Enhancement of bone formation by drawn poly(L-lactide)

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Polymer Science

Background:

• Poly(L-lactide) (PLLA) is a biodegradable polymer with potential biomedical applications.
• Piezoelectricity in polymers can be induced by mechanical drawing.
• The effect of piezoelectric properties of PLLA on bone healing is not well understood.

Purpose of the Study:

• To investigate the relationship between the draw ratio of PLLA and its piezoelectric properties.
• To evaluate the efficacy of piezoelectric PLLA rods in promoting fracture healing in a feline tibial model.

Main Methods:

• PLLA was molded into films and rods and subjected to longitudinal drawing to varying draw ratios.
• Piezoelectric constants were measured for PLLA films.
• Drawn PLLA rods were intramedullarily implanted in feline tibiae for internal fixation.
• Fracture healing was assessed by callus formation after 8 weeks.

Main Results:

• PLLA piezoelectric constants increased with draw ratio, peaking around a draw ratio of 5.
• PLLA samples with a draw ratio of 5 exhibited fibrilization.
• Intramedullary implantation of drawn PLLA rods significantly promoted fracture healing and callus formation compared to undrawn PLLA or polyethylene controls.

Conclusions:

• The piezoelectric properties of PLLA are dependent on the draw ratio.
• Drawn PLLA rods demonstrate significant potential for enhancing fracture healing through their piezoelectric effect.
• The piezoelectric current generated by PLLA implants may play a crucial role in bone regeneration.