Proximal hip geometry and hip fracture risk assessment in a Korean population

Effects of femoral neck width and hip axis length on incident hip fracture risk: a registry-based cohort study

BMD measured with DXA is widely used in clinical practice to assess fracture risk and guide management. DXA can also assess hip geometry, including femoral neck width (FNW) and hip axis length (HAL), which have both been associated with increased risk for hip fracture independently from BMD. Our objective was to assess if FNW predicts hip fracture independently from other factors including HAL. We performed a retrospective cohort study using the Province of Manitoba BMD registry. The study population comprised 75 095 individuals (90.8% women), mean age 64.7 yr, with baseline hip BMD and hip geometry parameters. Linked health records were used to ascertain subsequent hospitalization with hip fracture as a primary diagnosis. During a mean follow-up of 8.3 (SD 5.1) yr, 2341 incident hip fractures were recorded. Each SD increase in age- and sex-adjusted FNW was associated with incident hip fracture (HR 1.15, 95% CI 1.10-1.19), which was unchanged after adjustment for height, weight, FN BMD, and clinical risk factors. However, FNW showed a significant positive correlation with HAL (r = 0.68). When further adjusted for HAL, FNW was no longer associated with increased risk for hip fracture (HR 0.98, 95% CI 0.94-1.03). A similar pattern was seen for FN, and intertrochanteric and non-hip fractures. In contrast, increased risk of hip fracture was consistently seen with each SD increase in HAL even after adjustment for all covariates including FNW (HR 1.35, 95% CI 1.28-1.42). In conclusion, FNW is a risk factor for hip fracture before but not after adjustment for HAL. HAL, on the other hand, robustly and independently predicts hip fracture, including both FN and trochanteric fractures.

Contralateral Neck-shaft Angle Lower Than 130° Is Associated With Clinical Failure in Nongeriatric Individuals: Analysis of the National Femoral Neck Fracture Database of 1066 Patients

BACKGROUND

Treatment of femoral neck fractures in patients who are nongeriatric (≤ 60 years) is challenging because of high failure rates. Anatomic parameters influence the biomechanical environment for fracture healing, but their associations with clinical prognosis remains unclear.

QUESTIONS/PURPOSES

(1) Which anatomic parameter that is identifiable on pelvic radiographs shows a statistical correlation with a higher risk of clinical failure defined as nonunion, avascular necrosis (AVN), reoperation, and functional failure (decrease in Harris hip score reaching the minimum clinically important difference) in the screw fixation of femoral neck fractures among nongeriatric patients? (2) How does the influence of anatomic parameters on clinical prognosis manifest: directly or mediated by additional mechanisms?

METHODS

This retrospective, multicenter study used a nationwide database in China. Between January 2014 and December 2020, we evaluated 1066 patients with femoral neck fractures with a median age of 53 years (interquartile range 46 to 56) and median follow-up period of 62 months. Anatomic parameters including femoral neck-shaft angle (NSA), femoral head radius, femoral neck width, femoral offset, acetabular center-edge angle, and acetabular sharp angle were variables of interest. The primary outcome was clinical failure including nonunion, AVN, reoperation, and functional failure (decrease in Harris hip score reaching the minimum clinically important difference). Risk factors for failure were first filtered using the Bayesian information criterion and then assessed with multiple regression adjusting for confounders. The mediation effect was further explored using model-based causal mediation analysis with a quasi-Bayesian Monte Carlo method.

RESULTS

Of all anatomic parameters we assessed, the contralateral NSA was associated with clinical failure, after adjusting for all potential covariates and confounding variables (adjusted odds ratio 0.92 [95% confidence interval 0.89 to 0.95]; p < 0.001). The optimal threshold for the NSA was 130°, with the highest Youden index of 0.27. Patients with an NSA < 130° (41% [441 of 1066]) demonstrated an increased occurrence of nonunion (15% [68 of 441] versus 5% [33 of 625]; p < 0.001), AVN (32% [141 of 441] versus 22% [136 of 625]; p < 0.001), functional failure (25% [110 of 441] versus 15% [93 of 625]), and reoperations (28% [122 of 441] versus 13% [79 of 625]). The impact of an NSA less than 130° on clinical failure was direct and substantially mediated by the type of displaced fracture (mediation proportion: 18.7%).

CONCLUSION

In our study of screw fixations for femoral neck fractures among nongeriatric patients, we identified that a contralateral NSA < 130° correlates with an increased risk of clinical failure including nonunion, AVN, functional failure, and reoperation. The effect is either direct or mediated through displaced fracture types. This is important for surgeons in order to recognize the elevated rate of clinical failure and nature of the challenging biomechanical environment, which should guide them in refining surgical details and selecting appropriate fixation and rehabilitation plans. Approaches to managing these fractures require further validation with large-scale clinical trials.

LEVEL OF EVIDENCE

Level III, prognostic study.

Hip Axis Length and Femoral Neck-Shaft Angle as Risk Factors for Proximal Femur Fractures in Octogenarians to Centenarians

(1) Background: The prevention of proximal femoral fractures among people of very advanced age is relevant as they are common and increasing in number. The aim of this study was to determine if the hip axis length (HAL) and the neck-shaft angle (caput-collum-diaphyseal CCD) are risk factors for those fractures among people aged 80 years and over. Consequently, it was additionally analysed if these parameters are associated with a certain fracture type. (2) Methods: Anteroposterior radiographs of the pelvis were collected to form three groups (femoral neck fractures (FNFx), trochanteric fractures (TFx) and non-fractured femora (NFx)). Two independent blinded observers separately conducted each measurement of the HAL and CCD. Statistical analysis was performed to determine the association between the measured parameters and type of fracture. (3) Results: One hundred and fifty patients (50 per group) were examined, of which the mean age was 92.7 ± 3.5 (range 81-104) years. Both the HAL and CCD of the FNFx group were significantly larger than in the TFx group (p = 0.013, 0.003). The CCD was higher in the FNFx than that of the NFx group (p = 0.001). No further significant differences of HAL and CCD were observed between the groups. (4) Conclusions: For people aged 80 years and over, an increased HAL represented no risk factor for proximal femur fractures, and a large HAL was associated with an increased occurrence of FNFx instead of TFx. A large CCD was associated with an increased risk of suffering a femoral neck fracture, showing evidence of the CCD being a risk factor for the extremely old population.

