evidence for changes in scapular motion after intervention is limited., Objective: To compare the effects of scapular movement training versus standardized exercises for individuals with shoulder pain., Methods: This will be a single-blinded randomized controlled trial. Sixty-four individuals with shoulder pain for at least 3 months, scapular dyskinesis, and a positive scapular assistance test will be randomly allocated to one of two groups: Scapular Movement Training (group 1) and Standardized Exercises (group 2). Group 1 will receive education about scapular position and movement, and be trained to modify the scapular movement pattern. Group 2 will perform stretching and strengthening exercises. Both groups will be treated twice a week for eight weeks. Three-dimensional scapular kinematics and muscle activity of the serratus anterior and upper, middle, and lower trapezius during elevation and lowering of the arm will be assessed at baseline and after 8 weeks of treatment. Pain intensity, function, fear avoidance beliefs, and kinesiophobia will be assessed at baseline and after 4 and 8 weeks of treatment, and 4 weeks after the end of treatment., Conclusions: The results of this study may contribute to a better understanding of the efficacy of scapular focused treatments for individuals with shoulder pain., Clinical Trial Registration: NCT03528499., (Copyright © 2020 Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia. Publicado por Elsevier España, S.L.U. All rights reserved.)

The tennis serve generates high musculoskeletal loads at the shoulder complex, making athletes particularly vulnerable to chronic injuries, especially adolescent players. Chronic injuries are commonly related to altered scapular kinematics. This study explored the effects of a history of shoulder problems involving humerothoracic and scapulothoracic kinematics during the tennis serve at low speed in adolescent competitive players with and without a history of dominant shoulder problems. Totally, 28 adolescent tennis players were split into two groups, those with and those without a history of shoulder problems. Data on humeral and scapular kinematics relative to the thorax were collected using an electromagnetic system during slow velocity serves. The two groups's humerothoracic and scapulothoracic 3D joint angles were compared both at the end of the cocking phase and at the end of the acceleration phase of the tennis serve. At the end of the cocking phase, the players with a 30 history of shoulder problems showed less humeral abduction and external rotation and more scapular upward rotation. This group also showed less humeral abduction at the end of the acceleration phase. Players with a history of shoulder problems adapted their humerothoracic and scapulothoracic orientations to preserve shoulder integrity during the tennis serve.

Background: Scapular kinematics of breast cancer survivors are most often evaluated during arm elevation. However, known compensations exist during functional task performance. The purpose of this study was to determine if scapular kinematics of breast cancer survivors during arm elevation are related to scapular kinematics during functional task performance., Methods: Scapular kinematics of 25 non-cancer controls and 25 breast cancer survivors (split by presence of impingement pain) during arm elevation in 3 planes and 3 reaching and lifting functional tasks were measured. Scapular upward rotation and scapulohumeral rhythm (SHR) at 30° increments of arm elevation were calculated. Between-group differences of upward rotation during arm elevation were evaluated with one-way ANOVAs (p < 0.05). The association of upward rotation angle and SHR during arm elevation and functional tasks was tested with Pearson correlations (p < 0.05)., Findings: Scapular upward rotation was reduced for the breast cancer survivor with pain at lower levels of arm elevation in each plane by up to 7.1° (p = .014 to 0.049). This is inconsistent with functional task results, in which upward rotation decrements occurred at higher levels of arm elevation. Upward rotation angles and SHR during arm elevation had an overall weak-to-moderate relationship (r = 0.003 to 0.970, p = .001 to 0.048) to values from functional tasks. Arm elevation during sagittal plane elevation demonstrated scapular upward rotation that was most closely associated to upward rotation during functional task performance., Interpretation: Inconsistent relationships suggests that clinical evaluations should adopt basic functional movements for scapular motion assessment to complement simple arm elevations., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Objective: To determine the construct validity, criterion validity, and responsiveness of measurement instruments evaluating scapular function., Design: Systematic review of measurement properties., Literature Search: The MEDLINE, Embase, CINAHL, and SPORTDiscus databases were systematically searched from inception until March 2019., Study Selection Criteria: Studies published in Dutch, English, or German were included when they evaluated at least 1 of the measurement properties of interest. No restrictions were made regarding participants' health status., Data Synthesis: Two reviewers independently evaluated study quality using the COSMIN checklist and extracted and analyzed data. Quality of evidence was graded by measurement property for each distinctive type of measurement., Results: Thirty-one measurement instruments in 14 studies were categorized into instruments to measure scapular posture and movement, and to assess scapular dyskinesis. Quality of evidence was at most moderate for 4 instruments with respect to criterion validity. Of these, criterion validity for instruments measuring scapular protraction/retraction posture and rotation angles up to 120° of thoracohumeral elevation was sufficient. Criterion validity for instruments measuring asymmetrical scapular posture, range of motion, and the lateral scapular slide test was insufficient. Quality of evidence for measurement properties of all other instruments was graded lower., Conclusion: There is currently insufficient evidence to recommend any instrument for the clinical examination of scapular function. Measurement instruments to assess scapular dyskinesis are prone to misinterpretation and should therefore not be used as such. J Orthop Sports Phys Ther 2020;50(11):632-641. doi:10.2519/jospt.2020.9265 .

