3D‐Printed Osteoinductive Polymeric Scaffolds with Optimized Architecture to Repair a Sheep Metatarsal Critical‐Size Bone Defect

The reconstruction of critical‐size bone defects in long bones remains a challenge for clinicians. A new osteoinductive medical device is developed here for long bone repair by combining a 3D‐printed architectured cylindrical scaffold made of clinical‐grade polylactic acid (PLA) with a polyelectrolyte film coating delivering the osteogenic bone morphogenetic protein 2 (BMP‐2). This film‐coated scaffold is used to repair a sheep metatarsal 25‐mm long critical‐size bone defect. In vitro and in vivo biocompatibility of the film‐coated PLA material is proved according to ISO standards. Scaffold geometry is found to influence BMP‐2 incorporation. Bone regeneration is followed using X‐ray scans, µCT scans, and histology. It is shown that scaffold internal geometry, notably pore shape, influenced bone regeneration, which is homogenous longitudinally. Scaffolds with cubic pores of ≈870 µm and a low BMP‐2 dose of ≈120 µg cm−3 induce the best bone regeneration without any adverse effects. The visual score given by clinicians during animal follow‐up is found to be an easy way to predict bone regeneration. This work opens perspectives for a clinical application in personalized bone regeneration. A new osteoinductive medical device combining a 3D‐printed cylindrical scaffold made of polylactic acid with a surface coating delivering the bone morphogenetic protein 2. This scaffold is used to repair a sheep metatarsal 25‐mm long critical‐size bone defect. Results show that scaffold internal geometry, notably pore shape, influences bone regeneration. Cubic geometry induces the best bone regeneration.