Distinctive Geometrical Traits of Proximal Femur Fractures-Original Article and Review of Literature

Background and Objectives: The incidence of proximal femoral fractures is escalating rapidly, generating a significant challenge for healthcare systems globally and, carrying serious social and economic implications. The primarily object of this study was to discover potential distinguishing factors between fractures occurring in the femoral neck and trochanteric region. Materials and Methods: We performed a prospective cohort study of the radiographic images of 70 people over 65 years of age who were admitted to the orthopedic department with hip fracture and who fulfilled our eligibility criteria. Neck Length (NL), Offset Lenth (OL), Hip Axis Length (HAL), Neck Shaft Angle (NSA), Wiberg Angle (WA), Acetabular Angle (AA), Femoral Neck Diameter (FND), Femoral Head Diameter (FHD), Femoral Shaft Diameter (FSD), Femoral Canal Diameter (FCD) and Tonnis classification were recorded. For the comparison of the categorical variables, Pearson's χ2 criterion was used, while Student's t-test was applied for the comparison of means of quantitative variables across fracture types. Results: There were no statistically significant variances observed while comparing the selected geometric parameters of the proximal femur with the type of fracture. This finding was reaffirmed in relation to age, gender, and Tonnis classification. However, a moderate correlation was noted, revealing comparatively reduced values of HAL, FHD, and FND in women as opposed to men. Conclusions: The inability of our research to establish the differentiative geometric factors between femoral neck and trochanteric fractures underscores the need for further investigations, which would take into consideration the intrinsic characteristics of the proximal femur.

The effect of pre-fracture proximal femur geometry on hip fracture type in elderly patients

This study aimed to analyze the relationship between fracture type by determining data on the geometry of the proximal femur in the pre-fracture period in patients over 65 years of age who had hip fractures as a result of low-energy trauma. A total of 127 patients who were admitted to the hospital for reasons other than hip pathology within 1 year before the occurrence of hip fracture and who had an anterior-posterior pelvic X-ray were included in the study. Measurements were made to evaluate the proximal femur geometry, neck shaft angle, central edge angle, femoral head diameter, femoral neck diameter, femoral neck length, femoral offset length, femoral neck axial length, hip axis length, and femoral shaft diameter. As a result of these measurements, analyses were performed to determine the relationship between the control group and fracture types. The mean Neck shaft angle scores were significantly higher in both fracture types than in the control group (P = .034, P = .002). The mean Femoral offset length values of both fracture types were lower than those of the control group (P = .002, P = .011, respectively). Multiple logistic regression analysis revealed that the risk of collum femoris fracture increased as the Femoral head diameter value increased. (OD = 0.21, P = .002). The geometric parameters of the proximal femur play an important role in the formation of hip fracture types. Therefore, differences in proximal femur geometry in hip fracture types should be considered, and patient-focused choices should be made regarding the surgical procedures and implants to be used during fracture fixation.

Evolutionary roots of the risk of hip fracture in humans

The transition to bipedal locomotion was a fundamental milestone in human evolution. Consequently, the human skeleton underwent substantial morphological adaptations. These adaptations are responsible for many of today's common physical impairments, including hip fractures. This study aims to reveal the morphological changes in the proximal femur, which increase the risk of intracapsular hip fractures in present-day populations. Our sample includes chimpanzees, early hominins, early Homo Neanderthals, as well as prehistoric and recent humans. Using Geometric Morphometric methods, we demonstrate differences in the proximal femur shape between hominids and populations that practiced different lifestyles. We show that the proximal femur morphology is a risk factor for intracapsular hip fracture independent of osteoporosis. Changes in the proximal femur, such as the shortening of the femoral neck and an increased anterolateral expansion of the greater trochanter, are associated with an increased risk for intracapsular hip fractures. We conclude that intracapsular hip fractures are a trade-off for efficient bipedal walking in humans, and their risk is exacerbated by reduced physical activity.

Age Related Trends in Structural Indices of Proximal Femur in Women Aged 20-70 in Southern Sri Lanka

Age related trends of the indices of hip structure help understanding how bone strength changes with age and the increased bone fragility in old age. Community-dwelling women aged 20-70years (n = 419) were selected by stratified random method and divided into age categories; 20-29years (n-69), 30-39years (n = 60), 40-49years (n = 69), 50-59years (n = 107) and 60-70years (n = 114). All subjects underwent dual energy x-ray absorptiometry (DXA) and hip structure analysis using Hologic Discovery scanner (Hologic Inc, Bedford, USA). Measured indices included hip axis length (HAL) and neck shaft angle (NSA) of the proximal femur. Cross sectional area (CSA), cross sectional moment of inertia (CSMI), section modulus (SM), cortical thickness (CT), buckling ration (BR) of three regions of interest; narrow neck, intertrochanteric region and femoral shaft, were also measured. Age related trends of all indices were studied with Locally Weighted Scatterplot Smoothing lines (LOESS) and ANOVA. Mean HAL and NSA values were not different between age categories. CSA, CSMI, SM and CT in three different regions showed curvilinear relationships with age. These indices gradually increased with age between 20-50 years and the maximum values were seen in the 40-49years age category and they declined afterwards. The decline of these indices was more rapid in the narrow neck and intertrochanter regions when compared with femoral shaft and the lowest mean CSA, CSMI, SM and CT in these two regions were seen in the 60-70 age category. BR showed a gradual decrease with age between 20-50 years and the lowest mean value was seen in the 40-49 age category. BR increased afterwards and the maximum mean value was seen in the 60-70 age category. This study demonstrates the dynamics of structural properties of proximal femur in the three selected cross sections of community-dwelling women aged 20-70 years and the increased bone fragility in old age.

