In vivo baseline measurements of hip joint range of motion in suspensory and nonsuspensory anthropoids

Hominoids and atelines are known to use suspensory behaviors and are assumed to possess greater hip joint mobility than nonsuspensory monkeys, particularly for range of abduction. This assumption has greatly influenced how extant and fossil primate hip joint morphology has been interpreted, despite the fact that there are no data available on hip mobility in hominoids or Ateles. This study uses in vivo measurements to test the hypothesis that suspensory anthropoids have significantly greater ranges of hip joint mobility than nonsuspensory anthropoids. Passive hip joint mobility was measured on a large sample of anesthetized captive anthropoids (nonhuman hominids = 43, hylobatids = 6, cercopithecids = 43, Ateles = 6, and Cebus = 6). Angular and linear data were collected using goniometers and tape measures. Range of motion (ROM) data were analyzed for significant differences by locomotor group using ANOVA and phylogenetic regression. The data demonstrate that suspensory anthropoids are capable of significantly greater hip abduction and external rotation. Degree of flexion and internal rotation were not larger in the suspensory primates, indicating that suspension is not associated with a global increase in hip mobility. Future work should consider the role of external rotation in abduction ability, how the physical position of the distal limb segments are influenced by differences in ROM proximally, as well as focus on bony and soft tissue differences that enable or restrict abduction and external rotation at the anthropoid hip joint.

Which method of hip joint centre localisation should be used in gait analysis?

Accurate localisation of the hip joint centre is required to obtain accurate kinematics, kinetics and musculoskeletal modelling results. Literature data showed that conclusions drawn from synthetic data, adult normal subjects and cerebral palsy children may vary markedly. This study investigated the localisation accuracy of the hip joint centre against EOS. The EOS system allowed us to register the hip joint centres with respect to the skin markers on standing subjects. A comprehensive set of predictive and functional calibration techniques were tested. For the functional calibration techniques, our results showed that algorithm, range of motion and self-performance of the movement were factors significantly affecting the results. Best results were obtained for comfortable range and self-performance of the movement. The best method in this scenario was the functional geometrical sphere fitting method which localised the hips 1.1cm from the EOS reference in average and 100% of the time within 3 cm. Worst results for functional calibration methods occurred when the movement was assisted with a reduced range of movement. The best method in this scenario was the Harrington et al. regression equations since it does not rely on a functional calibration movement. Harrington et al. equations put the hips 1.7 cm from the EOS reference in average and 97% of the time within 3 cm. We conclude that accurate localisation of the hip joint centre is possible in gait analysis providing that method to localise the hip joint centres are adapted to the population studied: functional geometrical sphere fitting when hip calibration movements are not a problem and Harrington et al. predictive equations otherwise.

Management of labral tears of the hip in young patients

Our understanding of labral tears in young patients has evolved significantly in recent years. Successful outcome depends on addressing all bony impingement to improve the intra-articular environment, and prevent further damage to the labrum and articular cartilage. Improved clinical outcomes are associated with labral repair; in cases of a deficient labrum, arthroscopic reconstruction techniques have been developed, with promising clinical outcomes. This article reviews the anatomy of the acetabular labrum, and discusses the pathogenesis of labral tears as well as various treatment options, including arthroscopic labral repair and reconstruction.

Leveraging gait dynamics to improve efficiency and performance of powered hip exoskeletons

This paper presents a new mechanical design for efficient exoskeleton actuation to power the sagittal plane motion in the human hip. The device uses a DC motor to drive a Scotch-Yoke mechanism and series elasticity to take advantage of the cyclic nature of human gait and to reduce power and control requirements of the exoskeleton. The mechanism creates a transmission that varies between 4:1 and infinity and does not require the motor to reverse direction when the hip joint reverses direction. This paper provides a detailed analysis of how the dynamic nature of human walking can be leveraged with this hip exoskeleton design.

Geometric indices of hip bone strength in young female football players

OBJECTIVE

The aim of this study was to compare geometric indices of hip bone strength in female football players and controls.

METHODS

18 adult female football players and 18 adult sedentary females participated in this study. The two groups were paired for age, weight and body mass index (BMI). Daily calcium intake (DCI) and daily protein intake (DPI) were evaluated by questionnaires. Total hip bone mineral density (BMD) and femoral neck BMD were measured by DXA. Cross-sectional area (CSA), an index of axial compression strength, section modulus (Z), an index of bending strength and cortical thickness (CT) were evaluated at the femoral neck (FN), the intertrochanteric (IT) and the femoral shaft (FS) regions by the hip structure analysis (HSA) program.

RESULTS

Age, weight, height, BMI, DCI and DPI were not different between the two groups. TH BMD, FN BMD, FN CSA, FN Z, FN CT, IT CSA, IT Z, IT CT, FS CSA and FS Z were significantly higher in football players compared to controls (crude percentage differences between the two groups varied between 8 and 19%; P<0.05). After adjusting for body weight using a one-way analysis of covariance (ANCOVA), TH BMD, FN BMD, FN CSA, FN Z, FN CT, IT CSA, IT Z, IT CT, FS CSA and FS Z remained significantly higher in football players compared to controls (adjusted percentage differences between the two groups varied between 7 and 17%; P<0.05).

CONCLUSION

This study suggests that, in adult females, football practice is associated with greater geometric indices of hip bone strength.

The influence of size, clearance, cartilage properties, thickness and hemiarthroplasty on the contact mechanics of the hip joint with biphasic layers

Computational models of the natural hip joint are needed to examine and optimise tissue sparing interventions where the natural cartilage remains part of the bearing surfaces. Although the importance of interstitial fluid pressurisation in the performance of cartilage has long been recognized, few studies have investigated the time dependent interstitial fluid pressurisation in a three dimensional natural hip joint model. The primary aim of this study was to develop a finite element model of the natural hip incorporating the biphasic cartilage layers that was capable of simulating the joint response over a prolonged physiological loading period. An initial set of sensitivity studies were also undertaken to investigate the influence of hip size, clearance, cartilage properties, thickness and hemiarthroplasty on the contact mechanics of the joint. The contact stress, contact area, fluid pressure and fluid support ratio were calculated and cross-compared between models with different parameters to evaluate their influence. It was found that the model predictions for the period soon after loading were sensitive to the hip size, clearance, cartilage aggregate modulus, thickness and hemiarthroplasty, while the time dependent behaviour over 3000 s was influenced by the hip clearance and cartilage aggregate modulus, permeability, thickness and hemiarthroplasty. The modelling methods developed in this study provide a basic platform for biphasic simulation of the whole hip joint onto which more sophisticated material models or other input parameters could be added in the future.

Three-dimensional morphologic study of the child's hip: which parameters are reproducible?

BACKGROUND

Biplanar x-ray images obtained with patients in a standing weightbearing position allow reconstruction of three-dimensional (3-D) bone geometries, with lower radiation exposure than CT scans and better bone definition than MRI.

QUESTIONS/PURPOSES

We determined the reproducibility of 3-D parameter values of the hips and pelves of healthy children, using biplanar x-ray images.

METHODS

We built 3-D models of the hips of 33 children without musculoskeletal problems: 10 subjects younger than 9 years and 23 who were 9 years or older. Three anatomic landmarks and nine hip and pelvic parameters were computed for each reconstruction. To determine the reliability of these landmarks and parameters, each bone was reconstructed four times by two independent observers, leading to a total of 264 reconstructions, and parameters were studied for the two age groups and compared between dancers and nondancers.

