Showing papers by "Jukka S. Jurvelin published in 2012"

Muscle Strength and Body Composition Are Clinical Indicators of Osteoporosis

Abstract: We examined the role of muscle strength, lean tissue distribution, and overall body composition as indicators of osteoporosis (OP) in a pooled sample of 979 Finnish postmenopausal women (mean age 68.1 years) from the Kuopio Osteoporosis Risk Factor and Prevention study. Bone mineral density (BMD) at the femoral neck (FN) and total body composition were assessed by dual-energy X-ray absorptiometry scans. The women (n = 979) were divided into three groups according to WHO criteria, based on FN BMD T score: normal (n = 474), osteopenia (n = 468), and OP (n = 37). Soft tissue proportions, fat mass index (FMI, fat/height²), lean mass index (LMI, lean/height²), and appendicular skeletal muscle mass (ASM, (arms + legs)/height²) were calculated. Handgrip and knee extension strength measurements were made. OP subjects had significantly smaller LMI (p = 0.001), ASM (p = 0.001), grip strength (p 0.05) compared to other subjects. Grip and knee extension strength were 19 and 16 % weaker in OP women compared to others, respectively. The area under the receiver operating characteristic curve was 69 % for grip and 71 % for knee extension strength. In tissue proportions only LMI showed predictive power (63 %, p = 0.016). An overall linear association of LMI (R2 = 0.007, p = 0.01) and FMI (R2 = 0.028, p < 0.001) with FN BMD remained significant. In the multivariate model, after adjusting for age, grip strength, leg extension strength, FMI, LMI, number of medications, alcohol consumption, current smoking, dietary calcium intake, and hormone therapy, grip strength (adjusted OR = 0.899, 95 % CI 0.84–0.97, p < 0.01), leg extension strength (OR = 0.998, 95 % CI 0.99–1, p < 0.05), and years of hormone therapy (OR = 0.905, 95 % CI 0.82–1, p < 0.05) remained as significant determinants of OP. Muscle strength tests, especially grip strength, serve as an independent and useful tool for postmenopausal OP risk assessment. In addition, lean mass contributes to OP in this age group. Muscle strength and lean mass should be considered separately since both are independently associated with postmenopausal BMD.

Multi-site bone ultrasound measurements in elderly women with and without previous hip fractures

Abstract: About 75% of patients suffering from osteoporosis are not diagnosed. This study describes a multi-site bone ultrasound method for osteoporosis diagnostics. In comparison with axial dual energy X-ray absorptiometry (DXA), the ultrasound method showed good diagnostic performance and could discriminate fracture subjects among elderly females. Axial DXA, the gold standard diagnostic method for osteoporosis, predicts fractures only moderately. At present, no reliable diagnostic methods are available at the primary health care level. Here, a multi-site ultrasound method is proposed for osteoporosis diagnostics. Thirty elderly women were examined using the ultrasound backscatter measurements in proximal femur, proximal radius, proximal and distal tibia in vivo. First, we predicted the areal bone mineral density (BMD) at femoral neck by ultrasound measurements in tibia combined with specific subject characteristics (density index, DI) and, second, we tested the ability of ultrasound backscatter measurements at proximal femur to discriminate between individuals with previously fractured hips from those without fractures. Areal BMD was determined by axial DXA. Combined ultrasound parameters, cortical thickness at distal and proximal tibia, with age and weight of the subject, provided a significant estimate of BMDneck (r = 0.86, p < 0.001, n = 30). When inserted into FRAX (World Health Organization fracture risk assessment tool), the DI indicated the same treatment proposal as the BMDneck with 86% sensitivity and 100% specificity. The receiver operating characteristic analyses, with a combination of ultrasound parameters and patient characteristics, discriminated fracture subjects from the controls similarly as the model combining BMDneck and patient characteristics. For the first time, ultrasound backscatter measurements of proximal femur were conducted in vivo. The results indicate that ultrasound parameters, combined with patient characteristics, may provide a means for osteoporosis diagnostics.