Introduction: There are many variations of scapula morphology. Evaluation of scapula morphology is necessary to elucidate shoulder joint movement. We aimed to analyze the bone morphology of various parts constituting the scapula to identify certain conserved features among them., Materials and Methods: Thirty-one healthy individuals were the subjects. We created a scapular three-dimensional (3D) model using computed tomography (CT). X and Y axes were set on a glenoid surface. We measured the approximate plane of the upper and lower scapular bodies and scapular spine and the central axis of the coracoid and acromion. The anatomical position of the scapular spine, upper and lower bodies, coracoid, and acromion was measured. The positional relationship between the upper and lower bodies and scapular spine and the coracoid and acromion was evaluated. The average angle of the upper and lower scapular bodies and the scapular spine with respect to the XZ plane was calculated. The average angle of the coracoid and acromion with the X-axis on the XY plane and Z-axis on the YZ plane was calculated., Results: On the XY plane, approximate planes of the upper and lower part of the body and the scapular spine were significantly correlated to each inclination. On the XY plane, inclinations of the central axes of the coracoid and acromion were significantly correlated., Conclusions: The findings revealed for the first time the correlation between the inclinations of the scapular body and scapular spine and the inclination angle between the coracoid and acromion., (© 2020 Wiley Periodicals, Inc.)

Objective: The primary aim was to investigate the effect of inferior shoulder mobilization on scapular and shoulder muscle activity during resisted shoulder abduction in asymptomatic individuals., Methods: This was a lab-based, repeated-measures, crossover, randomized controlled study. Twenty-two participants were recruited. The order of experimental conditions was randomized. Each participant performed 5 repetitions of resisted shoulder abduction before and after the control and mobilization (grade +IV inferior shoulder mobilization, 3 sets, 60 seconds) conditions. Surface electromyography recorded the muscle activity of anterior, middle, and posterior deltoid; supraspinatus; infraspinatus; upper and lower trapezius; serratus anterior; and latissimus dorsi muscles., Results: Muscle activity levels reduced for infraspinatus (11.3% MVIC, 95% CI: 1.7-20.8), middle (22.4% MVIC, 95% CI: 15.9-28.8) and posterior deltoid (8.7 % MVIC, 95% CI: 4.6-12.9), and serratus anterior (-28.1% MVIC, 95% CI: 15.6-40.8) muscles after the mobilization condition during the eccentric phase of shoulder abduction. No carryover effects were observed, and within-session reliability was excellent (intraclass correlation coefficient scores ranging from 0.94 to 0.99)., Conclusion: Our findings suggest that inferior glenohumeral mobilization reduces activity levels of some scapular and shoulder muscles. Given the exploratory nature of our study, changes in muscle activity levels may have been found by chance. Confirmatory studies are required., (Copyright © 2020. Published by Elsevier Inc.)

