TY - JOUR
T1 - Increased matrix mineralization in the immature femoral head following ischemic osteonecrosis
AU - Hofstaetter, Jochen G.
AU - Roschger, Paul
AU - Klaushofer, Klaus
AU - Kim, Harry K W
N1 - Funding Information:
We thank Gerda Dinst, Daniela Gabriel, Phaedra Messmer and Sabrina Thon for careful sample preparations and qBEI measurements at the bone material laboratory of the Ludwig Boltzmann Institute of Osteology, Vienna, Austria. We also thank Margie Ehrmann for editing the manuscript. This study was supported by research grants from the AUVA (Austrian Social Insurance for Occupational Risk), the WGKK (Social Health Insurance Vienna), the FWF (The Austrian Science Fund) Project no. P19009-N20 and Shriners Hospitals for Children, Florida, USA.
PY - 2010/2
Y1 - 2010/2
N2 - Traditionally, it is believed that structural failure of the ischemic epiphysis as well as changes in radiodensity seen in the early stage of Legg-Calvé-Perthes disease is due to the repair process. However, little is known if matrix properties are altered following ischemic injury of the juvenile femoral head. The purpose of this study was to determine the matrix mineralization density, an important determinant of material quality and strength, of the proximal femoral epiphysis in an experimental animal model of Perthes disease. Ten piglets were surgically induced with femoral head ischemia and euthanized at 4 and 8 weeks following surgery. Contralateral, unoperated femoral heads were used as controls. Bone and calcified cartilage mineralization density distribution parameters were determined using quantitative backscattered electron imaging (qBEI) in the epiphyseal calcified articular cartilage, subchondral bone and central trabecular bone region. Histological as well as radiographic assessment was also performed. In the necrotic calcified epiphyseal cartilage matrix, a significant increase in the mean degree of mineralization (CaMean: +24%, p < 0.0001) as well as the homogeneity of mineralization (CaWidth: - 21%, p < 0.05) and a significantly reduced amount of low mineralized matrix (CaLow: - 49%, p < 0.0001) were already present at 4 weeks post-ischemia induction. Similar changes, but more moderate, were also seen in the subchondral bone region. In contrast, in the necrotic central trabecular region, significant changes in matrix mineralization were found at 8 weeks (CaMean: +4%, p < 0.05; CaWidth: - 22%, p < 0.05; CaLow: - 8%, p < 0.05) but not at 4 weeks post-ischemia induction. Our findings indicate that the process of matrix mineralization continues in necrotic calcified articular cartilage and bone following femoral head ischemia, which leads to a higher and more homogenous mineralized tissue matrix altering its intrinsic material properties. This may also explain the increased radiodensity seen in the early stage of Perthes disease prior to the initiation of the repair process.
AB - Traditionally, it is believed that structural failure of the ischemic epiphysis as well as changes in radiodensity seen in the early stage of Legg-Calvé-Perthes disease is due to the repair process. However, little is known if matrix properties are altered following ischemic injury of the juvenile femoral head. The purpose of this study was to determine the matrix mineralization density, an important determinant of material quality and strength, of the proximal femoral epiphysis in an experimental animal model of Perthes disease. Ten piglets were surgically induced with femoral head ischemia and euthanized at 4 and 8 weeks following surgery. Contralateral, unoperated femoral heads were used as controls. Bone and calcified cartilage mineralization density distribution parameters were determined using quantitative backscattered electron imaging (qBEI) in the epiphyseal calcified articular cartilage, subchondral bone and central trabecular bone region. Histological as well as radiographic assessment was also performed. In the necrotic calcified epiphyseal cartilage matrix, a significant increase in the mean degree of mineralization (CaMean: +24%, p < 0.0001) as well as the homogeneity of mineralization (CaWidth: - 21%, p < 0.05) and a significantly reduced amount of low mineralized matrix (CaLow: - 49%, p < 0.0001) were already present at 4 weeks post-ischemia induction. Similar changes, but more moderate, were also seen in the subchondral bone region. In contrast, in the necrotic central trabecular region, significant changes in matrix mineralization were found at 8 weeks (CaMean: +4%, p < 0.05; CaWidth: - 22%, p < 0.05; CaLow: - 8%, p < 0.05) but not at 4 weeks post-ischemia induction. Our findings indicate that the process of matrix mineralization continues in necrotic calcified articular cartilage and bone following femoral head ischemia, which leads to a higher and more homogenous mineralized tissue matrix altering its intrinsic material properties. This may also explain the increased radiodensity seen in the early stage of Perthes disease prior to the initiation of the repair process.
KW - Backscattered electron imaging
KW - Bone material properties
KW - Legg-Calvé-Perthes disease
KW - Mineralization
KW - Osteonecrosis
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U2 - 10.1016/j.bone.2009.10.006
DO - 10.1016/j.bone.2009.10.006
M3 - Article
C2 - 19833243
AN - SCOPUS:74449089176
SN - 8756-3282
VL - 46
SP - 379
EP - 385
JO - Bone
JF - Bone
IS - 2
ER -