Improved Performance of Hip DXA Using a Novel Region of Interest in the Upper Part of the Femoral Neck: In Vitro Study Using Bone Strength as a Standard of Reference

doi:10.1385/JCD:8:4:488

Journal of Clinical Densitometry

Volume 8, Issue 4, Winter 2005, Pages 488-494

https://doi.org/10.1385/JCD:8:4:488 Get rights and content

Abstract

We tested the hypothesis that bone mineral density (BMD) and bone mineral content (BMC) in proximal human femur specimens in the upper neck region of interest (ROI) and femoral neck axis length (FNAL) provide a significantly better prediction of femoral bone strength than standard ROIs in vitro. BMD and BMC were measured in 110 proximal femur specimens using a standard dual-energy X-ray absorptiometry (DXA) scanner. The analysis included a new ROI in the upper neck as well as the standard ROIs. FNAL was obtained from the scan images. The specimens' failure-load was measured in a mechanical loading device, simulating a fall on the greater trochanter. For the standard ROIs, correlations between failure-load and BMD ranged from R² = 0.64 (shaft ROI) to R² = 0.70, p < 0.001 (femoral neck). Prediction of strength by BMD did not significantly differ from those of BMC (R² ranging from 0.65 to 0.75, p < 0.001). In the upper neck ROI, for both BMD and BMC correlations with failure-load were higher (R² = 0.76 and 0.81, respectively; p < 0.001). A lower, yet still significant, correlation was found between FNAL and bone strength (R² = 0.23, p < 0.001). Normalization of failure-load with respect to FNAL did not significantly increase the correlations with densitometric measures. This study provides in vitro evidence indicating that among the ROIs of the proximal femur the newly defined upper neck ROI provides the best prediction of bone strength. Only a weak association was observed between failure load and FNAL.

References (28)

XG Cheng et al.
Assessment of the strength of proximal femur in vitro: relationship to femoral bone mineral density and femoral geometry
Bone
(1997)
DD Cody et al.
Femoral strength is better predicted by finite element models than QCT and DXA
J Biomech
(1999)
N Crabtree et al.
Hip geometry, bone mineral distribution, and bone strength in European men and women: the EPOS study
Bone
(2000)
TF Lang et al.
Volumetric quantitative computed tomography of the proximal femur: precision and relation to bone strength
Bone
(1997)
KL Bell et al.
Regional differences in cortical porosity in the fractured femoral neck
Bone
(1999)
TM Boyce et al.
Cortical aging differences and fracture implications for the human femoral neck
Bone
(1993)
ML Bouxsein et al.
Prediction of the strength of the elderly proximal femur by bone mineral density and quantitative ultrasound measurements of the heel and tibia
Bone
(1999)
CE DeLaet et al.
Incremental cost of medical care after hip fracture and first vertebral fracture: the Rotterdam study
Osteoporos Int
(1999)
AC Courtney et al.
Effects of loading rate on strength of the proximal femur
Calcif Tissue Int
(1994)
EM Lochmüller et al.
In situ femoral dual-energy X-ray absorptiometry related to ash weight, bone size and density, and its relationship with mechanical failure loads of the proximal femur
Osteoporos Int
(2000)

NJ Crabtree et al.

Improving risk assessment: hip geometry, bone mineral distribution and bone strength in hip fracture cases and controls. The EPOS study. European Prospective Osteoporosis Study

Osteoporos Int

(2002)

F Duboeuf et al.

Different morphometric and densitometric parameters predict cervical and trochanteric hip fracture: the EPIDOS Study

J Bone Miner Res

(1997)

JC Lotz et al.

Fracture prediction for the proximal femur using finite element models: Part I—Linear analysis

J Biomech Eng

(1991)

TJ Beck et al.

