[Semirigid plate osteosyntheses using absorbable polymers as temporary implants. II. Animal experiment studies]

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Tissue Engineering

Background:

• Biodegradable polymers like polylactide-L are explored for orthopedic applications.
• Understanding their mechanical stability and degradation profile in vivo is crucial.
• Assessing tissue compatibility and impact on bone healing is essential for clinical translation.

Purpose of the Study:

• To evaluate the mechanical stability and degradation of polylactide-L test rods in vivo.
• To compare the performance of polylactide-L with copolymer materials.
• To investigate the effect of polylactide-L fixation on bone healing in a canine model.

Main Methods:

• Three-point bending tests were performed on polylactide-L rods before and after implantation in rat muscle.
• Copolymer materials were subjected to similar in vivo testing.
• Transverse osteotomies in beagle radii were stabilized using polylactide-L plates and screws.

Main Results:

• Polylactide-L rods lost approximately 50% of their initial 130 N/mm2 stability within 5 weeks post-implantation.
• Copolymer materials exhibited lower initial strength and faster degradation.
• All tested materials demonstrated good tissue compatibility.
• Delayed bony union and significant callus formation were observed in the stabilized beagle radii.

Conclusions:

• Polylactide-L demonstrates good initial strength and tissue compatibility but undergoes rapid in vivo degradation.
• Copolymers offer less initial strength and degrade even faster.
• The use of polylactide-L for internal fixation may impede optimal bone healing, suggesting limitations for load-bearing applications.