Deterioration of bone microstructure by aging and menopause in Japanese healthy women: analysis by HR-pQCT.

INTRODUCTION: Second-generation high-resolution peripheral quantitative computed tomography (HR-pQCT) has provide higher quality of bone images with a voxel size of 61 µm, enabling direct measurements of trabecular thickness. In addition to the standard parameters, the non-metric trabecular parameters such as trabecular morphology (plate to rod-like structures), connectivity, and anisotropy can also be analyzed. The purpose of this study is to investigate deterioration of bone microstructure in healthy Japanese women by measuring standard and non-metric parameters using HR-pQCT. MATERIALS AND METHODS: Study participants were 61 healthy Japanese women (31-70 years). The distal radius and tibia were scanned using second-generation HR-pQCT, and microstructures of trabecular and cortical bone were measured. Non-metric trabecular parameters included structure model index (SMI), trabecular bone pattern factor (TBPf), connectivity density (Conn.D), number of nodes (N.Nd/TV), degree of anisotropy (DA), and star volume of marrow space (V*ms). Estimated bone strength was evaluated by micro finite element analysis. Associations between bone microstructure, estimated bone strength, age, and menopause were analyzed. RESULTS: Trabecular number declined with age, and trabecular separation increased. SMI and TBPf increased, Conn.D and N.Nd/TV declined, and V*ms increased. Cortical BMD and thickness declined with age, and porosity increased. Stiffness and failure load decreased with age. Cortical thickness and estimated bone strength were affected by menopause. Cortical thickness was most associated with estimated bone strength. CONCLUSIONS: Trabecular and cortical bone microstructure were deteriorated markedly with age. Cortical thickness decreased after menopause and was most related to bone strength. Non-metric parameters give additional information about osteoporotic changes of trabecular bone.

Analysis of fracture healing process by HR-pQCT in patients with distal radius fracture.

INTRODUCTION: High-resolution peripheral quantitative computed tomography (HR-pQCT) has enabled us to observe the changes in bone microarchitecture over time in vivo. In this study, the process of fracture healing was analyzed using HR-pQCT in patients with distal radius fracture who underwent osteosynthesis. MATERIALS AND METHODS: A total of 10 fracture sites identified from four patients with a distal radius fracture who underwent internal fixation with a volar locking plate (mean age 68.8 years, all women) were investigated. HR-pQCT was performed within a week (baseline) 4, 12, and 24 weeks after fracture. Rectangular region of interest (ROI) was established in the fracture site, inner callus, and external callus area, and the changes in bone mineral density (BMD) in each region were analyzed. RESULTS: From baseline to 24 weeks post-fracture, the BMD changed from 105.5 (95% CI 98.6-113) to 428.0 (331-554) mgHA/ccm at the fracture site, from 111.0 (104-119) to 375.3 (290-486) mgHA/ccm at the inner callus area, and from 98.5 (91.6-106) to 171.6 (132-222) mgHA/ccm at the external callus area. The BMD increased at the fracture site and inner callus area, but increased only slightly at the external callus area. At 24 weeks post-fracture, the BMD at the fracture site and inner callus area was significantly higher than the external callus area. CONCLUSION: In the healing process of postoperative distal radius fractures, increased BMD at the inner surface of the fracture site was confirmed in all fractures. Bone formation on the endosteal side may be a necessary condition for bone union of distal radius fractures.

The effects of volar locking plates for distal radius fractures on the image quality of high-resolution peripheral quantitative computed tomography.

INTRODUCTION: High-resolution peripheral quantitative computed tomography (HR-pQCT) has enabled us to observe changes of bone microstructure during fracture healing. However, a method of analyzing the healing process after osteosynthesis has yet to be established due to implant artifacts. The purpose of this study was to investigate the effects of volar locking plates for distal radius fractures on the image quality of HR-pQCT. METHODS: Four different types of plates for distal radius fractures were evaluated. The scan region of HR-pQCT was the center of each plate, not including the screw insertion sites. To assess plate-generated noise, each plate was fixed to the top of a water-filled rubber glove, scanned by HR-pQCT, and the signal-to-noise ratio (SNR) of the region under the plates was calculated. To investigate accuracy, 12 cadaveric radii with and without each plate were scanned by HR-pQCT, and differences between the measured values with and without the plate were evaluated. Differences between the measurements of the entire circumference and of the dorsal third of the radius were also compared. Reproducibility of the in vivo measurement was investigated by repeated scans of 10 patients with distal radius fractures who had undergone surgery with a volar locking plate. RESULTS: The SNR was significantly higher away from the plate than immediately below the plate. Percentage differences of the measurement values between with and without the plate were 1.4%-3.2% for cortical bone mineral density (Ct.BMD) and 7.2%-9.8% for cortical bone thickness (Ct.Th) when the entire circumference was measured. When the dorsal third was measured, they were 0.3%-1.7% for Ct.BMD and 1.8%-2.7% for Ct.Th. The root-mean-square coefficient of variation (RMS%CV) was 1.12% for Ct.BMD and 4.18% for Ct.Th. CONCLUSIONS: The accuracy and reproducibility of cortical bone measurements with a volar locking plate on HR-pQCT were acceptable when the dorsal third of the Ct.BMD was analyzed, and this method would be useful for in vivo analysis of the fracture healing process after osteosynthesis.

