Proximal Femoral Geometry Research Articles

CORR Insights®: Can Radiographs Predict the Use of Modular Stems in Developmental Dysplasia of the Hip?

P redicting from plain radiographs when a patient’s complex proximal femoral anatomy might benefit from a femoral prosthesis that differs from those used in routine primary THA can be difficult. This occurs most commonly in patients with excessive anteversion and increased valgus neck-shaft angle. We have all been there, waiting in the operating room, unable to proceed to the next step in the operation, because the correct equipment is unavailable. Most, but certainly not all, of these delays are avoidable. Steve Jobs once stated, ‘‘My favorite things in life don’t cost money. It is really clear that the most precious resource we all have is time’’ [1]. Complex primary and revision hip arthroplasty often require extensive preoperative planning. This planning takes valuable time, and our time is short; however, time spent preparing for surgery can save much more time—and more valuable time—in the operating room later. Things would be better still if we could have a higher degree of confidence that the preoperative planning we perform will not allow for unpleasant surprises during surgery. The paper by Peters et al. is the first to describe threshold angles from preoperative radiographs—including coronal neck-shaft angle, sagittal neckshaft angle, and calculated femoral neck anteversion—that can help the surgeon determine preoperatively whether nonstandard femoral stems may be needed to successfully address complex proximal femoral geometry.

Using 3D digital image correlation to visualise the progress of failure of human proximal femur

An accurate measuring tool is required to measure the full-field displacement of the complex geometry of the human proximal femur when subjected to axial loads. Optical techniques, such as digital image correlation (DIC), have been used extensively in order to measure planar or volumetric displacement. Even though DIC methods are now in frequent use in experimental bone mechanics, this technique has only recently been reported to measure 3D proximal ex-vivo femur displacement fields during loading under axial loads. The innovation of this study is to extend the use of the DIC technique to visualise and track the progress of failure of the proximal femur under limb stance configuration. An experimental protocol has been proposed and validated on eight human cadaveric femurs. The results indicated that failure takes place by shearing in the head–neck region. Furthermore, it was found that this method enables to extract additional information on the fracture profile and its initiation. The obtained information can facilitate the interpretation of the in vitro failure behaviour of human femur under axial loading conditions which will serve the validation of hip models.

Proximal femur geometry assessed by hip structural analysis in hip fracture in women.

In the pathogenesis of hip fracture, proximal femur geometry plays a key role as well as decreased bone density. The hip structural analysis (HSA) processes dual energy X-ray absorptiometry (DXA) images containing information on the geometry closely related to the strength of the proximal femur. The objective of this study was to investigate bone mineral density (BMD) and mechanical properties of the proximal femur in a group of women with a previous contralateral hip fragility fracture compared to women without history of hip fracture. In a population of postmenopausal women, we evaluated bone density by DXA and bone geometry using the HSA parameters (femoral strength index, cross-sectional moment of inertia, cross-sectional area, section modulus, and buckling ratio) including hip axis length (HAL) and neck shaft angle. Of a total of 62 postmenopausal women, twenty-six with a history of hip fracture had a mean femoral neck BMD significantly lower in comparison with 36 women in the control group (0.703 versus 0.768 g/cm(2), p = 0.0347). There was a statistically significant difference between groups also for HAL (106.75 mm in fracture group versus 100.93 mm in control group, p = 0.0015). Our results demonstrated that all the geometrical parameters resulted worst into the group of patients with history of hip fracture, even though only the HAL was significantly lower in control subjects. In our opinion HSA is useful to characterize the risk of hip fracture in postmenopausal women, providing additional data on the spatial distribution of bone mass strongly related to bone strength.

Exercise capacity independently predicts bone mineral density and proximal femoral geometry in patients with acute decompensated heart failure.

