Osteoporotic Vertebral Fracture Prevalence in Elderly Chinese Men and Women: A Comparison of Endplate/Cortex Fracture-Based and Morphometrical Deformity-Based Methods.

This study aims to evaluate endplate/cortex fracture (ECF)-based method for detecting osteoporotic vertebral fracture (VF) in elderly Chinese population (age ≥ 65 years). The radiographs of 1954 elderly Chinese men (mean: 72.3 years) and 1953 elderly Chinese women (mean: 72.5 years) were evaluated according to Genant's morphometrical vertebral deformity (VD) severity criteria, as well as identified VF according to ECF without necessary requirement of VD. According to ECF, grade-1, -2, and -3 VF prevalence was 1.89%, 1.74%, and 2.25% in men, and 3.33%, 3.07%, and 5.89% in women, respectively. In men and women, 15.7% (35 of 223) and 34.5% (48 of 139) of vertebrae with VD grade-1 deformity were ECF(+, with fracture), respectively. In men and women, 89.7% (35 of 39) and 66.7% (48 of 72) of vertebrae with ECF grade-1 fracture had VD grade-1 deformity. For grade-1 change, ECF(+) subjects tended to have a lower BMD than the VD(+) subjects. In subjects with VD grade-2 deformity, those who were also EC (+) tended to have a lower BMD than those were ECF(-). In all grades, VD(-) and ECF(-) subjects tended to have highest BMD, whereas VD(+) and ECF(+) subjects tended to have lowest BMD. ECF may be more specific for assessing mild VF than the criteria based on vertebral deformity.

Prevalence and risk factors of lumbar spondylolisthesis in elderly Chinese men and women.

OBJECTIVE: A screening survey for osteoporotic fractures in men and women in Hong Kong represents the first large-scale prospective population-based study on bone health in elderly (≥65 years) Chinese men and women. This study aims to identify the prevalence and potential risk factors of lumbar spondylolisthesis in these subjects. METHODS: The lateral lumbar radiographs of 1,994 male and 1,996 female patients were analysed using the Meyerding classification. RESULTS: Amongst the men, 380 (19.1%) had at least one spondylolisthesis and 43 (11.3%) had slips at two or more levels; 283 had anterolisthesis, 85 had retrolisthesis, whereas 12 subjects had both anterolisthesis and retrolisthesis. Amongst the women, 499 (25.0%) had at least one spondylolisthesis and 69 (13.8%) had slips at two or more levels; 459 had anterolisthesis, 34 had retrolisthesis, whereas 6 subjects had both anterolisthesis and retrolisthesis. Advanced age, short height, higher body mass index (BMI), higher bone mineral density (BMD) and degenerative arthritis are associated with spondylolisthesis. Lower Physical Activity Scale for the Elderly (PASE) score was associated with spondylolisthesis in men; higher body weight, angina and lower grip strength were associated with spondylolisthesis in women. CONCLUSION: The male/female ratio of lumbar spondylolisthesis prevalence was 1:1.3 in elderly Chinese. Men are more likely to have retrolisthesis. KEY POINTS: • The prevalence of spondylolisthesis is 19.1% in elderly Chinese men. • The prevalence of spondylolisthesis is 25.0% in elderly Chinese women. • Men are more likely to have retrolisthesis. • Anterolisthesis is most commonly seen at the L4/L5 level. • Retrolisthesis is most commonly seen at the L3/L4 level.

Prevalence and sex difference of lumbar disc space narrowing in elderly chinese men and women: osteoporotic fractures in men (Hong Kong) and osteoporotic fractures in women (Hong Kong) studies.

