International urogynecology journal vol:17 pages:58-59
IUGA edition:31 location:Athens, Greece date:2006
Objectives: Increasingly more xenografts are used to augment fascial repairs for prolapse. Previous experiments
revealed that a collagen matrix derived from small intestinal submucosa (SIS, Cook) was degraded within 60 days and replaced by a progressively weakening scar. Cross-linked porcine dermal collagen (Pelvicol, Bard) was more resistant to degradation, but at 365 days half of the implants demonstrated signs of degradation, the other half remaining intact (1). We wanted to follow up the latter process in a 2-year follow up study in the rabbit model.
Materials and methods: Four 2.5×2.5 cm full thickness
abdominal wall defects were created in eight New Zealand
rabbits, resulting in 32 implant sites. In a random fashion the defects were primarily closed with one either Prolene
(Ethicon), SIS or Pelvicol. At 545 and 720 days four rabbits
were sacrificed providing minimally five implants for each
material and for each time group. The macroscopic appearance
of the implant was noted and freshly harvested explant
strips (1-cm wide) were tested by tensiometry (Instron).
Microscopic evaluation consisted of quantification of polymorphonuclear cells, mononuclear cells (MNC), foreign
body giant cells and newly formed vessels on Hematoxylin
and Eosin (H&E) and Movat stained parafin sections.
Results: Three of the eight rabbits, all from the 545 group,
died from unknown reasons, before sacrifice could take
place. Macroscopically 80% of all Pelvicol implants
remained nearly intact except that the material showed
three to four bursts spread over the implant area and half of them. These implants felt hard, rigid and stiff. The
remaining 20% Pelvicol implants had a moth-eaten aspect
with 90% of the mesh surface remaining intact. SIS
implants were macroscopically not recognisable anymore
and replaced by a connective tissue scar. On tensiometry all
biopsies were tearing at the interface with no significant
difference in strength between the different materials. There were two clinical herniation sites at sacrifice, one in the SIS (545 days) and Pelvicol (545 days) group. Pelvicol explants showed a strong chronic inflammatory infiltrate (100 MNC/hpf), limited to the interface. The connective tissue deposition was paralleling the implant (encapsulation), except from rare small islands of connective tissue invading the implant. SIS was entirely replaced by slightly organised connective tissue consisting of collagen, fat and muscle tissue with almost no inflammatory cells (5 MNC/hpf).
Prolene explants had a milder chronic inflammatory cell
infiltrate (10 MNC/hpf) and fibrosis with an intermediately
dense collagen deposition.
Conclusion: Pelvicol implants remain virtually intact up to
two years after implantation They are encapsulated by the
host but become stiff and non-compliant. SIS is entirely
replaced by a mix of connective tissue.
1. Claerhout F et al. Long term evaluation of the host
response to two different collagen based and polypropylene
implants in a rabbit model for abdominal wall hernia repair. ICS Paris 2004.