Abstract
Conclusive evidence supporting a clinical difference between posterior-stabilized
(PS) and cruciate-retaining (CR) designs in total knee arthroplasty (TKA) does not
currently exist, despite both designs being used for decades. Proponents of PS designs
that employ a cam-and-post mechanism cite in vivo fluoroscopic data that demonstrate
improved posterior rollback; however, optimal rollback has never been correlated to
superior clinical outcomes. Recently, anterior-lipped and more conforming CR bearings,
such as ultracongruent, medial pivot, and dual-pivot designs, have been used to substitute
for the posterior cruciate ligament and obviate the need for the cam–post mechanism
of a traditional PS design. Advantages of avoiding a PS TKA include eliminating the
risk of box cut induced femoral condylar fracture, improving operative efficiency
by removing procedural steps, removing the articulation that is a source of wear,
postdeformation, breakage, or dislocation, and eliminating patellar clunk. Health
care reform efforts mandate cost reduction, and procedural efficiencies and minimizing
inventory through the removal of unnecessary bearing options foster that initiative.
Keywords
knee kinematics - cam–post - total knee arthroplasty - posterior-stabilized articulations
