Abstract
Autograft (AG) is the gold standard for bone grafts, but limited quantities and patient morbidity are associated with its use. AG extenders have been proposed to minimize the volume of AG while maintaining the osteoinductive properties of the implant. In this study, poly(ester urethane) (PEUR) and poly(thioketal urethane) (PTKUR) AG extenders were implanted in a 20-mm rabbit radius defect model to evaluate new bone formation and graft remodeling. Outcomes including µCT and histomorphometry were measured at 12 weeks and compared to an AG (no polymer) control. AG control examples exhibited new bone formation, but inconsistent healing was observed. The implanted AG control was resorbed by 12 weeks, while AG extenders maintained implanted AG throughout the study. Bone growth from the defect interfaces was observed in both AG extenders, but residual polymer inhibited cellular infiltration and subsequent bone formation within the center of the implant. PEUR-AG extenders degraded more rapidly than PTKUR-AG extenders. These observations demonstrated that AG extenders supported new bone formation and that polymer composition did not have an effect on overall bone formation. Furthermore, the results indicated that early cellular infiltration is necessary for harnessing the osteoinductive capabilities of AG.
Highlights
Autograft (AG) bone is considered the gold standard in bone grafting
The AG extenders displayed new bone growth at the host bone/graft interfaces, and graft remodeling was observed in both AG extenders, near the proximal and distal ends of the defect where new bone and decreasing residual graft were observed
Bridging of the defect was not observed in any of the AG extender samples. Both AG extenders exhibited increasing opacity within the grafts over the 12-week time course, and no qualitative differences in new bone formation within the graft were observed between poly(thioketal urethane) (PTKUR)- and poly(ester urethane) (PEUR)-AG groups
Summary
Autograft (AG) bone is considered the gold standard in bone grafting. It is osteoinductive, osteoconductive, and osteogenic, and it does not pose a risk for disease transmission [1,2,3]. AG comes in various forms including both cancellous and cortical [3]. Cancellous AG is most often harvested from the iliac crest (IC); other donor sites such as the posterior superior iliac spine, femur, proximal tibia, and distal radius are utilized [4,5,6,7]. Cancellous AG contains mesenchymal stem cells (MSCs), osteoblasts, and growth factors including bone morphogenetic proteins (BMPs), which contribute to its osteoinductivity [3,8]. Cortical AG is ideal for defects that require structural support as it offers superior mechanical properties compared with cancellous AG.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