Associations of dietary polyunsaturated fatty acids with bone mineral density in elderly women.

Abstract: Associations of dietary polyunsaturated fatty acids with bone mineral density in elderly women

Body mass index and bone loss among postmenopausal women: the 10-year follow-up of the OSTPRE cohort

Abstract: Obesity protects against osteoporosis, but the magnitude of this association has been difficult to assess from cross-sectional or short term studies. We examined the time course of bone loss as a function of body mass index (BMI) in early and late postmenopausal women. Our study population (n = 300) was a random sample of the population-based Kuopio Osteoporosis Risk Factor and Prevention (OSTPRE) Study, Finland. We excluded women without complete BMD results, premenopausal women during the second bone densitometry and women who had used hormone replacement therapy, bisphosphonates or calcitonin. BMI along with femoral neck and spinal bone mineral density (BMD) were assessed three times by dual-energy X-ray absorptiometry during a mean follow-up of 10.5 years (SD 0.5). The mean baseline age was 53.6 years (SD 2.8), time since menopause 2.9 years (SD 4.3) and BMI 27.3 kg/m2 (SD 4.4). The data was analyzed by linear mixed models. Thus, we were able to approximate the bone loss up to 20 postmenopausal years. To illustrate, a woman with a baseline BMI of 20 kg/m2 became osteopenic 2 (spine) and 4 (femoral neck) years after menopause, while obesity (BMI of 30 kg/m2) delayed the incidence of osteopenia by 5 (spine) and 9 (femoral neck) years, respectively. The delay was due to high baseline BMD of the obese, while bone loss rate was similar for both lean and obese subjects. This lean versus obese difference may also be partly due to altered X-ray attenuation due to fat mass.

Fourier Transform Infrared Spectroscopic Imaging and Multivariate Regression for Prediction of Proteoglycan Content of Articular Cartilage

Abstract: Fourier Transform Infrared (FT-IR) spectroscopic imaging has been earlier applied for the spatial estimation of the collagen and the proteoglycan (PG) contents of articular cartilage (AC). However, earlier studies have been limited to the use of univariate analysis techniques. Current analysis methods lack the needed specificity for collagen and PGs. The aim of the present study was to evaluate the suitability of partial least squares regression (PLSR) and principal component regression (PCR) methods for the analysis of the PG content of AC. Multivariate regression models were compared with earlier used univariate methods and tested with a sample material consisting of healthy and enzymatically degraded steer AC. Chondroitinase ABC enzyme was used to increase the variation in PG content levels as compared to intact AC. Digital densitometric measurements of Safranin O –stained sections provided the reference for PG content. The results showed that multivariate regression models predict PG content of AC significantly better than earlier used absorbance spectrum (i.e. the area of carbohydrate region with or without amide I normalization) or second derivative spectrum univariate parameters. Increased molecular specificity favours the use of multivariate regression models, but they require more knowledge of chemometric analysis and extended laboratory resources for gathering reference data for establishing the models. When true molecular specificity is required, the multivariate models should be used.

Delayed Computed Tomography Arthrography of Human Knee Cartilage In Vivo.

Abstract: Objective:We investigated the feasibility of delayed computed tomography (CT) arthrography for evaluation of human knee cartilage in vivo. Especially, the diffusion of contrast agent out of the joint space and the optimal time points for imaging were determined.Design:Two patients were imaged using delayed CT arthrography and delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) techniques.Results:Two hours after injection, the concentration of contrast agent in the joint space was still high enough (20% to 24.5% of the initial concentration at 0 minutes) to allow delayed CT arthrography. The half-life of the contrast agent in the joint space varied from 30 to 60 minutes. The contrast agent concentration in patellar and femoral cartilage reached the maximum after 30 and 60 minutes, respectively. According to dGEMRIC, there were no differences between patients. However, in delayed CT arthrography, the penetration of the contrast agent was higher in the osteoarthritic knee cartilage.Conclusions:Contrast agent remained in the joint space long enough to enable delayed CT arthrography of cartilage. After 30 minutes, the normalized contrast agent concentration was higher in the cartilage of the osteoarthritic knee in comparison with the healthy knee. To conclude, delayed CT arthrography exhibited potential for use in the clinical evaluation of cartilage integrity.

