• Korean Journal of Applied Biomechanics
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• v.20 no.2
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• pp.197-204
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• 2010

Scapular position and motion are essential for normal upper limb mobility; Further, the posture of patients with thoracic kyphosis is related to shoulder girdle function and disorder. The purpose of this study was to examine the effects of thoracic posture on the shoulder range of motion and on three-dimensional scapular kinematics. Thirty healthy subjects performed right-arm abduction along the frontal plane while standing in both erect and in slouched trunk posture. The scapular position and rotation, and shoulder and thoracic angles were recorded using a motion analysis system. The scapular upward rotation and internal rotation were significantly altered according to postural tatiges; however, scapular tilt was not affected. Shoulder angle was significantly decreased in the slouched posture as c rpared to tatt in the erect posture. Thus, a slouched posture(thoracic kyphosis) significantly affects the shoulder range of motion and scapular kinematics during shoulder abduction in the frontal plane.

• The Journal of Korean Physical Therapy
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• v.26 no.3
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• pp.140-146
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• 2014

Purpose: Differences in scapular kinematics and muscle activity appear in the forward head and rounded shoulder posture (FHRSP). Thus, the aim of this study was to investigate the following effects according to different postures on scapular kinematics and muscle activity around scapular region in individuals with and without FHRSP during overhead reaching task. Methods: Thirty pain-free subjects with/without FHRSP participated in this study. All subjects were positioned into three positions: habitual head posture (HHP), self-perceived ideal head posture (SIHP) and therapist-perceived neutral head posture (TNHP). Muscle activities of upper trapezius (UT), lower trapezius (LT) and serratus anterior (SA) were measured during overhead reaching task. Results: Muscle activity of trapezius muscle (UT and LT) during HHP was significantly higher than SIHP and TNHP in FHRSP group (p<0.05), but there was no difference between SIHP and TNHP. SA also significantly increased muscle activity in HHP more than SIHP and TNHP in FHRSP group (p<0.05), but there was no significant difference between SIHP and TNHP. In Non-FHRSP group, although there was a tendency of different muscle activities among three postures, it was not statistically significant. Conclusion: This result demonstrates that muscle activity associated with overhead reaching task is increased in HHP which affects the scapular kinematics and SIHP contributes changed scapular kinematics and proper recruitment of muscle activity in FHRSP similarly to TNHP.

• Physical Therapy Korea
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• v.23 no.3
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• pp.68-75
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• 2016

Background: Shoulder horizontal adduction (HA) is performed in many activities of daily living. The limited range of motion (LROM) of HA is affected by the tightness of the posterior deltoid, infraspinatus, teres major, and posterior capsule of glenohumeral joint. The LROM of shoulder HA contributes to excessive scapular abduction. Objects: The aim of this study is to compare the scapular abduction distance and three-dimensional displacement of the scapula during shoulder horizontal adduction between subjects with and without the LROM of shoulder HA. Methods: 24 subjects (12 people in LROM group and 12 people in normal ROM group) participated. Subjects with less than $115^{\circ}$ of HA ROM were included in LROM group. Shoulder HA was performed 3 times for measuring scapular abduction distance and three-dimensional displacement of the scapula. Tape measure was used for measuring scapular abduction distance. Scapular abduction distance was normalized by dividing the scapular size. Polhemus Liberty was used for measuring the three-dimensional displacement of the scapula. Results: Normalized scapular abduction distance was significantly greater in LROM group than normal ROM group (p<.001). Three-dimensional displacement of the scapula during shoulder HA was greater in LROM group than normal ROM group (p<.05). Conclusion: LROM group had a greater scapular abduction and three-dimensional displacement of the scapula during shoulder HA compared to normal ROM group.

• PNF and Movement
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• v.4 no.1
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• pp.1-7
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• 2006

Objective : The purpose of this study was conducted to find scapular movement instability related with shoulder complex and provide strengthening the scapular muscles with proprioceptive neuromuscular facilitation(PNF). Methods : This is a literature study with books and articles, seminar note and book for PNF international course. Results : The scapular serve as the platform for humeral motions. The scapulothoracic articulation is stabilized and controlled, in part, by the scapular muscles. Therefore, if scapular muscle function is altered, then dysfunctional scapulothoracic kinematics may result. Strengthening exercise for scapular muscles are a common part of rehabilitation programs designed for patients with scapular instability. Conclusion : Treatment of the scapular instability is provided. It is that treatment with combination of isotonic, stabilize reversal on different patient's positions.