OBJECTIVE: Osteoporotic Fractures in Men (Hong Kong) and Osteoporotic Fractures in Women (Hong Kong) represent the first large-scale prospective population-based studies on bone health in elderly (age≥65 years) Chinese men (n=2,000) and women (n=2,000). We undertook the current study to investigate the prevalence of lumbar disc space narrowing in these subjects, and to identify the potential relationship between disc space narrowing and sex, bone mineral density (BMD), and other demographic and clinical data. METHODS: On lumbar lateral radiographs, L1/L2-L4/L5 disc space was classified into 4 categories: 0=normal; 1=mild narrowing; 2=moderate narrowing; 3=severe narrowing. We compared demographic and clinical data between subjects with and those without total disc space narrowing scores≥3. RESULTS: Disc space narrowing was more common in elderly women than in elderly men. The mean±SD disc space narrowing score for the 4 discs was 2.71±2.21 for men and 3.08±2.50 for women (P<0.0001). For the 3 age groups of 65-69 years, 70-79 years, and ≥80 years, the average disc space narrowing score increased with increasing age in both men and women, and to a greater degree in women than in men. The average disc space narrowing score differences between women and men were 0.12, 0.40, and 0.90, respectively, in the 3 age groups. For both men and women, a disc space narrowing score≥3 was associated with older age, higher spine and hip BMD, low back pain, and restricted leg mobility. CONCLUSION: The prevalence and severity of disc space narrowing are higher in elderly women than in elderly men. With increasing age, disc space narrowing progresses at a greater rate in women than in men. A disc space narrowing score≥3 is associated with higher spine and hip BMD.

Visual functioning and quality of life among the older people in Hong Kong.

OBJECTIVES: This study aimed to examine the association of visual functioning and health-related quality of life (HRQOL) among the older community in Hong Kong. DESIGN: This study used the baseline examination of a cohort study MrOs and MsOs (a large study for osteoporosis in men and women). SETTING: This study was set in the Hong Kong community. PARTICIPANTS: A total of 4000 ambulatory community-dwelling Chinese men and women aged 65 years or above participated in this study. MEASUREMENTS: Health-related quality of life was assessed by Medical Outcomes Study Short Form-12 (SF-12), with physical component summary (PCS) and mental component summary (MCS) scores. Demographics, medical history, mental status, and quality of life were obtained from face-to-face interviews, using standard structured questionnaire. Visual functions (i.e., binocular visual acuity, contrast sensitivity, and stereopsis) were assessed by different visual tests after refraction corrections. Different visual functions were tested simultaneously in multiple ordinal logistic regression models. RESULTS: Better binocular visual acuity, contrast sensitivity, and stereopsis were associated with higher PCS. Visual acuity and contrast sensitivity was associated with PCS after adjustment of different visual functions and sex, age, education level, cognitive status, and history of diabetes in multivariate analysis, (OR = 0.73, 95% CI = 0.54 0.98) for low vision (≤6/24) compared with ≥6/9 in visual acuity and (OR = 1.34, 95% CI = 1.09 1.64) for contrast sensitivity row b 5-8 (best) compared with 0-1 (worst). MCS was only associated with visual acuity and contrast sensitivity, but no association was found after adjustment. CONCLUSION: Apparent association was found between visual functions and HRQOL among older community in Hong Kong. In addition to visual acuity, contrast sensitivity is also important, so eye care should also cover.

'Healthier Chinese spine': an update of osteoporotic fractures in men (MrOS) and in women (MsOS) Hong Kong spine radiograph studies.

For the MrOS (Hong Kong) and MsOS (Hong Kong) baseline (BL) studies, community-dwelling 2,000 Chinese men (mean age: 72.3 years) and 2,000 Chinese women (mean age: 72.5 years) were recruited from 2001 to 2003. These two studies have spanned two decades till now. This review summarizes our spine radiograph results. Senile and post-menopausal osteoporosis were associated with intervertebral disc volume reduction; and in women, menopause accelerates disc degeneration. Elderly women's osteoporotic vertebral fracture (OVF) prevalence was double of that of elderly men. For year-4 follow-up (FU), male participants with BL OVF had little increased risk for further OVF. In our study comparing OVF rates in age-matched Hong Kong Chinese women and Italian Caucasian women (mean age: 74.1 years), endplate and/or cortex fracture (ECF) prevalence was 26% for Chinese and 47% for Italian. OVF with ≥40% vertebral height loss was recorded among 9.5% of the Chinese subjects while among 26% of the Italian subjects. OVFs in Italian subjects were more likely to be multiple and generally severer. Clinical spine fractures were recorded 133 cases/100,000 person-years in MrOS (Hong Kong) participants and 273 cases/100,000 person-years in MsOS (Hong Kong) participants. Literature review suggests the clinical vertebral fracture rates among elderly Hong Kong Chinese subjects are approximately half of those of American, Australian, and Canadian subjects. Data synthesis suggests elderly Caucasians have a higher degenerative spondylolisthesis prevalence, being approximately 70% higher than that of elderly Hong Kong Chinese. Literature review of other authors' publications shows, compared with Caucasians, Chinese have a much lower incident rate of back pain. We conclude that elderly Chinese have a generally healthier spine relative to elderly Caucasians.

