Hindfoot alignment assessment by the foot-ankle offset: a diagnostic study.

Area of Science:

• Orthopedics
• Biomedical Engineering
• Radiology

Background:

• Foot-ankle offset (FAO) is a 3D biometric measurement of hindfoot alignment (HA) using weight-bearing computed tomography (WBCT).
• Investigating FAO distribution in a large patient cohort can identify thresholds for pathologies.
• This study hypothesizes that specific FAO values may indicate increased risk for associated conditions.

Purpose of the Study:

• To investigate the distribution of Foot-ankle offset (FAO) in a large patient cohort.
• To identify threshold FAO values associated with increased risk of valgus or varus pathologies.
• To establish a potential
• safe zone
• for hindfoot alignment.

Main Methods:

• Prospective, monocentric diagnostic study of 125 subjects (250 feet) using bilateral WBCT.
• Hindfoot alignment (HA) measured via FAO on 3D WBCT datasets and tibio-calcaneal angles (TCA) on 2D views.
• Receiver operating characteristic (ROC) curve analysis to determine threshold FAO values for predicting pathology risk.

Main Results:

• Mean FAO was 1.65% ± 4.72% and mean TCA was 4.15° ± 7.67°.
• Threshold FAO values of -1.64% (AUC=0.72) and 2.71% (AUC=0.93) predicted lateral and medial pathologies, respectively.
• A
• safe zone
• for FAO was identified between -1.64% and 2.71%.

Conclusions:

• Patients with FAO between -1.64% and 2.71% exhibit the lowest risk of degenerative foot and ankle pathology.
• This FAO range can serve as a target for patients undergoing realignment procedures.
• The identified FAO range provides a valuable metric for assessing hindfoot alignment and associated pathology risk.