Comparison of ultrasound and optical coherence tomography techniques for evaluation of integrity of spontaneously repaired horse cartilage

Abstract: The aim of this study was to compare sensitivity of ultrasound and optical coherence tomography (OCT) techniques for the evaluation of the integrity of spontaneously repaired horse cartilage. Articular surfaces of horse intercarpal joints, featuring both intact tissue and spontaneously healed chondral or osteochondral defects, were imaged ex vivo with arthroscopic ultrasound and laboratory OCT devices. Quantitative ultrasound (integrated reflection coefficient (IRC), apparent integrated backscattering coefficient (AIB) and ultrasound roughness index (URI)) and optical parameters (optical reflection coefficient (ORC), optical roughness index (ORI) and optical backscattering (OBS)) were determined and compared with histological integrity and mechanical properties of the tissue. Spontaneously healed tissue could be quantitatively discerned from the intact tissue with ultrasound and OCT techniques. Furthermore, several significant correlations (p < 0.05) were detected between ultrasound and OCT parameters. Su...

Estimation of 3D shape, internal density and mechanics of proximal femur by combining bone mineral density images with shape and density templates

Abstract: Measurement of bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) alone is only a moderate predictor of fracture risk. Finite element analysis (FEA) of bone mechanics, based on DXA images, may improve the prediction of fracture risk. We developed a method to estimate the 3D shape and density distribution of the proximal femur, using a 2D BMD image and a femur shape template. Proximal femurs of eighteen human cadavers were imaged using computed tomography and divided into two sets (N = 9 + 9). The template was created from the samples in first set by using 3D generalized Procrustes analysis and thin-plate splines. Subsequently, the template and 2D BMD image were utilized to estimate the shape and internal density distribution of the femurs in the second set. Finally, FEA was conducted based on the original and the estimated bone models to evaluate the effect of geometrical and density distributional errors on the mechanical strength. The volumetric errors induced by the estimation itself were low (<1.4%). In the estimation of bones in the second set, the mean distance difference between the estimated and the original bone surfaces was 0.80 ± 0.19 mm, suggesting feasible estimation of the femoral shape. The mean absolute error in voxel-by-voxel BMD was 120±8 mg cm⁻³. In FEA, the stiffness of the proximal femur differed by -7±16% between the original and estimated bones. The present method, in comparison with methods used in previous studies, improved the prediction of the geometry, the BMD distribution and the mechanical characteristics of the proximal femur. Potentially, the proposed method could ultimately improve the determination of bone fracture risk.

Nondestructive fluorescence-based quantification of threose-induced collagen cross-linking in bovine articular cartilage.

Abstract: Extensive collagen cross-linking affects the mechanical competence of articular cartilage: it can make the cartilage stiffer and more brittle. The concentrations of the best known cross-links, pyri ...

Contrast-Enhanced Micro-Computed Tomography in Evaluation of Spontaneous Repair of Equine Cartilage.