Age-related changes in female femoral neck geometry: implications for bone strength

Calcif Tissue Int 53 Suppl

(1993)

Cited by (25)

Femoral neck bone adaptation to weight-bearing physical activity by computational analysis
2013, Journal of Biomechanics
Citation Excerpt :
A central and well confined Ward′s area suggests a more balanced femoral neck bone mass distribution within all the anatomic subregions of the femoral neck. However, a Ward′s area less confined superiorly, as macroscopically characterized by lower bone mineral density and cortical thinning at the upper part of the femoral neck, seems to be of importance in determining resistance to fracture (Boehm et al., 2005; Johannesdottir et al., 2011; Li et al., 2009). Given the significance that physical activity/exercise may have in preventing hip fragility (Nikander et al., 2009, 2010) and the fact that most of the clinical research employed planar dual energy x-ray absorptiometry (DXA), which is not very useful for understanding where bone mass has been added or subtracted within a three-dimensional bone geometry in response to mechanical loading (Bolotin et al., 2001; Proff and Römer, 2009), this work had the main goal to investigate, by means of three-dimensional finite element method and a suitable bone remodeling model the association between weight-bearing physical activity and bone mass distribution among anatomic subregions (superior, inferior anterior and posterior) of femoral neck.
Individual differences in bone mass distribution at the proximal femur may be determined by daily weight-bearing physical activity (PA) since bone self-adapts according to the mechanical loads that is submitted. The aim of this study was to analyse computationally the effect of different weight-bearing PA types in the adaptation of the femoral neck (FN) by analysing regional differences in bone mineral density (BMD) at the integral FN and its superior, inferior, anterior and posterior subregions. To achieve this, it was adopted a 3-D femoral finite element (FE) model coupled with a suitable bone remodeling model. Different PA types were determined based both on ordinary lifestyle and mechanically more demanding PA as low magnitude impacts (L–I), moderate-magnitude impacts from odd directions (O–I) and high-magnitude vertical impacts (H–I). It was observed that as time spent in weight-bearing PA increases, BMD augment around the integral FN, but with different bone mass gain rates between subregions depending on the magnitude and directions of the hip contact forces; H–I was the type of weight-bearing PA which structurally most favor the gain of bone mass superiorly at the FN while both the H–I and the O–I types of PA promoted the largest bone mass gain rates at the anterior and posterior subregions of the FN. Because these types of weight-bearing PA were associated with a more uniform bone mass spatial distribution at the FN, they should provide a potential basis for targeted PA-based intervention programs for improving hip strength.
Three-dimensional structural analysis of the proximal femur in an age-stratified sample of women
2013, Bone
Citation Excerpt :
These findings were further confirmed by a number of DXA studies splitting the neckbox ROI into an upper and a lower part. All three studies found either better correlation of the upper part with bone strength [25] or improved hip fracture prediction [26,27] compared to the complete ROI. Collectively, these findings suggest that age-related decreases in the cortical bone in the superior regions of the femur neck may be particularly detrimental and predispose to hip fracture risk.
Aging is associated with worsening bone structure and increasing risk of hip fracture. However, the commonly used clinical tool, dual-energy x-ray absorptiometry, does not provide information on changes with age or disease separately in trabecular versus cortical bone or in bone geometry. Here we used 3D quantitative computed tomography (QCT) to analyze age-related changes in femoral volumetric bone mineral density (vBMD) and structure in a well characterized, population-based cohort of Rochester, Minnesota women.
MIAF-Femur (MIAF: medical image analysis framework) was used for the analysis of CT datasets from 358 women age 20 to 97 years. Integral, “apparent” cortical (rather than true cortical vBMD, due to volume averaging effects) and trabecular vBMD, volume, and bone mineral content (BMC) as well as cortical thickness of the femur head, neck, trochanter, inter-trochanteric, and proximal shaft volumes of interest (VOIs) were measured. In addition, changes in vBMD in the superior, inferior, posterior and anterior quadrants of the femur neck were assessed.
Cross-sectional percent decreases in vBMD across life were 2- to 5-fold higher in trabecular versus cortical bone at all sites in the femur, although absolute changes in the trabecular and cortical bone were fairly similar. In addition, the slopes of the relationships of trabecular vBMD with age were generally similar in pre- and postmenopausal women, whereas apparent cortical vBMD in the femur neck, trochanter, inter-trochanteric region, and proximal shaft remained relatively stable in premenopausal women but decreased significantly with age following the menopause. Bone volume increased at all sites, more so in pre- compared to postmenopausal women. Age-related BMC changes were not significant in premenopausal women, but BMC losses were highly significant in postmenopausal women. Detailed analyses of femur neck cortical bone showed that percent apparent vBMD decreases in the superior quadrants were 2- to 3-fold greater than in the inferior quadrants; changes in absolute values were most different (~ 2-fold) between the superior-posterior and inferior-posterior quadrants.