Correlation between vertebral bone microstructure and estimated strength in elderly women: An ex-vivo HR-pQCT study of cadaveric spine.

PURPOSE: A vertebral fracture is the most common complication of osteoporosis, and various factors are involved in its occurrence. The purpose of this study was to investigate the role of trabecular and cortical bone microstructure on vertebral strength using high-resolution peripheral quantitative computed tomography (HR-pQCT). METHODS: Three female cadaveric spines were investigated (average age: 80.3 years). The whole spine (T1-L4) was scanned by second-generation HR-pQCT at a voxel size of 60.7 µm. Bone microstructure analysis and micro finite element analysis were performed after excluding the upper and lower endplates and posterior elements of a total of 48 vertebrae. Correlations between trabecular and cortical bone microstructure parameters and estimated vertebral strength were analyzed by univariate and multivariate regression models. RESULTS: Cortical thickness (Ct.Th) and trabecular thickness (Tb.Th) were strongly correlated with estimated failure load on univariate analysis (r = 0.89, 0.82). Trabecular volumetric bone mineral density (Tb.vBMD), bone volume fraction (BV/TV), trabecular number (Tb.N), and Ct.Th were correlated with estimated failure load on multivariate regression analysis. CONCLUSIONS: It was suggested that, in addition to trabecular bone (Tb.vBMD, BV/TV, Tb.N), cortical bone (Ct.Th) contributed significantly to vertebral strength in elderly women.

Risk of venous thromboembolism after total knee arthroplasty in patients with rheumatoid arthritis.

OBJECTIVE: To compare the incidence of venous thromboembolism (VTE) following total knee arthroplasty (TKA) between patients with rheumatoid arthritis (RA) and those with osteoarthritis (OA). METHODS: The subjects were composed of 1084 Japanese patients with OA and 204 with RA. Primary effectiveness outcomes were any deep vein thrombosis (DVT) as detected by bilateral ultrasonography up to postoperative Day 10 (POD10) and pulmonary embolism (PE) up to POD28. The main safety outcomes were bleeding and death from any cause up to POD28. Plasma D-dimer levels were measured before and at POD10 after TKA. RESULTS: The study cohort was composed of 1288 patients from 34 hospitals. There was no death up to POD28. PE occurred in 2 patients with OA and in no patients with RA. The incidence of primary effectiveness outcome was 24.3% and 24.0% in patients with OA and RA, respectively. The incidence of major bleeding up to POD28 was 1.3% and 0.5% in patients with OA and RA, respectively. No differences in the incidence of VTE (symptomatic/asymptomatic DVT plus PE) or bleeding were noted between patients with RA and OA. D-dimer levels on POD10 were significantly higher in patients with OA compared with those with RA. Also, D-dimer levels on POD10 were significantly lower in patients receiving fondaparinux than in patients without pharmacological prophylaxis. CONCLUSION: Despite some differences in demographic data, patients with RA and OA have equivalent risks of VTE and bleeding following TKA.

Serum levels of BAFF for assessing the disease activity of Takayasu arteritis.

OBJECTIVES: Takayasu arteritis (TA) is a chronic vasculitis that affects large elastic arteries. Monitoring of disease activity is crucial because the disease may progress despite treatment with glucocorticoids. Elevated levels of B cell activating factor belonging to TNF family (BAFF) have been observed in patients with autoimmune diseases. In this study, we investigated whether dysregulation of BAFF occurs in TA. METHODS: Serum levels of BAFF were measured in sera from 9 patients with TA including 6 patients with follow up after induction therapy. RESULTS: Circulating BAFF levels in TA patients were higher than in those in healthy subjects. The high levels of BAFF in active TA patients were decreased when the patients entered remission. CONCLUSIONS: To our knowledge, this is the first study to show elevated levels of BAFF in active TA patients. These findings suggest that this cytokine contributes to vasculitis in TA and raise the possibility that monitoring of serum BAFF might aid clinicians in making adequate treatment adjustments in TA patients.

Serum amyloid A is a useful marker to evaluate the disease activity of Takayasu's arteritis.

Takayasu's arteritis (TA) is a rare large vessel vasculitis that is difficult to diagnose in the early stages. Therefore, it is also very difficult to manage and prevent irreversible vascular damage in TA. A 19-year-old female patient with back pain was examined using [(18)F]-FDG-PET to detect the source of inflammation. Specific accumulation of [(18)F]-FDG was observed in the thoracic and abdominal aorta, leading to the diagnosis of TA. Corticosteroid treatment resulted in clinical remission. However, the serum amyloid A (SAA) levels remained elevated. A follow-up scan showed residual uptake of [(18)F]-FDG in the thoracic aorta suggesting subclinical vascular inflammation. Methotrexate was combined with the corticosteroid, and the elevated levels of SAA became normalized. The present case suggests that monitoring serum levels of SAA and [(18)F]-FDG-PET could help clinicians to make adequate treatment adjustments in TA patients.