RESULTS

Taking into account all reconstructions, the interobserver reproducibility ranged from 2 to 4 mm for landmark positions or distance parameters, and 2° to 6° for angular parameters. The most reproducible point was the center of the femoral head (range, 0.2-17 mm). The distance between this center and its projection on the plane fitting the edge of the acetabulum, and the pelvic tilt were the most reproducible parameters.

CONCLUSIONS

Reproducible 3-D reconstructions of hips and pelves of children were possible using biplanar x-ray images, regardless of the children's ages. Although we report preliminary values for 3-D parameters in healthy children's hips, further work is needed to obtain direct validation of our parameters using CT reconstructions of cadaveric specimens to avoid high doses of radiation.

Can local muscles augment stability in the hip? A narrative literature review

Hip pain and dysfunction are increasingly recognised as important causes of morbidity in younger and older adults. Pathology compromising the passive stability of the hip joint, including acetabular labral injury, may lead to increased femoral head translation, greater joint contact pressures and ultimately degenerative hip disease. Activation of hip muscles may play an important role in augmenting the stability in the normal and the passively unstable hip. Research at other joints suggests that the local, rather than global, muscles are well suited to provide subtle joint compression, limiting translation, with minimal metabolic cost. Based on the known characteristics of local muscles and the limited research available on hip muscles, it is proposed that the local hip muscles; quadratus femoris, gluteus minimus, gemelli, obturator internus and externus, iliocapsularis and the deep fibres of iliopsoas, may be primary stabilisers of the hip joint. Interventions aimed at restoring isolated neuromuscular function of the primary hip stabilisers may be considered when treating people with passive hip instability prior to commencing global muscle rehabilitation. Finally, further research is needed to investigate the potential association between function of the hip muscles (including muscles likely to have a role in stabilising the hip) and hip pathology affecting hip stability such as acetabular labral lesions.

[Geometry of the hip joint: methodology and guidelines]

An hip fracture is an significant personal, family and health issue of people older than 65 years. In the first year of the fracture up to 30% of the injured die and about 50% of them never regain their formal degree of independence in fulfilling day-to-day activities. Estimations are that throughout 30 years in the world there will be around 6 million hip fractures per year which is about four times the todays amount. Todays predictions of hip fractures based on the hip geometry have shown us that the hip geometry is an independent variable of the bone mineral density. The hip geometry is more resistant to the effect of various factors than the bone mineral density and the changes throu life are a lot slower. The uniqueness and the sensitivity of the hip geometry in predicting a fracture is high and acceptable in research results of most authors. In this review we present the previous relevant knowledge about the measures and factors which determines the hip geometry and the accepted amount of pictorial methods of hip display. We have compared the methodology and the patients of eleven randomly picked writings on predicting hip fracture based on the hip geometry. We highlight the need of further refinement of the methodology and the more balanced selection of patients for a greater conformity in future writings. The hip geometry has shown it self as an useful diagnostical instrument but there is still more room for its improvement.

A system for individualized prosthetic modeling of the femoral head

The matching quality between the femoral head prosthesis and the acetabulum plays an important role in the operative treatment of femoral head prosthetics and femoral head replacement. To obtain the optimal model of the femoral head prosthesis for the target sufferer, an individualized modeling system is shown in this paper. It can recover the necrotic femoral heads into the satisfactory models. These models can well match with the acetabulum. This new system affords a theoretical model for the accurate operation position fixing in the orthopedic clinic. And this system also provides an innovative practical means for the individualized modeling of the artificial femoral head prosthesis.

Design and optimization of the oriented groove on the hip implant surface to promote bone microstructure integrity

We proposed a novel surface modification for an artificial hip joint stem from the viewpoint of maintenance and establishment of appropriate bone function and microstructure, represented by the preferred alignment of biological apatite (BAp) and collagen (Col). Oriented grooves were introduced into the proximal medial region of the femoral stem to control the principal stress applied to the bone inside the grooves, which is a dominant factor contributing to the promotion of Col/BAp alignment. The groove angle and the stem material were optimized based on the stress inside the grooves through a finite element analysis (FEA). Only the groove oriented proximally by 60° from the normal direction of the stem surface generated the healthy maximum principal stress distribution. The magnitude of the maximum principal stress inside the groove decreased with increasing the stem Young's modulus, while the direction of the stress did not largely changed. An in vivo implantation experiment showed that this groove was effective in inducing the new bone with preferential Col/BAp alignment along the groove depth direction which corresponded to the direction of maximum principal stress inside the groove. The anisotropic principal stress distribution and the oriented microstructure inside the groove are similar to those found in the femoral trabeculae; therefore, the creation of the oriented groove is a potent surface modification for optimizing implant design for a long-term fixation.

Morphometric and ultrasonographic study of the human fetal hip joint during intrauterine development

The main method for the early screening of the developmental dysplasia of the hip (DDH) is the ultrasound imaging. There are several studies about the ultrasound imaging of newborns' hips, but only a few studies include the prenatal period of life. Our aim was to examine the prenatal development of the hip joint through the evolution of the α angle seen on the ultrasound, described in the Graf R method, combined with anatomical dissection.

MATERIALS AND METHODS

Thirty-one post-mortem fetal hips were analyzed trough anatomical dissection, in 25 cases trough ultrasound imaging, in which the α angle was measured. Based on the morphometric examination, we applied the sine rule and we calculated the α1 angle, which also represents the coverage of the femoral head.

RESULTS

Based on the morphometric examination, not only the diameters of the femoral head and of the acetabulum, but also the joint cavity (X) showed an increase during development. Both of the α angles (measured α, calculated α1) showed a decrease as the fetus developed.

CONCLUSIONS

The decrease of the angles (α, α1) and the increase of the joint cavity during development correspond to the findings of the main research papers: the hip joint is less stable in the perinatal life. The α angle can be accurately determined only after the ossification of the acetabulum had started, in our case after the fetus is older than 18 weeks.

Predicting proximal femur rotation by morphological analyses using translucent 3-dimensional computed tomography

BACKGROUND

Predicting rotation of proximal femur in femur fracture surgeries is important to prevent malrotation.

OBJECTIVE

We aimed to prevent malrotation by developing a simple guideline that enables the prediction of proximal femur rotation using translucent 3-dimensional computed tomography (3D CT).

DESIGN

Retrospective.

SETTING

One tertiary general hospital in the Republic of Korea.

PATIENTS

Thirty-six subjects who underwent CT angiographies for vascular evaluation.

INTERVENTION

Translucent 3D CT images were created from the CT data.

MAIN OUTCOME MEASURE

Morphologic ratios of the great trochanter (GT) and lesser trochanter (LT) with the hip center as a basic point were measured at neutral position and at 5°, 10°, 15°, 20°, 25°, and 30° of internal rotation (IR) and external rotation (ER). The rotation angles at which the GT ratio becomes 0.5 and 0.33 and the rotation angles at which the LT ratio becomes 0.0 and 1.0 were determined to serve as guide angles.

RESULTS

Both the proportion of GT and LT compared with proximal femur with hip center as a reference (GT and LT ratio) gradually increased in the shift from IR to ER. At a neutral position, the GT and LT ratios were approximately 0.4 and 0.5, respectively. At 10°-15° of ER, the approximate GT and LT ratios were 0.5 and 1.0, respectively. At 30° of ER, the GT ratio exceeded 0.6, and the LT ratio exceeded 1.0. Between 10° and 15° of IR, the GT ratio decreased to approximately 0.33 and the LT ratio decreased to 0.0, which indicated that the LT was invisible.

CONCLUSIONS

We suggested practical values which might be useful as a reference in the operating room practically and hope that our findings would be helpful to prevent malrotation while performing proximal femur or femur shaft surgeries.

