Polycaprolactone/glass bioabsorbable implant in a rabbit humerus fracture model

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Tissue Engineering

Background:

• Bioabsorbable internal fixators (polylactic acid, polyglycolic acid, polyparadioxanone) face challenges like delayed inflammation and low strength.
• Phosphate glass fiber/polycaprolactone (PCL) composite offers a potential alternative for internal fixation devices.

Purpose of the Study:

• To compare the performance of PCL intramedullary pins against traditional stainless steel pins.
• To evaluate the biocompatibility, mechanical properties, and bone healing response in a rabbit humerus osteotomy model.

Main Methods:

• Intramedullary pins made of PCL and stainless steel were implanted in rabbit humerus osteotomies.
• Radiographs and mechanical testing to failure were conducted at 0, 6, and 12 weeks post-surgery.
• Histological examination of tissues around the pins was performed at 6 and 12 weeks.

Main Results:

• PCL pins demonstrated good biocompatibility with minimal inflammation.
• Initial mechanical testing showed PCL fixation was weaker than stainless steel.
• Significant stress shielding was observed in stainless steel-healed humeri compared to PCL-healed humeri.
• All PCL-immobilized osteotomies exhibited robust periosteal callus formation and healed.

Conclusions:

• PCL composite intramedullary pins are well-tolerated and promote effective bone healing in a rabbit model.
• While initially weaker, PCL pins mitigate stress shielding issues associated with stainless steel implants.
• PCL composites represent a promising alternative biomaterial for internal fracture fixation.