Heart failure is associated with increased risk of osteoporosis. We evaluated the prevalence and predictors of osteoporosis in hospitalized patients with ADHF using quantitative computed tomography. Osteoporosis and vertebral fracture are prevalent in patients with ADHF and exercise capacity independently predicts bone mass and femoral bone geometry. Heart failure is associated with reduced bone mass and increased risk of osteoporotic fractures. However, the prevalence and predictors of osteoporosis in hospitalized patients with acute decompensated heart failure (ADHF) are not well understood. Sixty-five patients (15 postmenopausal females and 50 males) with ADHF were prospectively and consecutively enrolled. After stabilization of heart failure symptoms, quantitative computed tomography for bone mineral density (BMD) and femoral geometry as well as biochemical, echocardiographic, and cardiopulmonary exercise tests were performed. Fifteen postmenopausal female showed a high prevalence of osteoporosis (40%) and vertebral fracture (53%). Among 50 male patients, 12% had osteoporosis and 32% had osteopenia, while vertebral fracture was found in 12%. Lumbar volumetric BMD (vBMD) was significantly lower in ischemic patients than non-ischemic patients (107.9 ± 47.5 vs. 145.4 ± 40.9 mg/cm(3), p = 0.005) in male. Exercise capacity, indicated by peak oxygen consumption (VO2), was significantly associated with lumbar vBMD (r = 0.576, p < 0.001) and total hip areal BMD (aBMD) (r = 0.512, p = 0.001) and cortical thickness of the femur neck (r = 0.544, p = 0.001). When controlled for age, body mass index, N-terminal proBrain natriuretic protein (NT-proBNP), etiology of heart failure, hemoglobin, and thigh circumference, multivariate regression analysis revealed peak VO2 independently predicted lumbar vBMD (β = 0.448, p = 0.031), total hip aBMD (β = 0.547, p = 0.021), and cortical thickness of the femur neck (β = 0.590, p = 0.011). In male patients with ADHF, osteoporosis and vertebral fracture are prevalent, and exercise capacity independently predicts bone mass and geometry. Given that heart failure patients with reduced exercise capacity carry a substantial increased risk of fracture, proper osteoporosis evaluation is important in these patients.

Is the canal flare index a reliable means of estimation of canal shape? Measurement of proximal femoral geometry by use of 3D models of the femur.

The canal flare index (CFI; the ratio of the diameter of the femoral canal at the isthmus in the anteroposterior (A-P) view to the diameter of the medullary canal 20mm above the lesser trochanter) is often used as a canal characteristic. Clinically, however, CFI measurements are sometimes untrustworthy because of femoral rotation and, especially, greater anteversion among Japanese patients. Our objectives were to analyze femoral geometry, by use of 3D CAD models, to evaluate the effects of rotational error, and to seek an index less affected by rotation. Computed axial tomography (CAT) scan data from 60 femurs were used. By use of CAD software, 3D femoral models were created. The outside of the femur and the inside canal width 20mm (P20) and 10mm proximal (P10), and 10mm (D10), 20mm (D20), 30mm (D30), and 40mm (D40) distal from the center of the lesser trochanter, and at the isthmus were measured for different angles of femoral rotation. CFI, FFI (femoral flare index; the ratio of the extra-cortical diameters at the same levels as for the CFI), and other canal ratios (P20/D10, P20/D20, P20/D30, and P20/D40) were then calculated and the effect of rotational errors was investigated. Mean CFI, FFI, P20/D10, P20/D20, P20/D30, and P20/D40 were 4.29, 2.08, 2.05, 2.49, 2.85, and 3.09 in the position without rotational error. CFI was not related to anteversion but had a negative correlation with isthmus canal width (only). In contrast FFI was almost constant at approximately 2.1 for different anteversion and age. With regard to the effect of rotational error, CFI changed by 1.31, FFI by 0.40, P20/D10 by 0.41, P20/D20 by 0.40, P20/D30 by 0.59, and P20/D40 by 0.80 for a variety of rotational angles. Outside femoral shape was little different for any person; as a result, FFI was almost constant. In contrast, CFI was revealed to be affected by canal width at the isthmus only. With regard to the effect of rotation, P20/D20 was much less affected by rotation than CFI; it could, therefore, be an appropriate index for expressing proximal canal shape.

Strong correlation between the morphology of the proximal femur and the geometry of the distal femoral trochlea.

