Toward an Integrated Perspective Regarding Clinically Significant Labral Injuries in Overhead Throwing Athletes: Form Follows Function

Abstract

Inconsistent outcomes of treatment of labral injuries in the overhead athlete suggest that deficiencies exist in the current knowledge about the roles of the labrum in overhead throwing athletes. These may include inadequate knowledge of labral anatomy and optimum glenohumeral joint (GHJ) mechanics, inadequate knowledge of the pathoanatomy and pathomechanics that create the clinical dysfunction and symptoms, or use of nonanatomic surgical techniques. These deficiencies suggest that a different perspective regarding labral anatomy and GHJ mechanics may provide a basis for examination and guidance for further scholarship and treatment. This perspective is based on the principle of form follows function, which states that the form, the shape or structure of an object, should be based on its intended function, or purpose, and can be utilized to address these deficiencies. It integrates anatomy/form and mechanics/function to provide more effective knowledge and resources for evaluation and treatment. Based on this perspective, this clinical commentary will review and discuss the mechanical function of the GHJ—to optimize task-specific ball-and-socket kinematics, concavity/compression, and dynamic GHJ stability in the overhead throwing athlete; the form of the glenoid labrum, its 3-component mechanical anatomy, and associated biceps tendon–labral complex, which exists to achieve that function; and the demonstrated alterations to the form that result in alteration of function. Alterations to the form, representing various types of labral injury, produce mechanical consequences in GHJ kinematics and contact pressures that can be associated with clinical symptoms and dysfunction. Surgical techniques that address restoring and optimizing the form by re-creating the 3-component mechanical anatomy have been demonstrated to restore the joint kinematics and contact pressures to the intact state. This perspective also provides implications regarding evaluation techniques and treatment guidelines and may serve to provide insights into the development of more effective techniques for restoration of the form that can optimize the function.