On challenges in clinical assessment of hip fracture risk using image-based biomechanical modelling: a critical review

INTRODUCTION

Hip fracture is a common health risk among elderly people, due to the prevalence of osteoporosis and accidental fall in the population. Accurate assessment of fracture risk is a crucial step for clinicians to consider patient-by-patient optimal treatments for effective prevention of fractures. Image-based biomechanical modeling has shown promising progress in assessment of fracture risk, and there is still a great possibility for improvement. The purpose of this paper is to identify key issues that need be addressed to improve image-based biomechanical modeling.

MATERIALS AND METHODS

We critically examined issues in consideration and determination of the four biomechanical variables, i.e., risk of fall, fall-induced impact force, bone geometry and bone material quality, which are essential for prediction of hip fracture risk. We closely inspected: limitations introduced by assumptions that are adopted in existing models; deficiencies in methods for construction of biomechanical models, especially for determination of bone material properties from bone images; problems caused by separate use of the variables in clinical study of hip fracture risk; availability of clinical information that are required for validation of biomechanical models.

RESULTS AND CONCLUSIONS

A number of critical issues and gaps were identified. Strategies for effectively addressing the issues were discussed.

Hip geometry in hip fracture patients in Greenland occurring over a 7.7-year period

Background

Hip geometry influences hip fracture risk. Hip fractures are common, and they are associated with pain, disability, premature death and marked costs on society. Osteoporotic fractures are frequent in Arctic populations and increase with advancing age in this society with a steep rise in life expectancy. Greenland Inuit is a distinct ethnic group, and data on hip geometry is missing. We thus aimed to describe hip geometry in 7.7 years of consecutive hip fracture patients in Greenland.

Methods

We evaluated collodiaphysial angle, femoral neck length, the outer and inner diameter of the femur at 2 and 5 centimetres below the centre of the lesser trochanter and the cortical thickness from pelvic and hip radiographs in all patients operated in Greenland over 7.7 years. We included all 84 patients with one non-fractured hip visible for geometric analysis. Analyses were conducted in duplicate.

Results

We found a collodiaphysial angle of 134.8/132.6^o in men/women (p = 0.06) and a femoral neck length of 38.0/33.9 mm in men/women (p = 0.001). Cortical thickness was affected by sex in the adjusted analysis (p < 0.001). Cortical thickness index at 5 cm below the centre of the lesser trochanter decreased with age (p = 0.026) and may be influenced by height (2 cm below the centre of the lesser trochanter, p = 0.053).

Conclusion

Our findings differed from European data and suggest a delicate balance in hip geometry in Arctic populations. Ethnic peculiarities influence the structure of the hip and may influence fracture risk. A focus on hip geometry and risk factors for osteoporotic fractures in Arctic populations is warranted.

Evaluation of Hip Geometry Parameters in Patients With a Distal Radius Fracture

BACKGROUND

Patients with a distal radius fracture (DRF) have an increased risk of subsequent fractures including hip fractures. The purpose of this study was to evaluate whether women with a DRF have certain hip geometry parameters known to indicate susceptibility to hip fractures.

METHODS

We compared bone mineral density (BMD) and hip geometry parameters (hip axis length, neck shaft angle, mean cortical thickness, femur neck width, cross-sectional area [CSA], cross-sectional moment of inertia, section modulus, and buckling ratio) in 181 women with a DRF (DRF group) and 362 propensity score-matched women without a fracture (control group). We evaluated the associations between DRF and hip geometry parameters using logistic regression analysis.

RESULTS

The DRF group had lower hip BMD; lower cortical thickness, CSA, and section modulus; and higher buckling ratio than the control group (all p < 0.05). The occurrence of a DRF was significantly associated with decreases in neck shaft angle (odds ratio [OR], 1.047; 95% confidence interval [CI], 1.008-1.088) and CSA (OR, 3.114; 95% CI, 1.820-5.326) after adjusting for age, BMI, and total hip BMD.

CONCLUSIONS

In this study, women with a DRF were more likely than women without a DRF to have hip geometry parameters known to indicate susceptibility to hip fractures. Our results suggest that not only low hip BMD but also a decreased CSA could account for the increased risk of subsequent hip fracture in patients with a DRF.

Comparison of hip subregion bone mineral density to the type of proximal femur fracture

Beta values of the intertrochanteric fracture group were about twice as high as those of the femoral neck fracture group. These results can be used to increase the awareness of proximal hip fracture among physicians and improve treatments and outcomes.

PURPOSE

To compare the BMD of the femoral neck region and the intertrochanteric region between the femoral neck fracture group and the intertrochanteric fracture group.

METHODS

We did a retrospective review of radiographs of the proximal femoral fractures in patients registered from 2010 to 2017. A total of 329 patients were classified into the femoral neck fracture group (group A, n = 162) and the femur intertrochanteric fracture group (group B, n = 167). We did intergroup comparisons of age, sex, BMI (body mass index), and bone mineral density (BMD) of the neck and intertrochanteric region, adjusting for age. We did multiple logistic regression analysis among these parameters.