Relationship between hip bone mineral density and lumbar disc degeneration: a study in elderly subjects using an eight-level MRI-based disc degeneration grading system.

PURPOSE: To study the relationship between hip bone mineral density (BMD), lumbar disc degeneration, and lumbar disc space narrowing in elderly subjects. MATERIALS AND METHODS: The study cohort comprised 196 females and 163 males (age range, 67-89 years) with no age difference between the two groups. Anteroposterior total hip areal BMD was measured with DXA and lumbar spine MRI was acquired using a 1.5 Tesla scanner. Lumbar disc degeneration was assessed using an eight-level grading system wherein each grade represents a stepwise progression from normal disc to severe disc degeneration and disc space narrowing. RESULTS: After controlling for the age effect, no significant relationship was observed between total hip T-score status and severity of disc degeneration. There was no significant difference in total hip BMD in the subjects with or without the disc space narrowing (P < 0.05). Female subjects are more likely to have a narrowed disc space than males at all levels, and being statistically significant at L3/4 and L4/5 levels, and with an overall significance of P = 0.007. CONCLUSION: There was no association observed between hip BMD and lumbar disc degeneration. Elderly females were more likely to have a narrowed lumbar disc space than elderly males.

Characteristics of age-related changes in bone compared between male and female reference Chinese populations in Hong Kong: a pQCT study.

There have been few comprehensive studies on the age-related changes in bone mineral density (BMD) and bone structure in Chinese people. Using peripheral quantitative computed tomography (pQCT), we assessed volumetric BMD of both trabecular and cortical bone and their geometry at both radius and tibia in 620 Chinese men and 638 women, aged 20­98 years, in Hong Kong. Cortical BMD did not start declining until after the age of 50 years in women and the age of 60 years in men. In contrast, trabecular BMD declined with age starting from adulthood in both sexes, and the rates of decline accelerated after the age of 50 years only in women. The integral and trabecular bone area expanded with age in older men and women, primarily at the tibia. Cortical bone area decreased significantly in older women, particularly at the tibia, while it decreased only slightly with aging in men. The moment of inertia decreased with age at the radius in older men and women. At the tibia, age-related decline accelerated in older women, but not in older men. It was concluded that trabecularization of bone in response to declining BMD and mechanical loading may be maladaptive by reducing cortical bone area, if periosteal apposition cannot keep pace with it.

Changes in Lumbopelvic Movement and Muscle Recruitment Associated with Prolonged Deep Squatting: A Pilot Study.

This study examined the changes in spinal kinematics and muscle recruitment of the lumbopelvic region associated with prolonged squatting. Eight subjects with chronic nonspecific low back pain (LBP) and eight asymptomatic subjects (AS) performed squat-to-stand and reverse movements, before and immediately after 15 min deep-squatting. Within-group and between-group differences in lumbopelvic kinematics and electromyographic activity acquired in lumbar erector spinae (ES), gluteus maximus (GM), and vastus lateralis (VL) were analyzed. During squat-to-stand after squatting, the LBP group showed slower then faster lumbar movement in the second and third quartiles, respectively. In the second quartile, the AS group moved with a significantly greater lumbar angle. However, significantly greater bilateral GM activity (+4⁻4.5%) was found in the LBP group only. A more profound decrease in bilateral ES activity (-10%) was also shown in the LBP group, yet this was nonsignificant compared to the AS group (-4%). In the third quartile, only the LBP group moved with a significantly greater lumbar angle, together with a significant increase in bilateral ES (+6⁻8%) and GM muscle (+2⁻3%) activity. The findings of the altered pattern of joint kinematics and recruitment of the key lumbopelvic muscles displayed in the LBP group inform on the possible mechanisms that may contribute to the increased risk of developing lumbar dysfunctions for people who work in prolonged squatting postures.

Age- and Gender-Associated Liver Physiological T1rho Dynamics Demonstrated with a Clinically Applicable Single-Breathhold Acquisition.