• Physical Therapy Korea
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• v.26 no.4
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• pp.53-62
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• 2019

Background: Shoulder function is achieved by the coordinated movements of the scapula, humerus, and thoracic spine, and shoulder disorders can be associated with altered scapular kinematics. The trunk plays an important role as the kinematic chain during arm elevation. Objects: The purpose of this study was to determine the effects of thoracic hyperkyphosis on scapular orientation and trunk motion. Methods: Thirty-one subjects (15 in the ideal thorax group and 16 in the thoracic hyperkyphosis group) performed right-arm abduction and adduction movements in an unconstrained plane. The scapular orientation and trunk motion were recorded using a motion analysis system. Results: Those subjects with thoracic hyperkyphosis displayed greater scapular posterior tilting at a $120^{\circ}$ shoulder elevation, greater scapular internal rotation throughout the arm raising phase, and greater trunk axial rotation at the upper ranges of the shoulder elevation, compared to those subjects with an ideal thorax (p<.05). Conclusion: Thoracic hyperkyphosis can cause scapular instability, greater trunk rotation and greater scapular posterior tilting, and may contribute to preventing the achievement of a full range of humeral abductions in an unconstrained plane.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.10 no.2
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• pp.23-29
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• 2012

Purpose : Purpose of this study was to investigate whether cervicothoracic posture was associated with scapula orientation and muscle activity during shoulder abduction. Methods : Cervicothoracic junction angle and thoracic kyphosis angle were measured in health twenty subjects. Then, scapular resting orientation and range of motion (upward/downward rotation, internal/external rotation) and muscle activity (upper trapezius, lower trapezius, serratus anterior) was determined using motion capture system and surface electromyography while subjects performed shoulder abduction. Results : Cervicothoracic junction angle was significantly associated with range of motion of scapular internal/external rotation during shoulder abduction. Thoracic kyphosis angle was significantly associated with scapular resting orientation of upward/downward rotation and average IEMG of lower trapezius. Conclusion : The result of this study shows that poor cervicothoracic posture is relationship with altered scapular kinematics cause of shoulder dysfunction. These findings suggested that cervicothoracic posture may be considered in occupation and exercise including arm elevation over head as well as used as predict factor to estimate shoulder dysfunction.

• Clinics in Shoulder and Elbow
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• v.25 no.4
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• pp.265-273
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• 2022

Background: Massive rotator cuff tears (MRCTs) with subscapularis (SSC) tears cause severe shoulder dysfunction. In the present study, the influence of SSC tears on three-dimensional (3D) shoulder kinematics during scapular plane abduction in patients with MRCTs was examined. Methods: This study included 15 patients who were divided into two groups: supraspinatus (SSP) and infraspinatus (ISP) tears with SSC tear (torn SSC group: 10 shoulders) or without SSC tear (intact SSC group: 5 shoulders). Single-plane fluoroscopic images during scapular plane elevation and computed tomography (CT)-derived 3D bone models were matched to the fluoroscopic images using two-dimensional (2D)/3D registration techniques. Changes in 3D kinematic results were compared. Results: The humeral head center at the beginning of arm elevation was significantly higher in the torn SSC group than in the intact SSC group (1.8±3.4 mm vs. -1.1±1.6 mm, p<0.05). In the torn SSC group, the center of the humeral head migrated superiorly, then significantly downward at 60° arm elevation (p<0.05). In the intact SSC group, significant difference was not observed in the superior-inferior translation of the humeral head between the elevation angles. Conclusions: In cases of MRCTs with a torn SSC, the center of the humeral head showed a superior translation at the initial phase of scapular plane abduction followed by inferior translation. These findings indicate the SSC muscle plays an important role in determining the dynamic stability of the glenohumeral joint in a superior-inferior direction in patients with MRCTs.