RESULTS

The BMD of the femoral neck and intertrochanteric was statistically significantly different between the two groups (p < 0.001), and the BMD of the femur intertrochanteric was also significantly different between the two groups (p < 0.001). BMD of both regions in the intertrochanteric fracture group was lower than that of the femoral neck fracture group. In linear regression analysis, the beta values of the intertrochanteric fracture group were about twice as high as those of the femoral neck fracture group.

CONCLUSION

In linear regression analysis, the beta values of the intertrochanteric fracture group were about twice as high as those of the femoral neck fracture group.

Elevated 1-Year Mortality Rate in Males Sustaining Low-Energy Proximal Femur Fractures and Subgroup Analysis Utilizing Age-Adjusted Charlson Comorbidity Index

INTRODUCTION

Low-energy proximal femur fractures are common in the aging population and the ability to identify patients at increased mortality risk provides surgeons information to improve informed decision-making with patients and families. We evaluated for gender differences in 1-year mortality after sustaining low-energy proximal femur fractures with subgroup analysis to identify the impact of fracture location, age, and comorbidities on mortality.

MATERIALS AND METHODS

Patients ≥40 years of age sustaining a low-energy proximal femur fracture identified at our institution between January 1, 2014, and December 31, 2017. International Classification of Diseases, Ninth Revision and International Classification of Diseases, Tenth Revision codes were used to identify comorbidities for calculation of the age-adjusted Charlson comorbidity index (ACCI). The county clerk database was searched to identify mortality within 1 year of injury. One-year mortality rates were calculated and multiple comparisons were made between genders controlling for age, fracture location, and/or ACCI.

RESULTS

Women presented with low-energy proximal femur fractures at a rate of almost 3:1 to men at our institution (P = .001). Men demonstrated a significantly increased ACCI at presentation (5.35 ± 2.55 vs 4.86 ± 1.77, P = .03). Men had an increased 1-year mortality rate for all (31.3% vs 21.5%, P = .004) and intertrochanteric (IT) fractures (36.2% vs 22.9%, P = .008). Controlling for ACCI, gender, and fracture location, men demonstrated increased mortality rate with IT fractures (P = .002) and trended toward but did not reach significance with femoral neck fractures (P = .07).

DISCUSSION

Men presenting with low-energy femur fractures are at an increased mortality risk compared to women. On average, men present with an overall worse health status as identified by ACCI, which could predispose these patients not only to fractures themselves but also impair their ability to recover from injury.

CONCLUSION

Men are at an increased 1-year mortality risk after sustaining proximal femur fractures.

CT based measurement of anatomical dimensions of femur and its relevance in nail designs for proximal femoral fractures

Introduction

The purpose of this study was to obtain computed tomography (CT) based measurements of femoral dimensions in adults, to identify its relevance with intramedullary nails used in the management of proximal femur fractures and to suggest a best fitting implant dimensions to our population. To best of our knowledge our study would be first to compile different CT based dimension in single study.

Methods

In our retrospective study of 50 femurs, CT based femoral dimensions measured in standardized cuts and compared with previous studies and commonly available proximal femur intramedullary devices.

Results

68.4 was the mean age in our study, neck shaft angle (NSA) was 127.2±5.2⁰, anteversion 11.2±7.4⁰, endosteal isthmus diameter was 11.9 ± 1.7 mm, anterior radius of curvature (ROC) was 116.8 ± 20 mm, horizontal femoral offset 37.5 ± 4.6 mm, medio-lateral angle 7.8±1.6⁰, with good inter and intra observer correlation. Femoral length and neck width was positively correlated to head diameter, horizontal femoral offset with medio-lateral (ML) angle. One of the 50 femur studied had the parameters in the range of available implant and could match appropriately.

Conclusion

CT based dimensions in our population is different from other population. Based on this study, a design modification of nails used in present day management of proximal femur fractures has been recommended.

Comparison of Proximal Femoral Geometry and Risk Factors between Femoral Neck Fractures and Femoral Intertrochanteric Fractures in an Elderly Chinese Population

Background

Few studies have investigated the differences in proximal femoral geometry and risk factors between patients with different types of hip fracture, especially in elderly Chinese. This study aimed to assess the differences in proximal femoral geometry parameters between patients with femoral neck fractures and patients with intertrochanteric fractures to provide guidance for individualized customized prosthesis and accurate reconstruction of proximal femurs in elderly Chinese patients.

Methods

We retrospectively studied the electronic medical records of 198 elderly patients over 65 years of age who were admitted to the orthopedic department with hip fractures between January 2017 and December 2017 in The Third Hospital, Hebei Medical University. Age, fracture site, gender, and proximal femoral geometry parameters (neck shaft angle [NSA], center edge angle [CEA], femoral head diameter [FHD], femoral neck diameter [FND], femoral neck axial length [FNAL], hip axial length [HAL], and femoral shaft diameter [FSD]) were recorded. Student's t-test was used to compare the continuous variables, Chi-square test was used to analyze categorical variables, and multiple logistic stepwise regression analysis was used to evaluate the influencing factors of hip fracture type.

Results

Statistically significant differences in NSA (137.63 ± 4.56° vs. 132.07 ± 4.17°, t = 1.598, P < 0.001), CEA (37.62 ± 6.77° vs. 43.11 ± 7.09°, t = 5.597, P < 0.001), FND (35.21 ± 3.25 mm vs. 34.09 ± 3.82 mm, t = 2.233, P = 0.027), and FNAL (99.30 ± 7.91 mm vs. 103.58 ± 8.39 mm, t = 3.715, P < 0.001) were found between the femoral neck fracture group and femoral intertrochanteric fracture group. FHD, FND, FSD, HAL, and FNAL were different between sexes (all P < 0.001). The greater NSA was the risk factor for femoral neck fractures (odds ratio [OR]: 0.70, P < 0.001), greater CEA and longer FNAL were risk factors for femoral intertrochanteric fractures (OR: 1.15, 1.17, all P < 0.001), and greater FND was a protective factor for femoral intertrochanteric fractures (OR: 0.74, P < 0.001).

