Collagen coated HASi granules as a substitute for artificial periosteum for the repair of critical size femoral defects in rat models

This study evaluated the regenerative potential of a mineralised collagenous periosteum in critical-size femoral defects in rats. A six-millimetre diaphyseal defect was created in the right femur of all animals and was grafted with a hydroxyapatite (HA)-doped collagen sleeve filled with silica-coated hydroxyapatite (HASi) granules. Healing was assessed using radiography, histology and bone turnover markers. The test graft showed early integration with host bone by the fourth week, evidenced by cortical bridging and medullary recanalisation by week twelve. Radiographically, the test graft material remained stable throughout the healing process and achieved complete healing by week twelve, while bone turnover marker analysis confirmed the early initiation of bone regeneration. Histological examination revealed uniform new bone deposition and advanced bone maturation with well-organised lamellar bone and bone marrow by week twelve, without signs of inflammation or fibrous tissue proliferation. The study demonstrated the bone healing efficacy of HA-doped collagen sleeve filled with HASi granules in critical-sized femoral defects in rats.