• Physical Therapy Korea
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• v.24 no.1
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• pp.86-96
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• 2017

Background: Scapular dyskinesis is characterized by altered scapular position and motion. Specifically, excess activation of the Upper trapezius (UT) combined with decreased Lower trapezius (LT) and Serratus anterior (SA) have been observed. The Standard push-up plus exercise (SPP) is considered as a therapeutic exercise for increasing SA activity and maintaining the scapular kinematics. In addition, Using the Sling surface can lead to higher muscle activity. However, the advantage of an unstable surface has been uncertatin. Objects: To compare the activation of the UT, LT, and lower serratus anterior (LSA) muscles during various push-up plus exercises with and without sling in subjects with scapular dyskinesis. Methods: Total 18 male subjects with scapular dyskinesis were recruited. The UT, LT, and LSA electromyographic activities and the UT/LSA and UT/LT EMG activity ratios were measured during three push-up plus exercises with and without sling. Two-way repeated of analysis of variance was used to determine the statistical significance. Results: The UT activity was significantly lower in all postures without sling than that with sling. In addition, the LSA activity was significantly greater without than with sling, and significantly large in SPP, Low back supported push-up plus (LSPP), and Quadruped push-up plus. Additionally, the UT/LSA and UT/LT activity ratios were lower in SPP and LSPP without sling than with the other four push-up plus exercises. Conclusion: The push-up plus without sling were considered to decrease UT and increase LSA activity compared with exercises with sling. Furthermore, SPP without sling seems to be a more effective exercise for increasing LSA activity and lowering the UT/LSA and UT/LT activity ratios in scapular dyskinesis subjects.

• Korean Journal of Applied Biomechanics
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• v.31 no.3
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• pp.155-161
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• 2021

Objective: There is a lack of studies using the 3D-2D image registration techniques on the mechanism of a shoulder injury for ice hockey players. This study aimed to analyze in vivo 3D glenohumeral joint arthrokinematics in collegiate ice hockey athletes and compare shoulder scaption with or without a hockey stick using the 3D-2D image registration technique. Method: We recruited 12 male elite ice hockey players (age, 19.88 ± 0.65 years). For arthrokinematic analysis of the common shoulder abduction movements of the injury pathogenesis of ice hockey players, participants abducted their dominant arm along the scapular plane and then grabbed a stick using the same motion under C-arm fluoroscopy with 16 frames per second. Computed tomography (CT) scans of the shoulder complex were obtained with a 0.6-mm slice pitch. Data from the humerus translation distances, scapula upward rotation, anterior-posterior tilt, internal to external rotation angles, and scapulohumeral rhythm (SHR) ratio on glenohumeral (GH) joint kinematics were outputted using a MATLAB customized code. Results: The humeral translation in the stick hand compared to the bare hand moved more anterior and more superior until the abduction angle reached 40°. When the GH joint in the stick hand was at the maximal abduction of the scapula, the scapula was externally rotated 2~5° relative to 0°. The SHR ratio relative to the abduction along the scapular plane at 40° indicated a statistically significant difference between the two groups (p < 0.05). Conclusion: With arm loading with the stick, the humeral and scapular kinematics showed a significant correlation in the initial section of the SHR. Although these correlations might be difficult in clinical settings, ice hockey athletes can lead to the movement difference of the scapulohumeral joints with inherent instability.

• Clinics in Shoulder and Elbow
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• v.18 no.3
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• pp.152-158
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• 2015

Background: Acromioclavicular (AC) stability is maintained through a complex combination of soft-tissue restraints that include coracoclavicular (CC), AC ligament and overlying muscles. Among these structures, the role of the CC ligament has continued to be studied because of its importance on shoulder kinematics, especially after AC injury. This study was designed to determine the geometric change of conoid and trapezoid ligaments and resulting stresses on these ligaments according to various scapular motions. Methods: The scapuloclavicular (SC) complex was isolated from a fresh-frozen cadaver by removing all soft tissues except the AC and CC ligaments. The anatomically aligned SC complex was then scanned with a high-resolution computed tomography scanner into 0.6- mm slices. The Finite element model of the SC complex was obtained and used for calculating the stress on different parts of the CC ligaments with simulated movements of the scapula. Results: Average stress on the conoid ligament during anterior tilt, internal rotation, and scapular protraction was higher, whereas the stress on the trapezoid ligament was more prominent during posterior tilt, external rotation, and retraction. Conclusions: We conclude that CC ligament plays an integral role in regulating horizontal SC motion as well as complex motions indicated by increased stress over the ligament with an incremental scapular position change. The conoid ligament is the key structure restraining scapular protraction that might occur in high-grade AC dislocation. Hence in CC ligament reconstructions involving only single bundle, every attempt must be made to reconstruct conoid part of CC ligament as anatomically as possible.