Publication: Correlation between 3D microstructural and 2D
histomorphometric properties of subchondral bone
with healthy and degenerative cartilage of the knee joint
Authors
Lahm, Andreas ; Kasch, Richard ; Spank, Heiko ; Erggelet, Christoph ; Esser, Jan ; Merk, Harry ; Mrosek, Eike
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Publisher
F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología
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DOI
https://doi.org/10.14670/HH-29.1477
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info:eu-repo/semantics/article
Description
Abstract
Cartilage degeneration of the knee joint is
considered to be a largely mechanically driven process.
We conducted a microstructural and histomorphometric analysis of subchondral bone samples of intact
cartilage and in samples with early and higher- grade
arthritic degeneration to compare the different states and
correlate the findings with the condition of hyaline
cartilage. These findings will enable us to evaluate
changes in biomechanical properties of subchondral
bone during the evolution of arthritic degeneration, for
which bone density alone is an insufficient parameter.
From a continuous series of 80 patients undergoing
implantation of total knee endoprosthesis 30
osteochondral samples with lesions macroscopically
classified as ICRS grade 1b (group A) and 30 samples
with ICRS grade 3a or 3b lesions (group B) were taken.
The bone samples were assessed by 2D histomorphometry (semiautomatic image analysis system)
and 3D microstructural analysis (high-resolution microCT system). The cartilage was examined using the
semiquantitative real-time PCR gene expression of
collagen type I and II and aggrecan.
Both histomorphometry and microstructural and
biomechanical analysis of subchondral bone in groups A
and B consistently revealed progressive changes of both
bone and cartilage compared with healthy controls.
The severity of cartilage degeneration as assessed by
RT PCR was significantly correlated with BV/TV (Bone
Volume Fraction), Tb.Th (Trabecular Thickness) showed
a slight increase.
Tb.N (Trabecular Number), Tb.Sp (Trabecular
separation) SMI (Structure Model Index), Conn.D
(Connectivity Density) and DA (Degree of Anisotropy)
were inversely correlated.
We saw sclerotic transformation and phagocytic
reticulum cells. Bone volume fraction decreased with an
increasing distance from the cartilage with the
differences compared with healthy controls becoming
greater in more advanced cartilage damage.
The density of subchondral bone alone is considered
an unreliable parameter for classifying changes evolving
over time. The progressive damage of subchondral bone
seen in the present study correlates well with cartilage
changes. Trabecular orientation is also impaired, which
explains the changes in biomechanical parameters and
the inadequate load transfer and excessive loading of
cartilage. Besides subchondral bone density, which in
turn correlates with cartilage thickness, other parameters
such as structure model index and grade of anisotropy
best reflect mechanical properties such as Young
modulus, compressive strength, tensile stress, and failure
energy.
However, it remains unclear whether the mechanical
interaction of the mineralized subchondral tissues with
articular cartilage works vice versa. The possibility of a
biochemical signalling from the degenerating cartilage
via the synovial fluid and bone- cartilage crosstalks via
subchondral pores may indeed explain a certain depth dependency of subchondral bone changes.
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