Commonly used adjuvants (liquid soap, foam sanitizer, or ultrasound gel) do not improve strength or curing time of fiberglass cast material

Background: Bone fractures are one of the most common injuries in the USA. Fiberglass tape is a commonly used casting material, and many medical professionals apply adjuvants including liquid hand soap, foam sanitizers, and ultrasound gel in the hopes of improving outcomes relating to ease of molding and eventual strength, lamination, and smoothness of cast material. However, the efficacy of these agents to improve fiberglass cast mechanics has not been scientifically evaluated. The purpose of this study was to assess the mechanical effects of commonly used adjuvants on fiberglass cast materials. Methods: Studies compared regularly shaped samples of water-activated, untreated fiberglass tape (Ossur Techform Premium) to water-activated fiberglass tape treated with one of three commonly used adjuvants (liquid soap, foam hand sanitizer, or ultrasound gel) during lamination. Material stiffness, yield stress, and ultimate load were measured by 3-point bending. Results: These studies demonstrated that that liquid soap and ultrasound gel did not affect fiberglass tape mechanical properties, but alcohol-based foam sanitizer significantly reduced stiffness (- 32.8%), yield stress (- 33.6%), and ultimate load (- 31.0%) of the cast material as compared to the control group. Regression slopes were not significantly different between groups, suggesting that no adjuvants improved material curing time. Conclusions: These data suggest that the application of adjuvants is not beneficial and potentially harmful to fiberglass cast behavior. Despite the widespread practice of adjuvant application by medical professionals during casting, results from the current study suggest that use of these agents for structural enhancement of fiberglass casts is not beneficial and should largely be discouraged.