Aseptic loosening of the glenoid component is one of the main reasons for the high revision rates of reverse total shoulder arthroplasty (RTSA). It has been reported that the bulky implant designs may lead to stress shielding. However, it is uncertain whether the shielding effect is severe enough to lead to bone resorption and glenoid loosening. The purpose of this study was to evaluate the level of stress-shielding and assess whether bone resorption plays a role in aseptic glenoid loosening following RTSA. A cadaveric in vitro test model was used to validate a finite element model (FEM) of the scapula. The FEM of the scapula, incorporating adaptive bone remodeling algorithms, was used to predict changes in postoperative bone density after RTSA. Changes in bone strength after implantation were also analyzed. The strain values predicted from the FEM of the scapula were in agreement with the in vitro measurements. Analysis of postoperative bone adaptation revealed that strain-induced bone resorption began at the peg of the implant and around the resected bone surface and then gradually expended to the peripheral regions. The bone strength also reduced postoperatively and appeared particularly around the implant peg. Strain-induced bone resorption is a likely source of the bone loss commonly observed in RTSA. The finite element glenoid bone remodeling simulation may be used as a tool to evaluate glenoid implant design., (© 2020 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals LLC on behalf of Orthopaedic Research Society.)

Background: Round shoulder posture (RSP) is one of the potential risks for shoulder impingement syndrome (SIS) due to alignment deviation of the scapula. Evidence on how the characteristics of a shoulder brace affecting the degree of RSP, shoulder kinematics, and associated muscle activity during movements is limited., Research Question: The purposes of this study were (1) to compare the effects of a shoulder brace on clinical RSP measurements, muscle activities and scapular kinematics during arm movements in subjects with shoulder impingement syndrome (SIS) and RSP; and (2) to compare the effects of two configurations (parallel and diagonal) and two tensions (comfortable and forced tension) of the brace straps on muscle activities and scapular kinematics during arm movements in subjects with SIS and RSP., Methods: Twenty-four participants (12 males; 12 females) with SIS and RSP were randomly assigned into 2 groups (comfortable then forced, and forced then comfortable) with 2 strap configurations in each tension condition. The pectoralis minor index (PMI), acromial distance (AD) and shoulder angle (SA) were used to assess the degree of RSP. Three-dimensional electromagnetic motion analysis and electromyography were used to record the scapular kinematics and muscle activity during arm movements., Results: All clinical measurements with the brace were significantly improved (p < 0.05). Under forced tension, muscle activities were higher with the diagonal configuration than with the parallel configuration in the lower trapezius (LT) (1.2-2.3% MVIC, p < 0.05) and serratus anterior (SA) (2.3% MVIC, p = 0.015). For upward rotation and posterior tilting of the scapula, the diagonal configuration was larger than the parallel configuration (1.5°, p = 0.038; 0.4°-0.5°, p < 0.05, respectively)., Significance: Different characteristics of the straps of the shoulder brace could alter muscle activity and scapular kinematics at different angles during arm movement. Based on the clinical treatment preference, the application of a shoulder brace with a diagonal configuration and forced tension is suggested for SIS and RSP subjects., Competing Interests: Declaration of Competing Interest We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Objective: The aim of this study was to assess the between-day reliability of the scapular locator for measuring scapular rotations during arm elevation in patients without shoulder pain/conditions/disorders., Methods: Twenty-three asymptomatic individuals were measured during 2 sessions separated by 24 hours. One observer measured scapular position with a scapular locator while participants held their arms at 30°, 60°, 90°, and 120° elevation in the scapular plane. Three trials were performed for each arm position., Results: At 30°, between-day intraclass correlation coefficients (ICCs) for all scapular rotations were poor (ICC 0.10-0.40). At higher arm elevations (60°, 90°, and 120°), ICCs ranged from 0.73 to 0.93 for scapular upward rotation, 0.80 to 0.87 for posterior tilt, and 0.37 to 0.62 for scapular internal rotation. For all scapular rotations, the standard error of measurement was less than 6°, and the smallest detectable difference ranged from 11° to 18°., Conclusion: The findings indicate good to excellent reliability for measuring scapular upward/downward rotation and anterior/posterior tilt between 60° and 120° of shoulder elevation in the scapular plane. However, low reliability was found for all scapular rotations at 30° elevation, and for scapular internal rotation at higher arm elevation., (Copyright © 2020. Published by Elsevier Inc.)

