Analysis of a kinetic multi-segment foot model. Part I: Model repeatability and kinematic validity

Area of Science:

• Biomechanics
• Orthopedics
• Pediatric Gait Analysis

Background:

• Multi-segment foot models are crucial for understanding foot and ankle function in clinical and research settings.
• Existing kinetic models are often too complex for practical clinical application.
• There is a need for simpler kinetic models to enhance knowledge of foot and ankle biomechanics.

Purpose of the Study:

• To present a novel, simplified three-segment kinetic foot model.
• To thoroughly evaluate the performance and repeatability of this model during normal gait in pediatric participants.
• To analyze model reference frames, joint centers, joint translations, and segment rigidity.

Main Methods:

• A three-segment kinetic foot model was developed and evaluated.
• Repeatability was assessed using within-tester and between-tester analyses on 10 healthy pediatric participants.
• Kinematic parameters were measured on 17 additional healthy pediatric participants during normal gait.

Main Results:

• Repeatability errors were generally low (median < 3°) for most sagittal and transverse plane measures, particularly for the Hindfoot and Forefoot segments.
• The least repeatable orientations were the Hindfoot coronal plane and Hallux transverse plane.
• Joint translations were minimal (< 2mm), and segment rigidity analysis indicated rigid body behavior for the Shank and Hindfoot, though the Forefoot deviated in terminal stance/pre-swing.

Conclusions:

• The developed three-segment kinetic foot model shows promising repeatability for analyzing pediatric gait.
• The model's findings on joint translations and segment rigidity align with existing literature.
• This simplified kinetic model offers a viable approach for clinical and research applications in foot and ankle biomechanics.