Abstract: Objective: Contrast-enhanced computed tomography (CECT) has been introduced for the evaluation of cartilage integrity. Furthermore, CECT enables imaging of the structure and density of subchondral bone. In this laboratory study, we investigate the potential of microCECT to simultaneously image cartilage and subchondral bone for the evaluation of tissue healing. Design: Osteochondral lesions (O = 6 mm) were surgically created in equine intercarpal joints (n = 7). After spontaneous healing for 12 months, the horses were sacrificed and osteochondral plugs (O = 14 mm),including the repair cartilage and adjacent intact tissue, were harvested. The nonfibrillar and fibrillar moduli and the permeability of cartilage were determined using indentation testing. Contrast agent diffusion into the samples was imaged for 36 hours using high-resolution CT. Results from CECT, mechanical testing, and microscopic analyses were compared and correlated. Results: The contrast agent diffusion coefficient showed a significant (P < 0.05) difference between the repair and adjacent intact tissue. MicroCECT revealed altered (P < 0.05) bone volume fraction, mineral density, and microstructure of subchondral bone at the repair site. The contrast agent diffusion coefficient correlated with the moduli of the nonfibrillar matrix (R = -0.662, P = 0.010), collagen fibril parallelism index (R = -0.588, P = 0.035), and glycosaminoglycan content (R = -0.503, P = 0.067). The repair cartilage was mechanically and structurally different from adjacent intact tissue (P < 0.05). Conclusions: MicroCECT enabled simultaneous quantitative evaluation of subchondral bone and monitoring of cartilage repair, distinguishing quantitatively the repair site from the adjacent intact tissue. As the only technique able to simultaneously image cartilage and determine subchondral bone mineral density and microstructure, CECT has potential clinical value.

Femoral Neck Bone Mineral Density after Resurfacing Hip Arthroplasty

Abstract: 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.

Changes in collagen cross-linking of articular cartilage are revealed by spectral reflectance imaging

Abstract: Excessive cross-linking of collagen during aging may contribute to degeneration of articular cartilage. Traditionally, the amount of cross-links is derived by using destructive high-performance liquid chromatography (HPLC). However, a sensitive, non-destructive method could help to evaluate tissue integrity, including cross-links. We increased collagen cross-linking in bovine articular cartilage by controlled threose incubation. During the incubation, optical spectral reflectance images of the samples were captured and related to HPLC results using regression analysis. Significant correlations with reflectance and cross-links were observed. When further developed the optical method may enable nondestructive evaluation of cross-links in vivo through a clinical arthroscope.

Application of dual frequency ultrasound method in through transmission measurements

Abstract: Soft tissue layers overlying bones, with unknown thickness, can produce significant errors to bone quantitative ultrasound measurements. In this study dual frequency ultrasound (DFUS) technique, developed originally for pulse-echo measurements, is applied and evaluated in a configuration typical to clinical through-transmission measurement. A mathematical algorithm is presented for determination of soft tissue composition, i.e. amount of lean and fat tissue, and correction of typical clinical parameters such as broadband ultrasound attenuation (BUA) and speed of sound (SOS). Ultrasound soft tissue phantoms mimicking lean and fat tissues, were tested in five different configurations by varying the composition (0-100% of fat). Different configurations were built using 10mm of fat or lean and 30mm of fat or lean, and total thickness of soft tissue constructs varied from 20mm to 40mm. Using through-transmission measurements at 0.5 MHz center frequency the thickness of soft tissue layers could be determined us...

Bone Loss and Seasonal Variation in Serial DXA Densitometry – A Population-Based Study

Abstract: Osteoporosis is a disease of increased skeleton fragility accompanied by low BMD and microarchitectural deterioration. Osteoporosis and bone fragility result in significant morbidity and medical and social costs (Dennison et al., 2005; Cummings et al., 2002). The risk of fractures is greater among women with low BMD although it explains only part of the increased fracture tendency among the elderly (National Osteoporosis Foundation, 1998).The diagnosis of osteoporosis is currently based on axial dual X-ray absorptiometry (DXA) measurements (National Osteoporosis Foundation 1998). In addition to being applicable for fracture prediction, axial DXA has a role in treatment monitoring protocols (Miller et al., 1996; Sowers et al., 1997). Furthermore, serial central DXA measurements have been used for research purposes to evaluate the riskand preventive factors for postmenopausal bone loss (Burger et al., 1998; Hannan et al., 2000; Sirola et al., 2003) Perimenopausal bone loss rates of over -2 percent /year in spinal and over -1 percent /year in the femoral region have generally been reported (Harris and Dawson-Hughes, 1992; Pouilles et al., 1993; Pouilles et al., 1995; Prior et al., 1998; Ito et al., 1999). In postmenopausal women, age related bone loss continues at age specific rate after the initial fastening during the menopausal transition (Hansen et al., 1995).