Conclusions

We demonstrate differences in geometric morphological parameters of the proximal femur in different hip fracture types, as well as an effect of sex. These differences should be considered in the selection of prostheses for fracture internal fixation and hip replacements. These data could help guide the design of individualized customized prostheses and improve the accurate reconstruction of the proximal femur for elderly Chinese hip fracture patients.

Automatic hip geometric feature extraction in DXA imaging using regional random forest

BACKGROUND

Hip fracture is considered one of the salient disability factors across the global population. People with hip fractures are prone to become permanently disabled or die from complications. Although currently the premier determiner, bone mineral density has some notable limitations in terms of hip fracture risk assessment.

OBJECTIVES

To learn more about bone strength, hip geometric features (HGFs) can be collected. However, organizing a hip fracture risk study for a large population using a manual HGFs collection technique would be too arduous to be practical. Thus, an automatic HGFs extraction technique is needed.

METHOD

This paper presents an automated HGFs extraction technique using regional random forest. Regional random forest localizes landmark points from femur DXA images using local constraints of hip anatomy. The local region constraints make random forest robust to noise and increase its performance because it processes the least number of points and patches.

RESULTS

The proposed system achieved an overall accuracy of 96.22% and 95.87% on phantom data and real human scanned data respectively.

CONCLUSION

The proposed technique's ability to measure HGFs could be useful in research on the cause and facts of hip fracture and could help in the development of new guidelines for hip fracture risk assessment in the future. The technique will reduce workload and improve the use of X-ray devices.

Pelvis and femur geometry: Relationships with impact characteristics during sideways falls on the hip

While metrics of pelvis and femur geometry have been demonstrated to influence hip fracture risk, attempts at linking geometry to underlying mechanisms have focused on fracture strength. We investigated the potential effects of femur and pelvis geometry on applied loads during lateral falls on the hip. Fifteen female volunteers underwent DXA imaging to characterize two pelvis and six femur geometric features. Additionally, participants completed low-energy sideways falls on the hip; peak impact force and pressure, contact area, and moment of force applied to the proximal femur were extracted. No geometric feature was significantly associated with peak impact force. Peak moment of force was significantly associated with femur moment arm (p = 0.005). Peak pressure was positively correlated with pelvis width and femur moment arm (p < 0.05), while contact area was negatively correlated with metrics of pelvis width and femur neck length (p < 0.05). This is the first study to link experimental measures of impact loads during sideways falls with image-based skeletal geometry from human volunteers. The results suggest that while skeletal geometry has limited effects on overall peak impact force during sideways falls, it does influence how impact loads are distributed at the skin surface, in addition to the bending moment applied to the proximal femur. These findings have implications for the design of protective interventions (e.g. wearable hip protectors), and for models of fall-related lateral impacts that could incorporate the relationships between skeletal geometry, external load magnitude/distribution, and tissue-level femur loads.

Hip geometry and femoral neck fractures: A meta-analysis

BACKGROUND

Several studies have reported hip geometry to predict the femoral neck fractures. However, they showed inconsistency.

OBJECTIVES

To determine the association between hip geometry and femoral neck fractures.

METHODS

Published literature from PubMed and Embase databases (until May 25th, 2017) was searched for eligible publications. The information related to (1) name of first author; (2) year of publication; (3) country of origin; (4) sample size of cases and controls and (5) mean and standard deviation of cases and controls were extracted. The pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) for the association between hip geometry and femoral neck fractures were assessed using random or fixed effect model. A Comprehensive Meta-analysis software, version 2.0, was used to analyse the data.

RESULTS

A total of 11 studies were included in this study. Our results showed that increase in hip axis length (OR 95% CI = 1.53 [1.06-2.21], p = 0.025), femoral neck angle (OR 95% CI = 1.47 [1.01-2.15], p = 0.044) and neck width (OR 95% CI = 2.68 [1.84-3.91], p < 0.001) was associated with the risk of femoral neck fractures, whereas we could not find the correlation between femoral neck axis length and the risk of femoral neck fractures.

CONCLUSION

There is strong evidence that elevated hip axis length, femoral neck angle and neck width are the risk factor for femoral neck fractures.The Translational Potential of this Article: Determining the hip axis length, femoral neck angle and neck width that are most highly associated with femoral neck fracture may allow clinicians to more accurately predict which individuals are likely to experience femoral neck fractures in the future.

The influence of acetabular morphology on prediction of proximal femur fractures types in an elderly population

INTRODUCTION

The role of proximal femur morphology to the development of certain proximal femur fracture types both femoral neck and trochanteric fractures has been observed. However, the relavance of acetabular morphology to the development of proximal femur fractures is not extensively questioned. Therefore the aim of the study was to determine whether there is a correlation between acetabular morphology and pathogenesis of 2 different hip fracture types after low energy trauma.

METHODS

This retrospective study includes 60 cases (41 women, 19 men) with a proximal femoral fracture after a low energy trauma between July 2012 and December 2014. Acetabular depth and acetabular index were measured on pelvic radiographs. Neck shaft angle, hip axis length and cortical index were measured on pelvic computed tomography scans. All measurements were performed on the contralateral hip.

