A systematic review of geographic differences in knee phenotypes based on the coronal plane alignment of the knee (CPAK) classification

Abstract Background The extent of geographic variation in knee phenotypes remains insufficiently documented. This systematic review intends to elucidate the regional disparities in the distribution of Coronal Plane Alignment of the Knee (CPAK) types across different geographic areas. Methods A syste...

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Main Authors: Guanghui Zhao, Chengyuan Ma, Zifan Luo, Jianbing Ma, Jianpeng Wang
Format: Article
Language:English
Published: BMC 2025-05-01
Series:Arthroplasty
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Online Access:https://doi.org/10.1186/s42836-025-00311-4
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author Guanghui Zhao
Chengyuan Ma
Zifan Luo
Jianbing Ma
Jianpeng Wang
author_facet Guanghui Zhao
Chengyuan Ma
Zifan Luo
Jianbing Ma
Jianpeng Wang
author_sort Guanghui Zhao
collection DOAJ
description Abstract Background The extent of geographic variation in knee phenotypes remains insufficiently documented. This systematic review intends to elucidate the regional disparities in the distribution of Coronal Plane Alignment of the Knee (CPAK) types across different geographic areas. Methods A systematic review of the literature was conducted in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies reporting the distribution of knee phenotypes, as classified by the CPAK system, in both healthy and arthritic populations, were included in the analysis. Based on the methods in the literature, the Hoy Risk of Bias Tool was used to assess the methodological quality of the included studies. To compare geographical differences in CPAK types among patients with arthritis, as well as healthy people. Results A total of 29 studies (28 retrospective and 1 prospective) were included in this review, encompassing 27,660 knees in 22,342 subjects. The methodological quality of the included studies was assessed using the Hoy Risk of Bias Tool, and the quality was good. Among the healthy knees (n = 4,082), CPAK type II was predominant in Europe (41.7%) and Asia (36.7%). In contrast, among arthritic knees (n = 21,632), CPAK type I was most common in Asia (51.3%), North America (32.8%), and Europe (32.8%), while CPAK type II was prevalent in Australia (29.3%) and Africa (25.5%). Notably, the proportions of CPAK type I (P < 0.001) and II (P = 0.002) knees varied significantly across different geographic regions among arthritic knees, while no significant differences were observed among healthy knees (P = 0.48, P = 0.305). Conclusion Significant variations in CPAK distributions among arthritic knees were observed across countries, while no significant differences were observed among healthy knees. Surgeons in different regions need to make individual surgical plans according to the CPAK types of patients. Video Abstract
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spelling doaj-art-8b209a8873fc4bc685b98072d53f46c32025-08-20T02:15:08ZengBMCArthroplasty2524-79482025-05-017111710.1186/s42836-025-00311-4A systematic review of geographic differences in knee phenotypes based on the coronal plane alignment of the knee (CPAK) classificationGuanghui Zhao0Chengyuan Ma1Zifan Luo2Jianbing Ma3Jianpeng Wang4Department of Joint Surgery, Honghui Hospital, Xi’an Jiaotong UniversityDepartment of Joint Surgery, Honghui Hospital, Xi’an Jiaotong UniversityDepartment of Joint Surgery, Honghui Hospital, Xi’an Jiaotong UniversityDepartment of Joint Surgery, Honghui Hospital, Xi’an Jiaotong UniversityDepartment of Joint Surgery, Honghui Hospital, Xi’an Jiaotong UniversityAbstract Background The extent of geographic variation in knee phenotypes remains insufficiently documented. This systematic review intends to elucidate the regional disparities in the distribution of Coronal Plane Alignment of the Knee (CPAK) types across different geographic areas. Methods A systematic review of the literature was conducted in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies reporting the distribution of knee phenotypes, as classified by the CPAK system, in both healthy and arthritic populations, were included in the analysis. Based on the methods in the literature, the Hoy Risk of Bias Tool was used to assess the methodological quality of the included studies. To compare geographical differences in CPAK types among patients with arthritis, as well as healthy people. Results A total of 29 studies (28 retrospective and 1 prospective) were included in this review, encompassing 27,660 knees in 22,342 subjects. The methodological quality of the included studies was assessed using the Hoy Risk of Bias Tool, and the quality was good. Among the healthy knees (n = 4,082), CPAK type II was predominant in Europe (41.7%) and Asia (36.7%). In contrast, among arthritic knees (n = 21,632), CPAK type I was most common in Asia (51.3%), North America (32.8%), and Europe (32.8%), while CPAK type II was prevalent in Australia (29.3%) and Africa (25.5%). Notably, the proportions of CPAK type I (P < 0.001) and II (P = 0.002) knees varied significantly across different geographic regions among arthritic knees, while no significant differences were observed among healthy knees (P = 0.48, P = 0.305). Conclusion Significant variations in CPAK distributions among arthritic knees were observed across countries, while no significant differences were observed among healthy knees. Surgeons in different regions need to make individual surgical plans according to the CPAK types of patients. Video Abstracthttps://doi.org/10.1186/s42836-025-00311-4Geographic differencesCoronal plane alignment knee classificationCPAKKnee phenotypesTotal knee arthroplasty
spellingShingle Guanghui Zhao
Chengyuan Ma
Zifan Luo
Jianbing Ma
Jianpeng Wang
A systematic review of geographic differences in knee phenotypes based on the coronal plane alignment of the knee (CPAK) classification
Arthroplasty
Geographic differences
Coronal plane alignment knee classification
CPAK
Knee phenotypes
Total knee arthroplasty
title A systematic review of geographic differences in knee phenotypes based on the coronal plane alignment of the knee (CPAK) classification
title_full A systematic review of geographic differences in knee phenotypes based on the coronal plane alignment of the knee (CPAK) classification
title_fullStr A systematic review of geographic differences in knee phenotypes based on the coronal plane alignment of the knee (CPAK) classification
title_full_unstemmed A systematic review of geographic differences in knee phenotypes based on the coronal plane alignment of the knee (CPAK) classification
title_short A systematic review of geographic differences in knee phenotypes based on the coronal plane alignment of the knee (CPAK) classification
title_sort systematic review of geographic differences in knee phenotypes based on the coronal plane alignment of the knee cpak classification
topic Geographic differences
Coronal plane alignment knee classification
CPAK
Knee phenotypes
Total knee arthroplasty
url https://doi.org/10.1186/s42836-025-00311-4
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