Ahmet Şenel1, Murat Eren1, Selman Sert1, Tahsin Gürpınar2, Engin Çarkçı1, Barış Polat3

1Department of Orthopedics and Traumatology, Istanbul Training and Research Hospital, Istanbul, Türkiye
2Department of Orthopedics and Traumatology, Inmotion Orthopaedics, Canberra, Australia
3Department of Orthopedics and Traumatology, Dr. Burhan Nalbantoğlu State Hospital, Nicosia, Cyprus

Keywords: Coronal Plane Alignment of the Knee classification, knee alignment, knee arthroplasty, Turkish population.


Objectives: This study aimed to phenotype healthy individuals and patients with arthritic knees in the Turkish population according to the Coronal Plane Alignment of the Knee (CPAK) classification.

Patients and methods: The retrospective cross-sectional study included 207 healthy individuals (109 males, 98 females; mean age: 32.9±8.4 years; range, 20 to 45 years) with a total of 414 knees (Group 1) and 296 patients (155 females, 141 males; mean age: 54.5±7.9 years; range, 43 to 80 years) with a total of 408 arthritic knees (Group 2) who met the inclusion criteria and underwent evaluation using digital long-leg radiographs between January 2019 and July 2023. Mechanical lateral distal femoral angle and medial proximal tibial angle were measured. Subsequently, the arithmetic hip-knee-ankle angle (aHKA) and joint line obliquity (JLO) were calculated. Based on the results obtained, participants in both groups were categorized according to the CPAK classification.

Results: In Group 1, the mean aHKA was 0.3°±2.5°, and the mean JLO was 175.2°±3.5°. In Group 2, the mean aHKA was -1.4°±3.9°, and the mean JLO was 174.6°±3.7°. The most common CPAK type in healthy individuals (Group 1) was type 2 (41.5%), followed by type 3 (14.7%) and type 1 (14.5%). In arthritis patients (Group 2), the most common CPAK type was type 2 (31.6%), followed by type 1 (28.2%) and type 3 (13.5%).

Conclusion: The CPAK classification serves as an important guide for categorizing lower extremity alignment. In the Turkish population, healthy individuals most commonly exhibited CPAK type 2, 3, and 1 alignments, respectively, while osteoarthritic patients predominantly displayed CPAK type 2, 1, and 3 alignments.

Citation: Şenel A, Eren M, Sert S, Gürpınar T, Çarkçı E, Polat B. Phenotyping of the Turkish population according to Coronal Plane Alignment of the Knee classification: A retrospective crosssectional study. Jt Dis Relat Surg 2024;35(1):194-201. doi: 10.52312/ jdrs.2023.1464.

Ethics Committee Approval

The study protocol was approved by the Istanbul Training and Research Hospital Clinical Research Ethics Committee (date: 15.09.2023, no: 229). The study was conducted in accordance with the principles of the Declaration of Helsinki.

Author Contributions

Idea/Concept: A.Ş., T.G.; Design: A.Ş., B.P.; Control/supervision: B.P., E.Ç.; Data collection: A.Ş., M.E., S.S.; Analysis: A.Ş., S.S.; Literature review: A.Ş., M.E., S.S.; Writing the article: A.Ş.; Critical review: B.P., T.G.

Conflict of Interest

The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.

Financial Disclosure

The authors received no financial support for the research and/or authorship of this article.

Data Sharing Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.