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Updated: Apr 14, 2026
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Automated Joint Space Detection Improves Bone Segmentation Accuracy
Published on: November 28, 2025
290
Surgically Relevant Knee Phenotypes: The Modified Coronal Plane Alignment of the Knee System-A Deep Learning-Based
Carmelo Burgio1, Karlos Zepeda1, Theofilos Karasavvidis1
1Department of Orthopaedic Surgery, Adult Reconstruction and Joint Replacement Service, Hospital for Special Surgery, New York, New York.
The Journal of Arthroplasty
|April 12, 2026
Summary
A modified coronal plane alignment of the knee (CPAK) classification system, utilizing deep learning, accurately categorizes knee phenotypes. This objective approach aids surgical decision-making for various knee alignments.
Area of Science:
- Orthopedics
- Biomedical Engineering
- Radiology
Background:
- The Coronal Plane Alignment of the Knee (CPAK) classification system, comprising nine phenotypes, faces challenges in definition consistency and surgical application clarity.
- A simplified, modified CPAK system is proposed to enhance accuracy and streamline surgical decision-making.
Purpose of the Study:
- To automate knee phenotyping using a deep learning (DL) model.
- To analyze the distribution of modified CPAK phenotypes in a large patient cohort.
Main Methods:
- A deep learning model was employed to analyze full-limb radiographs from 972 patients (1,944 knees).
- Measurements of the lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) were performed.
- Knee phenotypes were classified based on overall limb alignment (aHKA) and joint-line angles (LDFA, MPTA).
Main Results:
- Seven distinct phenotypes were identified, with five accounting for 99.2% of knees.
- The most common phenotypes included varus knees (26.9%), neutral knees (25.6%), and valgus knees (24.2%).
- Varus phenotypes were primarily tibial-driven (99.2%), while valgus phenotypes were femoral-driven (98.9%).
Conclusions:
- The modified CPAK system offers an objective and practical evaluation of knee alignment.
- This system provides a clear, surgically relevant assessment of coronal knee alignment by considering limb alignment and joint-line deformities.
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