Morphological characteristics of the developing proximal femur: A biomechanical perspective (original) (raw)
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The heterogeneity in femoral neck structure and strength
Journal of Bone and Mineral Research, 2013
Most measures of femoral neck strength derived using dual-energy X-ray absorptiometry or computed tomography (CT) assume the femoral neck is a cylinder with a single cortical thickness. We hypothesized that these simplifications introduce errors in estimating strength and that detailed analyses will identify new parameters that more accurately predict femoral neck strength.
Evolution of the angle of obliquity of the femoral diaphysis during growth — correlations
Surgical and Radiologic Anatomy, 1997
Numerous studies of the bicondylar angle of the adult femur have been carried out in human anatomy, paleoanthropology and primatology. The aim of this paper is to study the evolution of this angle in relation to age and acquisition of walking in young children. Seventy-seven radiographs of children, ranging from 5 months to 17 years postnatally, and of four dead newborn were analysed. The measurements concern the bicondylar angle (A.O.F.), the collo-diaphyseal angle (A.C.D.), the length of the femoral neck (L.N.) and of the femur (L.F.) and the interacetabular distance (D.I.A.). Some children were x-rayed at different ages, which permits a longitudinal as well cross-sectional study. The results show that there is no sexual dimorphism and that the increase in the angle is closely related to the age of the child. The bicondylar angle starts at 0° at birth and then increases progressively with growth to reach adult values of at least 6°-8° between 4 and 8 years postnatally. In adults, the mean values are between 8° and 11°a nd the maximum range is between 6° and 14°. The obliquity angle corresponds to an angular remodeling of the femoral diaphysis, which is independant of the growth and shape of the distal femoral epiphysis. The tibio-femoral angle measures the evolution of a physiologic phenomenon, from the load "in varus" to the load "in valgus" of the lower limb. It is linked with the bicondylar angle but is different from it.
Morphological and structural characteristics of the proximal femur in human and rat
Bone, 1997
Because the ovarieetomized rat model of postmenopausal osteoporosis is the most commonly used small animal model to investigate consequences of bone loss on bone structure and strength, or to assess benefits of the various therapeutic strategies to improve bone mass and strength, the attempt was made to compaxe histoanatomicai and structural characteristics of the femoral neck beiween human and rat models. In addition to different biomechanics, there is a significant difference in g]ross-and microanatomy of the proximal femur between humans and rats. Percent of the cortical bone component is much Mgher in rats (72.5%) relative to humans (12.5%). Also, cortical bone at the femoral neck in rats is evenly distributed, whereas in humans there is a considerable difference in the amount of the cortical bone between the superior half of the femoral neck with cortical thickness being only 0.3 mm, and the inferior half of the neck having 6-mm-thick cortex. Humans have far more cancellous bone at the femoral neck (22.7% average) relative to rats (6.8%). In addition, cancellous bone at the femoral neck in humans is unevenly distributed between the bone center and its periphery. Human samples exhibited striking differences in the cancellous bone structure between weight-bearing and tensile trabecular groups exhibiting clear trabecular orientation consisting of plates and rods, and trabeculae around the neutral bone axis with little mechanical activity exhibiting rod-like trabeculae only. Although humans and rats have a periosteum covering the femoral neck, and each lacks the muscular attachment at intracapsular portions of the femoral neck, rats, in contrast to humans, have the ability to quickly adapt cortical thickness and increase inertia to meet mechanical needs via modeling-dependent periosteal apposition.
Mechanobiology of femoral neck structure during adolescence
The Journal of Rehabilitation Research and Development
Understanding femoral neck structure may be critical to preventing fractures at this site . We examined the correlates of changes in the femoral neck during adolescence . Dual energy x-ray absorptiometry measurements of proximal femora were made in 101 Caucasian youths (ages 9 to 26 years). Relationships were examined between developmental parameters (age, pubertal stage, height, body mass, lean mass, and fat mass) and femoral structure (bone mineral content, bone mineral density, neck width, cross-sectional area, and cross-sectional strength) . Lean body mass was the best predictor of femoral neck structure, explaining 53-87 percent of the variance, and was independent of gender. Body mass only explained 51-79 percent of the variance . Previously we found body mass to be the strongest predictor of femoral mid-diaphyseal cross-sectional properties . These findings suggest that trabecular bone of the femoral neck may be more responsive to its mechanical environment than the cortical diaphysis . In addi-tion, lean body mass may be a more reliable predictor of muscle loading than body mass.
