PLLA-stents

Characterising Stent Microstructure to Shed Light on Performance and Safety

Bioresorbable PLLA (poly‑L‑lactic acid) stents are increasingly used in vascular treatments to open narrowed or blocked vessels, restore blood flow, and provide temporary structural support.

PLLA is widely adopted for bioresorbable stents thanks to its biocompatibility, predictable hydrolytic degradation, and tunable mechanical properties. Because these stents are not permanent, they avoid long‑term complications associated with metal stents - such as chronic inflammation or impaired vessel remodelling - and they improve CT/MR visibility after dissolution, enabling clearer ongoing assessment and future treatment planning.

Since PLLA stents take 1–2 years to fully degrade at body temperature, a team of researchers from Boston Scientific, and a collaboration of universities, including Galway, and Queens University, Belfast set out to evaluate how the material breaks down over this period and whether any degradation‑related failures could affect safety. Their study focused specifically on braided PLLA stents, an understudied class that behave differently from other designs.

Braided stents degrade under both physiological conditions (37 °C) and thermally accelerated ageing, but understanding how their microstructure evolves over time is essential for predicting performance.

To investigate this, the scientists used wide‑angle X‑ray scattering (WAXS) at Diamond to characterise the microstructure and crystalline phases of undegraded PLLA monofilaments. This allowed them to identify the initial crystalline forms and assess how heat‑setting influences structural stability. These insights were combined with complementary techniques to build a complete picture linking microstructure with thermal behaviour, mechanical performance, and overall stent stability.

Find out what they discovered

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