The Variable Axis Knee Prosthesis: A Legacy of Dr. David G. Murray

An important and often overlooked legacy and orthopaedic innovation of Dr. David G. Murray is the Variable Axis knee prosthesis. Conceptualized by Dr. Murray in 1972 and engineered over the ensuing 2 years, the unique "ball-in-socket" design of the prosthesis represented the first unconstrained cruciate-substituting knee prosthesis. Its metal-backed tibial component with modular polyethylene inserts of varying thicknesses and angular designs was also an innovative first and is a design feature that was incorporated into virtually all subsequent prosthetic knees. Released for clinical application in 1974, the Variable Axis knee prosthesis enjoyed over a decade of successful clinical use but was ultimately supplanted by the more anatomically configured Total Condylar-type designs.