Vertebral bone density after hip rearthroplasty assessed by quantitative computed tomography

An investigation of the bone mineral density of lumbar vertebrae L1 to L3 with quantitative computed tomography was undertaken in 12 patients who had undergone hip rearthroplasty because of aseptic prosthetic loosening. The same measurements were carried out in a control group of 13 patients who had undergone hip arthroplasty, but not rearthroplasty. A good correlation was found between the cancellous bone mineral density in lumbar vertebrae L1 to L3 in each patient. In contrast to earlier findings of a post-traumatic effect on the appendicular skeleton after rearthroplasty, no significant difference was found in vertebral bone mineral density after the rearthroplasty.     

Proximal femoral density and geometry measurements by quantitative computed tomography: association with hip fracture

INTRODUCTION: Bone mineral density and geometry measurements by volumetric quantitative computed tomography (vQCT) have been utilized in clinical research studies of aging, pharmacologic intervention and mechanical unloading, but there is relatively little information about the association of these measures with hip fracture. To address this issue, we have carried out a study comparing vQCT parameters in elderly Chinese women with hip fractures with measurements in age-matched controls. MATERIALS AND METHODS: Forty-five women (mean age 74.71+/-5.94) with hip fractures were compared to 66 age-matched control subjects (mean age 70.70+/-4.66). vQCT was employed to characterize the volumetric bone mineral density in cortical, trabecular, and integral volumes of interest in the proximal femur. In addition to the volume of interest measurements, we computed the cross-sectional areas of the femoral neck and intertrochanteric planes, the femoral neck axis length, indices of femoral neck bending and compressive strength, and measures of femoral neck cortical geometry. To determine if cortical geometry measures were associated with hip fracture independently of trabecular vBMD, we carried out multi-variate analyses including these parameters in a logistic regression model. RESULTS AND CONCLUSIONS: All vQCT measurements discriminated between fractured subjects and age-matched controls. There was no significant difference in predictive strength between volumetric and areal representations of BMD and trabecular and integral vBMD showed comparable discriminatory power, although both of these measures were more correlated to fracture status than cortical vBMD. We found that fractured subjects had larger femoral neck cross-sectional areas, consistent with adaptation to lower BMD in these osteoporotic subjects. The larger neck cross-sectional areas resulted in bending strength indices in the fractured subjects that were comparable or larger than those of the control subjects. In multi-variate analyses, reduced femoral neck cortical thickness and buckling ratio indices were associated with fracture status independently of trabecular vBMD.     

髋部定量CT骨密度与髋螺钉置入位置分析

目的对髋部不同空间位置骨松质作定量CT骨密度测定,从骨密度的角度来分析内固定手术治疗老年股骨粗隆间骨折时髋螺钉的合理安放位置。方法选择年龄大于60岁的老年妇女共66例行双侧髋部CT扫描,其中股骨粗隆间骨折35例（骨折组）,无骨折的正常老年妇女31例（对照组）。测定从髋螺钉入口到股骨头的CT值。同时对股骨头内密度较高的压力骨小梁（PCT）及其内、外、前、后侧5个区域的骨松质作定量CT骨密度测定。结果骨折组从髋螺钉人口内侧到股骨头下区域的CT值为负值。骨折组PCT及其内、外、前、后侧的定量CT骨密度分别为（229．71±55．58）、（64．58±25．31）、（39．50±22．56）、（79．85±24．89）、（79．08±19．99）mg／cm^3,而对照组分别为（296．36±40．48）、（85．31±26．99）、（69．49±20．88）、（99．96±27．62）、（98．57±29．38）mg/cm^3。两组PCT的骨密度均明显高于其周围4个区域,差异有统计学意义（P〈0．01）。两组间比较,骨折组5个区域骨密度均明显低于对照组,差异有统计学意义（P〈0．01）。结论从骨密度角度来讲,自髋螺钉人口到股骨头下这一区域的组织密度低于软组织密度,对置入的髋螺钉无锚定力量。PCT是髋部密度最高的骨松质,对髋螺钉锚定起主要作用。在股骨头的外上、前方和后方3个区域内,骨松质的密度远低于压力骨小梁,为髋螺钉发生切割的危险区。老年人存在严重的骨小梁退变,因此正确放置髋螺钉尤其重要。     

