A new method for evaluating ankle foot orthosis characteristics: BRUCE

Area of Science:

• Biomechanics
• Orthotics and Prosthetics
• Gait Analysis

Background:

• Mechanical characteristics of ankle-foot orthoses (AFOs), including stiffness and neutral angles, are crucial for pathological gait but rarely quantified.
• Understanding these properties is essential for optimizing AFO function and patient outcomes.

Purpose of the Study:

• To introduce a novel device, BRUCE, designed to quantify the mechanical characteristics of AFOs.
• To assess the reliability of BRUCE in measuring ankle and metatarsal-phalangeal (MTP) joint stiffness and neutral angles.

Main Methods:

• BRUCE utilizes a replicated human leg model to manually measure AFO joint configuration and forces.
• Linear fitting is employed to determine neutral angles and stiffnesses around the ankle and MTP joints.
• Reliability was evaluated through repeated measurements of four AFOs, assessing inter-session, intra-session, and inter-observer variability.

Main Results:

• Ankle and MTP stiffness measurements demonstrated very high reliability (ICC=0.98-1.00).
• Ankle and MTP neutral angle measurements showed reasonable reliability (ICC=0.79-0.92), with inter-observer differences being a key factor.
• Excellent reliability for neutral angles was achieved with a single tester (ICC=0.99-0.99).

Conclusions:

• The BRUCE device provides reliable quantification of AFO mechanical properties.
• Objective data on AFO characteristics can enhance understanding of their role in correcting pathological gait.
• Improved AFO prescription based on objective data is expected to maximize functional benefits for patients.