{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T04:50:42Z","timestamp":1787028642816,"version":"build-2736575974"},"reference-count":42,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2024,2,6]],"date-time":"2024-02-06T00:00:00Z","timestamp":1707177600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JCM"],"abstract":"<jats:p>Background: Classifications of AAFD\/PCFD have evolved with an increased understanding of the pathology involved. A review of classification systems helps identify deficiencies and respective contributions to the evolution in understanding the classification of AAFD\/PCFD. Methods: Using multiple electronic database searches (Medline, PubMed) and Google search, original papers classifying AAFD\/PCFD were identified. Nine original papers were identified that met the inclusion criteria. Results: Johnson\u2019s original classification and multiple variants provided a significant leap in understanding and communicating the pathology but remained tibialis posterior tendon-focused. Drawbacks of these classifications include the implication of causality, linearity of progression through stages, an oversimplification of stage 2 deformity, and a failure to understand that multiple tendons react, not just tibialis posterior. Later classifications, such as the PCFD classification, are deformity-centric. Early ligament laxity\/instability in normal attitude feet and all stages of cavus feet can present with pain and instability with minor\/no deformity. These may not be captured in deformity-based classifications. The authors developed the \u2018Triple Classification\u2019 (TC) understanding that primary pathology is a progressive ligament failure\/laxity that presents as tendon reactivity, deformity, and painful impingement, variably manifested depending on starting foot morphology. In this classification, starting foot morphology is typed, ligament laxities are staged, and deformity is zoned. Conclusions: This review has used identified deficiencies within classification systems for AAFD\/PCFD to delink ligament laxity, deformity, and foot type and develop the \u2018Triple classification\u2019. Advantages of the TC may include representing foot types with no deformity, defining complex secondary instabilities, delinking foot types, tendon reactivity\/ligament instability, and deformity to represent these independently in a new classification system. Level of Evidence: Level V.<\/jats:p>","DOI":"10.3390\/jcm13040942","type":"journal-article","created":{"date-parts":[[2024,2,7]],"date-time":"2024-02-07T06:12:58Z","timestamp":1707286378000},"page":"942","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["Review of Classification Systems for Adult Acquired Flatfoot Deformity\/Progressive Collapsing Foot Deformity and the Novel Development of the Triple Classification Delinking Instability\/Deformity\/Reactivity and Foot Type"],"prefix":"10.3390","volume":"13","author":[{"given":"Chandra Seker","family":"Pasapula","sequence":"first","affiliation":[{"name":"The Queen Elizabeth Hospital Kings Lynn, NHS Foundation Trust, King\u2019s Lynn PE30 4ET, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Makhib Rashid","family":"Choudkhuri","sequence":"additional","affiliation":[{"name":"The Queen Elizabeth Hospital Kings Lynn, NHS Foundation Trust, King\u2019s Lynn PE30 4ET, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eva R. Gil","family":"Monz\u00f3","sequence":"additional","affiliation":[{"name":"Hospital Universitario Doctor Peset, 46017 Valencia, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vivek","family":"Dhukaram","sequence":"additional","affiliation":[{"name":"University Hospitals Coventry & Warwickshire, Coventry CV2 2DX, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sajid","family":"Shariff","sequence":"additional","affiliation":[{"name":"Medway Maritime Hospital, NHS Foundation Trust, Kent ME7 5NY, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vit\u0101lijs","family":"Pasterse","sequence":"additional","affiliation":[{"name":"Riga East Clinical University Hospital, LV-1038 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Douglas","family":"Richie","sequence":"additional","affiliation":[{"name":"California School of Podiatric Medicine, Samuel Merritt University, Oakland, CA 94609, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tamas","family":"Kobezda","sequence":"additional","affiliation":[{"name":"The Queen Elizabeth Hospital Kings Lynn, NHS Foundation Trust, King\u2019s Lynn PE30 4ET, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Georgios","family":"Solomou","sequence":"additional","affiliation":[{"name":"School of Clinical Medicine, University of Cambridge, Cambridge CB2 2EL, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Steven","family":"Cutts","sequence":"additional","affiliation":[{"name":"James Paget University Hospitals, NHS Foundation Trust, Great Yarmouth NR31 6LA, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,2,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"196","DOI":"10.1097\/00003086-198902000-00022","article-title":"Tibialis posterior tendon dysfunction","volume":"239","author":"Johnson","year":"1989","journal-title":"Clin. 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