These data demonstrate that patterns of changes with age within the femur differ in the trabecular versus cortical bone. In the cortical compartment which, due to limitations in spatial resolution, contains some subcortical bone and should be regarded as an “apparent” cortical VOI, the superior quadrants in the femur neck undergo the greatest decreases. These findings may have important implications for understanding the structural basis for increased hip fracture risk with aging.
Male-female differences in the association between incident hip fracture and proximal femoral strength: A finite element analysis study
2011, Bone
Citation Excerpt :
The strength of the proximal femur as measured on cadaveric femora under single-limb stance loading is more strongly predicted by QCT-based patient-specific FE modeling (r2 = 0.77 to 0.96 [4,6,7]) than by aBMD from DXA [4]. Studies of cadaveric femora under loading from a fall onto the greater trochanter have shown similar trends [8–11]. Although FE models can strongly predict actual, measured hip bone strength, there is limited experience in using this technique to predict hip fracture in vivo.
Hip fracture risk is usually evaluated using dual energy X-ray absorptiometry (DXA) or quantitative computed tomography (QCT) which provide surrogate measures for proximal femoral strength. However, proximal femoral strength can best be estimated explicitly by combining QCT with finite element (FE) analysis. To evaluate this technique for predicting hip fracture in older men and women, we performed a nested age- and sex-matched case–control study in the Age Gene/Environment Susceptibility (AGES) Reykjavik cohort. Baseline (pre-fracture) QCT scans of 5500 subjects were obtained. During 4–7 years follow-up, 51 men and 77 women sustained hip fractures. Ninety-seven men and 152 women were randomly selected as age- and sex-matched controls. FE-strength of the left hip of each subject for stance (F_Stance) and posterolateral fall (F_Fall) loading, and total femur areal bone mineral density (aBMD) were computed from the QCT data. F_Stance and F_Fall in incident hip fracture subjects were 13%–25% less than in control subjects (p ≤ 0.006) after controlling for demographic parameters. The difference between FE strengths of fracture and control subjects was disproportionately greater in men (stance, 22%; fall, 25%) than in women (stance, 13%; fall, 18%) (p ≤ 0.033), considering that F_Stance and F_Fall in fracture subjects were greater in men than in women (p < 0.001). For men, F_Stance was associated with hip fracture after accounting for aBMD (p = 0.013). These data indicate that F_Stance provides information about fracture risk that is beyond that provided by aBMD (p = 0.013). These findings support further exploration of possible sex differences in the predictors of hip fracture and of sex-specific strategies for using FE analysis to manage osteoporosis.
Identify fracture-critical regions inside the proximal femur using statistical parametric mapping
2009, Bone
Citation Excerpt :
Bone mineral density (BMD) measurements such as dual x-ray absorptiometry (DXA) [24] or volumetric quantitative computed tomography (vQCT) [6] evaluate regions of interest that are defined with respect to identifiable anatomic landmarks [2–4,9,19]. Regions such as the femoral neck, integrate the superior and inferior cortex, although the former may be more sensitive as a fracture risk estimator [5]. Although manufacturers have subdivided the DXA femoral neck region of interest into superior and inferior halves, the selection of these regions is based on sub-division of an existing ROI rather than on choosing a region which is specifically optimized for fracture risk estimation.
We identified regions inside the proximal femur that are most strongly associated with hip fracture. Bone densitometry based on such fracture-critical regions showed improved power in discriminating fracture patients from controls.
Hip fractures typically occur in lateral falls, with focal mechanical failure of the sub-volumes of tissue in which the applied stress exceeds the strength. In this study, we describe a new methodology to identify proximal femoral tissue elements with highest association with hip fracture. We hypothesize that bone mineral density (BMD) measured in such sub-volumes discriminates hip fracture risk better than BMD in standard anatomic regions such as the femoral neck and trochanter.
We employed inter-subject registration to transform hip QCT images of 37 patients with hip fractures and 38 age-matched controls into a voxel-based statistical atlas. Within voxels, we performed t-tests between the two groups to identify the regions which differed most. We then randomly divided the 75 scans into a training set and a test set. From the training set, we derived a fracture-driven region of interest (ROI) based on association with fracture. In the test set, we measured BMD in this ROI to determine fracture discrimination efficacy using ROC analysis. Additionally, we compared the BMD distribution differences between the 29 patients with neck fractures and the 8 patients with trochanteric fractures.
