Khalifa AA, Moustafa M, Lemma S, Fayez M, Abdelaal AM, Fadle AA. Coronal plane alignment of the knee phenotypes and ankle joint coronal plane alignment patterns in Egyptian population. World J Orthop 2026; 17(1): 111824 [DOI: 10.5312/wjo.v17.i1.111824]
Corresponding Author of This Article
Ahmed A Khalifa, MD, Assistant Professor, FRCS, Department of Orthopaedics, Qena Faculty of Medicine and University Hospital, South Valley University, Kilo 6 Qena-Safaga Highway, Qena 83523, Egypt. ahmed_adel0391@med.svu.edu.eg
Research Domain of This Article
Orthopedics
Article-Type of This Article
Retrospective Study
Open-Access Policy of This Article
This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
World J Orthop. Jan 18, 2026; 17(1): 111824 Published online Jan 18, 2026. doi: 10.5312/wjo.v17.i1.111824
Coronal plane alignment of the knee phenotypes and ankle joint coronal plane alignment patterns in Egyptian population
Ahmed A Khalifa, Mohamed Moustafa, Shikuria Lemma, Mostafa Fayez, Ahmed M Abdelaal, Amr A Fadle
Ahmed A Khalifa, Department of Orthopaedics, Qena Faculty of Medicine and University Hospital, South Valley University, Qena 83523, Egypt
Mohamed Moustafa, Mostafa Fayez, Ahmed M Abdelaal, Amr A Fadle, Department of Orthopedic Surgery and Traumatology, Assiut University Hospital, Assiut 71515, Egypt
Shikuria Lemma, Department of Orthopaedics, Black Lion Specialized Hospital, Addis Ababa 1165, Ethiopia
Author contributions: Khalifa AA carried out the study conception and design; Khalifa AA, Fayez M, Lemma S, and Moustafa M performed data acquisition, assessment, literature search, and prepared the images and tables; Fadle AA and Lemma S performed the measurements; Khalifa AA carried out the statistical analysis; Khalifa AA, Abdelaal MA, and Fadle AA drafted the manuscript; Abdelaal AM and Khalifa AA did the critical revision. All authors read, discussed, and approved the final manuscript.
Institutional review board statement: This study was approved by Institutional Review Board of Faculty of Medicine in Assiut University, No. 04-2024-300470.
Informed consent statement: This study was conducted retrospectively using anonymized radiographic data. No patient-identifiable information was collected or reported, and no direct patient contact occurred. Therefore, the requirement for informed consent was waived.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
Data sharing statement: All the data are included within the manuscript; however, the raw data could be provided and shared upon a written request sent to the corresponding author.
Open Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Ahmed A Khalifa, MD, Assistant Professor, FRCS, Department of Orthopaedics, Qena Faculty of Medicine and University Hospital, South Valley University, Kilo 6 Qena-Safaga Highway, Qena 83523, Egypt. ahmed_adel0391@med.svu.edu.eg
Received: July 10, 2025 Revised: August 24, 2025 Accepted: November 13, 2025 Published online: January 18, 2026 Processing time: 183 Days and 12.6 Hours
Abstract
BACKGROUND
In an era leaning toward a personalized alignment of total knee arthroplasty, coronal plane alignment of the knee (CPAK) phenotypes for each population are studied; furthermore, other possible variables affecting the alignment, such as ankle joint alignment, should be considered.
AIM
To determine CPAK distribution in the North African (Egyptian) population with knee osteoarthritis and to assess ankle joint line orientation (AJLO) adaptations across different CPAK types.
METHODS
A cross-sectional study was conducted on patients with primary knee osteoarthritis and normal ankle joints. Radiographic parameters included the mechanical lateral distal femoral angle, medial proximal tibial angle, and the derived calculations of joint line obliquity (JLO) and arithmetic hip-knee-ankle angle (aHKA). The tibial plafond horizontal angle (TPHA) was used for AJLO assessment, where 0° is neutral (type N), < 0° is varus (type A), and > 0° is valgus (type B). The nine CPAK types were further divided into 27 subtypes after incorporating the three AJLO types.
RESULTS
A total of 527 patients (1054 knees) were included for CPAK classification, and 435 patients (870 knees and ankles) for AJLO assessment. The mean age was 57.2 ± 7.8 years, with 79.5% females. Most knees (76.4%) demonstrated varus alignment (mean aHKA was -5.51° ± 4.84°) and apex distal JLO (55.3%) (mean JLO was 176.43° ± 4.53°). CPAK types I (44.3%), IV (28.6%), and II (10%) were the most common. Regarding AJLO, 70.2% of ankles exhibited varus orientation (mean TPHA was -5.21° ± 6.45°). The most frequent combined subtypes were CPAK type I-A (33.7%), IV-A (21.5%), and I-N (6.9%). A significant positive correlation was found between the TPHA and aHKA (r = 0.40, P < 0.001).
CONCLUSION
In this North African cohort, varus knee alignment with apex distal JLO and varus AJLO predominated. CPAK types I, IV, and II were the most common types, while subtypes I-A, IV-A, and I-N were commonly occurring after incorporating AJLO types; furthermore, the AJLO was significantly correlated to aHKA.
Core Tip: We consider the current study one of the few studies that have investigated the coronal plane alignment of the knee in a North African population; furthermore, adding subtypes based on the ankle joint line orientation was not previously proposed. After evaluating 527 patients (1054 knees), we found that most knees demonstrated varus alignment (76.4%) and an apex distal joint line obliquity (55.3%). Understanding the coronal plane alignment of the knee classification in our knee osteoarthritis population will help surgeons who are willing to adopt a more personalized total knee arthroplasty alignment approach; furthermore, the added subtypes based on the ankle joint line orientation should be considered during preoperative planning.
