D. Tramaglini et al., THE INFLUENCE OF FLANGE COMPLIANCE AND MECHANICAL LOADING ON THE TISSUE-RESPONSE TO PERCUTANEOUS DEVICES, Journal of applied biomaterials, 4(2), 1993, pp. 183-194
The failure of most percutaneous devices (PD) is caused by infection i
nitiated by a lack of a tight seal at the skin-device interface. This
interface can be disrupted by both extrinsic and intrinsic forces. Man
y stress reduction methods have been proposed, the most common being t
he application of a subcutaneous flange. It is widely believed that th
e bending compliance of the flange plays a significant role in the suc
cess or failure of a PD. A study was conducted to observe the effect o
f flange compliance on local host response in both a functional and no
nfunctional setting. Two PDs having flanges with different bending rig
idities were implanted percutaneously in goats (n = 8). After a healin
g period of 2 weeks, half of these devices were externally stimulated
with a random load. All the implants were retrieved after 4 weeks and
evaluated histologically. The tissue capsule was significantly thicker
and the incidence of severe fibrosis and/or necrosis was higher at th
e flange rim of the functional implants, irrespective of flange compli
ance. The more compliant devices were encapsulated with a thick fibrou
s capsule more frequently than the less compliant ones, irrespective o
f functional status. The more compliant devices also had a greater inc
idence of foreign body giant cells in the corner region and elicited s
evere acute inflammation at the corner and top of the flange more freq
uently than the less compliant implants. Numerous areas of degeneratin
g foreign body giant cells accompanied with fibroblastic proliferation
and dystrophic mineralization were identified in many -of the capsule
s beneath the flanges. It was concluded that the rigid implants elicit
ed a more desirable tissue response than the compliant implants while
the functional implants elicited a less desirable response than the no
nfunctional ones. There was no synergistic or antagonistic relationshi
p between the functional status of the device and flange compliance.