Volumetric bone mineral density at the spine and hip in Chinese American and White women

This study evaluated racial differences in bone size and volumetric density at the spine and hip in pre- and postmenopausal Chinese American and White women. Compared with White women, Chinese American women have greater cortical volumetric bone density (vBMD) at the hip, congruent with the results at the peripheral skeleton.

INTRODUCTION

Chinese American women have lower rates of fracture than White women despite lower areal bone density. At the forearm and tibia, however, Chinese American women have higher cortical vBMD as well as greater trabecular and cortical thickness, but smaller bone area as measured by high-resolution peripheral quantitative computed tomography (HR-pQCT) compared with White women. Since HR-pQCT data are obtained at peripheral sites, it is unclear whether these differences are relevant to the clinically important lumbar spine and hip. This study assesses racial differences in bone size and vBMD at the spine and hip in Chinese American and White women.

METHODS

QCT of the spine and hip was measured to assess racial differences in bone size, structure, and vBMD in pre- (n = 83) and postmenopausal (n = 50) Chinese American and White women. Data were adjusted for weight, height, physical activity, total calcium intake, parathyroid hormone, and 25-hydroxyvitamin D levels.

RESULTS

Among premenopausal women, lumbar spine trabecular vBMD was 5.8% greater in Chinese American versus White women (p = 0.01). At the hip, cortical vBMD was 3% greater at the femoral neck (p = 0.05) and 3.6% greater at the total hip (p = 0.01) in premenopausal Chinese American compared with White women. Among postmenopausal women, there was no difference in lumbar spine trabecular vBMD. Cortical vBMD was 4% greater at the total hip (p = 0.02) and tended to be greater at the femoral neck (p = 0.058) in Chinese American versus White women.

CONCLUSIONS

Consistent with earlier findings in the peripheral skeleton, cortical vBMD is greater at the hip in Chinese American versus White women.

Simultaneous bilateral hip joint imaging at 7 Tesla using fast transmit B₁ shimming methods and multichannel transmission - a feasibility study

The objective of this study was to demonstrate the feasibility of simultaneous bilateral hip imaging at 7 Tesla. Hip joint MRI becomes clinically critical since recent advances have made hip arthroscopy an efficacious approach to treat a variety of early hip diseases. The success of these treatments requires a reliable and accurate diagnosis of intraarticular abnormalities at an early stage. Articular cartilage assessment is especially important to guide surgical decisions but is difficult to achieve with current MR methods. Because of gains in tissue contrast and spatial resolution reported at ultra high magnetic fields, there are strong expectations that imaging the hip joint at 7 Tesla will improve diagnostic accuracy. Furthermore, there is growing evidence that the majority of these hip abnormalities occur bilaterally, emphasizing the need for bilateral imaging. However, obtaining high quality images in the human torso, in particular of both hips simultaneously, must overcome a major challenge arising from the damped traveling wave behaviour of RF waves at 7 Tesla that leads to severe inhomogeneities in transmit B1 (B(1) (+) ) phase and magnitude, typically resulting in areas of low signal and contrast, and consequently impairing use for clinical applications. To overcome this problem, a 16-channel stripline transceiver RF coil was used, together with a B1 shimming algorithm aiming at maximizing B(1) (+) in six regions of interest over the hips that were identified on axial scout images. Our successful results demonstrate that this approach effectively reduces inhomogeneities observed before B1 shimming and provides high joint tissue contrast in both hips while reducing the required RF power. Critical to this success was a fast small flip angle B(1) (+) calibration scan that permitted the computation of subject-specific B1 shimming solutions, a necessary step to account for large spatial variations in B(1) (+) phase observed in different subjects.

The Chitranjan Ranawat award: is neutral mechanical alignment normal for all patients? The concept of constitutional varus

BACKGROUND

Most knee surgeons have believed during TKA neutral mechanical alignment should be restored. A number of patients may exist, however, for whom neutral mechanical alignment is abnormal. Patients with so-called "constitutional varus" knees have had varus alignment since they reached skeletal maturity. Restoring neutral alignment in these cases may in fact be abnormal and undesirable and would likely require some degree of medial soft tissue release to achieve neutral alignment.

QUESTIONS/PURPOSES

We investigated what percentage of the normal population has constitutional varus knees and what are the contributing factors.

SUBJECTS AND METHODS

We recruited a cohort of 250 asymptomatic adult volunteers between 20 and 27 years old for this cross-sectional study. All volunteers had full-leg standing digital radiographs on which 19 alignment parameters were analyzed. The incidence of constitutional varus alignment was determined and contributing factors were analyzed using multivariate prediction models.

RESULTS

Thirty-two percent of men and 17% of women had constitutional varus knees with a natural mechanical alignment of 3° varus or more. Constitutional varus was associated with increased sports activity during growth, increased femoral varus bowing, an increased varus femoral neck-shaft angle, and an increased femoral anatomic mechanical angle.

CONCLUSIONS

An important fraction of the normal population has a natural alignment at the end of growth of 3° varus or more. This might be a consequence of Hueter-Volkmann's law. Restoration of mechanical alignment to neutral in these cases may not be desirable and would be unnatural for them.

Intra- and extra-articular planes of reference for use in total hip arthroplasty: a preliminary study

PURPOSE

Acetabular component malalignment in total hip arthroplasty can lead to potential complications such as dislocation, component impingement and excessive wear. Computer-assisted orthopaedic surgery systems generally use the anterior pelvic plane (APP). Our aim was to investigate the reliability of anatomical landmarks accessible during surgery and to define new potential planes of reference.

METHODS

Three types of palpations were performed: virtual, on dry bones and on two cadaveric specimens. Four landmarks were selected, the reproducibility of their positioning ranging from 0.9 to 2.3 mm. We then defined five planes and tested them during palpations on two cadaveric specimens.

RESULTS

Two planes produced a mean orientation error of 5.0° [standard deviation (SD 3.3°)] and 5.6° (SD 2.7°).

CONCLUSIONS

Even if further studies are needed to test the reliability of such planes on a larger scale in vivo during surgery, these results demonstrated the feasibility of defining a new plane of reference as an alternative to the APP.

In vivo precision of dual-energy X-ray absorptiometry-derived hip structural analysis in adults

Precision is integral to the monitoring of bone mineral density (BMD) change using dual-energy X-ray absorptiometry (DXA). Hip structural analysis (HSA) is a relatively recent method of assessing cross-sectional geometrical strength from the 2-dimensional images produced by DXA scans. By performing serial scans, we evaluated the in vivo precision of DXA-derived HSA in adults using a GE Lunar iDXA absorptiometer (GE Medical Systems, Madison, WI) in males and females (n=42), mean age of 34.5 (standard deviation [SD]: 8.5; range: 19.3-52.6)yr with a heterogeneous sample. Two consecutive intelligent DXA (iDXA) scans with repositioning of both femurs were conducted for each participant. The coefficient of variation, root-mean-square (RMS) averages of SD, and hence the least significant change (95%) were calculated. We found a high level of precision for BMD measurements of both the total hip and femoral neck, with RMS-SD=0.006 and 0.010 g/cm(2) and percent coefficient of variation (%CV)=0.52% and 0.94%, respectively. We also found good precision for HSA-derived geometrical properties, including sectional modulus, cross-sectional moment of inertia, and cross-sectional area, with %CV (average of the left and right sides) at 4.48%, 3.78%, and 3.13%, respectively. Precision was poorer for buckling ratio and femoral strength index with %CV 28.5% and 9.25%, respectively. The iDXA provides high precision for BMD measurements and with varying levels of precision for HSA geometrical properties.

