Development of titanium fixation screw for hydroxyapatite osteosynthesis (APACERAM)

Area of Science:

• Biomaterials Engineering
• Craniofacial Surgery
• Orthopedic Implants

Background:

• Cranioplasty commonly uses custom hydroxyapatite (HAP) ceramic implants for skull defects.
• Standard miniplate fixation with commercial screws presents challenges due to HAP's brittleness.
• A need exists for improved fixation methods in HAP cranioplasty.

Purpose of the Study:

• To develop and evaluate a novel screw optimized for miniplate fixation of hydroxyapatite (HAP) implants.
• To address the limitations of existing screws in stabilizing brittle HAP bone grafts.
• To enhance the reliability of cranioplasty procedures using custom HAP implants.

Main Methods:

• Hydroxyapatite (HAP) blocks were prepared with specific porosity and thickness.
• Drilling created standardized holes in the HAP blocks for screw insertion.
• Five screw types were tested for HAP integrity post-insertion, pull-out fixation strength, and plate fastening torque.

Main Results:

• Screw performance was evaluated based on HAP condition, pull-out strength, and maximum torque.
• The optimal screw design was identified as cylindrical with specific dimensions.
• Key dimensions for the effective screw were determined: 4.8 mm length, 1.6 mm diameter, and 0.2 mm edge height.

Conclusions:

• A novel screw design demonstrates high fixation potential for the miniplate technique in cranioplasty.
• The developed screw effectively addresses the challenges associated with stabilizing brittle HAP implants.
• This innovation offers improved stability and reliability for cranioplasty procedures.