A Computational Study of Complex Varus Instability of the Human Elbow Joint

摘要

The intact human elbow joint is one of the most inherently stable joints of the body with stability conferred through a complex interplay between highly congruous osseous constraints, capsuloligamentous constraints, and active muscle contractions. [1, 2] Deficits in any of these structures can create instabilities that impede normal joint function.When considering losses in varus stability specifically, the relative importance of a number of structures has been the subject of ongoing biomechanical research. Chief among these are the coronoid process of the ulna (CP), the radial head (RH), and the lateral ulnar collateral ligament (LUCL). Graduated resections of the coronoid process performed in cadavera suggest that the structure is the predominant constraint to varus displacement at high flexion angles. [1, 3] However, at lower angles of flexion, the intact coronoid process alone only accounts for approximately half of the joint's resistance to varus, with the remainder being attributed to the LUCL and RH. Through the development of a rigid body kinematic model of the elbow joint, it was our aim to elucidate the mechanism through which these three structures provide varus stability to the elbow joint as well as provide a means for quantifying various physiological parameters that are difficult or impractical to measure experimentally. To that end, previously validated elbow computational model attributes were expanded and combined with novel computational setups to provide quantitative measures of varus resisting load which were then validated against published cadaveric experimentation. [3-5]