To understand women's and men's physiological ranges of liver T1rho relaxation time measured with a single breathhold black blood sequence, this healthy volunteer study was conducted in 62 women (mean age, 38.9 y; range, 18-75 y) and 34 men (mean age, 44.7 y; range, 24-80 y). Approval from the institutional ethics committee was obtained. Magnetic resonance imaging was performed with a 3.0T scanner with six spin-lock times of 0, 10, 20, 25, 35, and 50 ms and a single breathhold of 12 s per slice acquisition. Six slices were acquired for each examination. The results demonstrated that the female liver T1rho value ranged between 35.07 and 51.97 ms and showed an age-dependent decrease, with younger women having a higher measurement. The male liver T1rho value ranged between 34.94 and 43.39 ms, with no evidential age dependence. Postmenopausal women had similar liver T1rho values as men. For women, there was a trend that the liver T1rho value could be 4% to 5% lower during the menstrual phase than during the nonmenstrual phase. For both women and men, no evidential association was seen between body mass index and liver T1rho.

Thoracolumbar Intervertebral Disc Area Morphometry in Elderly Chinese Men and Women: Radiographic Quantifications at Baseline and Changes at Year-4 Follow-up.

STUDY DESIGN: A population-based radiographic study with longitudinal follow-up. OBJECTIVE: To develop a quantitative index for lumbar disc space narrowing (DSN) evaluation in elderly subjects; to determine how DSN in the elderly is influenced by osteoporosis and sex. SUMMARY OF BACKGROUND DATA: There is paucity of research on quantitative classification of lumbar DSN based on disc areal morphometry. METHODS: With the database of Osteoporotic Fractures in Men (Hong Kong) and Osteoporotic Fractures in Women (Hong Kong) Studies and those who attended the year-4 follow-up (n = 1519 for men and n = 1546 for women), data of 491 women and 592 men were randomly selected. The anterior, middle, and posterior heights; anteroposterior diameter; and area of intervertebral discs (T4T5 to L4L5) were measured on lateral radiographs. Disc area index for lumbar spine (DAIL, disc area divided by the mean of the sum of square of the adjacent upper and lower vertebrae mid-height anterior-posterior diameter) was developed and compared with semiquantitative DSN expert grading. RESULTS: DAIL correlated with semiquantitative grading, with sensitivity and specificity varying from 87.3% to 96.8% for grade 1 DSN (<30% reduction in disc height), and 92.9% to 100% for grade 3 DSN (>60% reduction in disc height). The thoracolumbar disc area loss among men and women during 4-years' follow-up period varied between 1.32% and 3.56%, and it was greater for women (mean: 2.44%) than for men (mean: 1.90%, P = 0.044). Majority of lumbar DSN progressions during 72 to 76 years old were progression from normal disc space to grade 1 DSN. Osteoporosis was associated with greater disc area decrease, both for thoracic and lumbar discs. CONCLUSION: Lumbar DSN can be quantified using DAIL. In elderly Chinese, intervertebral disc narrowing over a 4-year period was greater in women than men, and associated with the presence of osteoporosis. LEVEL OF EVIDENCE: 3.

Prevalent osteoporotic vertebral fractures more likely involve the upper endplate than the lower endplate and even more so in males.

BACKGROUND: While the importance of identifying osteoporotic vertebral endplate fracture (EPF) is being recognized; the pathophysiological understanding of EPF till now remain insufficient. In this population-based cross-sectional radiograph study, we aim to investigate the anatomic location characteristics of osteoporotic EPF. METHODS: This study analyzed the anatomical location of osteoporotic EPFs in elderly Chinese population (age ≥65 years). The T4-L4 radiographs of 1,954 elderly Chinese men (mean: 72.3 years) and 1,953 elderly Chinese women (mean: 72.5 years) were evaluated to identify EPF, and vertebral bodies were graded according to Genant's vertebral deformity criteria. RESULTS: Of the 101,582 endplates analyzed, there were 505 EPFs (males: 27.7%; females: 72.3%). Excluding those with both upper endplate and lower endplate involvements, the ratio of upper EPF to lower EPF was 9.63 for males and 4.3 for females (P<0.05). Thoracolumbar junction, particularly L1 (26.4% for males and 24.1% for females) and followed by T12 (20.7% for males and 19.7% for females), had highest prevalence of EPF. With an endplate divided into 5 segments of equal length in the anteroposterior direction and grade 0.5 & 1, grade 2 vertebral deformities analyzed, fractures occurred mostly at the middle segment (70.1% for upper endplates in males and 78.6% for upper endplates in females), followed by second anterior segment (20.9% for upper endplates in males and 14.4% for upper endplates in females). The most anterior and most posterior segments were not primarily involved in EPF. CONCLUSIONS: Osteoporotic EPFs more likely involve the upper endplate rather than lower endplate, with a trend for this effect to be greater in men than in women. These characteristics may help radiographic differential diagnosis for osteoporotic EPF.