Femoral neck bone mineral density after resurfacing hip arthroplasty

Introduction: Resurfacing hip arthroplasty (RHA) has been suggested to provide an alternative to conventional total hip arthroplasty in younger, active patients. It seems to have an ability to conserve the bone mass on the femoral side. Some controversy exists regarding to the possible disadvantages of RHA and some of them are connected to poor femoral bone quality after surgery. Hence we wanted to study the bone mineral density changes 3 and 12 months after RHA. Materials and Methods: A total of 26 patients (22 men and 4 women, 28 hips) underwent a hip resurfacing arthroplasty. The mean age of the patients was 55,2 (range 38-69) years. Bone mineral density (BMD) of the proximal femur was measured by using the dual-energy X-ray absorptiometry (DXA) postoperatively and within 3 and 12 months from surgery. For analysis, we divided the femoral neck area into four equal-sized regions of interest ranging from the prosthesis to the trochanter level. Results: At three months follow-up the BMD changes varied between -5.1% (ROI C) and + 1.9% (ROI A), as compared with the immediate postoperative values. After one year follow-up the BMD changes were + 1.1% in the ROI A, + 5.4% in the ROI B, -3.9% in the ROI C and + 1.3% in the ROI D. The changes in BMD were not statistically significant. Discussion: While there is still much debate and room for additional research in this topic, the results suggest that BMD is conserved in the femoral neck one year after hip resurfacing arthroplasty.     

Secondary contributors to bone loss in osteoporosis related hip fractures

SUMMARY: Osteoporosis treatment of patients with hip fractures is necessary to prevent subsequent fractures. Secondary causes for bone loss are present in more than 80% of patients with hip fractures, and therefore, assessment of Vitamin D status, disorders in calcium absorption and excretion, monoclonal gammopathies, and renal function should be performed. Identifying and managing these disorders will improve detection and enhance treatment aimed at reducing the risk of recurrent fractures in older adults. INTRODUCTION: The purpose of this study was to determine the prevalence of disorders affecting bone and mineral metabolism in individuals with osteoporotic hip fractures. METHODS: Community dwelling individuals with hip fractures (HFx) 50 years of age and older. Assessment for vitamin D, renal and parathyroid status, calcium absorption, and plasma cell disorders. RESULTS: Of 157 HFx, mean age 70 +/- 10 years, HFx had higher creatinine (p = 0.002, 95% C.I. -0.09, 0.05); lower 25 OH vitamin D (p = 0.019, 95% C.I. 6.5, 2.7), albumin (p = 0.007, 95% C.I. 0.36, 0.009), and 24-h urine calcium (p = 0.024, 95% CI 51, 21) as compared to controls. More than 80% of HFx had at least one previously undiagnosed condition, with vitamin D insufficiency (61%), chronic kidney disease (16%) (CKD), monoclonal gammopathy (6%), and low calcium absorption (5%) being the most common. One case each of multiple myeloma and solitary plasmocytoma were identified. CONCLUSIONS: Osteoporosis treatment of HFx is necessary to prevent subsequent fractures. Secondary causes for bone loss are remarkably common in HFx; therefore, assessment of vitamin D status, disorders in calcium absorption and excretion, protein electrophoresis, and renal function should be performed. Identifying and correcting these disorders will improve detection and enhance treatment aimed at reducing the risk of recurrent fractures in older adults.     

Differences in hip quantitative computed tomography (QCT) measurements of bone mineral density and bone strength between glucocorticoid-treated and glucocorticoid-naïve postmenopausal women

Chronic treatment with glucocorticoids (GCs) leads to significant bone loss and increased risk of fractures. In chronically GC-treated patients, hip fracture risk is nearly 50%. The purpose of this investigation was to determine if there are differences in the quantities of trabecular and cortical bone and bone strength of the hip between GC-treated osteoporotic patients and controls. Methods: Study subjects were GC-treated osteoporotic postmenopausal women, and controls were postmenopausal women, recruited for separate clinical trials. Quantitative computed tomography (QCT) and dual-energy X-ray absorptiometry (DXA) of the hip were obtained from all subjects. QCT outcome variables measured included total, cortical, and trabecular BMD of hip subregions (femoral neck and trochanter) and total hip. In addition, finite element modeling (FEM) was performed on a subset of 19 cases and 38 controls, matched on age (± 5 years), weight (± 5 kg), and history of hormone replacement (>1 year use) to assess failure load in stance and fall loading conditions. Generalized linear models were used to adjust the QCT variables for covariates between groups. Multiple regression was performed to identify independent predictors of bone strength from the QCT variables. Results: Compared with controls, GC-treated subjects were significantly (p<0.05) younger, weighed less, and had more years of hormone replacement. QCT of the hip in GC-treated subjects for total femoral integral, cortical, and trabecular BMD averaged 4.9–23.2% (p<0.002) less than controls, and similar results were seen by hip subregion including the trochanter and femoral neck. DXA of the total hip was 17% lower in GC subjects than controls (p<0.05). Compared with controls, FEM failure load in GC subjects was 15% (p<0.05) and 16% (p=0.07) lower for stance and fall loading conditions, respectively. Multiple regression analysis demonstrated that a combination of QCT measures was correlated with bone strength as measured by FEM. Conclusions: Chronic GC treatment in postmenopausal women resulted in significantly decreased BMD of the hip, measured by QCT, with loss of both trabecular and cortical bone. In addition, GC treatment decreased bone strength as determined by FEM. The reduced cortical and trabecular bone mass in the hip may contribute to the disproportionately high hip fracture rates observed in GC-treated subjects.This work was supported by grants from the NIH 1R01AG05407, 1R01AR40431, 1R01AR46197, the Doris Duke Clinical Research Fellowship (CRF) Program for Medical Students (#20000684) K24AR048841-02 and the Rosalind Russell Arthritis Foundation.     

