measuring-3d-vivo-shoulder-kinematics-using-biplanar

Measuring 3D In-vivo Shoulder Kinematics using Biplanar Videoradiography

The shoulder is one of the human body's most complex joint systems, with motion occurring through the coordinated actions of four individual joints, ...

Henry Ford Health System

Decreased scapulothoracic upward rotation has been theorized to increase an individual's risk for rotator cuff compression by reducing the clearance for the tendons in the subacromial space (ie, subacromial proximities). However, the impact of decreased scapulothoracic upward rotation on subacromial proximities has not been tested during dynamic in vivo shoulder motion.

The Impact of Decreased Scapulothoracic Upward Rotation on Subacromial Proximities.

Asymptomatic Rotator Cuff Tears.

Alterations in glenohumeral and scapulothoracic kinematics have been theorized to contribute to rotator cuff pathology by impacting the magnitude of the subacromial space.

Shoulder kinematics impact subacromial proximities: a review of the literature.

Scapulothoracic upward rotation (UR) is an important shoulder complex motion allowing for a larger functional work space and improved glenohumeral muscle function. However, the kinematic mechanisms producing scapulothoracic UR remain unclear, limiting the understanding of normal and abnormal shoulder movements.

The Coupled Kinematics of Scapulothoracic Upward Rotation.

The rotator cuff is theorized to contribute to force couples required to produce glenohumeral kinematics. Impairment in these force couples would theoretically result in impaired ball-and-socket kinematics. Although less frequently used than traditional kinematic descriptors (e.g., Euler angles, joint translations), helical axes are capable of identifying alterations in ball-and-socket kinematics by quantifying the variability (i.e., dispersion) in axis orientation and position during motion. Consequently, assessing glenohumeral helical dispersion may provide indirect evidence of rotator cuff function. The purpose of this exploratory study was to determine the extent to which rotator cuff pathology is associated with alterations in ball-and-socket kinematics. Fifty-one participants were classified into one of five groups based on an assessment of the supraspinatus using diagnostic imaging: asymptomatic healthy, asymptomatic tendinosis, asymptomatic partial-thickness tear, asymptomatic full-thickness tear, symptomatic full-thickness tear. Glenohumeral kinematics were quantified during coronal plane abduction using a biplane x-ray system and described using instantaneous helical axes. The degree to which glenohumeral motion coincided with ball-and-socket kinematics was described using the angular and positional dispersion about the optimal helical axis and pivot, respectively. No statistically significant difference was observed between groups in angular dispersion. However, symptomatic individuals with a full-thickness supraspinatus tear had significantly more positional dispersion than asymptomatic individuals with a healthy supraspinatus or tendinosis. These findings suggest that symptomatic individuals with a full-thickness supraspinatus tear exhibit impaired ball-and-socket kinematics, which is believed to be associated with a disruption of the glenohumeral force couples.

Article	Year
The Impact of Decreased Scapulothoracic Upward Rotation on Subacromial Proximities. The Journal of orthopaedic and sports physical therapy\| PubMed ID: 30658048	2019
Asymptomatic Rotator Cuff Tears. JBJS reviews\| PubMed ID: 31246863	2019
Shoulder kinematics impact subacromial proximities: a review of the literature. Brazilian journal of physical therapy\| PubMed ID: 31377124	2020
The Coupled Kinematics of Scapulothoracic Upward Rotation. Physical therapy\| PubMed ID: 31696926	2020
Instantaneous helical axis estimation of glenohumeral kinematics: The impact of rotator cuff pathology. Journal of biomechanics\| PubMed ID: 32807327	2020

Rebekah L. Lawrence

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