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Experimental Investigation of Secondary Flow Structures Downstream of a Model Type IV Stent Failure in a 180° Curved Artery Test Section
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Analysis of ureteric stent kinking forces: the role of curvature in stent failure

Matthew S Christman1, James O L'Esperance, Chong H Choe

  • 1Department of Urology, Naval Medical Center San Diego, San Diego, CA, USA.

BJU International
|August 29, 2009
PubMed
Abstract

Insights

Silhouette ureteric stents demonstrate superior resistance to kinking and curvature, potentially reducing failures in malignant ureteral obstructions. Smaller stents generally allow more bending before failure.

Area of Science:

  • Urology
  • Biomedical Engineering
  • Medical Device Design

Background:

  • Ureteral stent failure is common, with malignant obstruction causing approximately 50% of failures.
  • Kinking and excessive curvature are primary modes of ureteric stent failure.

Purpose of the Study:

  • To quantify the kinking forces and degree of curvature leading to failure in various ureteral stents.
  • To identify stent designs with improved resistance to mechanical failure.

Main Methods:

  • Mechanical testing of multiple ureteral stent models (Silhouette, Sof-Curl Tecoflex, Polaris Ultra, Percuflex) with varying French sizes.
  • Measurement of the force required to induce stent kinking.
  • Calculation of the degree of curvature at the point of stent failure.

Main Results:

  • Silhouette 4.6 F and 6 F stents exhibited the highest resistance to kinking and curvature-induced failure.
  • Smaller diameter stents generally tolerated greater degrees of curvature before failure compared to larger stents.

Conclusions:

  • Silhouette ureteric stents offer enhanced resistance to kinking and greater allowable curvature.
  • These properties may lead to reduced stent failure rates in patients with malignant ureteral obstruction and other retroperitoneal conditions.

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