ABSTRACT
At present, it is difficult to establish a unifying integrative approach in the study of glenohumeral stability
and upper extremity strength. The glenohumeral joint is the most mobile articulation of the human
body, involving interacting and interrelated geometric variables relating bones, muscles, and ligaments,
that needs further exploration and understanding. The purpose of the current study was to propose
a method of geometrical description of the glenoid fossa in order to deduce an unrecognized inter-
relationship between glenoid concavity and the deltoid attachment on the glenohumeral head position.
It supports the concept of a new biomechanical parameter, the dynamic glenohumeral stability index
proposed by Lee and An,16 which considers not only the force vectors generated by the deltoid muscle
but also the concavity compression mechanism. Recent analyses of the glenohumeral joint have not
focused on the contribution of geometric parameters like the shape of the glenoid fossa, radius of the
humerus, the attachment of the deltoideus lateral part in relation to the glenoid fossa, and the angular
measure of the articular surface of the humerus head.
