Sex-specific patterns and limited bilateral symmetry in coronal knee alignment: Insights from the modified coronal plane alignment of the knee classification
Year: 2025
Type: article
Abstract: Objective The modified Coronal Plane Alignment of the Knee (CPAK) classification broadens the neutral boundaries of arithmetic hip–knee–ankle angle (aHKA) and introduces the concept of arithmetic joint line obliquity (aJLO). This study aimed to compare the original and modified CPAK classifications and to evaluate their impact on sex-specific distribution and bilateral asymmetry. Design A total of 673 adults (400 women) from the Iwaki Health Promotion Project were analyzed. The aHKA was calculated as follows: aHKA=medial proximal tibial angle (MPTA) – lateral distal femoral angle (LDFA). The aJLO was calculated as follows: 90° – (LDFA + MPTA)/2. The original CPAK classification categorized knees into nine phenotypes using the aHKA and JLO, with neutral boundaries defined as 0° ± 2°. The modified CPAK classification adopted a wider neutral boundary of 0° ± 3° for the aHKA and aJLO. Sex-stratified analyses and bilateral comparisons were conducted. Results The modified CPAK classification redistributed the phenotypes more evenly and increased the proportion of neutral–neutral type V knees to 23.2% (vs. only 3.1% with the original CPAK classification). Men more frequently showed varus phenotypes, particularly type I (20.8%), whereas women had a higher prevalence of neutral (25.8%) and valgus phenotypes. Bilateral knee analysis revealed strong correlations with aHKA ( r = 0.71, p < 0.001) and aJLO ( r = 0.73, p < 0.001). However, only 58% of individuals showed identical CPAK types bilaterally. Conclusions Compared with the original system, the modified CPAK classification offers a more balanced representation of coronal alignment in Asian knees.
Authors: Kyota Ishibashi, Ryoto Kura, Eiji Sasaki, Hikaru Kristi Ishibashi, Yuka Kimura, Yukiko Sakamoto, Eiichi Tsuda, Yasuyuki Ishibashi
Institution: Hirosaki University
Language: English
Subfield: Surgery
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $1,610
Awards: Epidemiological Study for Creating Diagnostic Criteria for Early Knee Osteoarthritis with High Prognostic Accuracy Using Artificial Intelligence, G2495941568, Cohort study and preventive approach for knee osteoarthrits and anterior cruciate ligament injury, G4917939509, G5230871073, G5257100210, Development of primary repair of anterior cruciate ligament injury using induced regenerative medicine, G8313764883, G8412045500, G8820372508, Establishing the new criteria for early knee osteoarthrits and its related biomarkers
OpenAlex ID: W7107869710