Revisiting terminology: The transition from 'functional alignment' to 'functional knee positioning'.

Abstract

Functional alignment (FA), now proposed to be termed Functional Knee Positioning (FKPos), is a modern, patient-specific approach to total knee arthroplasty (TKA) that emphasises a three-dimensional (3D) methodology. This approach integrates 3D bony anatomy, mediolateral laxities in extension and flexion, and anterior compartment geometry and laxity to achieve personalised implant positioning and has evolved thanks to the development of advanced surgical aids, such as robotics. The term "Functional Alignment" inadequately captures the 3D nature of the technique, which leverages robotic systems to dynamically optimise patello-femoral (PF) and tibio-femoral (TF) soft tissue balance while preserving the native ligamentous structure, often referred to as the knee's 'DNA'. FKPos highlights the biomechanical decoupling of the PF and TF joints, ensuring proper PF and TF kinematics and addressing unique anatomical and alignment variations. Clinical outcomes for FKPos have demonstrated improved functional recovery, patient satisfaction and reduced complications compared to traditional alignment methods. Adopting the term FKPos more accurately represents the holistic and personalised nature of this innovative surgical approach to TKA.