Previous investigations suggested that the geometry of the proximal femur may be related to osteoarthritis of the tibiofemoral joint and various patellofemoral joint conditions. This study aims to investigate the correlation between proximal and distal femoral geometry. Such a correlation could aid our understanding of patient complications after total knee arthroplasty (TKA) and be of benefit for further development of kinematic approaches in TKA. CT scans of 60 subjects (30 males, 30 females) were used to identify anatomical landmarks to calculate anatomical parameters of the femur, including the femoral neck anteversion angle, neck-shaft angle (NSA), mediolateral offset (ML-offset), condylar twist angle (CTA), trochlear sulcus angle (TSA) and medial/lateral trochlear inclination angles (MTIA/LTIA). Correlation analyses were carried out to assess the relationship between these parameters, and the effect of gender was investigated. The CTA, TSA and LTIA showed no correlation with any proximal parameter. The MTIA was correlated with all three proximal parameters, mostly with the NSA and ML-offset. Per 5° increase in NSA, the MTIA was 2.1° lower (p<0.01), and for every 5mm increase in ML-offset, there was a 2.6° increase in MTIA (p<0.01). These results were strongest and statistically significant in females and not in males and were independent of length and weight. Proximal femoral geometry is distinctively linked with trochlear morphology. In order to improve knowledge on the physiological kinematics of the knee joint and to improve the concept of kinematic knee replacement, the proximal femur seems to be a factor of clinical importance. III.

Contributions of fat mass and fat distribution to hip bone strength in healthy postmenopausal Chinese women.

The fat and bone connection is complicated, and the effect of adipose tissue on hip bone strength remains unclear. The aim of this study was to clarify the relative contribution of body fat accumulation and fat distribution to the determination of proximal femur strength in healthy postmenopausal Chinese women. This cross-sectional study enrolled 528 healthy postmenopausal women without medication history or known diseases. Total lean mass (LM), appendicular LM (ALM), percentage of lean mass (PLM), total fat mass (FM), appendicular FM (AFM), percentage of body fat (PBF), android and gynoid fat amount, android-to-gynoid fat ratio (AOI), bone mineral density (BMD), and proximal femur geometry were measured by dual energy X-ray absorptiometry. Hip structure analysis was used to compute some variables as geometric strength-related parameters by analyzing the images of the hip generated from DXA scans. Correlation analyses among anthropometrics, variables of body composition and bone mass, and geometric indices of hip bone strength were performed with stepwise linear regression analyses as well as Pearson's correlation analysis. In univariate analysis, there were significantly inverse correlations between age, years since menopause (YSM), hip BMD, and hip geometric parameters. Bone data were positively related to height, body weight, LM, ALM, FM, AFM, and PBF but negatively related to AOI and amount of android fat (all P<0.05). AFM and AOI were significantly related to most anthropometric parameters. AFM was positively associated with height, body weight, and BMI. AFM was negatively associated with age and YSM. AOI was negatively associated with height, body weight, and BMI. AOI positively associated with age and YSM. LM, ALM, and FM had a positive relationship with anthropometric parameters (P<0.05 for all). PLM had a negative relationship with those parameters. The correlation between LM, ALM, FM, PLM, ALM, age, and YSM was not significant. In multivariate linear regression analysis, the hip bone strength was observed to have a consistent and unchanged positive association with AFM and a negative association with AOI, whereas its association with other variables of body composition was not significant after adjusting for age, years since menopause, height, body weight, and BMI. AFM may be a positively protective effect for hip bone strength while AOI, rather than android fat, shows a strong negative association with hip bone strength after making an adjustment for confounders (age, YSM, height, body weight, and BMI) in healthy postmenopausal Chinese women. Rational weight control and AOI reduction during menopause may have vital clinical significance in decreasing postmenopausal osteoporosis.

Associations between serum 25-hydroxyvitamin D and bone mineral density and proximal femur geometry in Koreans: the Korean National Health and Nutrition Examination Survey (KNHANES) 2008-2009.

