Mechanical Evaluation of Soft Cast (Scotchcast, 3M) and Conventional Rigid and Semi-rigid Coaptation Methods

Summary

A clinically relevant model was created to mechanically evaluate different rigid and semi-rigid coaptation methods. Modulus of elasticity, yield stress, resilience and stiffness was measured to describe material strength and structure stiffness. Rigid Vetcast Plus, 3 M (VCP), new semi-rigid Softcast Scotchcast, 3 M (SC), conventional semi-rigid fibreglass slab reinforced modified Rober t Jone s (SMRJ ) bandages, and modified Robert Jones (MRJ ) bandages were tested with different thicknesses or configurations. Rigid (VCP) was the strongest and stiffest coaptation method. The reason for this was a strong bond between fibres and resin and between layers. New semi-rigid (SC) was the strongest of the semi-rigid coaptation methods followed by (SMRJ ) bandages and (MRJ ) bandages. With semi-rigid (SC) imperfections and voids in bond allowed some shear movement between fibres and resin and between layers giving cylindrical structures some resilience. Stiffness of semi-rigid (SMRJ ) was influenced by the position of the slab relative to the bending plane. Compressed cotton with semi-rigid (MRJ ) had very limited resistance to a bending force.

New semi-rigid Softcast Scotch-cat, 3M (SC) was mechanically evaluated in an in vitro external coaptation model and compared to rigid Vetcast Plus, 3M (VCP), semi-rigid fibreglass slab reinforced modified Robert Jones (SMRJ) bandages, and modified Robert Jones (MRJ) bandages. Vetcast Plus (VCP) was overall the strongest, Scotchcast (SC) was the strongest of the semi-rigid coaptation methods.

Keywords

External coaptation - composite material - rigid coaptation - semi-rigid coaptation

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