RESULTS

Mean age was 77.56 ± 8.99 years (range 61-92 years). No statistically significant difference was found with regard to neck shaft angle, acetabular depth or cortical index measurements between patients with femoral neck fracture and patients with trochanteric femoral fractures (p>0.05). Acetabular index measurement was higher (p = 0.001) and hip axis length measurement was lower (p = 0.001) in trochanteric fracture group as compared to femoral neck fracture.

CONCLUSIONS

The rate of trochanteric femur fractures is higher in patients with high acetabular index, whereas the rate of femoral neck fractures is higher in patients with increased hip axis length.

Proximal Femoral Geometry as Fracture Risk Factor in Female Patients with Osteoporotic Hip Fracture

Background

Proximal femoral geometry may be a risk factor of osteoporotic hip fractures. However, there existed great differences among studies depending on race, sex and age of subjects. The purpose of the present study is to analyze proximal femoral geometry and bone mineral density (BMD) in the osteoporotic hip fracture patients. Furthermore, we investigated proximal femoral geometric parameters affecting fractures, and whether the geometric parameters could be an independent risk factor of fractures regardless of BMD.

Methods

This study was conducted on 197 women aged 65 years or more who were hospitalized with osteoporotic hip fracture (femur neck fractures ; 84, intertrochanteric fractures; 113). Control group included 551 women who visited to check osteoporosis. Femur BMD and proximal femoral geometry for all subjects were measured using dual energy X-ray absorptiometry (DXA), and compared between the control and fracture groups. Besides, proximal femoral geometric parameters associated with fractures were statistically analyzed.

Results

There were statistically significant differences in the age and weight, cross-sectional area (CSA)/length/width of the femoral neck and BMD of the proximal femur between fracture group and control group. BMD of the proximal femur in the control group was higher than in the fracture group. For the femoral neck fractures group, the odds ratio (OR) for fractures decrease in the CSA and neck length (NL) of the femur increased by 1.97 times and 1.73 times respectively, regardless of BMD. The OR for fractures increase in the femoral neck width increased by 1.53 times. In the intertrochanteric fracture group, the OR for fractures increase in the femoral neck width increased by 1.45 times regardless of BMD.

Conclusions

We found that an increase of the femoral neck width could be a proximal femoral geometric parameter which plays important roles as a risk factor for fracture independently of BMD.

Sex- and age-related differences in femoral neck cross-sectional structural changes in mainland Chinese men and women measured using dual-energy X-ray absorptiometry

We investigated age-related changes in estimated bone strength and cross-sectional structure of the femoral neck (FN) in mainland Chinese men and women (according to age and sex) using dual-energy X-ray absorptiometry (DXA). A total of 3855 healthy adults (2713 women, 1142 men; ages 25-91years) were analyzed by FN bone mineral density (BMD) assessment and hip structural/strength analysis (HSA), including cross-sectional moment of inertia (CSMI), cross-sectional area (CSA), section modulus (Z), periosteal diameter (PD), endocortical diameter (ED), and cortical thickness (CT) using DXA. HSA differences between age and sex groups were adjusted for body weight, height and FN BMD. Trends according to age were estimated by linear regression analysis. There was no inverse correlation between HSA parameters and age in young adults. Some HSA parameters (CSMI, CSA, Z, CT) decreased significantly with age, whereas PD and ED increased significantly. Older adults had less estimated bone strength and CT and higher PD and ED (p<0.05) than young adults. Men had greater increases in PD and ED than women across all ages. FN strength decreases with age in both sexes, caused by FN cross-sectional structural deterioration. Indirect comparison of our data with those from other populations showed less age-related FN periosteal apposition in Chinese than Caucasian men, but similar amounts in women. This may partly explain different male/female hip fracture rates among ethnic groups. Chinese men have more structural disadvantages regarding FN geometry during aging than Caucasian men, possibly conferring added susceptibility to hip fracture.

Negative Impact of Aromatase Inhibitors on Proximal Femoral Bone Mass and Geometry in Postmenopausal Women with Breast Cancer

Aromatase inhibitors (AIs), the standard therapy for estrogen receptor- or progesterone receptor-positive breast cancer in postmenopausal women, lead to increased hip fractures in breast cancer patients. To investigate the mechanism of increased incidence of hip fractures in breast cancer patients treated with AIs, we evaluated bone mineral density (BMD) in the cortical and trabecular compartments and assessed femoral geometry using quantitative computed tomography (QCT) in breast cancer patients. In total, 249 early breast cancer patients who underwent QCT in their fifties (mean age 54.3 years) were retrospectively analyzed. Proximal femoral BMD and geometrical parameters were compared. In all regions of the proximal femur, cortical areal BMDs were lower in the AI group than in the non-AI group (p < 0.05). Cortical thickness of the femoral neck, trochanter, and total hip was significantly lower in the AI group compared with the non-AI group (p < 0.05). Analysis of the narrowest section of the femoral neck showed significantly thinner cortical bone and smaller cortical area in the AI group than in the non-AI group (p < 0.05), especially in the superoposterior quadrant. Bone strength parameters in the femoral neck, such as the section modulus and cross-sectional moment of inertia, were significantly lower in the AI group than in the non-AI group (p < 0.05). In conclusion, AI treatment in breast cancer patients is associated with deterioration of femoral cortical BMD and geometry, which could contribute in site-specific weakened bone strength and increased incidence of hip fractures.

