Assessment of hand trabecular bone texture with high resolution direct digital radiograph in rheumatoid arthritis: a case control study

OBJECTIVES

Rheumatoid arthritis is characterized by an early inflammatory related periarticular osteopenia. A new high resolution direct digital X-ray device has been recently developed to provide bone texture analysis which is designed to assess changes in trabecular bone architecture. For the first time, we have evaluated trabecular bone texture impairment in rheumatoid arthritis patients compared to healthy controls.

METHODS

In this cross-sectional study, the reproducibility was assessed by three separate digital X-rays of the right hand, with repositioning in 14 late rheumatoid arthritis patients and 14 healthy subjects. Then, trabecular bone texture of the MCP2 and MCP3 from patients enrolled in a prospective cohort of 78 rheumatoid arthritis patients was compared with that of 50 healthy subjects, using three texture parameters: Hmean, co-occurrence and run-length.

RESULTS

The coefficients of variation of the high resolution direct digital X-ray measurements ranged from 0.5 to 1.8%. Only the Hmean parameter was significantly decreased in rheumatoid arthritis patients compared to healthy subjects at MCP2 (0.637±0.040 vs. 0.654±0.032, P<0.05) and at MCP3 (0.646±0.044 vs. 0.665±0.037, P<0.05). This reduction was significantly correlated to disease activity.

CONCLUSIONS

This study demonstrated both the good reproducibility of the high resolution digital X-ray measurements and the trabecular bone texture impairment at MCP joints in rheumatoid arthritis patients. In addition to provide a high resolution hand radiograph, this technique may represent an interesting tool to easily quantify periarticular osteopenia with a low radiation dose.

Bone assessment in children with chronic kidney disease: data from two new bone imaging techniques in a single-center pilot study

Bone damage in children with chronic kidney disease (CKD) is a challenge for pediatric nephrologists. Areal measurements of bone mineral density (BMD) by dual x-ray absorptiometry (DXA) have been routinely performed to assess bone mass but recent international guidelines have concluded that DXA was of less value in CKD. The aim of this study is to evaluate bone quality in CKD children using new bone imaging techniques in a pilot cross-sectional single-center study. We performed bone imaging (high-resolution peripheral quantitative computed tomography, HR-pQCT, XtremeCT, Scanco Medical AG, Switzerland), to assess compartmental volumetric BMD and trabecular microarchitecture in 22 CKD children and 19 controls. In seven younger patients (i.e., under 10 years of age), we performed bone texture analysis (BMA, D3A Medical Systems, France) in comparison to 15 healthy prepubertal controls. Among older children, CKD patients had significantly lower height and body weight without significant impairment of BMD and microarchitecture than healthy controls. In univariate analysis, there were significant correlations between cortical BMD and glomerular filtration rate (r= -0.46), age (r=0.60) and body mass index (r=0.67). In younger children, bone texture parameters were not different between patients and controls. Our results did not show significant differences between healthy controls and CKD children for compartmental bone densities and microarchitecture, but the small sample size and the heterogeneity of the CKD group require caution in the interpretation. Novel bone imaging techniques seem feasible in children, and further longitudinal studies are required to thoroughly explore long-term cardiovascular and bone consequences of phosphate-calcium metabolism deregulation during CKD.

Assessment of bone microarchitecture in chronic kidney disease: a comparison of 2D bone texture analysis and high-resolution peripheral quantitative computed tomography at the radius and tibia

Bone microarchitecture can be studied noninvasively using high-resolution peripheral quantitative computed tomography (HR-pQCT). However, this technique is not widely available, so more simple techniques may be useful. BMA is a new 2D high-resolution digital X-ray device, allowing for bone texture analysis with a fractal parameter (H(mean)). The aims of this study were (1) to evaluate the reproducibility of BMA at two novel sites (radius and tibia) in addition to the conventional site (calcaneus), (2) to compare the results obtained with BMA at all of those sites, and (3) to study the relationship between H(mean) and trabecular microarchitecture measured with an in vivo 3D device (HR-pQCT) at the distal tibia and radius. BMA measurements were performed at three sites (calcaneus, distal tibia, and radius) in 14 healthy volunteers to measure the short-term reproducibility and in a group of 77 patients with chronic kidney disease to compare BMA results to HR-pQCT results. The coefficient of variation of H(mean) was 1.2, 2.1, and 4.7% at the calcaneus, radius, and tibia, respectively. We found significant associations between trabecular volumetric bone mineral density and microarchitectural variables measured by HR-pQCT and H(mean) at the three sites (e.g., Pearson correlation between radial trabecular number and radial H(mean) r = 0.472, P < 0.001). This study demonstrated a significant but moderate relationship between 2D bone texture and 3D trabecular microarchitecture. BMA is a new reproducible technique with few technical constraints. Thus, it may represent an interesting tool for evaluating bone structure, in association with biological parameters and DXA.