By evaluating fracture discrimination power based on ROC analysis, the fracture-driven ROI had an AUC (area under curve) of 0.92, while anatomic ROIs (including the entire proximal femur, the femoral neck, trochanter and their cortical and trabecular compartments) had AUC values between 0.78 and 0.87. We also observed that the neck fracture patients had lower BMD (p = 0.014) in a small region near the femoral neck and the femoral head, and patients with trochanteric fractures had lower BMD in trochanteric regions such as in the internal calcar septum (p = 0.006).
We have identified the sub-volumes of proximal femoral tissue which have the strongest association with hip fracture. The power to predict fracture can be improved, by focusing on BMD measurements in the fracture-critical regions, rather than in standard ROIs.
Prediction of the fracture load of whole proximal femur specimens by topological analysis of the mineral distribution in DXA-scan images
2008, Bone
Citation Excerpt :
Since we did not apply any normalization procedure for adjustment of image size, the segmented bone area of the proximal femur as depicted by the scanner-generated image directly enters our evaluation. Femoral bone mineral is routinely measured in standard regions of interest (ROI) such as the femoral neck, the trochanteric or shaft regions, or the Ward's triangle showing high correlation with susceptibility to fracture in vivo and with ultimate compressive strength in vitro [19,21–23]. With the arrival of advanced imaging technologies and sophisticated software for image post-processing, new regions of interest have evolved and more recently, geometric dimensions, e.g., hip axis length (HAL) or femoral neck axis length (FNAL), are considered in conjunction with BMD allowing to enhance the predictive potential further [7,22,24–26].
To evaluate scanner-generated images of hip specimens obtained from dual energy X-ray absorptiometry (DXA) by quantitative image analysis of bone mineral distribution in the standard regions of interest (ROI), to predict the ultimate mechanical strength, and to compare the predictive potential with standard densitometry.
Femoral bone mineral density (BMD) of 100 hip specimens was obtained by DXA in the total hip, shaft, trochanteric, and neck ROI. Maximum compressive strength (MCS) of the specimens was measured in a mechanical loading device simulating a fall on the greater trochanter. The topology of bone mineral distribution in the scan images was evaluated by image processing methods based on the Minkowski functionals (MF) using the optimized topological parameter MF2D. Correlation and multivariate analysis were employed to assess the statistical potential of BMD and MF2D with respect to predict the mechanical strength of the femur specimens.
R² for the correlation between load-to-failure and BMD varied between 0.73 and 0.79 (exponential curve fit, p < 0.001), being highest in the trochanteric ROI. Correlation between load-to-failure of the specimens with the topological parameter MF2D ranged from R²= 0.8 to 0.91 (p < 0.001). In a multivariate model combining the topological information from all ROIs, correlation with MCS rose to R² = 0.94.
The topological parameter MF2D can be employed to predict the mechanical strength of proximal femur specimens from DXA-generated images. Performance is superior to standard evaluation of DXA. In the future, the proposed image processing method may serve to improve the assessment of an individual's fracture risk.
Macro- and Microimaging of Bone Architecture
2008, Principles of Bone Biology: Volume 1-2, Third Edition
At the macroscopic level the term bone is used for the organ bone as a distinct entity of the skeleton. At this level bone architecture describes the overall shape and geometry of bone as well as the differentiation into cancellous (also referred to as trabecular) and cortical bone. Typical parameters describing architecture are cortical thickness, moment of inertia and other geometrical measures. Bone mineral density (BMD) of the whole bone or of well-defined subvolumes is another important parameter. At the microscopic level, i.e., if the spatial resolution of the acquired images is better than 100μm, bone architectural assessment is predominantly associated with trabecular structure, i.e., the interconnecting lattice of bone tissue filled with marrow. Typical parameters are trabecular thickness and separation of trabeculae and parameters comprehensively describing the network architecture, such as the structure model index (SMI). Macroimaging of bone architecture employs x-ray-based imaging modalities either using planar methods such as conventional radiography and dual x-ray absorptiometry (DXA), or volumetric methods such as quantitative computed tomography (QCT). Methods of microimaging are: three-dimensional (3D) microcomputed tomography (μCT) and three-dimensional micromagnetic resonance imaging (μMRI). Although it is not precisely defined, the range between macro- and microimaging i.e., from approximately 100μm to 500 μm, is usually denoted as high-resolution CT (hrCT) and MRI (hrMRI) imaging for CT and MRI.