Background: During nonoperative or postoperative rehabilitation after sports injuries, exercise selection is often based on minimal load on the injured/repaired glenohumeral structures, while optimally activating scapulothoracic muscles. Previous research explored scapular muscle activity during rehabilitation exercises using surface electromyography (EMG). However, limited information exists about the deeper lying muscle activity, measured with fine-wire electrodes, even more in combination with 3-dimensional scapular kinematics., Purpose: To report scapular kinematics synchronously with surface and fine-wire EMG during specific shoulder exercises for early rehabilitation., Study Design: Descriptive laboratory study., Methods: A total of 23 healthy male patients were recruited. Three-dimensional scapular kinematics were measured combined with EMG recording of 8 muscles during 4 commonly used shoulder exercises (inferior glide, low row, lawnmower, and robbery). Upper (UT), middle (MT), and lower (LT) trapezius and serratus anterior muscle activities were measured with bipolar surface electrodes. Intramuscular electrodes were placed in the levator scapulae (LS), rhomboid major (RM), pectoralis minor (Pm), and infraspinatus (IS) muscles. All data were normalized as a percentage of maximal voluntary isometric contraction (%MVIC). A linear mixed model with Bonferroni correction was applied for statistical analysis., Results: Scapular kinematics revealed an anterior tilt position during the inferior glide, low row, and robbery ( P < .05). An upward rotation position between 20° and 30° was reached in all exercises except low row. Inferior glide (31°) and low row (42°) represented a significantly increased internal rotation position compared with lawnmower and robbery. Lawnmower and robbery showed significantly ( P < .05) more MT (lawnmower, 36% MVIC; robbery, 39% MVIC) and RM (lawnmower, 59% MVIC; robbery, 66% MVIC) activation compared with inferior glide and low row. Lawnmower and robbery showed significantly ( P < .05) less Pm activation (9.5%-12% MVIC). LS was significantly more active during robbery (58% MVIC) compared with inferior glide and low row (27%-36% MVIC) ( P < .05). IS showed moderate activity (24%-37% MVIC) for all exercises, except low row (13% MVIC)., Conclusion/clinical Relevance: This study provides new insights about scapular positions and activation of the deeper layer muscles during 4 commonly used shoulder rehabilitation exercises. The lawnmower showed a favorable position of the scapula with less Pm activity in contrast to the low row. The inferior glide, lawnmower, and robbery should not be implemented in early phases of shoulder rehabilitation because of their moderate muscle activity.

