Design and development of usability tests for moldable bone substitute

The objective of this study was to design and develop techniques and methods to test the usability of moldable bone grafts. There is currently no standardized procedure to characterize these kinds of medical devices from the mechano-physical point of view. This study was conducted in collaboration with GreenBone Ortho s.p.a., an Italian company which develops solutions for bone regeneration. The company uses wood-derived materials to obtain resorbable calcium phosphate through transformation chemical processes. The company is studying an alternative use of their calcium phosphate product: the granular particulate obtained from crushing is combined with a chemical binder and an aqueous solution to form the moldable bone graft. This work started from the assessment of the surgeons' needs regarding the deployment of these implantable medical devices. Usability tests were developed to evaluate the ease of use, the handling characteristics, and the performance of the product in simulated clinical settings in terms of cohesion, stability, anti-washout and adhesiveness properties. To achieve these goals, in this work different combinations of binders, granules and aqueous solution were formulated. Several experimental usability test set-ups were modified and tested until reaching definitive protocols that could simulate realistic application conditions during the surgical operation and the wound environment. It resulted that the designed tests were able to distinguish a trend in the behaviour of the moldable bone graft prototype tested, both from a qualitative and quantitative point of view. It was possible to identify properties addressable to the presence of different binders within the formulation, in proportion to the quantity of that binder. The methods have been developed and thoroughly validated, and different moldable bone graft prototype compositions have successfully been characterized.