3D foot and ankle radiographic measurement toolbox

Two-dimensional radiographic measurements remain the clinical standard for evaluating foot and ankle deformities, despite increasing use of three-dimensional weightbearing computed tomography (WBCT). While WBCT enables improved visualization of osseous relationships under static load, translation of familiar two-dimensional radiographic metrics into three-dimensional imaging environments has been limited by manual workflows and a lack of standardized computational frameworks. To address this gap, we developed the three-dimensional Foot and Ankle Radiographic Measurements (3D FARM) toolbox to automatically compute clinically relevant radiographic measurements from bone models. WBCT scans from 180 adult feet across six clinical groups (rectus, cavus, planus, Charcot-Marie-Tooth, progressive collapsing foot deformity, and tibiotalar/subtalar osteoarthritis) were analyzed. Fourteen bones per foot were segmented using both semi-automatic and manual methods. The 3D FARM toolbox automatically computes 20 commonly used radiographic measurements using anatomically defined coordinate systems. Agreement between segmentation methods was evaluated using intraclass correlation coefficients and mean bias. Measurements from reference manual segmentations were used to generate group-specific reference values. Agreement between semi-automatic and manual segmentations was excellent for 18 of 20 measurements, with the remaining measurements demonstrating good to moderate agreement. Mean bias across measurements was minimal. Group-specific reference values demonstrated distinct distributions across pathologies and aligned qualitatively with published radiographic measurements. The 3D FARM toolbox enables reproducible, automated extraction of clinically familiar radiographic measurements from WBCT data. Strong agreement with manual segmentation and establishment of adult pathology-specific reference values support its use as a standardized framework for three-dimensional foot and ankle deformity assessment.