Diagnostic Accuracy of the Progressive Collapsing Foot Deformity (PCFD) Classification

Area of Science:

• Orthopedics
• Foot and Ankle Surgery
• Medical Classification Systems

Background:

• A new classification system, progressive collapsing foot deformity (PCFD), was proposed for flatfoot deformities.
• The PCFD system includes 2 stages and 5 classes to categorize complex flatfoot presentations.

Purpose of the Study:

• To validate the diagnostic accuracy of the proposed PCFD classification.
• To compare accuracy rates across different experience levels of foot and ankle specialists.

Main Methods:

• A survey-based study involving 13 fellowship programs.
• Participants (fellows, junior surgeons, senior surgeons) classified 20 flatfoot cases using PCFD.
• Diagnostic accuracy for overall, class, and stage were calculated and compared among groups.

Main Results:

• Overall diagnostic accuracy was 71.0%, class accuracy 78.3%, and stage accuracy 81.7%.
• Significant differences in overall and class accuracy were found between fellows and more experienced surgeons.
• Class B was overdiagnosed, Class D was underdiagnosed, with varying misdiagnosis rates for other classes.

Conclusions:

• The PCFD classification demonstrates fair overall diagnostic accuracy.
• Highest accuracy was observed for hindfoot valgus and ankle instability.
• Further validation is required for classes with lower diagnostic accuracy, such as midfoot/forefoot abduction and forefoot varus.