The association between 25-hydroxyvitamin D (25(OH)D) levels and bone mineral density (BMD) and proximal femur bone geometry was examined in the Korean population. A positive relationship between skeletal health and 25(OH)D levels was observed. However, there were no significant differences in skeletal health between the groups with 25(OH)D level of 50-75nmol/L and greater than 75nmol/L. Vitamin D plays an important role in calcium and phosphate homeostasis and normal mineralization of bone. However, the optimal level of vitamin D for skeletal health has not been clearly established. We analyzed the associations between serum 25(OH)D and BMD and proximal femur bone geometry and determined the optimal 25(OH)D level. This was a cross-sectional study of 10,062 participants (20-95years, 4,455 men, 5,607 women) in the Fourth Korea National Health and Nutrition Examination Surveys (KNHANES IV) conducted from 2008 to 2009. Participants were divided into groups according to 25(OH)D level (<25, 25-50, 50-75, and ≥75nmol/L). BMD and proximal femur geometric indices were measured. The group with 25(OH)D levels of 50-75nmol/L had greater bone density values, with the exception of the lumbar spine, and also had greater femur neck cortical thickness, cross-sectional area, and cross-sectional moment of inertia, as well as a lesser buckling ratio than the groups with 25(OH)D level of 25-50nmol/L and less than 25nmol/L. However, there were no significant differences in BMD and proximal femur geometry properties between the groups with 50-75nmol/L and greater than 75nmol/L of 25(OH)D. The skeletal outcomes, including BMD and proximal femur geometric indices observed in this study, suggest that serum 25(OH)D levels of 50 to <75nmol/L are optimal for skeletal health.

Reliability of radiologic measures of hip displacement in a cohort of preschool-aged children with cerebral palsy.

Radiologic hip surveillance is recommended for children with cerebral palsy (CP) at risk of hip displacement. Young children with abnormal proximal femoral geometry (Hilgenreiner epiphyseal angle, HEA) may be more likely to develop hip displacement, less likely to respond to nonsurgical intervention, and may benefit from earlier surgical referral. The reliability of radiographic measures of migration percentage (MP) in the immature pelvis of young children has been reported in smaller retrospective studies; HEA has not been examined in this population. This prospective study describes the reliability of MP and HEA in very young children with CP. Participants were entered from tertiary referral center CP clinics into a prospectively recruited population-based cohort for hip surveillance with pelvic radiography using standardized patient position, at 18, 24, 30, 36, and 48 months. All Gross Motor Function Classification System (GMFCS) levels were included. Two independent raters assessed radiographs for HEA and MP. The intraclass correlation coefficient (ICC) was computed as a measure of interrater and intrarater reliability. The correlation coefficient between HEA and femoral position was computed. Ninety-eight children less than 25 months (spasticity=83, 85%; GMFCS IV-V=38, 39%), and 114 children 25 to 48 months (spasticity=96, 85%; GMFCS IV-V=37, 32%) were included from 133 unique participants (spasticity=111, 84%; GMFCS IV-V=42, 32%). Of these 79 children were studied in both age groups. Overall interrater and intrarater reliability of MP was high [ICC=0.93; 95% confidence interval (CI), 0.91-0.95]; SEM was 3.9% (single) and 5.5% (sequential). Perfect concordance for classification of marked hip displacement (MP>30%) occurred in 217 cases (95.2%); nonweighted κ=0.80; 95% CI, 0.68-0.91. For HEA, overall reliability was high (ICC=0.89; 95% CI, 0.85-0.93); SEM=4.8% (single) and 6.7% (sequential). Correlation between changes in HEA and femoral abduction was poor (coefficient=-0.27, P=0.244). MP and HEA can be reliably applied to very young children with CP, with high reliability for both measures. Measured HEA values appear to be independent of patient position, and may reflect genuine changes in proximal femoral geometry. A longitudinal study should be performed to determine the relationship between HEA and later hip outcomes. Level I/II--testing and development of diagnostic tests.

Extent of physeal involvement in Legg-Calvé-Perthes disease.

The growth plate involvement (GPI) index is reportedly a reliable predictor of final radiographic outcome in Legg-Calvé-Perthes disease (LCPD). We determined whether (1) the GPI index was associated with the lateral pillar classification, (2) the GPI index could predict the final radiographic outcome, and (3) the geometry of proximal femur was affected by presence of physeal involvement. We reviewed 47 patients with unilateral LCPD who were treated conservatively. The mean duration of follow-up was 9.5years (range, five to 13years). The affected hips were categorized into those with and without physeal involvement. Herring classifications were determined and the GPI indices were estimated at the stage of maximum fragmentation. The Stulberg classification, leg length discrepancy (LLD), articulotrochanteric distance (ATD) index, neck-shaft angle (NSA), neck width and height were determined at skeletal maturity. The GPI indices were lower in Herring groups A and B (p < 0.001) and Stulberg classes I and II (p = 0.002), and these values were increased in the Herring group B/C and C and Stulberg classes III, IV and V. However, the age of onset, LLD and ATD index at skeletal maturity were not associated with the GPI index. The NSA of the affected hips with physeal involvement was significantly different compared to that of unaffected hips (p < 0.001). The GPI index could be used to determine the extent of physeal involvement in LCPD, and might be considered one of the prognostic values of radiographic development in patients with LCPD who are treated conservatively.