Variation in cross-sectional indicator of femoral robusticity in Homo sapiens and Neandertals
Scientific Reports, 2022
Variations in the cross-sectional properties of long bones are used to reconstruct the activity of human groups and differences in their respective habitual behaviors. Knowledge of what factors influence bone structure in Homo sapiens and Neandertals is still insufficient thus, this study investigated which biological and environmental variables influence variations in the femoral robusticity indicator of these two species. The sample consisted of 13 adult Neandertals from the Middle Paleolithic and 1959 adult individuals of H. sapiens ranging chronologically from the Upper Paleolithic to recent times. The femoral biomechanical properties were derived from the European data set, the subject literature, and new CT scans. The material was tested using a Mantel test and statistical models. In the models, the polar moment of area (J) was the dependent variable; sex, age, chronological period, type of lifestyle, percentage of the cortical area (%CA), the ratio of second moment areas of inertia about the X and Y axes (Ix/Iy), and maximum slope of the terrain were independent covariates. The Mantel tests revealed spatial autocorrelation of the femoral index in H. sapiens but not in Neandertals. A generalized additive mixed model showed that sex, %CA, Ix/Iy, chronological period, and terrain significantly influenced variation in the robusticity indicator of H. sapiens femora. A linear mixed model revealed that none of the analyzed variables correlated with the femoral robusticity indicator of Neandertals. We did not confirm that the gradual decline in the femoral robusticity indicator of H. sapiens from the Middle Paleolithic to recent times is related to the type of lifestyle; however, it may be associated with lower levels of mechanical loading during adolescence. The lack of correlation between the analysed variables and the indicator of femoral robusticity in Neandertals may suggest that they needed a different level of mechanical stimulus to produce a morphological response in the long bone than H. sapiens. The structure of a bone is optimized in accordance with altered loading regimes, as manifested in the specific morphology, the orientation of the trabecular networks, and the size and distribution of the osteons 1. However, the precise mechanism of mechanical signal detection is still investigated 1-3 especially given that each bone differs in terms of sensitivity to mechanical stimuli 4. Recently, most research has assessed limb bone organization using cross-sectional geometry, which is typically calculated from periosteal and endosteal contours of specific cross-sections 5-8. Due to the broader availability of CT and the development of semiautomated techniques, interpopulation comparisons on larger scales can now be carried out. Thus, cross-sectional geometry is being used to measure diaphyseal variables which characterize bending and torsional rigidity 9. According to Macintosh and Stock 10 , minimizing stress in cortical bone renders the postcranial skeleton (especially the lower limbs) highly reactive to changes in types and levels of mobility and activity patterns. This variability in bone morphology can be applied in paleontological and bioarchaeological research to reconstruct
Interface Focus
The distal femoral metaphyseal surface presents dramatically different morphologies in juvenile extant hominoids—humans have relatively flat metaphyseal surfaces when compared with the more complex metaphyseal surfaces of apes. It has long been speculated that these different morphologies reflect different biomechanical demands placed on the growth plate during locomotor behaviour, with the more complex metaphyseal surfaces of apes acting to protect the growth plate during flexed-knee behaviours like squatting and climbing. To test this hypothesis, we built subject-specific parametric finite-element models from the surface scans of the femora of five Pan and six Homo juveniles. We then simulated the loading conditions of either a straight-leg or flexed-knee gait and measured the resulting stresses at the growth plate. When subjected to the simulated flexed-knee loading conditions, both the maximum and mean von Mises stresses were significantly lower in the Pan models than in the Hom...
Biomechanical and system analysis of the human femoral bone: correlation and anatomical approach
Journal of Orthopaedic Surgery and Research, 2007
The human femur is the subsystem of the locomotor apparatus and has got four levels of its organization. This phenomenon is the result of the evolution of the locomotor apparatus, encompassing both constitutional and individual variability. The main aim of this investigation was to study the organization of the human femur as a system of collaborating anatomical structures and, on the basis of system analysis, to define the less stable parameters, whose reorganization can cause the exchange of the system's status.
