Using a novel endoprosthetic device to modulate mechanical strain in gyroid scaffolds in large bone defects

This study investigates the strain behavior of highly porous gyroid scaffolds composed of pure deproteinized ovine bone mineral (OBM) and evaluates the role of a novel endoprosthetic “sleeve“ in modulating mechanical response in ovine cadaveric bone with a critical size defect stabilized by a Locking Compression Plate (LCP) under physiological loading. Scaffold-sleeve assemblies were constructed by inserting scaffolds into sleeves which were implanted into critical metatarsal segmental defects. The scaffold-sleeve constructs were stabilized with locking compression plates (LCP) and subjected to cyclic compressive loading (0–150 N). Measurements were made on surrogate PLA scaffolds and then translated to bioceramic scaffolds. Strains were measured using three-element 0°/±45° rosette gauges mounted on scaffolds with and without the sleeve. Results indicated that scaffold strains ranged between 200 and 300 µε, comparable to strain levels in native bone without defects. Notably, the presence of the endoprosthetic sleeve significantly reduced transverse strain by 8.2% to approximately 0.03%. These findings show that the inclusion of an endoprosthetic sleeve can effectively modulate local strain environments of highly porous scaffolds in large bone defects.