Accelerated bone formation by biphasic calcium phosphate with a novel sub-micron surface topography

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Regenerative Medicine

Background:

• Calcium phosphate (CaP) bone grafts show promise for critical-size bone defects.
• CaP osteoinductive potential is influenced by surface topography.
• Novel biphasic calcium phosphate (BCP) and tricalcium phosphate (TCP) materials were synthesized.

Purpose of the Study:

• To compare the osteoinductive potential of BCP and TCP bone grafts with varying surface topographies.
• To elucidate the role of surface feature size and morphology in CaP-driven bone formation.
• To evaluate the impact of sub-micron vs. micron-scale needle-shaped and grain-shaped topographies.

Main Methods:

• Physicochemical characterization of four CaP materials (BCP<µm, BCPµm, TCP<µm, TCPµm).
• Implantation in dorsal muscle of beagles for 12 weeks.
• Histomorphometric analysis to quantify new bone formation.

Main Results:

• Sub-micron needle-shaped BCP (BCP<µm) induced earlier bone formation (3-6 weeks) than grain-shaped TCP (TCP<µm, 6-9 weeks).
• After 12 weeks, bone formation was equivalent between BCP<µm and TCP<µm.
• Micron-scale BCP (BCPµm) showed limited bone formation; micron-scale TCP (TCPµm) showed none.
• Osteoinduction strength: surface feature size > surface feature morphology > substrate chemistry.

Conclusions:

• Sub-micron needle-shaped BCP exhibits accelerated bone formation and slower resorption compared to similar TCP.
• Surface topography, specifically sub-micron needle-like features, is critical for enhanced osteoinduction.
• These findings suggest potential for improved bone healing in orthopedic applications.