Background: Modifications of posture in a segment may influence the posture of adjacent and nonadjacent segments and muscular activity. The spine-shoulder and spine-pelvis relationships suggest that the pelvis may influence shoulder posture., Objective: To investigate the effect of the active reduction of the anterior pelvic tilt on shoulder and trunk posture during static standing posture and on the electromyographic activity of the scapular upward rotators during elevation and lowering of the arm., Methods: Thirty-one young adults were assessed in a relaxed standing position and a standing position with 30% active reduction of the anterior pelvic tilt. The pelvic tilt, trunk posture, and forward shoulder posture during the static standing posture and the electromyographic activity during elevation and lowering of the arm were assessed., Results: Paired t-tests indicated that the active reduction of the anterior pelvic tilt reduced the trunk extension (MD=1.09; 95%CI=-2.79 to -1.03). There were no effects on the forward shoulder posture (MD=0.09; 95%CI=-0.92 to 1.09). Repeated measures of analyses of variance indicated an increase in lower trapezius electromyographic activity (MD=3.6; 95%CI=1.28 to 5.92). There was a greater reduction in upper trapezius activity after pelvic tilt reduction during arm elevation (MD=1.52%; 95%CI=-2.79 to -0.25) compared to that during the lowering phase. There were no effects of pelvic tilt reduction on the electromyographic activity of the serratus anterior (MD=3.26; 95%CI=-3.36 to 9.87)., Conclusion: The influence of pelvic posture on the trunk posture and lower trapezius activation should be considered when assessing or planning exercise for individuals with shoulder or trunk conditions., (Copyright © 2019 Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia. Publicado por Elsevier Editora Ltda. All rights reserved.)

Context: The shoulder joint and girdle are highly loaded during field hockey play. To optimize performance and to better substantiate preventive programs, it is important to gain insight into shoulder-girdle muscle function and balance in this athlete population., Objective: To evaluate relative scapular muscle-activity ratios through surface electromyography during maximal isokinetic strength testing in elite male field hockey players compared with nonathletes., Design: Cross-sectional study., Setting: Institutional laboratory., Patients or Other Participants: Twenty-five elite field hockey players from the Belgian National Team and 25 age- and sex-matched nonathletes., Intervention(s): We measured bilateral activity in 4 scapular muscles (upper trapezius [UT], middle trapezius [MT], lower trapezius [LT], and serratus anterior [SA]) during an external-internal rotation and protraction-retraction isokinetic shoulder protocol., Main Outcome Measure(s): Relative scapular muscle-activity ratios, or balance ratios, of the UT : MT, UT : LT, UT : SA, SA : MT, and SA : LT., Results: We noted lower ratios bilaterally in the athlete group compared with the control group for the UT : MT, UT : LT, and SA : MT ratios during protraction, retraction, and external rotation, respectively, and unilaterally (dominant side only) for the UT : LT ratio during protraction. No consistent trend was present for established side differences in the studied balance ratios., Conclusions: Compared with nonathletes, elite field hockey players had altered intramuscular (within the trapezius) and intermuscular (between the trapezius and SA) balance ratios during maximal shoulder-girdle contractions, with relatively more MT and LT activity. This may reflect a sport-specific adaptation to optimize coordinated activity of the scapulothoracic muscles, meeting the specific demands of field hockey movements and simultaneously better protecting the shoulder against injury. Our results can assist in optimizing high-performance training and in supporting injury-prevention programs, which are key to both successful and long-lasting athletic careers.

