The majority of shoulder injuries occur due to repetitive overhead movements, with baseball pitching being the most common mechanism for overuse injury. Before studying the treatment of these shoulder injuries, it is paramount that the health professional have an understanding of the etiology of and the underlying mechanisms for shoulder pathology. The act of overhead throwing is an eloquent full-body motion that requires tremendous coordination from the time of force generation to follow-through. The shoulder complex is a crucial component of the upper body kinetic chain as it transmits force created in the lower body to the arm and hand to produce velocity and accuracy with ball release. The focus of this article is on the biomechanics of the throwing motion, with emphasis on the kinematics of the shoulder. The established phases of the throwing motion will be reviewed in a stepwise manner and the contributions of osseous and soft-tissue structures to the successful completion of each phase will be discussed.

No abstract

No abstract

Multi-center clinical trials incorporating shoulder kinematics are currently uncommon. The absence of repeatability and limits of agreement (LoA) studies between different centers employing different motion analysis protocols has led to a lack dataset compatibility. Therefore, the aim of this work was to determine the repeatability and LoA between two shoulder kinematic protocols. The first one uses a scapula tracker (ST), the International Society of Biomechanics anatomical frames and an optoelectronic measurement system, and the second uses a spine tracker, the INAIL Shoulder and Elbow Outpatient protocol (ISEO) and an inertial and magnetic measurement system. First within-protocol repeatability for each approach was assessed on a group of 23 healthy subjects and compared with the literature. Then, the between-protocol agreement was evaluated. The within-protocol repeatability was similar for the ST ([Formula: see text] = 2.35°, [Formula: see text] = 0.97°, SEM = 2.5°) and ISEO ([Formula: see text] = 2.24°, [Formula: see text] = 0.97°, SEM = 2.3°) protocols and comparable with data from published literature. The between-protocol agreement analysis showed comparable scapula medio-lateral rotation measurements for up to 120° of flexion-extension and up to 100° of scapula plane ab-adduction. Scapula protraction-retraction measurements were in agreement for a smaller range of humeral elevation. The results of this study suggest comparable repeatability for the ST and ISEO protocols and between-protocol agreement for two scapula rotations. Different thresholds for repeatability and LoA may be adapted to suit different clinical hypotheses.

No abstract

Basic science study. Level III.

No abstract

No abstract