DEFINITION OF THE KNEE PHENOTYPE IN THE UKRAINIAN POPULATION BASED ON THE CPAK CLASSIFICATION
DOI:
https://doi.org/10.15674/0030-59872026119-26Keywords:
Knee joint, alignment, CPAK, aHKA, JLO, knee joint phenotypesAbstract
Native coronal alignment of the knee joint demonstrates marked individual variability, which influences total knee arthroplasty planning and functional outcomes. The CPAK classification allows systematization of these anatomical variations based on the parameters aHKA and JLO. Although CPAK phenotypes have been described in several populations, data regarding the Ukrainian population have so far been lacking. Objective. To determine the characteristics of native lower-limb alignment and CPAK phenotypes of the knee joint in the Ukrainian population. Methods. A total of 500 full-length standing radiographs of the lower limbs were analyzed: 300 in the healthy group and 200 in the group with Kellgren-Lawrence grade III–IV osteoarthritis. LDFA and MPTA were measured, aHKA and JLO were calculated in accordance with CPAK principles, and knees were subsequently classified within the 3×3 CPAK matrix. Results. In the healthy group, the most common CPAK phenotypes were type II (24.7 %), type I (21.7 %), and type V (21.0 %). Neutral aHKA was observed in 47.3 %, varus in 39.3 %, and valgus in 13.3 %. The most frequent JLO orientation was apex distal (50.3 %). In sex-specific subgroups, type II predominated in males (28 %) and type V in females (25 %). In the osteoarthritis group, varus aHKA values predominated (58 %), with CPAK phenotypes I (35.5 %), IV (22 %), and II (19.5 %) being most common. Conclusions. This study describes for the first time the distribution of CPAK phenotypes of the knee joint in the Ukrainian population. Among healthy individuals, CPAK phenotypes I, II, and V were most prevalent, with neutral alignment observed in 47 %. In patients with grade III–IV osteoarthritis, a marked shift toward varus alignment was noted, with varus phenotypes accounting for 58 %, whereas neutral phenotypes were observed in only 34 %. These findings reflect population specific patterns of native coronal knee alignment and may serve as a basis for further research into the clinical relevance of CPAK phenotypes and their impact on outcomes of total knee arthroplasty.
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Copyright (c) 2026 Mykola Moroz, Roman Kozak, Oleg Kostogryz, Yrij Kostogryz, Mykola Kyrylenko
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