In vivo behavior in rabbit radius bone defect of scaffolds based on nanocarbonate hydroxyapatite

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Orthopedic Surgery

Background:

• Bone defects often require bone grafts, but autografts and allografts have limitations.
• Synthetic bone substitutes are needed to overcome these limitations.
• Nanocarbonate hydroxyapatite (nCHA) is a promising biomaterial for bone regeneration.

Purpose of the Study:

• To evaluate the bone-inducing capacity of nCHA-based scaffolds in a rabbit radius critical defect model.
• To compare nCHA scaffolds alone (SAG), enriched with osteostatin (SAGO), or bone marrow aspirate (SAGB) against controls and autografts.

Main Methods:

• 15-mm critical radius defects were created in New Zealand rabbits.
• Implantation of nCHA scaffolds (SAG, SAGO, SAGB), unfilled defects (CE), and iliac crest autografts (GS).
• Radiological follow-up (2, 4, 6, 12 weeks), micro-CT, and histological analysis at 12 weeks.

Main Results:

• Radiological assessment showed bone formation: GS (75%-100%), SAG/SAGB (50%-75%), CE (control).
• Micro-CT revealed increased bone volume/tissue volume: GS (0.53), SAG (0.40), SAGB (0.31), CE (0.26).
• Histology showed limited resorption and partial osseointegration for SAG/SAGB; SAGO exhibited connective tissue encapsulation.

Conclusions:

• nCHA scaffolds (SAG, SAGB) promote bone formation compared to unfilled defects, though less than autografts.
• Osteostatin enrichment (SAGO) did not enhance bone regeneration and led to encapsulation.
• nCHA materials are a significant advance for bone grafting, but further research is needed to match autograft performance.