Age-related hypermineralization in the female proximal human femur

Abstract

Hip fracture incidence increases exponentially with age in virtually every human population that has been studied. In spite of this, relatively few studies have examined age-related changes in the metaphyseal cortex of the proximal femur. The present study investigates cortical aging changes in the female proximal femur, with particular reference to regions of hypermineralization. Thirty-three femora from Caucasian females were obtained at autopsy and analyzed using backscattered electron imaging. Variations in hypermineralized tissue area, cortical bone area, and porosity were quantified with standard stereological methods. Cortical width was quantified with digital calipers. Gender differences were examined by statistical comparison with previously published results. Hypermineralized tissue volume was significantly (P < 0.001) greater in elderly individuals. Hypermineralized tissue preferentially appeared near ligamentous or tendinous insertion sites, suggesting the hypermineralized tissue may be a calcified fibrocartilage. Cortical width significantly (P < 0.001) decreased with age and porosity significantly (P < 0.001) increased with age, however the changes were site-specific. The femoral neck and intertrochanteric cortices had a smaller change in cortical width and porosity with age than the diaphysis, but the femoral neck and intertrochanteric cortices had a larger increase in hypermineralized tissue. Comparison with previous data suggests that cortical aging in the proximal femur is similar between males and females and is unlikely to explain the higher incidence of fracture in females. However, the data strongly indicates that age-related changes in the femoral diaphysis cannot be directly extrapolated to either the femoral neck or intertrochanteric cortices.

Young-elderly differences in bone density, geometry and strength indices depend on proximal femur sub-region: A cross sectional study in Caucasian-American women

“…These results are consistent with findings reporting increased mineralized tissue, areas of higher mineral content than the adjacent cortex, at the FN in elderly populations [4,5,37]. The origin of these highly mineralized areas may be due to subperiosteal calcification derived from the periosteum [11], necrotic tissue where minerals continue to accumulate [5] or calcified fibrocartilagenous tissue at points of attachments of tendons or capsules [5,37]. The presence of fully mineralized tissue areas may have implications for fracture strength and it has been reported that these highly mineralized regions make the formation and expansion of cracks easier [10].…”

“…The higher value of cBMD at the FN in the elderly women, compared to the TR (which decreased with age), may be due to the presence of highly mineralized areas in the FN cortex of elderly women. These results are consistent with findings reporting increased mineralized tissue, areas of higher mineral content than the adjacent cortex, at the FN in elderly populations [4,5,37]. The origin of these highly mineralized areas may be due to subperiosteal calcification derived from the periosteum [11], necrotic tissue where minerals continue to accumulate [5] or calcified fibrocartilagenous tissue at points of attachments of tendons or capsules [5,37].…”

“…Various reports have supported the role of periosteal apposition as a mechanism to preserve bone strength in the context of agerelated trabecular and cortical bone loss [1,3,7,9,12,19,30,31,33,36,37]. However, none of these reports have focused on examining age-related material and geometric changes in the trochanter and comparing these changes to those observed in the femoral neck.…”

RETRACTED: The periosteum

“…Previous studies have documented that both periosteal calcification and calcified fibrocartilage undergo osteonal remodeling. 134,140 Although this study did not document any calcified fibrocartilage, the abundant periosteal mineralized tissue did contain individual osteons, clearly separated from the periosteal bone surface, in some regions. Such mechanism could be an alternative explanation for femoral neck periosteal expansion with age.…”

Use of multiple acoustic wave modes for assessment of long bones: Model study

“…This leads to thinning of the cortex and trabecularization of the inner cortical layer [10]. On the other hand, hypermineralization of the bone and increase of true bone mineral density noted in aged patients [11] can lead to higher ultrasound velocity in the outer layer, thus, can confound the diagnostic outcome based on the velocity alone. That is why the knowledge about changes in elastic properties and the effective thickness of the cortex are of equal diagnostic value for better assessment of different types of osteopenia and detecting osteoporosis development in long bones at earlier stages.…”