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Journal of Clinical Densitometry

Abstract

References (28)

Assessment of the strength of proximal femur in vitro: relationship to femoral bone mineral density and femoral geometry

Bone

Femoral strength is better predicted by finite element models than QCT and DXA

J Biomech

Hip geometry, bone mineral distribution, and bone strength in European men and women: the EPOS study

Bone

Volumetric quantitative computed tomography of the proximal femur: precision and relation to bone strength

Bone

Regional differences in cortical porosity in the fractured femoral neck

Bone

Cortical aging differences and fracture implications for the human femoral neck

Bone

Prediction of the strength of the elderly proximal femur by bone mineral density and quantitative ultrasound measurements of the heel and tibia

Bone

Incremental cost of medical care after hip fracture and first vertebral fracture: the Rotterdam study

Osteoporos Int

Effects of loading rate on strength of the proximal femur

Calcif Tissue Int

In situ femoral dual-energy X-ray absorptiometry related to ash weight, bone size and density, and its relationship with mechanical failure loads of the proximal femur

Osteoporos Int

Improving risk assessment: hip geometry, bone mineral distribution and bone strength in hip fracture cases and controls. The EPOS study. European Prospective Osteoporosis Study

Osteoporos Int

Different morphometric and densitometric parameters predict cervical and trochanteric hip fracture: the EPIDOS Study

J Bone Miner Res

Fracture prediction for the proximal femur using finite element models: Part I—Linear analysis

J Biomech Eng

Age-related changes in female femoral neck geometry: implications for bone strength

Calcif Tissue Int 53 Suppl

Cited by (25)

Femoral neck bone adaptation to weight-bearing physical activity by computational analysis

Three-dimensional structural analysis of the proximal femur in an age-stratified sample of women

Male-female differences in the association between incident hip fracture and proximal femoral strength: A finite element analysis study

Identify fracture-critical regions inside the proximal femur using statistical parametric mapping

Prediction of the fracture load of whole proximal femur specimens by topological analysis of the mineral distribution in DXA-scan images

Macro- and Microimaging of Bone Architecture

Original ArticleImproved Performance of Hip DXA Using a Novel Region of Interest in the Upper Part of the Femoral Neck: In Vitro Study Using Bone Strength as a Standard of Reference

Abstract

Bone

J Biomech

Bone

Bone

Bone

Bone

Bone

Incremental cost of medical care after hip fracture and first vertebral fracture: the Rotterdam study

Osteoporos Int

Effects of loading rate on strength of the proximal femur

Calcif Tissue Int

In situ femoral dual-energy X-ray absorptiometry related to ash weight, bone size and density, and its relationship with mechanical failure loads of the proximal femur

Osteoporos Int

Improving risk assessment: hip geometry, bone mineral distribution and bone strength in hip fracture cases and controls. The EPOS study. European Prospective Osteoporosis Study

Osteoporos Int

Different morphometric and densitometric parameters predict cervical and trochanteric hip fracture: the EPIDOS Study

J Bone Miner Res

Fracture prediction for the proximal femur using finite element models: Part I—Linear analysis

J Biomech Eng

Age-related changes in female femoral neck geometry: implications for bone strength

Calcif Tissue Int 53 Suppl

Original Article
Improved Performance of Hip DXA Using a Novel Region of Interest in the Upper Part of the Femoral Neck: In Vitro Study Using Bone Strength as a Standard of Reference