Design and Fabrication of Mechanically Controlled Pedorthosis to Treat Congenital Talipes Equino Varus (CTEV)

Objectives: Clubfoot scientifically coined as Congenital Talipes Equino Varus (CTEV) is a deformity in which the afflicted foot appears to be rotated internally at the ankle and shape the subject to walk on the sides of their foot. To diagnose clubfoot deformity non-surgical technique such as serial casting and implementing an Ankle Foot Orthosis (AFO) is preferred over surgical method. This paper aims at developing a mechanically governed non-surgical corrective mechanism that rectifies clubfoot deformity in infants. Methodology: To design the supportive device, following three parameters, are to be considered: Foot Bi-Malleolar angle (FBM), Angle of Plantar Flexion (PF), Angle of Dorsi Flexion (DF). The FBM, PF and DF angle for a healthy infant ranges from 85 - 90˚, 0 - 40˚ and 0 - 22˚ but for a child with clubfoot it is constrained within 50 - 65˚, 0 - 22˚, 0 - 12˚. This deformation can be corrected with the help of mechanically controlled hinge joint and sliding pair mechanism. The orthosis predominantly consists of two main parts sole and cylindrical pair joint. The sole part which is connected to the lower link using a hexagonal nut and bolt creates a hinge joint and thus providing movement along PF. The bottom link in-turn is connected with the cylindrical pair joint and thus allowing 360˚ movement along FBM. Thus hinge joint provides the counter force on the forefoot. Similarly, cylindrical pair joint provides the counter force on mid and hind foot thus directing the bone growth to its pristine. Findings: The initial wearable prototype of the pedorthosis has been proposed, designed and fabricated using thermoforming process. Applications: This wearable orthosis can be fitted to a subject and the growth pattern can be studied. Feasibility of the concept can be understood by virtually evaluating using finite element analysis.