Background: The Scapular Assistance Test was suggested to directly assess the influence of scapular motion on pain and indirectly measure the function of the scapular rotators. However, it is still not clear if individuals with a positive Scapular Assistance Test actually present changes in scapular motion and muscle strength. This study compared scapular kinematics and muscle strength between those with a positive Scapular Assistance Test and those with a negative Scapular Assistance Test., Methods: Fifty individuals with shoulder pain were randomly allocated to: positive (n = 25) or negative Scapular Assistance Test (n = 25) group. Scapular kinematics was measured during elevation and lowering of the arm. Strength of the serratus anterior and lower trapezius was also measured. Two-way analysis of variance was used to compare kinematics between groups. Unpaired Student's t-test and Mann-Whitney test were used to compare strength of serratus anterior and lower trapezius, respectively., Findings: There were no differences (P > 0.05) in scapular internal rotation and upward rotation between both groups. For scapular tilt, there was group main effect (P < 0.05) during elevation and lowering of the arm, whereas the positive Scapular Assistance Test group presented greater scapular anterior tilt. There was no difference (P > 0.05) in strength between groups., Interpretation: Individuals with a positive Scapular Assistance Test are more likely to present decreased scapular posterior tilt in those with shoulder pain. Strength of the scapular muscles seems to be same in those with a positive and a negative Scapular Assistance Test., Competing Interests: Declaration of competing interest We affirm that we have no financial affiliation or involvement with any commercial organization that has a direct financial interest in any matter included in this manuscript, except as disclosed in an attachment and cited in the manuscript. Any other conflict of interest (i.e., personal associations or involvement as a director, officer, or expert witness) is also disclosed in attachment., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Persons with subacromial impingement syndrome (SIS) have an imbalance in scapular muscle recruitment. To avoid humeral head compression against the coracoacromial arch during the early stages of rehabilitation, physical therapists recommend movements targeting scapular retraction, shoulder depression, and arm extension such as the inverted row (IR) exercise. The purposes of this study were to describe: (1) scapular balance ratios during an IR and (2) the magnitudes of recruitment of spinal stabilizer muscles. Scapular muscle balance ratios from 26 healthy participants were calculated from electromyographic (EMG) activity of the upper trapezius (UTP), lower trapezius (LTP), middle trapezius (MTP), serratus anterior (SA), posterior deltoid (PD), latissimus dorsi (LD), and biceps brachii (BB) during an IR on stable and unstable support surfaces. Balance ratios were obtained by dividing normalized EMG activity of the UTP by the normalized EMG values from each of the other six muscles. Four median scapular balance ratios (UTP/MTP, UTP/PD, UTP/LD, and UTP/BB) ranged from 0.9 to 2.2, whereas the UTP/LTP ratio ranged from 1.6 to 2.2 and the UTP/SA ratio ranged from 1 to 4.7. Activation of seven muscles promoted safe containment of the humeral head within the glenoid fossa during the IR in healthy persons and potentially people with the tendency for development of SIS. Four spinal stabilizer muscles were examined: longissimus thoracis (LT), multifidus (MF), rectus abdominis (RA), and external oblique (EO). Spinal stabilizer EMG activation values ranged from 34% to 40% maximum voluntary isometric contraction (MVIC) for the RA and EO and from 54% to 66% MVIC for the LT and MF.

Purpose: In this study, our aim was to evaluate the glenoid version, height, and width measurements based on gender, side, age, height, and hand dominance in the Turkish population using computed tomography (CT) images., Methods: In our study, CT images of 140 patients (62 females and 78 males; mean age: 39.6 years) who had no shoulder complaints were evaluated retrospectively. Glenoid version (GV), AP diameter (width), and SI diameter (height) on both shoulders were measured on the CT images. Correlations between patient gender, side, age, height, and hand dominance and the GV and size were evaluated., Results: The right shoulder had a mean GV of -0.93 ± 7.80 degrees and the left shoulder had a GV of -0.88 ± 6.63 degrees ( p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder ( p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder ( p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder ( p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder ( p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder ( p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder ( p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder ( p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (., Conclusion: Hand dominance had an effect on the glenoid version, while patient gender, age, and height had an effect on the glenoid size. The glenoid width in the Turkish population was similar to that of the European and American populations, and the glenoid height was similar to that of the Asian population. Our GV values were similar to those of the Asian population and more anteverted compared to the Western population. We believe that our findings will be useful in preoperative planning and in the production of implants for our population., Competing Interests: 
The authors declare that there are no conflicts of interest., (Copyright © 2020 Abdulkadir Sarı et al.)