Bone mineral density distribution in the proximal femur and its relationship to morphologic factors in progressed unilateral hip osteoarthritis

Although an adverse relationship between osteoporosis and osteoarthritis (OA) has been reported, it remains controversial. In most previous reports of OA, bone mineral density (BMD) changes in the subtrochanteric region have not been clarified, whilst BMD of the femoral neck and trochanteric region has been well investigated. In our current study, we investigated the BMD ratio compared to the contralateral side in the whole proximal femurs of hip OA patients. We aimed to clarify the morphologic factor that may influence these BMD ratios. We performed dual energy X-ray absorptiometry (DEXA) analysis of 69 hip joints from unilateral progressed OA cases. The minimum joint space, center edge angle, Sharp angle, acetabular head index, neck-shaft angle, and leg length discrepancy were also measured as radiographic factors. The correlation between BMD ratio and radiographic morphologic factors was then evaluated by logistic regression. The BMD ratio was higher in the femoral neck than in the distal region. In terms of radiographic factors, the neck-shaft angle was revealed to influence the decreased BMD ratio in the distal subtrochanteric part, whilst the leg length discrepancy and Sharp angle showed a relationship with the increased BMD ratio in the proximal neck region. The discrepancy in the BMD ratio between the femoral neck and the distal subtrochanteric region in the proximal femur is influenced by several morphologic factors.

Femoral version, neck-shaft angle, and acetabular anteversion in Chinese Han population: a retrospective analysis of 466 healthy adults

Anatomic data regarding femoral version, neck-shaft angle, and acetabular anteversion are still limited in Chinese Han adult population. The aim of this study was to investigate the effects of age, sex, and body laterality on the 3 important anatomic indicators in Chinese Han healthy adults. Measurements were performed independently by 3 experienced observers using the picture archiving and communication system (PACS) in healthy adults who had received imaging tests of the femur and acetabulum between January 2009 and October 2014. Relevant data were measured and analyzed. A total of 466 adults (353 males and 113 females) were included. The mean femoral version, neck-shaft angle, and acetabular anteversion for all were 10.62, 133.02, and18.79, respectively. Age-based analysis showed that adults younger than 60 years had a significantly higher neck-shaft angle (P < 0.001) but a significantly lower acetabular anteversion (P < 0.001) than those older than 60 years. Sex-based analysis revealed that females had significantly higher values of femoral version (P < 0.001) and acetabular anteversion (P < 0.001) than males. Laterality-based analysis found the left side had a significantly lower acetabular anteversion (P < 0.001) than the right side. Outcomes of multiple linear regression analysis indicated that femoral version may be associated with sex (P < 0.001) but not age (P = 0.076) or laterality (P = 0.430), neck-shaft angle may be associated with age (P < 0.001) but not sex (P = 0.378) or laterality (P = 0.233), and acetabular anteversion may be associated with age (P < 0.001) and sex (P < 0.001) but not laterality (P = 0.060). In this representative Chinese cohort, neck-shaft angle may decrease, whereas acetabular anteversion may increase with age, females may have higher values of femoral version and acetabular anteversion than males, and the right body side may have a higher value of acetabular anteversion than the left side.

Biomechanical rationale for implant choices in femoral neck fracture fixation in the non-elderly

Femoral neck fractures represent a relatively uncommon injury in the non-elderly population often resulting from high-energy trauma. The cornerstone of their management is anatomic reduction and stable internal fixation of the femoral neck in an attempt to salvage the femoral head. Complications including avascular necrosis of the femoral head, non-union and post-traumatic osteoarthritis are not uncommon. The clinical outcomes of these patients can be improved with good pre-operative planning, optimization of surgical procedures and introduction of new improved implants and techniques. In the herein study, we attempt to describe the biomechanical properties of the hip and compare the performance of the most commonly used devices. Experimental evidence suggests that in Pauwels type III fracture patterns a cephalomedullary nail was significantly stronger in axial loading. Moreover, in unstable basicervical patterns cannulated screws (triangular configuration) demonstrated a lower ultimate load to failure, whereas in subcapital or transervical patterns both the cannulated screws (triangular configuration) and the sliding hip screw demonstrated no compromise in fixation strength. The fracture pattern appears to be the major determinant of the ideal type of implant to be selected. For a successful outcome each patient needs to be considered on an individual basis taking into account all patient and implant related factors.

Factors contributing to inherent varus alignment of lower limb in normal Asian adults: role of tibial plateau inclination

PURPOSE

This prospective study aimed to evaluate radiographically, mechanical or hip-knee-ankle (HKA) axis in healthy, asymptomatic, Asian (Indian and Korean) adults between 20 and 40 years of age to determine the incidence of inherent varus (mechanical limb alignment of >3° varus) and the factors influencing it.

METHODS

Three hundred and eighty-eight lower limbs were evaluated using full length, standing hip-to-ankle radiographs in 198 healthy, asymptomatic, Asian (Indian and Korean) adults between 20 and 40 years of age to assess the hip-knee-ankle (HKA) angle, medial proximal tibial angle (MPTA), femoral bowing and femoral neck-shaft angle to determine the incidence of inherent varus (mechanical limb alignment of >3° varus) and the factors influencing it.

RESULTS

Overall, the mean HKA angle was 177.6°±2.6° with 34.5% of limbs in inherent varus (mean HKA angle 174.9°±1.8°). The incidence of inherent varus was significantly higher (p=0.01) in males (40%) compared to females (28%) but similar among Indian (34%) and Korean subjects (35%). The hip-knee-ankle (HKA) angle showed significant positive correlation (r=0.82, p<0.001) with only the medial proximal tibial angle (MPTA).

CONCLUSIONS

Inherent varus alignment of the lower limb is fairly common among asymptomatic, Asian adults. These results raise several pertinent questions regarding the role of inherent varus in the aetiopathogenesis of knee osteoarthritis and in lower limb realignment procedures.

Changes in bone mineral density of both proximal femurs after total knee arthroplasty

Background

This study investigated the effects of total knee arthroplasty (TKA) on bone mineral density (BMD) of the proximal femur in patients who underwent the procedure.