Sexual dimorphism of femoral neck cross-sectional bone geometry in athletes and non-athletes: a hip structural analysis study

The characterisation of bone geometry in male and female athletes may increase our understanding of how physical loading may enhance bone strength in both sexes. This study investigated sexual dimorphism in hip geometry of athletes and age- and sex-matched non-athletes. Dual energy X-ray absorptiometry of the left proximal femur was performed in 62 male (n = 31; 30.2 ± 4.6 years) and female (n = 31; 27.9 ± 5.2 years) competitive endurance runners, and 36 male (n = 18; 28.7 ± 5.8 years) and female (n = 18; 29.1 ± 5.3 years) non-athletes. The hip structural analysis programme determined areal bone mineral density (aBMD), bone area (BA), hip axis length, cross-sectional area (CSA), and cross-sectional moment of inertia (CSMI) of the femoral neck. Strength indices were derived from the femoral strength index (FSI) (Yoshikawa et al., J Bone Miner Res 9:1053-1064, 1994). Despite similar size-adjusted aBMD, sexual dimorphism was apparent for BA, CSA and CSMI, with superior values in men compared to women (P < 0.01). FSI was greater in male and female athletes than non-athletes (P < 0.01). From all groups, results in male athletes inferred greatest resistance to axial (CSA) and bending loads (FSI). Estimates of bone strength (FSI) were greater in female athletes than male and female non-athletes, supporting the osteogenic value of regular loading of the hip.

The influence of participation in Better Bones and Balance™ on skeletal health: evaluation of a community-based exercise program to reduce fall and fracture risk

Older women participating in Better Bones and Balance™ (BBB) had similar bone mass at the hip compared to a sample of low active/sedentary controls. However, both groups had higher than expected hip BMD, despite higher risk for osteoporosis among BBB participants.

INTRODUCTION

BBB is a community-based fall and fracture risk reduction program shown to reduce bone loss at the hip in older women under controlled laboratory conditions. Whether bone benefits are derived from BBB as delivered in the community setting is unknown. The purpose of this study is to evaluate the relationship between community-based BBB participation and parameters of skeletal health in postmenopausal women.

METHODS

Women were recruited from BBB classes (n=69) and compared to low active/sedentary controls (n=46); total sample aged 69 + 7.7 years. Bone mineral density (BMD) of the hip and spine was measured using DXA; hip bone structure [cross-sectional area, cross-sectional moment of inertia] at the narrow neck and intertrochanter were derived using hip structural analysis software. Diet, physical activity, and health history were assessed by questionnaires. Group differences in bone outcomes were determined using ANCOVA controlling for age and body mass.

RESULTS

While controls were heavier and exhibited greater total body BMD compared to BBB participants (p<0.05), there were no differences between groups in hip or spine BMD or bone structural outcomes (p>0.05) despite BBB participants reporting more frequent prior diagnoses of or risk factors for osteoporosis compared to controls. Both controls and BBB participants had higher than average T-scores at the hip (p<0.05) when compared to an age-matched cohort from NHANES.

CONCLUSIONS

These data suggest that participation in BBB may not result in direct benefits to bone. However long-term participation may be associated with other positive outcomes.

Association between weight changes and changes in hip geometric indices in the Japanese female population during 10-year follow-up: Japanese Population-based Osteoporosis (JPOS) Cohort Study

During a 10-year follow-up of 893 women of various ages from the Japanese Population-based Osteoporosis Cohort Study, we evaluated the relationship between weight changes and hip geometric strength assessed by hip structure analysis. Our findings suggest that maintaining weight may help retain geometric strength and reduce hip fracture risk.

INTRODUCTION

The effects of changes in anthropometric indices on hip geometry in women of various ages are unclear. We evaluated these effects by analyzing 10-year longitudinal data from a representative sample of Japanese women.

METHODS

Dual-energy X-ray absorptiometry scans of the proximal femur were performed at baseline and at the 10-year follow-up. Data were analyzed with the Hip Structure Analysis (HSA) program, which yields geometric strength indices including cross-sectional area (CSA), section modulus (SM) and subperiosteal diameter (PD) at regions of interest (ROIs) in the narrow neck (NN), intertrochanter, and femoral shaft (FS) regions. Annual percent change of each HSA index was determined. Height and weight were measured at baseline and follow-up.

RESULTS

After excluding subjects with factors affecting bone metabolism, we evaluated 893 women (18-79 years old at baseline). The greatest changes in most HSA indices during the follow-up were observed in subjects aged ≥ 70 years at all ROIs. PD modestly but significantly expanded with age, but this change was not significant in subjects aged ≥ 70 years or those who had entered menopause ≥ 20 years before baseline. An increasing trend in weight was associated with an increase or smaller decline in CSA and SM at the NN and FS regions regardless of menopausal status after adjusting for age, height, and weight at baseline and change of estimated volumetric bone mineral density. Changes in height showed a much weaker association with HSA indices.

CONCLUSIONS

Maintaining weight may help retain hip geometric strength and reduce the risk of hip fracture.

[Acetabular anteversion angle of the hip in the Mexican adult population measured with computed tomography]

BACKGROUND

Knowledge of the radiogrametric characteristics of a specific skeletal segment in a healthy population is of the utmost clinical importance. The main justification for this study is that there is no published description of the radiogrametric parameter of acetabular anteversion in a healthy Mexican adult population.

MATERIAL AND METHODS

A prospective, descriptive and cross-sectional study was conducted. Individuals of both genders older than 18 years and orthopedically healthy were included. They underwent a two-dimensional axial tomographic study of both hips to measure the acetabular anteversion angles. The statistical analysis consisted of obtaining central trend and scatter measurements. A multivariate analysis of variance (ANOVA) and statistical significance were performed.

RESULTS

118 individuals were studied, 60 males and 58 females, with a mean age of 47.7 +/- 16.7, and a range of 18-85 years. The anteversion of the entire group was 18.6 degrees + 4.1 degrees. Anteversion in males was 17.3 degrees +/- 3.5 degrees (10 degrees - 25 degrees) and in females 19.8 degrees +/- 4.7 degrees (10 degrees - 31 degrees). There were no statistically significant differences (p < or = 0.05) in right and left anteversion in the entire group. However, there were statistically significant differences (p > or = 0.005) both in the right and left sides when males and females were compared.

CONCLUSIONS

Our study showed that there are great variations in the anteversion ranges of a healthy population. When our results are compared with those published by other authors the mean of most measurements exceeds 15 degrees. This should be useful to make therapeutic decisions that involve acetabular anteversion.

An in vivo comparison of hip structure analysis (HSA) with measurements obtained by QCT

SUMMARY

In a population of elderly women, bone cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), section modulus (Z), femoral neck axis length (FNAL), and width measured with hip structure analysis (HSA) on dual-energy x-ray absorptiometry (DXA) images in the femoral neck and trochanteric regions are highly correlated to quantitative computed tomography (QCT) measurements.

INTRODUCTION

HSA is a method of obtaining measurements of proximal femur structure using 2D DXA technology. This study was designed to examine the correlations between HSA measurements and 3D QCT.

METHODS

Forty-one women (mean age, 82.8 ± 2.5 years) were measured using DXA and a 64-slice CT scanner (1 mm slice thickness, 0.29 mm in plane resolution). HSA parameters were calculated at the narrow neck (NN) and trochanteric (IT) regions on the DXA image. These regions were then translated to anatomically equivalent regions on the QCT dataset by co-registering the DXA image and QCT dataset using four DXA images acquired at different angles.

