Characterization of load dependent creep behavior in medically relevant absorbable polymers.

Area of Science:

• Biomaterials Science
• Polymer Science
• Medical Device Engineering

Background:

• Synthetic absorbable polymers are increasingly used in medical devices requiring long-term structural support.
• Current devices may undergo permanent deformations and geometric changes in vivo.
• Viscoelastic properties are critical for devices under long-term loading but are often overlooked in preclinical assessments.

Purpose of the Study:

• To investigate the static creep, creep recovery, and cyclic creep responses of poly(l-lactide) (PLLA) and poly(l-co-glycolide) (PLGA).
• To evaluate these responses under physiologically relevant loading magnitudes.
• To correlate material properties with observed creep behavior.

Main Methods:

• Static creep, creep recovery, and cyclic creep tests were performed on PLLA and PLGA samples.
• Tests were conducted across a range of physiologically relevant load magnitudes.
• Material crystallinity was assessed and correlated with creep behavior.

Main Results:

• Both PLLA and PLGA exhibited significant creep and failure at loads below their ultimate material properties.
• Material-specific responses to loading were observed.
• A strong correlation was found between the extent of creep and the material's crystallinity.

Conclusions:

• PLLA and PLGA demonstrate notable viscoelastic behavior under physiological loading.
• Creep and crystallinity are key factors influencing the performance of absorbable polymers in medical devices.
• Viscoelastic properties should be integrated into the material selection process for absorbable medical devices.