CORONAL PLANE ALIGNMENT OF THE KNEE (CPAK) CLASSIFICATION AND PHENOTYPING

A PERSONALIZED APPROACH TO IMPROVING FUNCTIONAL OUTCOMES IN TOTAL KNEE ARTHROPLASTY

Abstract

Summary: The CPAK (Coronal Plane Alignment of the Knee) classification is an innovative system for phenotyping coronal-plane knee alignment, introduced by MacDessi and colleagues in 2021. It extends the traditional radiographic description by mathematically reconstructing the patient’s prearthritic anatomy using the arithmetic HKA (aHKA) and joint line obliquity (JLO). The system stratifies patients into nine phenotypes, with only 15-20% of the population exhibiting a truly neutral phenotype (Type V). This article is the first in the Bulgarian medical literature to present the CPAK classification and its clinical application. Based on our clinical experience and the international literature, we outline the advantages of kinematic alignment compared with conventional mechanical alignment in patients with different phenotypes.⁶

Keywords: CPAK classification, kinematic alignment, total knee arthroplasty, phenotyping, arithmetic HKA, joint line obliquity