RESULTS

At the NN and IT regions, high linear correlations were measured between HSA and QCT for CSA r = 0.95 and 0.93, CSMI r = 0.94 and 0.93, and Z r = 0.93 and 0.89, respectively. All correlations were highly significant (p < 0.001), but there were differences in slope and offset between the two techniques, at least in part due to differences in calibration between the two techniques. FNAL and width of the bone at the NN and IT regions, physical measurements independent of the calibration, were highly correlated (r = 0.90-0.95, p < 0.001) and had slopes close to 1.0 (range, 0.978 to 1.003).

CONCLUSION

CSA, CSMI, Z, FNAL, and width measured by HSA correlate highly to high-resolution QCT.

Bisphosphonates and glucocorticoid osteoporosis in men: results of a randomized controlled trial comparing zoledronic acid with risedronate

BACKGROUND

We studied 265 men (mean age 56.4 years; range 18-83 years), among patients enrolled in two arms of a double-blind, 1-year study comparing the effects of zoledronic acid (ZOL) with risedronate (RIS) in patients either commencing (prednisolone 7.5 mg/day or equivalent) (prevention arm, n=88) or continuing glucocorticoid therapy (treatment arm, n=177).

METHODS

Patients received either a single ZOL 5 mg infusion or RIS 5 mg oral daily at randomization, along with calcium (1000 mg) and vitamin D (400-1200 IU). Primary endpoint: difference in percentage change from baseline in bone mineral density (BMD) at the lumbar spine (LS) at 12 months. Secondary endpoints: percentage changes in BMD at total hip (TH) and femoral neck (FN), relative changes in bone turnover markers (β-CTx and P1NP), and overall safety.

FINDINGS

In the treatment subpopulation, ZOL increased LS BMD by 4.7% vs. 3.3% for RIS and at TH the percentage changes were 1.8% vs. 0.2%, respectively. In the prevention subpopulation, bone loss was prevented by both treatments. At LS the percentage changes were 2.5% vs. -0.2% for ZOL vs. RIS and at TH the percentage changes were 1.1% vs. -0.4%, respectively. ZOL significantly increased lumbar spine BMD more than RIS at Month 12 in both the prevention population (p=0.0024) and the treatment subpopulation (p=0.0232) in men. In the treatment subpopulation, ZOL demonstrated a significantly greater reduction in serum β-CTx and P1NP relative to RIS at all time-points. In the prevention subpopulation, ZOL significantly reduced β-CTx at all time-points, and P1NP at Month 3 (p=0.0297) only. Both treatments were well tolerated in men, albeit with a higher incidence of influenza-like illness and pyrexia events post-infusion with ZOL.

INTERPRETATION

Once-yearly ZOL preserves or increases BMD within 1 year to a greater extent than daily RIS in men receiving glucocorticoid therapy.

Physical activity, calcium intake and childhood bone mineral: a population-based cross-sectional study

In a free-living cohort of 4-year old children, mean daily time in moderate-vigorous physical activity and daily calcium intake at 3 years, were positively related to hip bone size and density. Relationships between physical activity and bone indices were stronger when calcium intake was above compared with below median (966 mg/day).

INTRODUCTION

We examined the cross-sectional relationships between childhood physical activity, dietary calcium intake and bone size and density.

METHODS

Children aged 4 years were recruited from the Southampton Women's Survey. They underwent measurement of bone mass by DXA (Hologic Discovery). Physical activity was assessed by accelerometry (Actiheart, Cambridge Neurotechnology Ltd, Cambridge, UK) for seven continuous days.

RESULTS

Four hundred twenty-two children (212 boys) participated. In a cross-sectional analysis, after adjusting for gender, daily mean time(minutes per day) spent in moderate to very vigorous activity (MVPA) was positively related to hip BA (R(2) = 3%, p < 0.001), BMC (R(2) = 4%, p < 0.001), aBMD (R (2) = 3%, p = 0.001) and estimated vBMD (R(2) = 2%, p = 0.01), but not height (r (s) = 0.04, p = 0.42) or weight (r(s) = 0.01, p = 0.76). Mean daily calcium intake (assessed at 3 years old) positively predicted bone indices in those with a calcium intake below the median (966 mg/day), but there was a much attenuated relationship in those above this. These associations persisted after inclusion of total energy, protein and phosphorus in multivariate models. The relationships between MVPA and bone indices were stronger in children with calcium intakes above the median. Thus, for aBMD, the variance explained by MVPA when daily calcium intake was below the median was 2% (p = 0.1) and above median was 6% (p = 0.001).

CONCLUSIONS

These results support the notion that adequate calcium intake may be required for optimal action of physical activity on bone development and that improving levels of physical activity and calcium intake in childhood may help to optimise accrual of bone mass.

Quantifying normal 3D hip ROM in healthy young adult males with clinical and laboratory tools: hip mobility restrictions appear to be plane-specific

BACKGROUND

Hip mobility is known to affect lumbar spine motion, yet the literature is unclear as to what constitutes normal, limited or excessive motion, given differences in methods, postures, age, etc. The purpose of this study was to establish normative and percentile data for hip rotation and extension, in a young adult male population, using varying methods of quantification.

METHODS

77 males (age 18-35) were recruited. Position data was captured using the Vicon Motion capture system, as participants were passively positioned in hip extension (using the Modified Thomas test) and prone hip rotation. 22 of these participants also had measurements obtained with a goniometer. 3D hip extension angles were calculated using Euler angles, and compared to those calculated in 2D. Goniometric results were compared to 2D measurements.

FINDINGS

Normal distribution of hip extension and rotation range of motion was established, as were average values for the 5th through 95th percentiles. No significant differences existed between hip extension angles measured with the 2D and 3D approaches. Goniometric measurements of hip extension averaged 3.9° less than 2D, less than 1° different for external rotation, and not different for internal rotation.

INTERPRETATION

The normative and percentile data documented here for hip rotation and extension appear to be validly quantified with goniometric techniques when compared to more objective techniques. Further, hip restriction in one plane may not predict restrictions in other planes.

Region-specific responses of adductor longus muscle to gravitational load-dependent activity in Wistar Hannover rats

Response of adductor longus (AL) muscle to gravitational unloading and reloading was studied. Male Wistar Hannover rats (5-wk old) were hindlimb-unloaded for 16 days with or without 16-day ambulation recovery. The electromyogram (EMG) activity in AL decreased after acute unloading, but that in the rostral region was even elevated during continuous unloading. The EMG levels in the caudal region gradually increased up to 6th day, but decreased again. Approximately 97% of fibers in the caudal region were pure type I at the beginning of experiment. Mean percentage of type I fibers in the rostral region was 61% and that of type I+II and II fiber was 14 and 25%, respectively. The percent type I fibers decreased and de novo appearance of type I+II was noted after unloading. But the fiber phenotype in caudal, not rostral and middle, region was normalized after 16-day ambulation. Pronounced atrophy after unloading and re-growth following ambulation was noted in type I fibers of the caudal region. Sarcomere length in the caudal region was passively shortened during unloading, but that in the rostral region was unchanged or even stretched slightly. Growth-associated increase of myonuclear number seen in the caudal region of control rats was inhibited by unloading. Number of mitotic active satellite cells decreased after unloading only in the caudal region. It was indicated that the responses of fiber properties in AL to unloading and reloading were closely related to the region-specific neural and mechanical activities, being the caudal region more responsive.

The retinacula of Weitbrecht in the adult hip

PURPOSE

The aim of the study was to describe the retinacula of Weitbrecht in the adult hip.

MATERIALS AND METHODS

Specimens were obtained from 30 adult hips, average age was 77 years (age range 43-91 years), 8 specimens were fixed by formalin solution and 22 were not fixed.

