ArticleJournal of experimental orthopaedics2025
Coronal Plane Alignment of the Knee (CPAK) distribution in a diverse Asian population: Influence of ethnicity, sex and bilaterality.
Article in Journal of experimental orthopaedics, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 6 papers.
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Who cites it
6 citing papers in PubMed.
- CPAK classification shows limited side-to-side agreement and limited reliability as a standalone surrogate for constitutional alignment in rheumatoid arthritis knees.Journal of experimental orthopaedics · 2026Article
- Posterior tibial slope accuracy in robotic-assisted TKA: a risk factor analysis focusing on CPAK phenotypes.Journal of robotic surgery · 2026Article
- Deep Learning-Based Full-Process Automatic CPAK Classification System and Its Application in the Analysis of Alignment Outcomes Before and After Knee Arthroplasty.Diagnostics (Basel, Switzerland) · 2026Article
- Reliability of the CPAK classification assessed on long-leg X-rays in patients undergoing total knee arthroplasty.Arthroplasty (London, England) · 2026Article
- Restricted kinematic total knee arthroplasty provided better functional outcomes and higher satisfaction rates for Asians of genu varum with apex distal joint line over unrestricted kinematic total knee arthroplasty.Arthroplasty (London, England) · 2025Article
- Coronal Plane Alignment of the Knee (CPAK) distribution in a diverse Asian population: Influence of ethnicity, sex and bilaterality.Journal of experimental orthopaedics · 2025Article
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10 authors.
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Abstract
Purpose: In total knee arthroplasty (TKA), it remains unclear which patients benefit from correction versus restoration of native knee alignment. The Coronal Plane Alignment of the Knee (CPAK) classification system was introduced in 2021 to describe native alignment, helping to characterise the effect of different TKA alignment techniques. This study aims to describe CPAK in an ethnically diverse population and characterise the relationship between CPAK and ethnicity, as well as the bilaterality of osteoarthritis and other patient factors. Methods: 503 primary TKAs were performed in a large tertiary institution in Singapore from 2014 to 2021. Pre-operative anteroposterior knee radiographs were collected for 441 procedures-all had ethnicity, age, sex and body mass index data. The medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA) were measured with good inter-observer correlation. Knees were then classified into nine CPAK categories based on arithmetic hip-knee-ankle (aHKA) angle and joint line obliquity (JLO). Results: 77% of the cohort were apex-distal (CPAK 1, 2 and 3), and 59% were varus (CPAK 1, 4 and 7); 44% were CPAK 1 (varus + apex-distal). Chinese and Indian knees followed near-identical patterns: CPAK 1 (46%) > CPAK 2 (20%) > CPAK 4 (15%). Malay knees had significantly fewer CPAK 1 ( Conclusion: Malay knees are less likely to be CPAK-1; this novel finding may explain ethnic differences in TKA outcomes described in the literature. Less than half of the bilateral knees had the same CPAK category bilaterally. The implications of this bilateral CPAK incongruence are unclear and require further study. Level of Evidence: Level II, prospective cohort study.
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