Scapular positioning and movement in unimpaired shoulders, shoulder impingement syndrome, and glenohumeral instability (original) (raw)
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Scapular inclination and inferior stability of the shoulder
Journal of Shoulder and Elbow Surgery, 1992
Eleven fresh-frozen cadaver shoulders were studied to examine the influence of scapular inclination on inferior stability of the glenohumeral ioint. All muscles except the rotator cuH were removed, and the capsule was vented. Inferior stability tests in the hanging position (sulcus test) and in 90°abduction (abduction inferior stability fABIS] test) were simulated by the application of a 7.5 kg load with the scapula inclined at -75°, 0°, 75°, and 30°in the sulcus test and at 75°, 30°, 45°, and 60°in the ABIS test. An electromagnetic tracking device was used to record the position of the humerus in relation to the glenoid. In the sulcus test all of the shoulders dislocated when the scapula was inclined at -75°. However, when the scapula was inclined at 30°, no shoulder dislocated before loading, and one shoulder dislocated after loading. As a result both the loaded and unloaded positions of the humeral head shifted significantly to the superior direction as the scapular inclination increased (p < 0.0007). In the ABIS test, however, the positions of the humeral head shifted inferiorly with an increase in scapular inclination (p < 0.0007), although none of the shoulders dislocated in any of the inclination angles. We conclude that scapular inclination contributes significantly to inferior stability of the glenohumeral [oint. Increased scapular inclination prevents inferior displacement of the humeral head, probably because of a bony cam eHect that causes tightening of the superior capsule. (J SHOULDER ELBOW SURG 7992; Disturbance of glenohumeral rhythm is often recognized in patients with shoulder instability.6, 15, 16 Thus, not only the position of the humerus in relation to the scapula but also that of the scapula to the body may playa role in stability. Basmajian and Bozcnr' were the first to direct attention to the slope of the glenoid fossa. From the observation of cadaver specimens they suggested that the slope of the glenoid fossa might lead to tightening of the superior capsule and thereby prevent inferior displacement of the humeral head. After studying rare cases of hypoplastic scapula in which the glenoid surface was facing downward, Sohc" pointed out that the individual could dislocate the glenohumeral joint downward at will. He From the Biomechanics laboratory, the Department of Orthopedics, Mayo Clinic/Mayo Fo undation, Rochester, M inn.
Middle East Journal of Rehabilitation and Health Studies
Context: With a key role in normal shoulder function, scapular kinematics have been investigated in shoulder impingement syndrome (SIS). Objectives: This systematic review aimed at determining scapular kinematic patterns in patients with SIS compared to in asymptomatic individuals. Data Sources: Databases such as PubMed, Scopus, Web of Science, Ovid, Embase and PEDRO were searched from January 1995 to June 2021. Study Selection: Articles in English published in peer-reviewed journals and using motion analysis systems to compare scapular kinematics between patients with SIS and asymptomatic subjects during arm elevation were included. Data Extraction: A modified Downs and Black checklist was used to assess the risk of bias of the included studies. A random-effects model was employed to perform a meta-analysis. Results: Nine out of 1650 screened abstracts were included for data extraction. Scapular upward rotation significantly decreased during arm elevation in SIS (SMD = -0.13, 95% C...
Annals of physical and rehabilitation medicine, 2018
The global range of motion of the arm is the result of a coordinated motion of the shoulder complex including glenohumeral (GH), scapulothoracic, sternoclavicular and acromioclavicular joints. This study is a non-systematic review of kinematic patterns in degenerated shoulders. It is a based on our own research on the kinematics of the shoulder complex and clinical experience. For patients with subacromial impingement syndrome without rotator-cuff tears, most kinematic studies showed a small superior humeral translation relative to the glenoid and decreased scapular lateral rotation and posterior tilt. These scapular kinematic modifications could decrease the subacromial space and favor rotator-cuff tendon injury. For patients with shoulder pain and restricted mobility, the studies showed a significant increase in scapular lateral rotation generally seen as a compensation mechanism of GH decreased range of motion. For patients with multidirectional GH instability, the studies found ...