RESULTS

Anterior retinaculum was found in 40% of examined specimens. The anterior retinaculum was in 83% of cases formed by a flat plate and in 17% by two to three parallel bands. Medial retinaculum was present constantly, extending from the attachment of the articular capsule at the base of the lesser trochanter towards the fovea capitis femoris as far as the edge of the articular cartilage. Typically, the retinaculum had the form of an inverted "T". Of the three retinacula, the medial one was the strongest. Lateral retinaculum was also present constantly. In 89% of cases, it had the form of a quadrilateral plate adjacent to the upper surface of the femoral neck. This plate arises from the insertion of the articular capsule on the upper part of the femoral neck at the base of the greater trochanter close to the trochanteric fossa. The plate extended along the upper edge of the femoral neck as far as the edge of the articular cartilage. Microscopic examination revealed fine blood vessels running through the retinacula.

CONCLUSION

Lateral retinaculum and medial retinaculum are constant synovial plicae in terms of both occurrence and localization. Nutritive arteries run through both the plicae to supply the femoral head.

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

The association between proximal femoral geometry and hip fracture risk were investigated. The risk of intertrochanteric fractures increased 1.64-fold and 2.32-fold with 1 standard deviation (sd) increase of hip axis length and neck-shaft angle, respectively, while the risk of femur neck fracture 2.03-fold with 1 sd decrease in femoral head offset.

INTRODUCTION

The purpose of this study was to determine the association between proximal femoral geometry (PFG) and the risk of hip fracture in femur neck (FN) and intertrochanteric (IT) fractures in a Korean population.

METHODS

The study included 151 patients (57 patients with IT fractures, 43 patients with FN fractures, and 51 control patients). Data on BMD, PFG parameters (hip axis length [HAL], neck-shaft angle [NSA], neck length, femoral head offset, neck diameter, shaft diameter (SD), and demographics [age, gender, height, and body weight]) were collected. Descriptive statistics and odds ratios of PFG parameters corrected with demographic variables were obtained using logistic regressions.

RESULTS

HAL (p = 0.046) and NSA (p = 0.003) were significantly greater in the patients with IT fracture than in the control patients, while neither parameter was significantly greater in patients with FN fractures than the control patients. The femoral head offset was significantly shorter in the patients with FN fractures (p = 0.003) compared with the control patients. In patients with IT fractures, the fracture risk increased 1.64-fold (p = 0.048) with a 1 sd increase of the HAL, while it increased 2.32-fold (p = 0.003) with a 1 sd increase of the NSA. In FN fractures, the fracture risk increased 2.03-fold (p = 0.012) with a 1 sd decrease in femoral head offset.

CONCLUSIONS

Our study showed that some PFG parameters as well as BMD values predict hip fractures in a Korean population, and their evaluation may be useful in the understanding of the biomechanics of hip fractures.

Registration stability of physical templates in hip surgery

We tested the registration stability of individualized templates in a consecutive study with 80 patients undergoing hip-resurfacing surgery. These templates physically encode registration and navigation parameters but do not require a computer during the actual surgery. The surgical target was the placement of the femoral guidance pin during hip resurfacing, which is a difficult and highly variable task using conventional instruments. The drill trajectory for the guidance pin of the femoral component was planned on a 3D computer model of the femur derived from a preoperative computed tomography (CT) scan. A surface-matched drilling template was designed to perform mechanical registration on the bone surface and had a hole for the drill guide; the template was created using a rapid prototyping machine. Intraoperatively, the individualized template was positioned on the patient anatomy and the pin was drilled into the femoral neck. The final achieved pin orientation and position were measured using an optoelectronic CT-based navigation system. The measured mean deviation between planned and actual central pin alignment of 0.05° in valgus and 2.8° in anteversion shows that the proposed individualized templates for hip resurfacing have reliable registration.

Reliability of various observers in determining common radiographic parameters of adult hip structural anatomy

BACKGROUND

Radiographic evaluation of the hip is extremely important in the diagnosis and treatment decisionmaking process for pre-arthritic hip disease. Many different radiographic measurements have been described as indicators of underlying structural hip deformity. The purpose of this study was to determine the interobserver and intraobserver reliability of various musculoskeletal physicians in performing selected measurements of adult structural hip anatomy.

METHODS

A blinded review of 45 sets of radiographs from patients with developmental dysplasia, femoro-acetabular impingement, and normal anatomy was performed. Data points included the lateral center-edge angle (LCEA), vertical-center-anterior angle (VCA), head-neck offset ratio (UNO), alpha angle, Tönnis angle, Tönnis osteoarthritis grade and a radiographic diagnosis. One orthopaedic fellow, two orthopaedic residents, and two attending musculoskeletal physiatrists analyzed radiographs on two separate occasions. One sports medicine orthopaedic attending physician completed a single analysis of the image sets. Intraobserver and interobserver reliability was established using intra-class correlation coefficients (ICC) for continuous variables. Agreement regarding categorical variables was performed using the kappa coefficient

RESULTS

Excellent intraobserver reliability was found for the following: LCEA (ICC = 0.88), VCA (0.88), Tönnis angle (0.83), HNO on the frog lateral (0.78), alpha angle on the frog lateral (0.76), HNO on the cross-table lateral (0.75), and angle alpha on the cross-table lateral (0.76). Intraobserver reliability for osteoarthritis grade was poor (weighted kappa = 0.57). For all data points, interobserver reliability was considerably worse, with 95% confidence intervals spanning below 0.55.

CONCLUSIONS

While the described measurements of adult structural hip anatomy provide excellent reliability for a given reader, these measurements are less reliable across readers. Taken in isolation, these measurements, as performed by observers with varied clinical experience and clinical backgrounds, are limited in determining a consistent radiographic diagnosis.

[The finite element modeling of human pelvis and its application in medicolegal expertise]

OBJECTIVE

To develop a novel three dimensional finite element(FE) model of the human pelvis and investigate the biomechanics of the pelvic injury and explore the applications of FE approach in forensic medicine.

METHODS

The FE model of pelvis including bilateral iliac bones, sacrum, bilateral femurs, joint cartilages and ligaments was developed with Mimics 13.1 based on the CT images. The CT value of material properties were assigned. A static pressure of 600 N was applied at the upper surface of the sacrum endplate downwards along the vertical axis of sacral bone to validate the model. To simulate the side impacts, the lateral forces of 1, 2, 3, 4 and 5 kN were applied to the trochanter surface of right femur, respectively. The von Mises stress contours, displacement contours and stress distribution curves were subsequently calculated.

RESULTS

An integrated FE model of pelvis including the joint cartilages and ligaments was successfully established. The model geometry coincided well with the CT images. The stress distributions of pelvis in erect position mainly located near the sacroiliac joints and the greater sciatic notches. Stress concentration was found on the superior and inferior pubis ramus, hip and sacroiliac joints on both sides under side impacts.

CONCLUSION

The established FE model has accurate and reliable biomechanical features. The FE model can be used to simulate injury and provide intuitive and accurate evidence for medicolegal expertise.

Radiological determination of the anatomic hip centre from pelvic landmarks

There are various methods to locate the rotation centre of the hip joint on standard pelvic radiographs. When the geometry of both femoral heads is abnormal, a number of methods are available to locate the physiological hip centre from anatomical landmarks on pelvic radiographs. The accuracy and reliability of six methods were retrospectively investigated on 115 standard pelvic radiographs of both hips of healthy individuals. As a reference against the hip joint centre predicted by these methods, we used the true anatomical centre of the femoral head. Measurements were normalized in relation to pelvic height. The calculated hip rotation centre most closely approached the true anatomical centre of the femoral head when the acetabular teardrop was used as a landmark.

