Scapular positioning and movement in unimpaired shoulders, shoulder impingement syndrome, and glenohumeral instability

Abstract

The purpose of this manuscript is to review the knowledge of scapular positioning at rest and scapular movement in different anatomic planes in asymptomatic subjects and patients with shoulder impingement syndrome (SIS) and glenohumeral shoulder instability. We reviewed the literature for all biomechanical and kinematic studies using keywords for impingement syndrome, shoulder instability, and scapular movement published in peer reviewed journal. Based on the predefined inclusion and exclusion criteria, 30 articles were selected for inclusion in the review. The literature is inconsistent regarding the scapular resting position. At rest, the scapula is positioned approximately horizontal, 35° of internal rotation and 10° anterior tilt. During shoulder elevation, most researchers agree that the scapula tilts posteriorly and rotates both upward and externally. It appears that during shoulder elevation, patients with SIS demonstrate a decreased upward scapular rotation, a decreased posterior tilt, and a decrease in external rotation. In patients with glenohumeral shoulder instability, a decreased scapular upward rotation and increased internal rotation is seen. This literature overview provides clinicians with insight into scapular kinematics in unimpaired shoulders and shoulders with impingement syndrome and instability.

Confiabilidade da avaliação da orientação e posição de repouso da escápula de indivíduos saudáveis e sedentários com o sistema eletromagnético de aquisição de dados

“…Although it was not possible to compare findings of this study with those previously reported in literature, studies on the reliability of measures of the dynamic movements of shoulder with the same system also found reliability results from good to excellent and SEM values similar to those shown here 9,13,14 .…”

“…Regarding the scapular position in relation to the thorax during maintenance of ortostatia, a variety of results can be found in literature 3,4,9 . The present study found that scapula of dominant limb is at approximately 4° of upward rotation, 31° of medial rotation and 10° of anterior tilt.…”

“…Positioning and orientation of the scapula on thorax are important to centralize the humeral head and base for normal function of shoulder joint complex during daily and sport activities [5][6][7]9 . Resting scapular position may be influenced by thorax shape, muscle activity and anatomic variations of acromioclavicular joint 7,9,13 . Moreover, many muscles are inserted on scapula and therefore its resting position influences the length-tension relationship and the efficiency of these muscles 7,12 .…”

“…Assessment of scapular positioning is a theme has been emphasized in scientific literature [1][2][3][4][5][6][7][8][9][10][11] . Positioning and orientation of the scapula on thorax are important to centralize the humeral head and base for normal function of shoulder joint complex during daily and sport activities [5][6][7]9 .…”

Influence of shoulder pain on muscle function: implications for the assessment and therapy of shoulder disorders

“…For instance, a lack of posterior tilting of the scapula has frequently been associated with the incidence of shoulder impingement symptoms. It is hypothesized that a reduced scapular posterior tilt reduces the subacromial space and thus potentially creates soft tissue impingement (chronic nociception) (Struyf et al 2011a). There is moderate evidence that the upper trapezius shows increased activity among patients suffering from shoulder impingement symptoms, and the lower trapezius Fig.…”