Kinematic and muscle activity characteristics of multidirectional shoulder joint instability during elevation

Abstract

Alterations of shoulder motion have been suggested to be associated with shoulder disorders. The objective of this study was to perform a 3D motion analysis (kinematic and electromyographical) of skeletal elements and muscles of shoulder joint in patients with multidirectional instability. Fifteen patients with multidirectional instability and 15 normal controls were investigated during continuous elevation in the scapular plane. The spatial coordinates of 16 anatomical points of the shoulder to determine kinematical parameters were quantified by an ultrasound-based motion analyzer. The activities of 12 muscles were measured by surface electromyography. Kinematic characteristics of motion were identified by scapulothoracic, glenohumeral, and humeral elevation angles; range of angles; scapulothoracic and glenohumeral rhythm; scapulothoracis, glenohumeral, and scapuloglenoid ratios; and the relative displacement between the rotation centers of the humerus and the scapula. The electromyographical characteristics of motion were modeled by the on-off pattern of muscle activity. Significant alterations in kinematical parameters were observed between patients and asymptomatic volunteers. The anterior, posterior, and inferior dislocations of shoulders with multidirectional instability could be properly modeled by the relative displacement between the rotation centers of the scapula and humerus. The shorter activity by m. pectoralis maior and all three parts of m. deltoideus and longer activity by m. supraspinatus, m. biceps brachii, and m. infraspinatus assure the centralization of the glenuhumeral head of a shoulder with multidirectional instability.

Clinical Assessment of Scapular Positioning in Patients with Shoulder Pain: State of the Art

“…There is evidence suggesting that scapular positioning is abnormal in patients with shoulder impingement syndrome, 2 symptoms of impingement, 10,11 atraumatic shoulder instability, 12 multidirectional shoulder joint instability, 13 and shoulder pain after neck dissection in cancer patients. 14,15 As no longitudinal study has yet been reported, it is not known if abnormal scapular positioning is a cause or consequence of shoulder pain or a secondary phenomenon caused by shoulder pain.…”

“…Inappropriate control of scapular positioning has frequently been linked to shoulder and neck disorders. [6][7][8][9] Moreover, scientific evidence supporting abnormal scapular positioning in patients with shoulder impingement syndrome, 2 symptoms of shoulder impingement, 10,11 atraumatic shoulder instability, 12 multidirectional shoulder joint instability, 13 and shoulder pain after neck dissection in patients with cancer 14,15 is accumulating. One study has shown that physiotherapy (primarily exercise therapy targeting the scapulothoracic muscles) was superior over no treatment in patients with subacromial impingement syndrome.…”

Intermediate biomechanical analysis of the effect of physiotherapy only compared with capsular shift and physiotherapy in multidirectional shoulder instability

“…We have previously described the detailed ultrasound-based shoulder kinematic and electromyographic measurement method. 8,9 Assessment parameters…”

Dynamic Three-Dimensional Ultrasound to Evaluate Scapular Movement Among Manual Wheelchair Users and Healthy Controls

“…8,9 With altered scapular kinematics being linked to a multitude of shoulder problems, the identification of changes in kinematics may allow for earlier detection of pathology and targeting of appropriate interventions. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] However, evaluation throughout the movement to maintain the distance between the acromion and humerus. 2.…”