Defect bridging was scaled to assess objectively defect bridging without the ability to measure volume of bone generated quantitatively due to the presence of the intramedullary nail.

For comparative purposes, images from a previous study using the same animal model were assessed using the same scaling method, comparing to the empty defect zone (see Fig. 7A), which was left without treatment and which never healed, indicative of a true critical sized defect [21]. Also, the use of intact periosteum with adherent cortical bone chips on the inner surface, from the previous study, is compared as the “best observed outcome” which provides target specifications for the periosteum substitute implant [21].