Analysis of ureteric stent kinking forces: the role of curvature in stent failure.
OBJECTIVE
To further characterize the kinking forces and degree of curvature that result in failure of various stents, as malignant obstruction of the ureter causes failure of about half of ureteric stents.


METHODS
Several stents (Silhouette 4.6 F and 6 F, Applied Medical, Rancho Santa Margarita, CA; Sof-Curl Tecoflex 6 F, Gyrus ACMI, Southborough, MA; Polaris Ultra 6 and 7 F, and Percuflex 6, 7 and 8 F stents, Boston Scientific, Natick, MA, USA) were tested. The amount of force necessary to result in kinking of the stent was measured, and the degree of curvature at failure was calculated for each stent.


RESULTS
The Silhouette 4.6 and 6 F stents were the most resistant to failure by kinking and curvature. In general, smaller stents allowed more curvature before failing than their larger counterparts.


CONCLUSIONS
The greater allowable curvature and resistance to kinking achieved by the Silhouette ureteric stents might result in fewer stent failures in cases of malignant obstruction or other retroperitoneal processes.
Christman
Matthew S
MS
Department of Urology, Naval Medical Center San Diego, San Diego, CA, USA.
L'Esperance
James O
JO
Choe
Chong H
CH
Stroup
Sean P
SP
Auge
Brian K
BK
D006801:Humans; D008422:Materials Testing; D011474:Prosthesis Design; D011475:Prosthesis Failure; D015607:Stents; D014517:Ureteral Obstruction / Q000601:surgery*