Primary hip arthroplasty templating on standard radiographs. A stepwise approach

In the past decade, the indications for hip replacements broadened and media induced patients' expectations in terms of function and longevity have been rising steadily. Improved technology addressed wear and fixation issues. However, more attention should be given to optimising hip biomechanics as this is essential to restore function. Pre-operative hip templating allows anticipating the correct implant position and potential difficulties prior to surgery. As such it is an essential part of the implantation process. We propose a four-step approach for hip templating on a standardised standing pelvic radiograph: 1. Identify anatomical landmarks (the medullary canal, the greater and lesser trochanter, the acetabular roof and the teardrop); 2. Assess the quality of the radiograph (femoral rotation, pelvic inclination and symmetry); 3. Identify mechanical references (the original acetabular and femoral rotation centre, the femoral and acetabular offset and the leg length and hip length discrepancy); 4. Optimise implant positioning to restore hip biomechanics. Hip templating helps recognising "difficult hips" where restoration of the original hip anatomy is no option. These hips should be approached carefully with a well defined pre-operative plan to minimise the chances of complication while maximising hip function. Although it is mainly under these circumstances that hip templating is a major asset, we believe that performing systematically a standardised preoperative templating should contribute to improved hip arthroplasty function and outcome.

A cadaveric study of posterior dislocation after total hip replacement-effects of head diameter and acetabular anteversion

The size of the femoral head and acetabular anteversion are crucial for stability in total hip replacements. This study examined the effects of head diameter and acetabular anteversion on the posterior instability after total hip replacement in an in vivo setting. The acetabular shell was inserted at 0-20° of anteversion at five degree intervals. By using different head sizes (28 mm, 32 mm, 36 mm), the degrees of dislocation were recorded by computer navigation. The 36-mm group consistently showed better stability compared with the 32- and 28-mm groups, regardless of the degree of cup anteversion. Within each group of head size, the hip was significantly more stable when the cup anteversion increased from 0° to 10°. The difference became insignificant when it increased from 15° to 20°.

Excision arthroplasty of the hip joint in dogs and cats. Clinical, radiographic, and gait analysis findings from the Department of Surgery, Veterinary Faculty of the Ludwig-Maximilians-University of Munich, Germany. 1997

From 1978 to 1989, 132 dogs and 51 cats underwent femoral head and neck ostectomy at the Department of Veterinary Surgery, Ludwig-Maximilians University, Munich, Germany. Clinical and radiographic re-evaluations were carried out an average of four years postoperatively in 81 (44%) of the animals, and gait analysis was also done in 17. The functional results were rated good in 38% of patients, satisfactory in 20%, and poor in 42%. However 96% of the owners were satisfied with the results. Kinetic and kinematic measurements showed that although femoral head and neck resection alleviated pain, it resulted in functional deficits in small as well as large breed dogs. These deficits were not visible during rapid movement.

Numerical simulations of the 3D virtual model of the human hip joint, using finite element method

In this paper, we present a three-dimensional mathematical model for a normal hip joint. The three-dimensional finite element model has been constructed based on Computer Tomograph scans of the bones. The obtained 3D model is studied using the finite element method, taking into consideration the real structure of the bone and the mechanical characteristics of cortical and spongy. The FE model of hip joint, the material properties used to simulate the behavior of the cortical and trabecular bone (of femur and coxal bone) and the cartilage, as well as the boundary conditions are presented. The distribution map of the axial and global movements on the global model and the distribution map of the axial and von Misses strain in the cartilaginous surface of the femur are presented.

Infantile hip arthroscopy: the relationship between neurovascular anatomy and the portal pathway

OBJECTIVE

In the past, studies of hip arthroscopy portal path relate with extra-articular structures were done in adults. This study was investigated in the infantile group.

MATERIAL AND METHOD

10 hips of fresh infantile cadavers. K-wire diameter 2.4 mm. are representing scope pathway. Three portals (anterior, anterolateral and posterolateral) in supine position without traction were chose to used in this study.

RESULTS

One cadaver was female and four were male. The mean age and weight when death occurred was 74 days and the mean weight was 3584.4 gm. At the anterior portal, the most lateral branch of LFCN was frequently injured. The average distant of femoral nerve to the K-wire was 11.2 (7-14) mm. Transverse branch of lateral femoral circumflex artery had an average distant 8.5(6-14) mm and the terminal branch could be identified in four hip and average distance was 1 mm. At the anterolateral portal two, greater trochanter were injured by K-wire. In the posterolateral portal the average distant from K-wire to sciatic nerve was 13.2 mm.

CONCLUSION

From this pilot study, the distance of major neurovascular structure as related to hip scope path is nearly a centimeter on average.

Determinants of bone mass and size in 7-year-old former term, late-preterm, and preterm boys

When compared, full-term prepubertal boys had greater regional bone size, higher total body (TB) bone mineral content (BMC), and regional bone density than preterm boys but higher TB bone content area and regional BMC than late-preterm boys. Implications include follow-up bone assessment and preterm formula feeding in late-preterm boys.

INTRODUCTION

This study was conducted to determine whether there are differences in bone mass and size among prepubertal boys born preterm (PT; < or =34 weeks gestation), late-preterm (LP; >34 and < or =37 weeks gestation), and at term (>37 weeks gestation) and to identify factors that are associated with bone mass and size in these children.

METHODS

Total body (TB), spine and hip dual energy X-ray absorptiometry and tibia peripheral quantitative computed tomography measures were obtained on 24 boys aged 5.7 to 8.3 years.

RESULTS

In multiple regression analysis adjusting for current weight, height, age, and jump power, term boys had greater cortical thickness (p = 0.03) and area (p = 0.01), higher trabecular volumetric bone mineral density (p = 0.05), TB bone mineral content (BMC; p = 0.007), and hip areal bone mineral density (aBMD; p = 0.01) than PT boys, and higher TB BMC (p = 0.01), TB bone area (p = 0.03), hip BMC (p = 0.02) and aBMD (p = 0.01), and femoral neck BMC (p = 0.05) and aBMD (p = 0.02) than LP boys. There were no differences in activity measures among gestation groups and no group-by-activity interactions.

CONCLUSION

Term boys have greater bone size and mass than PT boys and higher bone mass than LP boys at several bone sites. Activity measures did not differ among gestation groups and did not explain bone differences.

[Clinical anatomical study on high congenital dislocation of hip in adults]

OBJECTIVE

To investigate the morphological anatomical abnormalities of high congenital dislocation of hip in adults and provide anatomical basis for the total hip arthroplasty (THA).

METHODS

From May 1997 to July 2008, 49 patients (57 hips) with high congenital dislocation of hip (Hartofilakidis type III) were treated. There were 6 males and 43 females with an average age of 29.4 years old (18-56 years old). The locations were left in 24 hips and right in 33 hips. The morphological parameters (including femoral length, isthmus, height of femoral head center, neck-shaft angle, medial head offset, anteversion angle, canal flare index, anteroposterior diameter of the true acetabulum, posterior thickness of the true acetabulum, depth of the true acetabulum) of suffering hips (dislocation group, n=57) were measured by preoperative X-ray, CT and intraoperative clinical observation and were compared with those of contralateral hips (control group, n=41). The intraoperative situations of hip were observed.