Lumbar Spondylolisthesis Progression and De Novo Spondylolisthesis in Elderly Chinese Men and Women: A Year-4 Follow-up Study.

STUDY DESIGN: Longitudinal follow-up study. OBJECTIVE: This current study aimed to further assess progression, incidence, and risk factors of lumbar spondylolisthesis in these subjects at 4-year follow-up. SUMMARY OF BACKGROUND DATA: A survey for osteoporotic fractures in Hong Kong during 2001 to 2003 represented the first large scale prospective population-based study on bone health in elderly (≥65 years) Chinese men and women. A follow-up study was performed at year-4. METHODS: The lateral lumbar radiographs of 1519 male and 1546 female subjects at year-4 follow-up were analyzed using the Meyerding classification, and compared with the baseline findings. RESULTS: Spondylolisthesis progressed in 13.0%, and de novo spondylolisthesis appeared in 12.4% in men. Spondylolisthesis progressed in 16.5%, and de novo spondylolisthesis appeared in 12.7% in women. In women, higher weight, body mass index, spine and hip bone mineral density (BMD), lower physical activity and lower grip strength were significant factors associated with spondylolisthesis progression, whereas only higher spine BMD was a marginally significant factor associated with spondylolisthesis progression for men. A weak association was noted between spondylolisthesis and lower back pain incidence in women, but not in men. CONCLUSION: Lumbar spondylolisthesis progression in elderly Chinese at 4-year follow-up was characterized by this study. LEVEL OF EVIDENCE: 3.

Multi-disciplinary Orthopaedics Rehabilitation Empowerment (MORE) program: A new standard of care for injured workers in Hong Kong.

BACKGROUND: The objective of this study is to evaluate the effects of the Multi-disciplinary Orthopaedics Rehabilitation Empowerment (MORE) Program on reducing chronic disability among injured workers and improving efficiency of work rehabilitation process. METHODS: A cohort of patients with workplace injuries in the lower back were recruited from orthopaedics clinics and assigned to either MORE group (n= 139) or control group (n= 106). Patients in MORE group received an early MRI screening and a coordinated multi-disciplinary management, while patients in the control group received conventional care. Outcome variables are time to return-to-work (RTW) from date of injury, waiting time for MRI screening and time to medical assessment board (MAB). RESULTS: Patients in the MORE Program had significantly shorter duration for RTW (MORE: 6.1 months, CONTROL: 12.8 months, p< 0.01), and more RTW cases (n= 64, 46.0%) compared to CONTROL group (n= 29, 27.4%). The MORE group also had much shorter waiting time for MRI scans (91.85 vs. 309.2 days, p< 0.001) and MAB referral after MRI scans (97.2 vs. 178.9 days, p= 0.001) compared to CONTROL group. CONCLUSIONS: The MORE Program which emphasizes early intervention and early MRI screening, is shown to be effective in shortening sick leave and improving RTW outcomes of injured workers.

Morphological changes of lumbar vertebral bodies and intervertebral discs associated with decrease in bone mineral density of the spine: a cross-sectional study in elderly subjects.

