BACKGROUND Despite the success of reverse shoulder arthroplasty (RSA) in treating patients with painful pseudoparalytic shoulders, instability is a common complication and currently the factors affecting stability are not well understood. The objective of this study was to investigate a number of factors as well as the interactions between factors to determine how they affect the stability of t...

Current reverse total shoulder arthroplasty prosthesis designs do not permit offset of the humerus in the sagittal plane. Posteriorly shifting the humerus has the theoretical benefit of lengthening the infraspinatus and teres minor muscles and their external rotation moment arms, thereby improving the tension and efficiency of each external rotator and subsequently requiring each muscle to prod...

Motor dysfunction is a major consequence after stroke and it is generally believed that the loss of motor ability is caused by the impairments in neural network that controls movement. To explore the abnormal mechanisms how the brain controls shoulder abduction and elbow flexion in “flexion synergy” following stroke, we used the functional corticomuscular coupling (FCMC) between the brain and t...

BACKGROUND Measuring range of movement is important in clinical shoulder assessment. Over the years, different techniques have been used to analyze upper limbs mobility. Smartphone image-based goniometer offers a noninvasive easy-to-use method of measuring arm abduction angle. However, the validity of this method has not been previously established. The purpose of this study was to investigate ...

There is a paucity of data in the literature on the restraining effects of the glenohumeral (GH) ligaments; cadaveric testing is one of the best methods for determining the function of these types of tissues. The aim of this work was to commission a custom-made six degrees of freedom (dof) joint loading apparatus and to establish a protocol for laxity testing of cadaveric shoulder specimens. Ni...

OBJECTIVES The Constant-Murley score (CS) has been used for more than 25 years to assess shoulder function. Strength by itself accounts for 25% of the total score. The measurement at 90° abduction seems to be sometimes limited by pain, particularly with tendinopathy or subacromial impingement. We compared the assessment of isometric strength in anterior forward flexion and abduction and its eff...

BACKGROUND Increased external rotation and decreased internal rotation have been noted to occur progressively in the throwing shoulder of baseball pitchers. HYPOTHESIS Proximal remodeling of the humerus contributes to the rotational asymmetry between shoulders in pitchers. STUDY DESIGN Descriptive anatomic study. METHODS Both shoulders of 19 male college baseball pitchers were evaluated a...

Objectives: The purpose of this study was to compare scapular kinematics during elevation phase of abduction, flexion, and scapular plane elevation phase between fifteen persons with shoulder impingement syndrome (SIS) and thirteen persons without it. Methods: Values of scapular kinematics include scapular superior and lateral translations, upward rotation, external rotation, and posterior t...

We studied 100 fresh human shoulders in cadavers (mean age 76 years), and the range of passive abduction (RPA) in 100 volunteers with normal shoulders and in 90 patients with instability of the joint, over a period of six years. The anatomical and clinical findings showed that passive abduction occurs within the glenohumeral joint only, is controlled by the inferior glenohumeral ligament and ha...

A comparison of electromyographic (EMG) activity of muscles between and within subjects, and during separate occasions of testing, requires normalization. The most common way for generating the reference level used for normalizing shoulder EMG data is with a maximum isometric voluntary contraction (MVIC). The purpose of this study was to develop a parsimonious set of standardized tests that gen...