Methods

Forty-eight patients scheduled to undergo unilateral TKA because of primary knee osteoarthritis were included in this study, which was conducted at a medical center between October 2006 and October 2009. In these 48 patients, 96 hips were evaluated. Measurement of BMD was performed preoperatively and one month, three months, six months, and one year after unilateral TKA. Repeated measured analysis of variance and paired t-tests for comparison of two repeated samples were used to compare differences between time points (preoperation, one, three, six, and 12 months) and between the operative and nonoperative sides.

Results

Preoperatively, BMD of the femoral neck, trochanter, and total hip on the operative side were lower than on the nonoperative side; however, there was no statistical difference. BMD of both femoral neck areas was significantly lower than preoperative BMD at one month and three months after TKA. BMD of both trochanter areas was significantly lower than preoperative BMD at one month and three months after TKA. BMD of both total hips was significantly lower than preoperative BMD at three months after TKA. However, no statistical differences of changes in BMD were observed between the operative and nonoperative sides at each measurement time.

Conclusions

According to our results, TKA was found to affect both proximal femurs during the acute period. However, TKA did not affect a change in BMD of the proximal femur during one year postoperative.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSION

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.

Ethnic variability in bone geometry as assessed by hip structure analysis: findings from the hip strength across the menopausal transition study

Racial/ethnic origin plays an important role in fracture risk. Racial/ethnic differences in fracture rates cannot be fully explained by bone mineral density (BMD). Studies examining the influence of bone geometry and strength on fracture risk have focused primarily on older adults and have not included people from diverse racial/ethnic backgrounds. Our goal was to explore racial/ethnic differences in hip geometry and strength in a large sample of midlife women. We performed hip structure analysis (HSA) on hip dual-energy X-ray absorptiometry (DXA) scans from 1942 premenopausal and early perimenopausal women. The sample included white (50%), African American (27%), Chinese (11%), and Japanese (12%) women aged 42 to 52 years. HSA was performed using software developed at Johns Hopkins University. African American women had higher conventional (8.4% to 9.7%) and HSA BMD (5.4% to 19.8%) than other groups with the exception being Japanese women, who had the highest HSA BMD (9.7% to 31.4%). HSA indices associated with more favorable geometry and greater strength and resistance to fracture were more prevalent in African American and Japanese women. Femurs of African American women had a smaller outer diameter, a larger cross-sectional area and section modulus, and a lower buckling ratio. Japanese women presented a different pattern with a higher section modulus and lower buckling ratio, similar to African American women, but a wider outer diameter; this was offset by a greater cross-sectional area and a more centrally located centroid. Chinese women had similar conventional BMD as white women but a smaller neck region area and HSA BMD at both regions. They also had a smaller cross-sectional area and section modulus, a more medially located centroid, and a higher buckling ratio than white women. The observed biomechanical differences may help explain racial/ethnic variability in fracture rates. Future research should explore the contribution of hip geometry to fracture risk across all race/ethnicities.

The relationship between radiological parameters from plain hip radiographs and bone mineral density in a Korean population

The purpose of this study was to investigate the association of the Singh index, cortical thickness index (CTI) and calcar-to-canal (CC) ratio with bone mineral density (BMD) as well as their relationship with physical parameters [age, gender, height, and body mass index (BMI)] in order to assess their potential as an indirect indicator of osteoporosis. BMD, Singh index, CTI and CC ratio as well as the physical parameters were obtained from hip radiographs and clinical records of 140 Korean adults. Linear relationships between the areal BMD of the femoral neck and the parameters as well as between each parameter were obtained. To determine the association between BMD and the radiological parameters, multiple regression analyses were performed after adjusting for the four physical parameters. The CTI was positively associated with BMD (p = 0.040), whereas the Singh index (p = 0.209) and CC ratio (p = 0.655) were not. The CTI was negatively associated with age (p = 0.02) and positively associated with height (p = 0.0001) and BMI (p = 0.001). The CC ratio was also positively associated with age (p = 0.0001) and negatively associated with height (p = 0.033). In conclusion, of three parameters available from plain radiograph (age, height, BMI), only CTI was significantly associated with BMD. CTI can provide a tool for rapid assessment of osteoporosis from plain hip radiographs.

Epidemiology and structural basis of racial differences in fragility fractures in Chinese and Caucasians

Chinese have similar vertebral fracture prevalence but lower incidence of hip and distal forearm fractures than in Caucasians. The underlying structural and biomechanical basis of racial differences in bone fragility is still largely undefined but Chinese assemble their smaller appendicular skeleton with thicker cortices and trabeculae compared with Caucasians. Vertebral fracture prevalence is similar by race, but the incidence of hip and distal forearm fractures is lower in Chinese than in Caucasians. This racial dimorphism cannot be explained by differences in areal bone mineral density (aBMD) as aBMD is lower in Chinese mainly due to their smaller size. The underlying structural and biomechanical basis of racial differences in bone fragility is still largely undefined but Chinese assemble their smaller appendicular skeleton with more mineralised bone matrix within it; the cortices are thicker and perhaps less porous while trabeculae are fewer but thicker and more connected. This configuration produces a bone with a lower surface/volume ratio, which in turn reduces the surface available for remodelling to occur upon so that the lower surface/volume ratio may make the bone less exposed to remodelling and the thicker cortices and trabeculae less vulnerable to remodelling when it does occur during advancing age. However, prospective studies are needed to define racial differences at the age of onset, rate of bone loss from the intracortical, endocortical and trabecular components of the endosteal envelope and bone formation upon the periosteal envelope; notions of bone 'loss' are derived mainly from cross-sectional studies. Studies of the site- and surface-specific changes in bone modelling and remodelling are needed to better define racial differences in bone fragility in old age.