Development of a Surrogate Biomodel for the Investigation of Clubfoot Bracing

Congenital talipes equinovarus (clubfoot) is a complex deformity of the lower extremity and foot occurring in 1/1000 live births. Regardless of treatment, whether conservative or surgical, clubfoot has a stubborn tendency to relapse, thus requiring postcorrection bracing. However, to date, there are no investigations specifically focused on clubfoot bracing from a bioengineering perspective. This study applied engineering principles to clubfoot bracing through construction of a surrogate biomodel. The surrogate was developed to represent an average 5-year-old human subject capable of biomechanical characteristics including joint articulation and kinematics. The components include skeleton, articulating joints, muscle-tendon systems, and ligaments. A protocol was developed to measure muscle-tendon tension in resting and braced positions of the surrogate. Measurement error ranged from 1% to 6% and was considered variance due to brace and investigator. In conclusion, this study shows that surrogate biomodeling is an accurate and repeatable method to investigate clubfoot bracing. The methodology is an effective means to evaluate wide ranging brace options and can be used to assist in future brace development and the tuning of brace parameters. Such patient-specific brace tuning may also lead to advanced braces that increase compliance.