Femoral bone density in young male adults with stress fractures

Femoral bone mineral density (BMD) was measured by dualphoton absorptiometry in 41 young military recruits who had one or several stress fractures, during their physical training program. These fractures involved the following locations: Femur (neck: n = 10, diaphysis: n = 2), calcaneus (n = 10), tibia (n = 8), fibula (n = 3), metatarsus (n = 8). The stress fracture group generally had a lower bone density than that of a control group, consisting of 48 young military recruits matched for age, height and weight. However, the BMD was significantly lower (-10%) in patients with femoral and calcaneal locations, but it did not differ for other locations. To determine the possible effect of this intense physical activity on bone mineral mass, bone mass was measured again in 35 subjects from the control group at the end of their training. The BMD remained stable or increased in 28 subjects, but decreased significantly (greater than 2%) in 7 subjects, demonstrating the individual variability in the adaptation of bone to this stress. Our results suggest that lowered bone mass could be a factor that encourages the development of stress fractures (femoral and calcaneal) in young subjects submitted to intense physical activity to which they are not accustomed.     

应用双能CT与定量CT对椎体骨密度测量的对照研究

目的应用双能CT(DECT)及定量CT(QCT)测量腰椎骨密度,评价利用双能CT测量骨密度(BMD)的可行性。方法对56名志愿者采用DECT检查,获得钙值图,测量骨钙CT值及骨髓CT值,同时应用QCT测量骨密度(BMD),分析骨钙CT值及骨髓CT值与BMD值的相关性。结果腰椎椎体骨钙CT值与BMD值呈显著正相关(L1-5椎体Pearson相关系数分别为:r=0.715,0.692,0.739,0.673,0.686,P0.01);骨髓CT值与BMD值呈正相关(L1-5椎体Pearson相关系数分别为r=0.343、0.315、0.439、0.440、0.456,L5椎体P0.05,其余椎体P0.01)。结论 DECT所测量腰椎骨钙CT值及骨髓CT值与QCT所测BMD值密切相关,可定量反映腰椎BMD变化。     

Periacetabular bone changes after uncemented total hip arthroplasty evaluated by quantitative computed tomography

Background?There are few dual X-ray absorptiometry (DXA) studies on periacetabular bone density changes after cup implantation. This study was designed to analyze the load-transfer mechanism and stress pattern of periacetabular cortical and cancellous bone after implantation of a ihemispherical titanium alloy press-fit cup with alumina-alumina pairing in vivo. We introduced a novel method of computed tomography (CT)-assisted osteodensitometry.

Method?We investigated 26 hips (26 patients) with osteoarthritis using conventional sequential CT examinations performed within the first 10 days after implantation, and after a mean period of 1.1 years postoperatively. Bone density of full, cancellous and cortical bone (mgCaHA/mL) was measured.

Results?At the time of follow-up, the mean bone density values of the cortical bone cranial to the cup increased by 3.6% (p = 0.03) while the cancellous bone density decreased by 18%. Cancellous bone loss was greater in the region ventral to the cup (–35%) than in the dorsal region (–30%). Cortical bone density decreased ventral to the cup (–6.4%). All these changes were statistically significant. The bone density changes in the dorsal cortical region were not significant.

Interpretation?The method presented is an excellent tool for detailed measurement of bone density changes around the cup after total hip arthroplasty, and allows a thorough assessment of stress shielding phenomena in vivo. The hemispherical titanium alloy press-fit cup is a rigid implant which stress shields cancellous bone and enhances load transfer to the cranial cortical bone. Further investigations will demonstrate the impact these factors have on the long-term results of the implant, and may allow a type-related predictable prognosis of the longevity of the prosthesis.     

