title: Microstructural alterations of silicone catheters in an animal experiment: histopathology and SEM findings.
abstract: BACKGROUND
  Biocompatibility of implants in humans has been classified as "inert," "tolerated," and "bioactive." In shunt-treated patients, catheter-induced complications account for up to 70% of all hardware failures. Our objective was to study whether foreign body reactions to silicone shunt catheters in subcutaneous tissue and at their distal, intraperitoneal ends leading to occlusion can be reproduced in an animal model.
  
  
  METHODS
  Twelve different silicone catheters were implanted in 6-week-old Wistar rats: (a) purely in the subcutaneous tissue and (b) through the subcutaneous tissue into the peritoneal cavity. One of the catheters was of our own design with a silicated surface. After 1 year, all catheters were explanted and were examined by histopathology and scanning electron microscopy (SEM).
  
  
  RESULTS
  Histopathological analysis revealed the development of collagenous membranes and chronic immune reactions around the catheters. Completely organized intraluminal obliteration was seen in six intraperitoneally inserted catheters. SEM demonstrated calcifications and signs of biodegradation. Silicated catheters showed the most extensive calcifications.
  
  
  CONCLUSIONS
  Hydrocephalus shunt catheters cannot be termed "inert" or "biotolerated." Rather, they must be regarded as "bio-active" implants. The extensive reaction on silicated catheters can act as reference to estimate the biocompatibility of surface modifications. The model proved appropriate for further studies.
authors: Department of Neurosurgery, Saarland University Faculty of Medicine, Saarland, Germany. regina.eymann@uks.eu
authors: Regina
authors: R
authors: Eymann
authors: Yoo-Jin
authors: YJ
authors: Kim
authors: Rainer Maria
authors: RM
authors: Bohle
authors: Sebastian
authors: S
authors: Antes
authors: Melanie
authors: M
authors: Schmitt
authors: Michael Dieter
authors: MD
authors: Menger
authors: Michael
authors: M
authors: Kiefer
mesh_terms: D032761:Animal Experimentation; D000818:Animals; D002404:Catheterization / Q000009:adverse effects / Q000295:instrumentation*; D020099:Coated Materials, Biocompatible; D005549:Foreign-Body Reaction / Q000209:etiology*; D008855:Microscopy, Electron, Scanning; D051381:Rats; D017208:Rats, Wistar; D012828:Silicones; D012867:Skin / Q000648:ultrastructure*
chemical_list: D020099:Coated Materials, Biocompatible; D012828:Silicones