Background and Purpose. Several factors such as posture, muscle force, range of motion, and scapular dysfunction are commonly believed to contribute to shoulder impingement. The purpose of this study was to compare 3-dimensional scapular kinematics, shoulder range of motion, shoulder muscle force, and posture in subjects with and without primary shoulder impingement syndrome. Subjects. Forty-five subjects with impingement syndrome were recruited and compared with 45 subjects without known pathology or impairments matched by age, sex, and hand dominance. Methods. Shoulder motion and thoracic spine posture were measured goniometrically, and force was measured with a dynamometer. An electromagnetic motion analysis system was used to capture shoulder kinematics during active elevation in both the sagittal and scapular planes as well as during external rotation with the arm at 90 degrees of elevation in the frontal plane. Results. The impingement group demonstrated slightly greater scapular upward rotation and clavicular elevation during flexion and slightly greater scapular posterior tilt and clavicular retraction during scapular-plane elevation compared with the control group. The impingement group demonstrated less range of motion and force in all directions compared with the control group. There were no differences in resting posture between the groups. Discussion and Conclusion. The kinematic differences found in subjects with impingement may represent scapulothoracic compensatory strategies for glenohumeral weakness or motion loss. The decreased range of motion and force found in subjects with impingement support rehabilitation approaches that focus on strengthening and restoring flexibility.

/pdf/shoulder-function-and-3-dimensional-scapular-kinematics-in-19ot5jn49x.pdf

Shoulder Function and 3-Dimensional Scapular Kinematics in People With and Without Shoulder Impingement Syndrome

Background and Purpose. A relationship between posture and impairment at the shoulder is theorized, but not supported by evidence. It is proposed that posture and impairment are not directly related, but linked by movement dysfunction. The purpose of this analysis was to explore the relationships among posture, pectoralis minor muscle length, and movement alterations at the shoulder. Subjects. Subjects who were asymptomatic for shoulder pathology were divided into 2 groups of 25 subjects each based on normalized pectoralis minor muscle resting length. Methods. Scapula orientation, thoracic kyphosis, and pectoralis minor muscle lengths were measured, and ratios and indexes of postural variables were calculated. All variables were analyzed for correlations and group differences. Results. Significant group differences were demonstrated for several posture variables, including thoracic spine kyphosis and scapular internal rotation. The distance from the sternal notch to the coracoid process demonstrated the highest correlation with pectoralis minor muscle length. Discussion and Conclusion. The findings indicate a relationship between posture and pectoralis minor muscle length and support a proposed model linking posture, an anatomical variable, movement dysfunction, and impairment. [Borstad JD. Resting position variables at the shoulder: evidence to support a posture-impairment association. Phys Ther . 2006;86:549–557.]

/pdf/resting-position-variables-at-the-shoulder-evidence-to-2awyxh0k28.pdf

Resting Position Variables at the Shoulder: Evidence to Support a Posture-Impairment Association

Objectives To examine the correction of posture, increase in strength and decrease in shoulder pain and dysfunction in varsity swimmers. Design and Setting Randomised clinical trial. Participants Twenty-eight National Collegiate Athletic Association division I varsity swimmers. Measurements Two testing sessions were conducted before and after an 8-week time period. Posture, strength and shoulder pain and function were assessed. Forward head angle was measured using a digital inclinometer, forward head translation was measured using a ruler and total scapular distance was measured with unmarked string. Average and peak values (N) of strength were measured with the hand-held dynamometer. The intervention subjects then participated in an 8-week exercise training programme to correct posture. The procedures were then repeated in the post-test. Results Signifi cant group by time interactions (p<0.05) were found in forward head angle and forward shoulder translation indicating a decrease in forward head angle and forward shoulder translation. Signifi cant main effects for time (p<0.05) were found in strength measures for all muscle groups indicating increased strength for shoulder girdle muscles tested. Conclusions The exercise intervention was successful at decreasing forward head and rounded shoulder postures in elite swimmers. This study supports the theoretical basis for clinical rehabilitation of posture and the shoulder.

/pdf/the-effects-of-an-exercise-intervention-on-forward-head-and-u8g5gkrhm6.pdf

The effects of an exercise intervention on forward head and rounded shoulder postures in elite swimmers

The overhead throwing motion is a complex activity that is achieved through activation of the kinetic chain. The kinetic chain refers to the linkage of multiple segments of the body that allows for transfer of forces and motion. The lower extremities and core provide a base of support, generating energy that is transferred eventually through the throwing arm and hand, resulting in release of the ball. The kinetic chain requires optimal anatomy, physiology, and mechanics and is involved in all 6 phases of overhead throwing: windup, stride, arm cocking, acceleration, deceleration, and follow-through. Breaks or deficits in the kinetic chain can lead to injury or decreased performance. Through an understanding of the mechanics and pathomechanics seen in each phase of throwing, the clinician can better evaluate and screen for potential kinetic chain deficits in the overhead throwing athlete. The purpose of this article is to review the biomechanics of the overhead throwing motion, the role of the kinetic chain in throwing, and the clinical evaluation and management of abnormal throwing mechanics and related injuries.

The Kinetic Chain Revisited: New Concepts on Throwing Mechanics and Injury.

The reliability of quantifying upright standing postures as a baseline diagnostic clinical tool

Clinicians often rely on visual inspection and descriptive terms to document a patient's forward shoulder posture. The purpose of this study was to assess the validity and intrarater reliability of four objective techniques to measure forward shoulder posture. Subjects were 25 males and 24 females. Subjects had a lateral cervical spine radiograph taken, from which the horizontal distance from the C7 spinous process to the anterior tip of the left anterior acromion process was measured. Subjects then proceeded twice through a random order of four measurements: the Baylor square, the double square, the Sahrmann technique, and scapular position. These results were then used to determine the intrarater reliability of each technique. Multiple regression analyses were performed on each measure's mean scores to determine both the correlation with and the predictive value for the radiographic measurement. The intraclass correlation coefficients for intrarater reliability ranged from .89 to .91. The correlation co...

https://www.jospt.org/doi/pdf/10.2519/jospt.1997.25.1.34

Lynne M. Mincey

Papers

Investigation of the Validity and Reliability of Four Objective Techniques for Measuring Forward Shoulder Posture