Pelvic body composition measurements by quantitative computed tomography: association with recent hip fracture

INTRODUCTION: Loss of subcutaneous fat, decreased muscle cross-sectional area (CSA) and increased muscle adiposity are related to declining physical function and disability in the elderly, but there is little information about the relationship of these tissue changes to hip fracture. Thus we have compared body composition measures in women with hip fractures to age-matched controls, using quantitative computed tomography (QCT) imaging of the hip to characterize total adiposity, muscle CSA and muscle attenuation coefficient, a measure of adiposity. MATERIALS AND METHODS: 45 Chinese women (mean age 74.71+/-5.94) with hip fractures were compared to 66 healthy control subjects (mean age 70.70+/-4.66). Hip QCT scans were analyzed to compute total adipose CSA as well as CSA and attenuation values of muscle groups in the CT scan field of view, including hip extensors, abductors, adductors and flexors. The total femur areal BMD (aBMD) was estimated from the QCT images. Logistic regression was employed to compare body composition measures between fracture subjects and controls after adjustment for age, height, BMI and aBMD. Receiver-operator curve (ROC) analyses determined whether combinations of aBMD and body composition had higher area under curve (AUC) than aBMD alone. RESULTS AND CONCLUSIONS: Fracture subjects had lower fat CSA (p<0.0001) than controls but had higher muscle adiposity as indicated by lower attenuation in the adductor, abductor and flexor groups (0.00001相似文献   

Periacetabular bone changes after uncemented total hip arthroplasty evaluated by quantitative computed tomography

Background There are few dual X-ray absorptiometry (DXA) studies on periacetabular bone density changes after cup implantation. This study was designed to analyze the load-transfer mechanism and stress pattern of periacetabular cortical and cancellous bone after implantation of a ihemispherical titanium alloy press-fit cup with alumina-alumina pairing in vivo. We introduced a novel method of computed tomography (CT)-assisted osteodensitometry.

Method We investigated 26 hips (26 patients) with osteoarthritis using conventional sequential CT examinations performed within the first 10 days after implantation, and after a mean period of 1.1 years postoperatively. Bone density of full, cancellous and cortical bone (mgCaHA/mL) was measured.

Results At the time of follow-up, the mean bone density values of the cortical bone cranial to the cup increased by 3.6% (p = 0.03) while the cancellous bone density decreased by 18%. Cancellous bone loss was greater in the region ventral to the cup (-35%) than in the dorsal region (-30%). Cortical bone density decreased ventral to the cup (-6.4%). All these changes were statistically significant. The bone density changes in the dorsal cortical region were not significant.

Interpretation The method presented is an excellent tool for detailed measurement of bone density changes around the cup after total hip arthroplasty, and allows a thorough assessment of stress shielding phenomena in vivo. The hemispherical titanium alloy press-fit cup is a rigid implant which stress shields cancellous bone and enhances load transfer to the cranial cortical bone. Further investigations will demonstrate the impact these factors have on the long-term results of the implant, and may allow a type-related predictable prognosis of the longevity of the prosthesis.     

Vertebral bone density by quantitative computed tomography mirrors bone structure histomorphometric parameters in hemodialysis patients

Diagnosing low bone mass is of clinical importance for hemodialysis (HD) patients due to its association with fractures and cardiovascular disease. We investigated whether bone density obtained by quantitative computed tomography (QCT) is associated with the histologically determined bone volume and microarchitecture parameters in HD patients. Twenty-six HD patients were studied. Bone biopsy samples were obtained from the iliac crest and trabecular bone volume, thickness, number and separation were evaluated by histomorphometry. Vertebral trabecular bone density (VTBD) was evaluated by QCT. VTBD correlated positively with trabecular bone volume (r = 0.69, p < 0.001), trabecular thickness (r = 0.45, p = 0.022) and trabecular number (r = 0.62, p < 0.001), and negatively with trabecular separation (r = ?0.50, p < 0.01). In the multiple linear regression analysis adjusting for age, gender and diabetes, VTBD remained associated with bone volume by histomorphometry (β = 0.06; 95 % CI 0.02–0.11; p = 0.006; R ² = 0.49). VTBD measured by QCT mirrored bone volume and microarchitecture parameters obtained by histomorphometry in HD patients.     

