Prototypical metal/polymer hybrid cerebral aneurysm clip: in vitro testing for closing force, slippage, and computed tomography artifact. Laboratory investigation.
OBJECTIVE
The aim of this study was to explore the possibility that a hybrid aneurysm clip with polymeric jaws bonded to a metal spring could provide mechanical properties comparable to those of an all-metal clip as well as diminished artifacts on computed tomography (CT) scanning.


METHODS
Three clips were created, and Clips I and 2 were tested for mechanical properties. Clip 1 consisted of an Elgiloy spring (a cobalt-chromium-nickel alloy) bonded to carbon fiber limbs; Clip 2 consisted of an Elgiloy spring with polymethylmethacrylate (PMMA) jaws; and Clip 3 consisted of PMMA limbs identical to those in Clip 2 but bonded to a titanium spring. Custom testing equipment was set up to measure the aneurysm clip clamping forces and slippage. Clips 2 and 3 were visualized in vivo using a 64-slice CT unit, and the slices were reformatted into 3D images.


RESULTS
According to the testing apparatus, Clip 2 had a similar closing force but less slippage than three similar commercial aneurysm clips. The artifact from the cobalt alloy spring on CT scanning largely offset the advantage of the nonmetal PMMA limbs, which created no artifact. The hybrid titanium/PMMA clip (Clip 3) created very little artifact on CT and allowed visualization of the phantom through the limbs.


CONCLUSIONS
It is feasible to build a potentially biocompatible hybrid cerebral aneurysm clip with mechanical properties that closely resemble those of conventional metallic clips. Further testing should be directed toward establishing the reliability and biocompatibility of such a clip and optimizing the contour and surface treatments of the polymer
Mamourian
Alexander C
AC
Department of Radiology, Dartmouth-Hitchcock Medical Center, Lebanon New Hampshire, USA. alexander.mamourian@uphs.upenn.edu
Mahadevan
Namrata
N
Reddy
Nischala
N
Marra
Steven P
SP
Weaver
John
J
D016477:Artifacts; D003035:Cobalt; D004867:Equipment Design; D004868:Equipment Failure; D005240:Feasibility Studies; D006801:Humans; D002532:Intracranial Aneurysm / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008422:Materials Testing; D008670:Metals; D019635:Neurosurgical Procedures / Q000295:instrumentation*; D011108:Polymers; D019904:Polymethyl Methacrylate; D013525:Surgical Instruments / Q000009:adverse effects*; D014025:Titanium; D014057:Tomography, X-Ray Computed
D008670:Metals; D011108:Polymers; D003035:Cobalt; D019904:Polymethyl Methacrylate; D014025:Titanium