Association Between Middle Facet Subluxation and Foot and Ankle Offset in Progressive Collapsing Foot Deformity

Abstract

Background: Subtalar middle facet (MF) subluxation was recognized as a reliable marker for progressive collapsing foot deformity (PCFD) diagnosis. Foot and Ankle Offset (FAO) is an established measurement, predictive of malalignment severity. The objective of this study was to assess the potential association between MF subluxation and FAO in PCFD patients. Methods: 56 individuals with flexible PCFD (74 feet) were assessed. Two blinded foot and ankle surgeons calculated MF uncoverage, MF incongruence, and FAO. Agreement was quantified using intraclass correlation coefficient (ICC). A multivariate regression analysis and partition prediction models were applied to assess relationship between values. Results: All ICCs were >0.80. MF subluxation and FAO were found to be correlated (rs = 0.56; P