Effective dose values in bone mineral measurements by photon absorptiometry and computed tomography

A high degree of uncertainty and irritation predominates in the assessment and comparison of radiation dose values resulting from measurements of bone mineral density of the lumbar spine by photon absorptiometry and X-ray computed tomography. The skin dose values which are usually given in the literature are of limited relevance because the size of the irradiated volumes, the relative sensitivity of the affected organs and the radiation energies are not taken into account. The concept of effective dose, sometimes called whole-body equivalent dose, has to be applied. A detailed analysis results in an effective dose value of about 1 µSv for absorptiometry and about 30 µSv for computed tomography when low kV and mAs values are used. Lateral localizer radiographs, which are necessary for slice selection in CT, mean an additional dose of 30 µSv. Lateral X-ray films of the spine which are frequently taken in combination with absorptiometry result in a dose of 700 µSv or more. The concept of effective dose, the basic data and assumptions used in its assessment and a comparison with other dose burdens (for example the natural background radiation, of typically 2400 µSv per year) are discussed in detail.     

QCT椎体骨密度测定诊断骨质疏松症

目的 探讨定量CT(QCT)椎体骨密度(BMD)测定在诊断骨质疏松症中的临床价值和诊断标准.方法 对53例健康无症状中老年人和68例临床拟诊骨质疏松患者进行L1-L4椎体BMD测定.结果 健康中老年人BMD随年龄增长而明显降低,有显著性差异.以BMD≤x-2.0SD为诊断骨质疏松症标准有68例,且各年龄段的BMD值均明显低于骨量截断值;如以BMD≤x-2.5SD为诊断标准则有60例.结论 QCT诊断骨质疏松症敏感、准确、重复性强,易于推广应用.以BMD≤x-2.0SD为诊断标准,更符合临床实际病例,并能减少漏诊.     

定量CT椎体骨密度测定诊断骨质疏松症

[目的]探讨定量CT（QCT）椎体骨密度（BMD）测定在诊断骨质疏松症中的临床价值和诊断标准。[方法]对53例健康无症状中老年人和68例临床拟诊骨质疏松患者进行L1-4。椎体BMD测定。[结果]健康中老年人BMD随年龄增长而明显降低，有显著性差异。以BMD≤x-2．0 SD为诊断骨质量疏松症标准有68例，且各年龄段的BMD值均明显低于骨量截断值；如以BMD≤x-2．5 SD为诊断标准则有60例。[结论]QCT诊断骨质疏松症敏感、准确、重复性强，易于推广应用。以BMD≤x-2．0SD为诊断标准，更符合临床实际病例，并能减少漏诊。     

Femoral fractures following total hip prosthesis

Fractures of the ipsilateral femur after hip arthroplasty are a serious problem. In most cases, minimal trauma is responsible for the fracture. Predisposing factors, such as severe osteoporosis, loosening of the stem of the prosthesis, or cortex perforations, are often found. Such fractures occurred between 1979 and 1989 in 30 patients, i.e. 2.3% of our patients who had received primary prosthesis and 2.9% of those who had undergone revision. The patients' ages at the time of fracture ranged from 41 to 88 years (mean 63 years), 33% of the patients in these group being female. The time lapse from implantation of the prosthesis to the fracture varied between 1 month and 11 years (mean 4.4 years). The fracture was at the level of the proximal trochanteric region in 3% of these patients, between the trochanteric line and the tip of the prosthesis in 20%, and below the tip of the prosthesis in 70%. Operative treatment was performed in 29 patients. Fractures were fixed with a compression plate in 19 (63%), and in 3 the plate fixation was reinforced with intramedullary cement. In 2 osteoporotic patients with supracondylar fractures the osteosynthesis ruptured and a successful revision operation with cement was performed. In 3 others internal fixation was combined with replacement of the prosthesis; 3 patients received a Wagner revision prosthesis and 1 a long-stem Protek tumor prosthesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Femoral neck fractures after hip resurfacing

Femoral neck fracture is an important early complication after hip resurfacing. Our aims were firstly to determine the incidence of fracture in an independent series and secondly, in a case control study, to investigate potential risk factors. Fifteen femoral neck fractures occurred in a series of 842 procedures, representing an incidence of 1.8%. No relationship existed between age, sex, and fracture incidence. Mechanical factors such as notching, femoral neck lengthening, and varus alignment of the femoral component were found to have a similar incidence in both fracture and control groups. The proportion of patients that had at least 1 mechanical risk factor was not different between the 2 groups (fracture group, 50%; control group, 41%). Established avascular necrosis of the femoral head was evident in all retrieved femoral heads (n = 9) of patients who sustained postoperative fracture; in none of these patients was avascular necrosis the initial diagnosis. This study suggests that in our practice, mechanical factors, such as neck notching, neck lengthening, or varus angulations, are not the primary cause of femoral neck fractures.