Challenges in post-mortem preparation of orthopedic implanted devices
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1
AccelLAB Inc., Pathology, Canada
Orthopedic implanted devices can be permanent or biodegradable and vary in material composition, physical properties and shapes. Implanted sites also vary depending on the device’s clinical indication. Because of this variability, routine histology methods are often inappropriate and need to be adjusted to the type of implant and implanted tissue.
Implant sites need to be harvested with surrounding tissue. The location of implant, nature and extent of the local tissue reaction should be recorded. For precise localization of the implant sites, in life or terminal radiographs and/or CT scans are useful. Location of the implants is identified and implanted tissues are immersion-fixed, generally in formalin.
Although the site of the implant was identified at necropsy, determining its exact location and plane of sectioning after tissue fixation are often difficult. High-resolution radiography and/or microCT scans are recommended to ensure appropriate device and bone orientation before trimming. Small saws for non-metallic implants, diamond saws or band saws for large and hard implants are used for further precise trimming. Histologic marking dyes and/or radiopaque markers can be used for additional implant orientation and identification of the sectioning plane. To preserve the implant-tissue interface, the device should not be removed. Nature of the implant influences whether bone is decalcified and embedded in paraffin or non-decalcified and embedded in resin. Ante-mortem fluorochromes injection and histological differentiation of osteoid from mature bone requires non-decalcified bone processing. Pilot studies or cadaveric trials mimicking the planned implantation procedures should be performed. These exploratory implanted devices should be allocated to different histological processing and imaging techniques to select the best histological procedures for a specific device (specific examples will be presented).
Various embedding resins can be used for undecalcified specimens. The goal is to match the embedding supporting medium hardness to the hardness of the implant and surrounding tissue to produce sections without artefacts. After resin embedding, non-metallic implants can be cut with a microtome and harder implants require ground sectioning. Most routine staining methods can be used in paraffin-embedded tissues; however, for plastic-embedded implants, staining procedures need to be modified. Semi-quantitative histological evaluation is performed to determine the potential local toxicity, generally following the ISO 10993-6 grading scheme. Histomorphometry can also be performed.
In summary, at tissue harvest and sample preparation, the exact location and orientation of the implant need to be properly visualized to produce quality slides. When necessary, high-resolution radiography or micro-CT scanning can be used. Preliminary tests with different histological processing techniques will determine the best histology procedure for a specific device.
Keywords:
Implant,
device,
Bone graft,
Imaging method
Conference:
10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016.
Presentation Type:
Poster
Topic:
Biomaterials evaluation in animal models
Citation:
Chagnon
M and
Savard
C
(2016).
Challenges in post-mortem preparation of orthopedic implanted devices.
Front. Bioeng. Biotechnol.
Conference Abstract:
10th World Biomaterials Congress.
doi: 10.3389/conf.FBIOE.2016.01.02052
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Received:
27 Mar 2016;
Published Online:
30 Mar 2016.
*
Correspondence:
Dr. Madeleine Chagnon, AccelLAB Inc., Pathology, Boisbriand, QC, Canada, Email1
Dr. Claudine Savard, AccelLAB Inc., Pathology, Boisbriand, QC, Canada, claudine.savard@accellab.com