Photocurable epoxy-based composite for rapid orthopedic soft casting†

Since the last century, plaster of Paris bandages have been the gold standard for orthopedic casting. Despite their extensive use, they have several drawbacks in day-to-day life, such as high weight and sensitivity to water. Moreover, they can cause skin burns, pressure sores, and other complications. Consequently, the urgency to propose alternative materials to solve these problems has emerged in the last decades, leading to the so-called soft casts, especially in pediatric orthopedics. In this context, a photocurable composite, based on the impregnation of a medical net with epoxy resins, is presented here. The impregnated medical net was rapidly transformed into a rigid device by means of visible light irradiation with an ad-hoc designed LED lamp (410–420 nm). Reaction activation was shifted to the visible range by exploiting isopropyl-9H-thioxanthen-9-one (ITX) as the photosensitizer, and the composites’ polymerization was evaluated via FT-IR analyses and thermal camera monitoring. The composites were also tested through tensile and three-point bending tests, revealing a stiffness comparable to that of soft casts already on the market. Compared to commercially available photocurable casts, this work introduces two key innovations: first, the employment of commercially available epoxy resins (monomer: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate), which enables avoiding the problems of oxygen inhibition; second, the use of a tubular medical net that is stretchable along the transversal direction, which is already used in the medical field for medication positioning. This latter advancement simplifies the application process compared to conventional techniques, making the obtained casts easy and fast to apply, light and breathable, thus maintaining promising properties for orthopedic rapid soft casts.