Biomedical Engineering Reference
In-Depth Information
of humans. several excellent summaries have been presented elsewhere on
specific topics, such as the mechanisms of failure of certain arthroplasties, the
interactions between titanium and bone, and so on. the interested reader is
referred, for example, to Pappas and co-workers,
2
morlock and co-workers,
3
al-saffar and co-workers,
4, 5
Jones and co-workers,
6
Revell,
7
Jacobs and co-
workers,
8
and Goodman,
9
for different aspects (loosening, wear particles and
more) of retrieved hip components, Steflik and co-workers,
10
sennerby and
co-workers,
11
and Bolind and co-workers,
12, 13
for retrieved dental implants,
Bolind and co-workers,
14
and Granström,
15
for retrieved maxillofacial implants
and Collier,
16
for retrieval analysis of spine components, and references
therein.
the aim of this chapter is to discuss some of the key factors for obtaining
information about the intact material-tissue interface in human bone. This will
include different methods of fixation and sample preparation. Further, some
different analytical techniques and examples of new techniques for studies
of the structure between bone and retrieved implants are presented.
15.2 Retrieval
Clinically used implants are retrieved for different reasons. some of the
most common causes are implant loosening, material failure, pain and post-
mortem examination. investigations of retrieved clinical implants are useful
for understanding the mechanisms of success and failure under clinical
conditions, information that may not be possible to achieve in experimental
models. the implants should preferably be removed with surrounding
tissue, allowing histological analysis. Furthermore, the proper handling of
the tissue is of utmost importance as the tissue rapidly starts to degenerate
owing to loss of blood and nutrition supply. Further, the need to categorize
the harvested implants is of utmost importance for back-tracking individual
implants with the complete medical history of the patients with radiographs.
A brief introduction to such programmes can be found elsewhere.
17
15.3 Tissue preservation
tissue is a living material and deterioration will rapidly occur after cessation
of blood flow owing to insufficient blood/nutrition supply. Therefore the tissue
must be preserved and different formulations have been optimized depending
on the type of tissue and analysis intended.
18
key factors to preserve are
the areas of interest, for example the general histology, the cellular details,
the RNA, the mineral content and more. As any modification will alter the
tissue and its content, the choice of fixative is important. For histology and
histomorphometry, aldehyde fixation allows long storage, however the RNA
content and certain details of the tissue are altered. to keep the RnA intact,