Human Proximal Femur Bone Adaptation to Variations in Hip Geometry

The study of bone mass distribution at proximal femur may contribute to understand the role of hip geometry on hip fracture risk. We examined how bone mineral density (BMD) of proximal femur adapts to inter individual variations in the femoral neck length (FNL), femoral neck width (FNW) and neck shaft angle (NSA). A parameterized and dimensionally scalable 3-D finite element model of a reference proximal femur geometry was incrementally adjusted to adopt physiological ranges at FNL (3.90-6.90cm), FNW (2.90-3.46cm), and NSA (109-141º), yielding a set of femora with different geometries. The bone mass distribution for each femur was obtained with a suitable bone remodelling model. The BMDs at the integral femoral neck (FN) and at the intertrochanteric (ITR) region, as well as the BMD ratio of inferomedial to superolateral (IM:SL) regions of FN and BMD ratio of FN:ITR were used to represent bone mass distribution. Results revealed that longer FNLs present greater BMD (g/cm3) at the FN, mainly at the SL region, and at the ITR region. Wider FNs were associated with reduced BMD at the FN, particularly at the SL region, and at the ITR region. Larger NSAs up to 129° were associated with BMD diminutions at the FN and ITR regions and with increases of the IM:SL BMD ratio while NSAs larger than 129° resulted in decrease of the IM:SL BMD ratio. These findings suggest hip geometry as moderator of the mechanical loading influence on bone mass distribution at proximal femur with higher FNL favoring the BMD of FN and ITR regions and greater FNW and NSA having the opposite effect. Augmented values of FNL and FNW seem also to favor more the BMD at the superolateral than at the inferomedial FN region.

Radiological assessments of proximal femoral geometry and its clinical significance in hip arthroplasty

To explore the reliability of the relationship between the tip of greater trochanter and the center of femoral head in restoring leg length discrepancy during hip arthroplasty. From June 2013 to October 2013, 370 standard anterior-posterior pelvic radiographs were performed. There were 160 males and 210 females with a mean age of 47.6 years. Landmarks were selected by Picture Archiving and Communication Systems (PACS) as follows: the center of femoral head of concentric circles, anatomic axis of proximal femur, the lines perpendicular to anatomic axis of proximal femur through the tip of greater trochanter and the center of femoral head. The distance between two intersected points, i.e. vertical distance between the tip of greater trochanter and the center of femoral head, aka greater trochanter height (GTH), was measured by two orthopedic surgeons respectively. If the tip of greater trochanter was above the center of femoral head, the distance was defined as positive. And the distance was negative if the tip of greater trochanter fell below the center of femoral head. The distance of male and female and that of right and left femurs were compared. Only 6 tips of greater trochanter were below the center of femoral head, 9 at the same level and 725 above the center of femoral head. And 96.89% of tips of the greater trochanter were at 0-15 mm above the center of femoral head. The difference between male and female (P = 0.032) and the difference between right and left sides were statistically significant (P < 0.001). The center of femoral head is not at the same level as the tip of greater trochanter. And the distances of right and left tips of greater trochanter to the ipsilateral center of femoral head are not always at the same level. So it should be cautious to employ the relationship between the tip of greater trochanter and the center of femoral head in restoring leg length discrepancy during hip arthroplasty.

Ancestral differences in femoral neck axis length: Possible implications for forensic anthropological analyses

In forensic anthropological contexts, very few methods of estimating ancestry from the postcranial skeleton are available. The cranium is widely recognized to show the greatest ancestral variation, and is often regarded by forensic anthropologists as the only reliable bone for estimating ancestry from unidentified skeletal remains. Several studies have demonstrated ancestral variation in aspects of the femur, but none have shown significant predictive power for discriminating multiple groups, and have therefore not gained wide acceptance by forensic anthropologists. Skeletal health experts (particularly bone densitometrists), however, have long recognized a relationship between proximal femur geometry (especially hip axis length) and osteoporosis-related fracture risk. Moreover, fracture risk has been noted to vary between ancestral groups. Here, we investigate whether measurements that are related to fracture risk might also be used to estimate ancestry from unidentified skeletal remains. Specifically, we investigate ancestral differences in femoral neck axis length (FNAL) and find significant differences between European, Asian and African groups in both women and men. FNAL was largest in European groups followed by African and then Asian groups. The greatest discriminating power was found between European and Asian groups, but was also significant between European and African groups. These differences may have utility in estimating ancestry in forensic anthropological contexts.

