76.
A Stereological Method for the Quantitative Evaluation of Cartilage
Repair Tissue
Foldager Casper Bindzus, Nyengaard Jens R., Lind Martin, Spector Myron
Orthopaedic Research Aarhus University Hospital, Denmark & Brigham &
Women's Hospital, Harvard Medical School, Boston, MA; Stereology and EM
Laboratory, CSGB, Aarhus University, Denmark; Sports Trauma Clinic,
Aarhus University Hospital, Denmark; Orthopaedic Research & Tissue
Engineering, Brigham & Women's Hospital, Harvard Medical School & VA
Boston Health Care System, Boston, MA
Background:
No quantitative methods for evaluation of cartilage repair
currently exists.
Purpose / Aim of Study:
The aim was to implement stereology into an easily
and quickly applied algorithm for the quantitative evaluation of the volumes of
various tissue types comprising cartilage repair.
Materials and Methods:
Repair tissue in a cylindrical chondral goat defect
(
Ø=4mm) was used as an example for application. Seven sections per defect,
with a 600 m spacing were stained with H&E. The tissue types in the repair
area were assigned to categories based on well-accepted criteria: hyaline
cartilage (HC-rounded cells in lacunae, in hyaline matrix); fibrocartilage (FC-
rounded cells in lacunae, in fibrous matrix); fibrous tissue (FT- elongated cells
not in lacunae, fibrous matrix); bone; scaffold/implant material; and “others.”
Stereological point counting was performed using the STEPanizer freeware.
Using “Cavalieri’s principle,” the design-based total defect volume and
coefficient of error (CE) was calculated. At higher magnification the various
tissue types were counted and the tissue type fractions were calculated.
Findings / Results:
The volumes of specific tissue types were readily
determined by the assignment into well-defined categories. In our defect
example, the volume was estimated to be 4.35mm3 (CE=0.0105). The specific
tissue type fractions were: HC=1.23mm3 (28.1%), FC=2.46mm3 (55.5%),
FT=0.60mm3 (13.9%). The total evaluation time was 1-2 hours per defect.
Conclusions:
We have developed a simple and unbiased tool for quantitative
evaluation of cartilage repair, which allows precise estimations with low CE of
volumes of tissue types in a defect. A stereologically valid, quantitative and
easily applied histomorphometric method could be a meaningful supplement to
existing semi-quantitative and descriptive methods for evaluating the outcome
in cartilage repair.
