Content validation of the progressive collapsing foot deformity classification

Objective: The aim of this study was to validate the content accuracy of the PCFD classification. Methods: A survey-based study distributed through international foot and ankle programs among surgeons with vast experience in practice to analyze the terminology and interpretations used in the PCFD classification. A returned survey with completion of all questions filled out was considered a valid record. Descriptive statistical analysis was applied using SAS version 9.4 for data processing, statistical analysis, and visualization. Results: Eighty-two valid returned surveys from surgeons in 22 countries with a mean of 16 years in clinical practice were included. Among them, 80.5% of the participants considered the PCFD classification helpful in guiding decision-making, 79.3% thought it helped facilitate diagnosis and documentation, 58.5% found it easy to use, 30.5% were unlikely to use the classification, and 29.3% noted that the interpretation of the classification was not clear. Regarding the accuracy, clarity, and clinical relevance of terminology, 42.7% had difficulty in using increased foot and ankle offset, 35.4% had difficulty in using increased hindfoot moment arm, 19.5% found peritalar subluxation not clear, 13.4% found the term sinus tarsi impingement an unclear description, and 8.5% found forefoot varus difficult to diagnose. Conclusions: This international survey-based study provides readers with insights into the content of the PCFD classification. The findings indicate that some terminologies used in the PCFD classification are not universally understood. The authors recommend that modifications may be beneficial to enhance the accuracy and user-friendliness of the PCFD classification. Level of Evidence II; Retrospective study.