Evaluation of proximal femoral geometry in plain anterior-posterior radiograph in eastern-Indian population.

The morphologic features of the proximal femur are used in preoperative planning prior to total hip arthroplasty. The standard commercially available marketed prostheses sometimes may not be the best fit to all subjects because of the large anatomic variation among different population. Orthopaedic surgeons always stress the need for a proper implant-patient match in hip joint replacements to avoid post-operative complication of mismatch which may affect the ultimate outcome of the operation. The present study was undertaken to measure the important parameters of upper end of femur in elderly Eastern Indian population which will help the prosthetist to manufacture ideal implant for the local population. This will also help the orthopaedic surgeons while positioning the implants during total hip replacement (THR) procedure in this population. Measurements were made on both sides, left and right from anterior-posterior radiograph of 102 subject (>50yrs, 42 male and 60 females) using AGFA software. Three parameters femoral head diameter (FHD), neck-shaft angle (NSA) and horizontal off-set (HO) were measured. SPSS software used for data analysis. Gender- wise no significant differences were found in NSA and FHD, but HO was significantly lower in female than that of male (p<.05).The values on both sides didn't differ significantly. Improved knowledge of the morphology of the proximal femora will assist the surgeon in restoring the geometry of the proximal femur during total hip arthroplasty and the data could be used as a guideline to design a more suitable implant for Eastern Indian population.

Femoral offset in total hip replacement: A study of anatomical offset in the Northern Ireland population

Femoral offset is defined as the perpendicular distance between the long axis of the femur and the centre of rotation of the femoral head. The variability of proximal femoral geometry in terms of offset is consistent with the theory that the geometry of the femur is determined by a large number of genetic and environmental factors. These influences appear to lead to unique endosteal geometry’s, as characteristic of each individual as any other feature of human anatomy. Traditionally commercially available and widely used hip prostheses offered a limited range of offset sizes. The older Charnley hips offered a choice of 35, 40 and 45mm offsets. These sizes were provided to match the mean population offset which has been reported as 43.0mm. This study investigates offset in a sample (n=477) of the Northern Ireland population having customised total hip replacement. The mean femoral offset for this group was 43.4mm (range 28–72mm). A modern femoral implant should construct a biomechanically favourable offset without unduly lengthening the leg. It is evident, therefore, that modern currently available stems require a large range of offsets to adequately cover the NI population variation in terms of anatomical offset.

The effects of once-weekly teriparatide on hip structure and biomechanical properties assessed by CT

SummaryOnce-weekly administration of 56.5 μg teriparatide improved cortical bone parameters and biomechanical parameters at the proximal femur by CT geometry analysis.IntroductionThe aim of this study was to evaluate the effects of weekly administration of teriparatide [human PTH (1–34)] on bone geometry, volumetric bone mineral density (vBMD), and parameters of bone strength at the proximal femur which were longitudinally investigated using computed tomography (CT).MethodsThe subjects were a subgroup of a recent, randomly assigned, double-blind study (578 subjects) comparing the anti-fracture efficacy of a once-weekly subcutaneous injection of 56.5 μg teriparatide with placebo (TOWER trial).ResultsSixty-six ambulatory postmenopausal women with osteoporosis were enrolled at 15 study sites having multi-detector row CT, and included women injected with teriparatide (n = 29, 74.2 ± 5.1 years) or with placebo (n = 37, 74.8 ± 5.3 years). CT data were obtained at baseline and follow-up scans were performed at 48 and 72 weeks. The data were analyzed to obtain cross-sectional densitometric, geometric, and biomechanical parameters including the section modulus (SM) and buckling ratio (BR) of the femoral neck, inter-trochanter, and femoral shaft. We found that once-weekly teriparatide increased cortical thickness/cross-sectional area (CSA) and total area, and improved biomechanical properties (i.e., decreasing BR) at the femoral neck and shaft. Teriparatide did not change the cortical perimeter.ConclusionsOur longitudinal analysis of proximal femur geometry by CT revealed that once-weekly administration of 56.5 μg teriparatide improved cortical bone parameters at the femoral neck and shaft and also improved biomechanical parameters.