STUDY DESIGN: Cross-sectional study. OBJECTIVE: To investigate changes in the morphology of the lumbar vertebrae and intervertebral discs associated with osteoporosis of the spine in elderly subjects. SUMMARY OF BACKGROUND DATA: Osteoporosis is a common condition that primarily affects the elderly with significant impact on quality of life. How exactly osteopenia and osteoporosis influence vertebral and intervertebral disc morphology remains unknown and needs exploration. METHODS: A total of 395 community-dwelling ambulatory adults from 67 to 89 years of age were studied. The lumbar bone mineral density (BMD) was measured by dual-energy x-ray absorptiometry. T2-weighted sagittal images of the lumbar spine were obtained using a 1.5-T magnet. For each subject, the anterior height (Ha), middle height (Hm), posterior height (Hp), and anterior-posterior (AP) dimension of the 5 lumbar vertebrae (L1-L5) and 6 intervertebral discs (T12-L1 to L5-S1) were measured. To minimize the age effect, volume of these vertebrae and discs was measured in subgroups of 47 men (mean age = 74 yr, range: 73-75 yr) and 67 women (mean age = 72 yr, range: 71-73 yr). Continuous variables were examined by analysis of covariance after adjustment of height and age. RESULTS: There was no significant age difference between the groups of normal BMD, osteopenia, and osteoporosis. For the vertebral bodies, lower BMD was associated with a decrease of Ha, Hm, and Hp but not AP in both sexes, leading to an increased biconcavity index. For the discs, lower BMD was associated with a decrease of Ha and Hp, as well as AP, and an increase in Hm in both men and women. The disc biconvexity index was increased. Lower BMD is associated with an overall decrease in both vertebral volume and disc volume. CONCLUSION: Lower BMD is associated with a decreasing trend in both lumbar vertebral and disc volumes in elderly subjects but an increase in the Hm of the intervertebral discs.

Sex-specific effect of Pirin gene on bone mineral density in a cohort of 4000 Chinese.

BACKGROUND: Osteoporosis is a common condition among elderly. Genetic mapping studies repeatedly located the distal short arms of X-chromosome as the quantitative trait loci (QTL) for BMD in mice. Fine mapping of a syntenic segment on Xp22 in a Caucasian female population suggested a moderate association between lumbar spine (LS) BMD and 2 intronic SNPs in the Pirin (PIR) gene, which encodes an iron-binding nuclear protein. This study aimed to examine genetic variations in the PIR gene by a comprehensive tagging method and its sex-specific effects on BMD and osteoporotic risk. METHODS: Two thousand men and 2000 women aged 65 or above were recruited from the community. BMDs at the LS, femoral neck, total hip and whole body were measured and followed up at 4-year. Genotyping was performed for tagSNPs of PIR gene including adjacent regions, and the PIR haplotypes were inferred using PHASE program. RESULTS: Analysis by linear regression showed a significant association between SNP rs5935970 and LS-BMD, while haplotype T-T-A was significantly associated with BMD of all measured sites. However, none of such associations were found in men. Linear Mixed Model also confirmed the same sex-specific and site-specific effect for longitudinal BMD changes. CONCLUSION: In addition to confirming the association between BMDs and the PIR gene, we also revealed that this finding is sex-specific, possibly due to an X-linked effect. This study demonstrated the importance of considering sex and genetic interactions in studies of disease predisposition and complex traits.

Reduced bone perfusion in proximal femur of subjects with decreased bone mineral density preferentially affects the femoral neck.

Using dynamic contrast enhanced MR imaging, this study investigated perfusion of the proximal femur in subjects with normal BMD, low bone mass and osteoporosis. Study cohort comprised healthy elderly Hong Kong Chinese volunteers consisting of 107 males (74.4+/-4.2 years, mean+/-SD) and 135 females (73.9+/-4.3 years). Right proximal femur BMD measurement by DXA and MR perfusion imaging (maximum enhancement, E(max) and enhancement slope, E(slope)) of the femoral head, neck, and proximal shaft were carried out within a one month interval. Normal BMD, low bone mass and osteoporotic subjects accounted for 46.7%, 44.9%, and 8.4% of males; and 32.6%, 43.7%, and 23.7% of females. Perfusion indices showed that femoral head perfusion was less perfused compared to the femoral shaft (E(max) and E(slope) indices of head region=28% of shaft region). Compared with normal BMD subjects, E(max) of femoral head, neck, and proximal femur shaft were reduced by 15+/-5% (mean+/-standard error); 40+/-4%; 15+/-5% respectively for low bone mass subjects, and 36+/-4%; 50+/-6%; 47+/-6% respectively for osteoporotic subjects. E(slope) of femoral head, neck, and proximal femur shaft were reduced by 17+/-7%; 41+/-5%; 4+/-7% for low bone mass subjects and 50+/-5%, 62+/-5%, 34+/-8% for osteoporotic subjects. In low bone mass and osteoporotic subjects there was a tendency for perfusion in the femoral neck to reduce to a greater degree relative to that in the femoral head and shaft.