Development of Cortical Bone Geometry in the Human Femoral and Tibial Diaphysis
Anatomical Record
"Ontogenetic growth processes in human long bones are key elements, determining the variability of adult bone structure. This study seeks to identify and describe the interaction between ontogenetic growth periods and changes in femoral and tibial diaphyseal shape. Femora and tibiae (n546) ranging developmentally from neonate to skeletally mature were obtained from the Norris Farms No. 36 archeological skeletal series. High-resolution X-ray computed tomography scans were collected. Wholediaphysis cortical bone drift patterns and relative bone envelope modeling activity across ages were assessed in five cross-sections per bone (total bone length: 20%, 35%, 50%, 65%, and 80%) by measuring the distance from the section centroid to the endosteal and periosteal margins in eight sectors using ImageJ. Pearson correlations were performed to document and interpret the relationship between the cross-sectional shape (Imax/Imin), total subperiosteal area, cortical area, and medullary cavity area for each slice location and age for both the femur and the tibia. Differences in cross-sectional shape between age groups at each cross-sectional position were assessed using nonparametric Mann-Whitney U tests. The data reveal that the femoral and tibial midshaft shape are relatively conserved throughout growth; yet, conversely, the proximal and distal femoral diaphysis and proximal tibial diaphysis appear more sensitive to developmentally induced changes in mechanical loading. Two time accelerated change are identified: early childhood and repuberty/adolescence."
Introduction: The age-related exponential increase in femoral-neck (FN) fracture risk is not fully explained by the corresponding decrease in bone mineral density of the FN. Aging affects FN fracture risk independently of bone mineral density, suggesting that there are other important age-related changes that must be considered [1,2]. Yoshikawa et al. [3] and Mayhew et al. [1] showed that bone loss occurs preferentially on the superior aspect of the FN. This region is under minimum mechanical stress during walking, whereas a fall on the hip reverses the stress pattern causing high compressive stresses at the superior FN (Fig. 1). Therefore, age-related bone loss occurs in the specific location that is most highly stressed by a fall. Mayhew et al. [1] propose that structural changes in the FN occur independently of osteoporosis and contribute greatly to the risk of FN fracture. They noted that bone loss at the superior aspect of the FN could make the bone susceptible to failure by buckling. Buckling is most commonly associated with slender columns. A column loaded in compression can bow laterally and, if the lateral displacement of the column surpasses a critical amount, the column will collapse. Mayhew et al. [1] show that cortical thinning occurs preferentially at the posterior-superior (Sup) FN whereas the inferior (Inf) cortical shell gains thickness with age. (The latter change is thought to be an adaptive response to walking, which causes large compressive stresses on the inferior FN.) If the FN does indeed behave like a shell, then the Sup region should be at high risk of buckling during a sideways fall. In the present study we advance our previous research on histomorphology of the FN with aging [4] by seeking to determine if there is evidence that the age-related increased risk of buckling might be curbed by compensatory changes in bone material organization. Methods: 29 human FNs (3 M, 26 F; 18-95 yrs) were embedded in methacrylate and a mid-transverse section from each was mounted on glass and ultramilled (100µm). 50X circular polarized light images were obtained in octants. The buckling ratio for each femoral neck was calculated as 1⁄2 the outer diameter of the femoral neck measured in the plane of bending (Sup.-Inf. axis) divided by the average cortical thickness in all eight (octant) locations [5]. Predominant CFO was expressed as the mean gray-level of each image, and population densities of complete secondary osteons (OPD) and their morphotype scores (MTS) were also quantified [4,6]. Osteon morphotypes are based on collagen/lamellar patterns that correlate with regional differences in habitual strain mode (compression vs. tension) [6]. We also quantified: fractional area of secondary bone (FASB, %), porosity (%), osteon area (On.Ar, µm 2), osteon circularity (On.Cr) (1.0 = perfect circle), Haversian canal area (HC.Ar), Haversian canal circularity (HC.Cr), osteon formation/infilling (On.Ar-HC.Ar), and cortical thickness (CT, mm). The regions quantified were defined as the Sup cortex (posterior, posterior-superior, superior;