Hip structural analysis: a comparison of DXA with CT in postmenopausal Japanese women

Geometry of the proximal femur is one determinant of fracture risk, and can be analyzed by a simple method using dual-energy X-ray absorptiometry (DXA). The aim of the present study was to investigate the accuracy of hip structural analysis (HSA) using clinical data in postmenopausal Japanese women. A total of 184 postmenopausal women aged 51–88 years (mean, 70.5 ± 8.7 years) who underwent artificial joint replacement surgery for osteoarthrosis of the hip or knee joint were included. Computed tomography (CT) data from preoperative assessment were utilized for analysis of proximal femoral geometry (CT-HSA) using QCTPro Software (Mindways Software Inc., Austin, TX) and compared with HSA results based on DXA (DXA-HSA). The results of femoral geometry were further compared with a CT-based finite-element method (CT/FEM). There was moderate to high correlation between DXA-HSA and CT-HSA (r=0.60-0.90, p<0.001), except for the buckling ratio in the intertrochanteric region. Moreover, the correlation of HSA with CT/FEM was similar between DXA-HSA and CT-HSA. The present results suggest that the geometry of proximal femoral cross sections can be reasonably well characterized using DXA.

Fetal and infant growth predict hip geometry at 6 y old: findings from the Southampton Women’s Survey

We investigated relationships between early growth and proximal femoral geometry at age 6 y in a prospective population-based cohort, the Southampton Women's Survey. In 493 mother-offspring pairs, we assessed linear size using high-resolution ultrasound at 11, 19, and 34 wk gestation (femur length) and at birth and 1, 2, 3, 4, and 6 y (crown-heel length/height). SD scores were created and conditional regression modeling generated mutually independent growth variables. Children underwent hip dual-energy X-ray absorptiometry (DXA) at 6 y; hip structure analysis software yielded measures of geometry and strength. There were strong associations between early linear growth and femoral neck section modulus (Z) at 6 y, with the strongest relationships observed for femur growth from 19 to 34 wk gestation (β = 0.26 cm(3)/SD, P < 0.0001), and for height growth from birth to 1 y (β = 0.25 cm(3)/SD, P < 0.0001) and 1 to 2 y (β = 0.33 cm(3)/SD, P < 0.0001), with progressively weaker relationships over years 3 (β = 0.23 cm(3)/SD, P = 0.0002) and 4 (β = 0.10 cm(3)/SD, P = 0.18). These results demonstrate that growth before age 3 y predicts proximal femoral geometry at 6 y old. These data suggest critical periods in which there is capacity for long-term influence on the later skeletal growth trajectory.

Evaluating accuracy of structural geometry by DXA methods with an anthropometric proximal femur phantom

DXA-derived bone structural geometry has been reported extensively but lacks an accuracy standard. In this study, we describe a novel anthropometric structural geometry phantom that simulates the proximal femur for use in assessing accuracy of geometry measurements by DXA or other X-ray methods. The phantom consists of seven different interchangeable neck modules with geometries that span the range of dimensions in an adult human proximal femur, including those representing osteoporosis. Ten repeated hip scans of each neck module using two current DXA scanner models were performed without repositioning. After scanner specific calibration, hip structure analysis was used to derive structural geometry. Scanner performance was similar for the two manufacturers. DXA-derived HSA geometric measurements were highly correlated with values derived directly from phantom geometry and position; R² between DXA and phantom measures were greater than 94% for all parameters, while precision error ranged between 0.3 and 3.9%. Despite high R² there were some systematic geometry errors for both scanners that were small for outer diameter, but increasing with complexity of geometrical parameter; e.g. buckling ratio. In summary, the anthropometric phantom and its fabrication concept were shown to be appropriate for evaluating proximal femoral structural geometry in two different DXA systems.

Proximal femur geometry as moderator factor for the effect of mechanical loading during gait: a bone remodeling analysis

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