Selection criteria in posterior tibialis tendon dysfunction, adult acquired flatfoot and progressive collapsing foot deformity research: a scoping review protocol.

<ns5:p>Introduction Over the past decades, multiple classification systems have been used to describe a spectrum of painful adult-acquired flatfoot. Among the most widely used classifications and terminology are posterior tibial tendon dysfunction (PTTD), adult-acquired flatfoot deformity (AAFD), and progressive collapsing foot deformity (PCFD). Although classification systems have evolved considerably over time, participant selection criteria have not been standardized across studies. Consequently, substantial heterogeneity exists in how these conditions are defined and operationalized in the literature. This variability limits comparability across studies, contributes to inconsistencies in reported outcomes, and ultimately limits the advancement of this field. Objectives The purpose of this scoping review will be to map and characterize the participant selection criteria used in research involving PTTD, AAFD, and PCFD, and to describe the extent of methodological variation across literature. Inclusion criteria Eligible studies will include peer-reviewed qualitative, quantitative, and mixed-methods research involving adults diagnosed with PTTD, AAFD, or PCFD. Studies will be excluded if they include asymptomatic flatfoot. Methods A comprehensive search will be conducted in MEDLINE (PubMed), SPORTDiscus, CINAHL, Cochrane Library (CENTRAL), Physiotherapy Evidence Database (PEDro), Scopus, and Google Scholar. Two independent reviewers will perform study selection, with disagreements resolved by consensus or a third reviewer. Data will be extracted using a piloted standardized form and will include study characteristics, inclusion and exclusion criteria, and demographic variables. Findings will be synthesized using descriptive numerical summaries and narrative mapping. Discussion By systematically mapping participant selection criteria and demographic characteristics across studies, this scoping review will explore the extent of methodological variability in the PTTD, AAFD, and PCFD literature. The findings will inform future efforts aimed at improving standardization of selection criteria, thereby enhancing methodological consistency and comparability across studies investigating this spectrum of painful adult-acquired flatfoot disorders.</ns5:p>