3D Biometrics for Hindfoot Alignment Using Weightbearing CT

Area of Science:

• Orthopedics
• Radiology
• Biomedical Engineering

Background:

• Traditional 2D radiography for hindfoot alignment is prone to bias.
• Weightbearing computed tomography (WBCT) offers a more accurate imaging modality.
• A novel 3D biometric tool, the Foot and Ankle Offset (FAO), was developed.

Purpose of the Study:

• To introduce and validate the Foot and Ankle Offset (FAO) as a 3D biometric tool for hindfoot alignment.
• To assess the distribution of FAO values in normal, varus, and valgus hindfoot alignments.
• To compare the efficacy of 3D biometrics with existing 2D methods in WBCT.

Main Methods:

• Retrospective analysis of 135 weightbearing computed tomography (WBCT) datasets.
• Utilized the TALAS system to process 3D coordinates of key anatomical landmarks.
• Calculated the Foot and Ankle Offset (FAO) for each dataset and assessed inter- and intraobserver reliability.

Main Results:

• Statistically significant differences in FAO values were found among normal (2.3% ± 2.9%), varus (-11.6% ± 6.9%), and valgus (11.4% ± 5.7%) groups (P < .001).
• The distribution of FAO in the normal population followed a Gaussian pattern.
• High inter- and intraobserver reliability (0.99 and 0.97, respectively) were achieved.

Conclusions:

• The Foot and Ankle Offset (FAO) is an efficient 3D tool for measuring hindfoot alignment using WBCT.
• This study pioneers the use of 3D biometrics for hindfoot alignment assessment.
• The FAO provides a precise and semiautomatic method for evaluating hindfoot alignment, overcoming limitations of 2D techniques.