Biomedical Engineering Reference
In-Depth Information
tissues with a high iron concentration. In one patient,
corrosion products were observed in the histology
sections. There was no evidence of infection, toxicity,
or an immune response in the histology from any
patients. Bone apposition as well as bone resorption
was observed in the histology of three of the patients.
Bone (when bony tissue samples were provided) was
undergoing remodeling, with foci of osteoclastic
resorption and intramembranous ossification. There
was no evidence of osteolysis in any of the tissue
samples provided. In another patient, lamellar bone
of the interspinous ligament tissue sample was
undergoing remodeling, with numerous foci of
osteoclastic resorption. Howship's lacunae and oste-
oclasts were frequently observed along the lamellar
bone in the interspinous ligament tissue sample. In
microscopic fields adjacent to this osteoclastic
resorption of bone, birefringent polymeric debris was
readily observed with polarized light microscopy.
Based on the size of the tissue sample provided, it is
not clear whether the observed bone resorption was
due to particle-induced osteolysis or whether bone
remodeling in the adjacent spinous processes was
occurring due to altered biomechanics associated
with the implantation of the device.
contacting devices use interdigitations and other
surface geometries to form macromechanical inter-
locks between bone and the PEEK devices. PEEK
particulate debris generates a macrophage (and foreign
body giant cell) response. Plasma cells, eosinophils,
and large populations of lymphocytes
d
which might
be indicative of an immune response
d
are not
observed in tissues adjacent to PEEK particulate
debris. This nonspecific inflammation has been
observed to PEEK particulate in nonclinical studies
and peri-implant
tissues associated with human
explants.
References
[1] J.C. Wataha, Biocompatibility of dental mate-
rials, in: K.J. Anusavice (Ed.), Phillips' Science
of Dental Materials, eleventh ed., Saunders,
Elsevier Science, St. Louis, MO, 2003, pp.
199
e
200 [Chapter 8].
[2] J. Black, Biological Performance of Materials:
Fundamentals of Biocompatibility, fourth ed.,
CRC Taylor & Francis, New York, 2006, p. 5.
[3] Biocompatibility and Biostability of PEEK,
online, July 2011. Available from:
http://www.
medicalpeek.org/
.
[4] S.M. Kurtz, J.N. Devine, PEEK biomaterials in
trauma, orthopedic, and spinal implants,
Biomaterials 28 (32) (2007) 4845
e
4869.
[5] D.F. Williams, A. McNamara, R.M. Turner,
Potential of polyetheretherketone (PEEK) and
carbon-fibre-reinforced PEEK in medical
applications, J. Mater. Sci. Lett. 6 (1987) 188.
[6] L.M. Wenz, K. Merritt, S.A. Brown, A. Moet,
A.D. Steffee, In vitro biocompatibility of poly-
etheretherketone and polysulfone composites, J.
Biomed. Mater. Res. 24 (2) (1990) 207
e
215.
[7] A. Hunter, C.W. Archer, P.S. Walker, G.W. Blunn,
Attachment and proliferation of osteoblasts and
fibroblasts on biomaterials for orthopaedic use,
Biomaterials 16 (4) (1995) 287
e
295.
[8] C. Morrison, R. Macnair, C. Macdonald,
A. Wykman, I. Goldie, M.H. Grant, In-vitro
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and osteoblasts, Biomaterials 16 (13) (1995)
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[9] R. Macnair, R. Wilkinson, C. MacDonald,
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of confocal
7.8 Summary and Conclusions
The available toxicity, genotoxicity, immunoge-
nicity, and soft and hard tissue animal studies, as well
as information gained from human explants, demon-
strate that PEEK and PEEK composite biomaterials
are biocompatible and bioinert in their bulk form.
Because PEEK is chemically inert with a hydrophobic
surface, it does not readily allow protein adsorption on
its surface. For this reason, PEEK polymers are known
to be inert (bioinert) in hard and soft tissues when
present as a bulk implant (not particulate debris). An
inert biomaterial has no adverse reaction or release of
ions or constituents. PEEK polymers, without addi-
tional coatings or modifications, are not known to be
bioactive biomaterials. Bioactivity refers to positive
interaction with tissue differentiation or stimulation of
wound healing in the tissues. Despite the fact that
PEEK biomaterials are not bioactive, direct bone
contact with PEEK implants has previously been
observed with PEEK implants. Although bone contact
is observed adjacent to PEEK implants, because PEEK
is not bioactive, bone will not form a chemical bond
with the material. Therefore, some PEEK bone
laser
scanning microscopy to