Physiotherapy Research International, 2013
Background and purpose. The purpose of the study was to investigate whether individuals with anterior glenohumeral joint (GHJ) instability exhibit different scapular orientation from individuals with healthy shoulders in a planar shoulder movement and a functional three-dimensional (3D) reaching task. Methods. This is a betweengroups study with repeated measures. Ten people with anterior GHJ instability and 15 people with healthy shoulders participated in the study. For the planar shoulder movement task, participants were asked to abduct the shoulder from the resting position to predetermined target angles (45 , 90 , and 135 of shoulder abduction) in the frontal plane. For the 3D reaching task, participants were asked to move the unconstrained arm to a remembered target location in space. Scapular orientation about three rotational axes was analysed at the target location and compared between the two groups of subjects. Results. For planar abduction, participants with GHJ instability and those with healthy shoulders exhibited similar scapular orientation changes in upward-downward rotation, anterior-posterior tipping and medial-lateral rotation. For 3D reaching, participants with GHJ instability and those with healthy shoulders also exhibited similar scapular orientation changes pointing to targets at various locations. Conclusions. Results of this study show that scapular orientation changes associated with shoulder abduction and functional reaching activities were similar in people with GHJ instability and those with healthy shoulders. The current study suggests that anterior GHJ instability has little impact on scapular kinematics during upper limb movements in a chronic condition without pain, muscle weakness or limited range of motion. Altered scapular kinematics may not contribute to the high recurrence rate of anterior GHJ dislocation.
Brazilian Journal of Physical Therapy, 2009
Objective: The purpose of this manuscript is to review current knowledge of how muscle activation and force production contribute to shoulder kinematics in healthy subjects and persons with shoulder impingement. Results: The middle and lower serratus anterior muscles produce scapular upward rotation, posterior tilting, and external rotation. Upper trapezius produces clavicular elevation and retraction. The middle trapezius is primarily a medial stabilizer of the scapula. The lower trapezius assists in medial stabilization and upward rotation of the scapula. The pectoralis minor is aligned to resist normal rotations of the scapula during arm elevation. The rotator cuff is critical to stabilization and prevention of excess superior translation of the humeral head, as well as production of glenohumeral external rotation during arm elevation. Alterations in activation amplitude or timing have been identified across various investigations of subjects with shoulder impingement as compared to healthy controls. These include decreased activation of the middle or lower serratus anterior and rotator cuff, delayed activation of middle and lower trapezius, and increased activation of the upper trapezius and middle deltoid in impingement subjects. In addition, subjects with a short resting length of the pectoralis minor exhibit altered scapular kinematic patterns similar to those found in persons with shoulder impingement. Conclusion: These normal muscle functional capabilities and alterations in patient populations should be considered when planning exercise approaches for the rehabilitation of these patients.
Medical Journal of the Islamic Republic of Iran, 2014
Background: Dysfunction in the kinetic chain caused by poor scapula stabilization can contribute to shoulder injuries and Shoulder Impingement Syndrome (SIS). The purpose of this study was to compare the effectiveness of two treatment approaches scapular stabilization based exercise therapy and physical therapy in patients with SIS. Methods: The study is a randomized clinical trial in which 68 patients with SIS were randomly assigned in two groups of exercise therapy (ET) and physical therapy (PT) and received 18 sessions of treatment. Pain, shoulders' range of abduction and external rotation, shoulder protraction, scapular rotation and symmetry as well as postural assessment and Pectoralis minor length were evaluated pre and post intervention. The paired-sample t test and the independent sample t test were applied respectively to determine the differences in each group and between two groups. Results: Our findings indicated significant differences in abduction and external rotation range, improvement of forward shoulder translation and increase in the flexibility of the involved shoulder between the two groups (respectively ; p=0.024, p=0.001, p<0/0001, p<0/0001). No significant difference was detected in pain reduction between the groups (p=0.576). Protraction of the shoulder (p<0.0001), forward head posture (p<0/0001) and mid thoracic curvature (p<0.0001) revealed a significant improvement in the ET group. Apparent changes occurred in scapular rotation and symmetry in both groups but no significant differences were observed between the two groups (respectively; p=0.183, p=0.578). Conclusion: The scapular stabilization based exercise intervention was successful in increasing shoulder range, decreasing forward head and shoulder postures and Pectoralis minor flexibility.
Journal of Rehabilitation Medicine, 2008
Objective: To determine variables among glenohumeral elevation and 3-dimensional scapular rotations that are related to shoulder function as assessed by the Disability of the Arm, Shoulder and Hand-Disability/Symptom (DASH-D/S) scale. Design: Prospective, cross-sectional study. Patients: Eighty-eight patients with shoulder pain and limited range of motion were included. Methods: Each patient performed 2 full active range of motion activities, forward flexion and abduction, and 2 activities of daily living, combing hair and simulating washing the back. Glenohumeral elevation and scapular rotations were measured by the Polhemus Fastrak electromagnetic system. Results: On multiple regression analysis, glenohumeral elevation in combing hair and scapular lateral rotation in both abduction and simulating washing the back were the best predictors of shoulder function and explained 39.7% of the variance of the DASH-D/S score. Conclusion: These findings support the classical rehabilitation of the shoulder based on glenohumeral elevation and suggest the importance of attention paid to scapular lateral rotation.