RESULTS

The height of dislocation was (45.41 +/- 2.15) mm. The length difference of both lower extremities was (40.41 +/- 2.02) mm. In dislocation group, isthmus was shortened; height of femoral head center, neck-shaft angle and medial head offset were decreased; and anteversion angle was increased. CT showed that the canal flare index was larger than 4.7, femoral shape was funnel-shaped according to Noble classification. Anteroposterior diameter of the true acetabulum became smaller, posterior thickness of the true acetabulum became thicker, and depth of the true acetabulum was shallower. There were statistically significant differences in the morphological parameters of femur and acetabulum between two groups (P < 0.05). The intraoperative measurements showed that the anteroposterior diameter of acetabulum was (32.98 +/- 1.02) mm and the depth of acetabulum was (14.21 +/- 0.56) mm. There was no statistically significant difference between intraoperative measurements and preoperative measurements (P > 0.05). The acetabulum was full of fat and fibrous tissues. Running of the sciatic nerve in 40 cases were changed and it ran upward and laterally.

CONCLUSION

When high congenital dislocation of the hip in adults is treated with THA, anatomical variation must be fully taken into account. The acetabulum is expanded toward posterosuperior, excessive reamed should be avoided to prevent femoral fractures, and appropriate or tailor-made prosthesis was selected.

Women and men with hip fractures have a longer femoral neck moment arm and greater impact load in a sideways fall

INTRODUCTION

In a case control study, we report that women and men with hip fractures have a longer moment arm of the force applied on the proximal femur during a sideways fall, a structural feature that may contribute to fracture risk. The impact load and its direction during a sideways fall onto the greater trochanter are partly determined by the geometry of the proximal femur. We hypothesized that the hip geometry in elderly with hip fractures produces a greater impact on the hip during a sideways fall.

METHODS

We studied 41 female (77.2 +/- 9.9 years) and 22 male (76.2 +/- 12.1 years) patients with hip fractures and 40 female (85.7 +/- 6.0 years) and 17 male (84.3 +/- 10.1 years) controls. Hip geometry was analyzed on the nonfracture hip in patients and left hip in controls using dual-energy X-ray absorptiometry.

RESULTS

There was no difference in areal bone mineral density (aBMD), hip axis length, femoral neck axis length, or neck-shaft angle between cases and controls. However, the moment arm of the force on the hip during a sideways fall was 7.3% and 9.5% longer resulting in 5.6% and 9.1% greater moment in such a fall in female and male cases relative to their respective controls independent of height and weight (all p < 0.056). In multivariate logistic regression analysis, only the moment arm length in a sideways fall was associated with increased risk of hip fracture in females (odds ratio = 1.91, 95%CI: 1.14-3.20 for each SD increase in moment arm length of sideways fall, p = 0.02) and males (odds ratio = 2.69, 95% CI, 1.19-6.09, p = 0.01).

CONCLUSIONS

A longer moment arm in the sideways fall increases the resultant force applied to the hip predisposing to hip fracture.

A new digital preoperative planning method for total hip arthroplasties

Preoperative templating is an important part of a THA. The ability to accurately determine magnification of the hip on the radiograph and apply identical magnification to the radiograph and template will improve accuracy of preoperative templating of THA. We designed a templating method using a new way of determining the hip magnification with a linear relationship between magnification of the hip and the reference object on top of the pubis symphysis; the relationship was determined on 50 radiographs. We then compared our method with two other templating methods: an analog method assuming an average hip magnification of 15% and a digital method determining the hip magnification with a one-to-one relationship between the reference object and the hip. All methods were reproducible. Uniform undersizing occurred when templating with the digital method based on the one-to-one relationship; the analog method best predicted the implanted prosthesis size, closely followed by our new digital templating method; the new method will be particularly applicable for preoperative THA when analog methods are replaced by digital methods.

MR arthrography of the hip joint: a practical approach

This paper briefly reviews the technique of direct MR arthrography, MR anatomy and pathologic conditions of the acetabular labrum. Normal variants that may simulate pathology are also illustrated.

[Alternative method for measuring the mechanical axis of the knee]

OBJECTIVE

To identify the existence of significant differences in the degrees of mal-alignment of the mechanical axis of the knee between a traditional measuring method and an alternative method. MATERIALS AND METHODS. One hundred mechanical axes of the knee were determined in patients of both sexes. The degree of axis mal-alignment was obtained first using the traditional measuring method and subsequently using the alternative method. The results obtained from the two methods were then compared. The measurement variable control was standardised by positioning the patients in the same place during radiography when beginning mechanical axis determination. A wooden ruler on which each centimetre was indicated by a metal strip and numbered at every 10-centimeter interval was used to evaluate the degree of pelvic mal-alignment. The ruler was then used as a mechanical axis correction reference in accordance with the characteristics of each patient.

RESULTS

The following results were obtained from 100 mechanical axes evaluated by the traditional method and by the alternative method, respectively: varus deformity of the right pelvic segment was 21 degrees +/- 16 degreesuv. 7 ++/-6. degrees varus deformity of the left pelvic segment was 22 _+/-170 degreesvs. 8 ++/-50 degrees valgus deformity of the right pelvic segment was 21 - /-150 degreess. 8 + +/-; and valgus deformity of the left pelvic segment was 16 +/- 11 vs. 6 +/- 5 degrees.

CONCLUSIONS

Our results suggest that the proposed method provides more accurate mechanical axis measurement and that the correction is exponential: the greater the angle measured traditionally, the greater the correction with our proposed method.

An articulated statistical shape model for accurate hip joint segmentation

In this paper we propose a framework for fully automatic, robust and accurate segmentation of the human pelvis and proximal femur in CT data. We propose a composite statistical shape model of femur and pelvis with a flexible hip joint, for which we extend the common definition of statistical shape models as well as the common strategy for their adaptation. We do not analyze the joint flexibility statistically, but model it explicitly by rotational parameters describing the bent in a ball-and-socket joint. A leave-one-out evaluation on 50 CT volumes shows that image driven adaptation of our composite shape model robustly produces accurate segmentations of both proximal femur and pelvis. As a second contribution, we evaluate a fine grain multi-object segmentation method based on graph optimization. It relies on accurate initializations of femur and pelvis, which our composite shape model can generate. Simultaneous optimization of both femur and pelvis yields more accurate results than separate optimizations of each structure. Shape model adaptation and graph based optimization are embedded in a fully automatic framework.

Hip axis length variation: its correlation with anthropometric measurements in women from three ethnic groups

We compared hip axis length (HAL) in 157 non-Hispanic white women, 292 African-American women, and 210 Mexican-American women. After adjusting for maximal hip girth, there were no residual differences in HAL by ethnicity. Differences in hip fracture risk seen between these groups cannot be explained by ethnic differences in HAL.

INTRODUCTION

Hip axis length (HAL) has been reported to be an independent predictor of hip fracture. Significant ethnic differences in HAL have been noted, but no direct comparison has been made between African-American, Mexican-American, and non-Hispanic white women using the same protocol.

METHODS

We compared 157 non-Hispanic white women from the Rancho Bernardo Study, 292 women from the Health Assessment Study of African-American Women, and 210 women from the Skeletal Health of Mexican-American Women Project. A standardized questionnaire was used to obtain medical history; height, weight, waist girth, and hip girth were measured; and percentage body fat and HAL were obtained using dual energy X-ray absorptiometry. All HAL comparisons were adjusted for maximum hip girth to control for differences in size magnification by fan-beam absorptiometry.

RESULTS

Though there were ethnic differences in the unadjusted HAL measurement, after adjusting for hip circumference, there were no residual differences in HAL with regard to ethnicity: 10.7 cm in Mexican-American women vs. 10.8 in non-Hispanic white women and African-American women (p = 0.61).

CONCLUSIONS

There were no ethnic differences in HAL in women from the three ethnic groups. Differences in fracture risk among these groups cannot be explained by ethnic differences in HAL.