Background: Scapular muscle exercise is important for patients with shoulder disorders. Distal variance leads to changes in shoulder muscle activation. Here, we aimed to determine whether scapular muscle activation is affected by different arm rotation angles., Methods: Overall, 30 healthy men participated in this study. The subjects were asked to keep their arms at 120 degrees of shoulder flexion while holding a 1.0-kg dumbbell in palms down (pronation) and palms up (supination) positions. Electromyography was used to measure anterior, middle, posterior deltoid, serratus anterior, upper, and lower trapezius muscle activation during the task. The muscle activations of each shoulder were compared between the pronation and supination positions., Results: Anterior deltoid and serratus anterior activations were significantly higher in supination than in pronation (p < .05). Alternatively, posterior deltoid and lower trapezius muscles were significantly more activated in pronation than in supination (p < .05)., Conclusion: Scapular muscle activation changed with arm rotation angle. Arm rotation angle should be assessed to estimate scapular muscle activation during exercise and motion analysis in clinical practice., Competing Interests: Declaration of Competing Interest The authors declare no conflicts of interest., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: The aim of this study was to compare the scapular kinematics and scapulohumeral rhythm of healthy participants during arm elevation and lowering and to find the difference between active motion and passive motion of the shoulder., Methods: The study examined the shoulders of 10 healthy men (mean age, 23.5 years; age range, 22-28 years). The shoulders of participants were elevated and lowered while fluoroscopic images were taken, and 3-dimensional bone models were created from 2-dimensional to 3-dimensional images using model registration techniques. The Euler angle sequences of the models' scapular kinematics and scapulohumeral rhythm were compared during active and passive shoulder motion., Results: There was a significant statistical difference of upward rotation during arm elevation between active and passive shoulder movements (P = .027). In particular, the upward rotation between 45° and 90° of elevation showed a statistically significant difference (P < .001). When the scapula was tilted posteriorly by active motion, it resulted in a statistically significant difference as there was more tilting in the high-degree range of motions than when it was tilted by passive motion (P < .001). There was no statistically significant difference between the 2 groups in scapular external rotation. However, during arm lowering, scapular kinematics did not show statistically significant difference between active and passive motion., Conclusions: The scapular kinematics showed statistically significant differences between active and passive motion of upward rotation and posterior tilting of the scapula during arm elevation, but there were none during lowering. In terms of upward rotation, active shoulders rotated more upward during arm elevation., (Copyright © 2019 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Optimal scapular position and movement are necessary for normal function of the shoulder joint and it is essential to focus on scapula in the rehabilitation for shoulder disorders. The aim of this study was to discover the relationship between the scapular initial position and scapular movement during dynamic motions in healthy young men. Thirty-four men participated in this study. The scapular angles at initial position and in elevation and lowering during flexion and abduction were measured using an electromagnetic tracking device. The scapular movements from 30° to 120° during flexion and abduction were calculated. Spearman's rank correlation coefficients were used to analyze the relationship between the scapular initial position and scapular movements. For upward rotation and posterior tilt of the scapula, there were significant positive correlations between the scapular initial position and scapular movement during flexion and abduction. For internal rotation, there were significant positive correlations, except 90° in lowering phase and 120° in both phases. While the humeral elevation increased, the correlation coefficients tended to decrease. Except for the internal rotation our results clarified the interactions between the scapular initial position and scapular movement during dynamic motions in healthy young men. The tendency of the decrease in correlation coefficient with elevation angle was shown., Competing Interests: The authors have declared that no competing interests exist.

Purpose: The aim of the study is to evaluate the difference in shape of the upper part and lower part of the Scapulothoracic Gliding Surface (STGS)., Methods: 3D-CT images of the thoracic cage of 50 patients were created in MIMICS ® . Three anatomical landmarks (insertion m. serratus anterior on 5th rib; transverse process of 2th and 7th vertebra) were used as an anteroposterior cutting plane to define the STGS. The upper part of the STG was defined as rib 2-5 and the lower part as 5-8. Next, in MATLAB ® , a script was used to create the sphere with best fit for upper and lower parts of STGS. The Root-Square-Mean Error (RSME) (mm) between two closest points on the fitted sphere and the STGS of both parts were calculated to determine the goodness-of-fit., Results: The RSME was found to be significantly lower for the area ribs 2-5 (mean 7.85 mm, SD 1.86) compared the area of ribs 5-8 (mean 10.08 mm, SD 1.90)., Conclusion: The STGS of the upper thoracic wall (2-5) is more spherical shaped than the STGS of the lower thoracic wall (rib 5-8).