Verification of the usefulness of shape acquisition using plastic casts during fabrication of a metal strut ankle-foot orthosis.

Abstract

[Purpose] When fabricating metal strut ankle-foot orthoses, previous studies have reported that shape acquisition is more efficient with a plastic cast than with a plaster of Paris bandage; however, this has not been quantitatively evaluated. This study aimed to clarify the usefulness of plastic casts by quantitatively evaluating the time spent and body shape accuracy among different methods of shape acquisition. [Participants and Methods] We compared the time spent and acquired shapes among the plaster of Paris bandage, plastic cast, and trace methods in 30 limbs of 15 healthy participants. Three-dimensional scans of the lower legs of participants were used as references to compare the three methods. [Results] The plastic cast method required less time than the plaster of Paris bandage method and provided a more accurate shape than the trace method did. However, the plastic cast method resulted in an increased overall width and circumferential diameter owing to the thickness of the stockinette and plastic cast. [Conclusion] The plastic cast method may be useful in reducing the time and burden of fabricating metal strut ankle-foot orthoses. The use of slightly narrow dimensions during the metal strut bending process can account for the increased width and diameter.