Assessment of hand bone loss in rheumatoid arthritis by high-resolution peripheral quantitative CT

OBJECTIVES

A new high-resolution peripheral quantitative CT (HR-pQCT) system allows for in vivo assessment of bone microarchitecture and volumetric bone mineral density (vBMD) with an 82 microm isotropic resolution. With this device, the microarchitecture impairment was evaluated in patients with rheumatoid arthritis (RA) in comparison with healthy controls and measured the erosion volume at metacarpal heads (MCPs).

METHODS

In this cross-sectional study, the reproducibility was first assessed by 3 HR-pQCT exams with repositioning in 14 patients with late RA and 14 healthy subjects. Then, HR-pQCT parameters were measured in a group of 93 patients with RA and 31 healthy controls. Two RA subgroups were distinguished: early RA (disease duration < or =2 years) (n=36) and late RA (n=57) and compared them to healthy controls.

RESULTS

The precision of the HR-pQCT volumetric measurements as assessed with coefficient of variation ranged from 0.7% to 1.8% in patients with late RA and from 0.6% to 1.4% in healthy subjects at MCPs. Total and trabecular vBMD and trabecular thickness were significantly decreased in patients with RA compared to healthy subjects and were significantly correlated to disease activity. The erosion volume was highly correlated to a semiquantitative assessment using the Outcome Measures in Rheumatoid Arthritis Clinical Trials (OMERACT) scoring system applied to the HR-pQCT slices.

CONCLUSIONS

This study demonstrated the good reproducibility of the HR-pQCT volumetric measurements at MCPs and confirmed the involvement of trabecular compartment in periarticular osteopoenia. Thus, HR-pQCT appears interesting to simultaneously assess differences in bone volumetric density, microarchitecture and erosions.

A comparative review of the different techniques to assess hand bone damage in rheumatoid arthritis

Inflammatory related hand bone damage in rheumatoid arthritis is characterized by erosions and periarticular osteoporosis and can lead to substantial clinical disability. So far, conventional radiograph has been considered to be the gold standard for detecting bone damage and monitoring disease progression, but it lacks sensitivity. So other techniques have been recently developed to identify erosions earlier, to be able to change therapy; if necessary. This report reviews, in its first part, the different ways of detecting erosions such as conventional radiograph, magnetic resonance imaging or imaging ultrasonography and, in its second part, the techniques used for the assessment of hand periarticular osteoporosis like dual-X-ray absorptiometry, digital-X-ray radiogrammetry or quantitative ultrasonography.

Serious infections in patients with ankylosing spondylitis with and without TNF blockers: a systematic review and meta-analysis of randomised placebo-controlled trials

BACKGROUND

Tumour necrosis factor (TNF) blockers are known to increase the risk of serious infections in rheumatoid arthritis. Despite wide use of TNF blockers in ankylosing spondylitis (AS), the infection risk has never been evaluated in this disease.

OBJECTIVES

To assess serious infections in patients with AS not exposed and exposed to TNF blockers.

METHODS

A systematic literature review up to May 2008 using PubMed, EMBASE and Cochrane Library was performed. All randomised controlled trials (RCTs) published between 1995 and 2008 monitoring serious infections, treated with non-steroidal anti-inflammatory drugs (NSAIDs) or TNF blockers, were included. Infection risks were calculated by naive pooling and for 100 patient-years (pyrs) of exposure. To assess the serious infection risk with TNF blockers, a meta-analysis of RCTs was performed using Mantel-Haenszel's method with several sensitivity analyses.

RESULTS

Fourteen RCTs were included (3345 patients). With placebo or NSAIDs (N=2202), two serious infections were observed (0.09%, range 0.01% to 0.3%)-that is, 0.4/100 pyrs. In TNF blocker trials, two serious infections were observed with placebo (2/500, 0.4% (0.0% to 1.4%), ie, 1.0/100 pyrs) versus 14 serious infections with TNF blockers (14/996, 0.7% (0.3% to 1.4%), ie, 1.9/100 pyrs). Meta-analysis of the RCTs showed that the increase in serious infections with TNF blockers compared with placebo was not significant: risk difference=0.4% (-0.8% [corrected] to 1.6%).

CONCLUSIONS

The absolute risk of serious infections in patients with AS not exposed to TNF blockers is low. The absolute risk of serious infections in patients receiving TNF blockers is higher, but the difference was found to be not significant, possibly through lack of power. Continued monitoring is necessary.

Influence of RANKL inhibition on immune system in the treatment of bone diseases

Receptor activator of nuclear factor-kappaB ligand (RANKL) is essential for osteoclast differentiation, activation and survival. Recently, denosumab, a human monoclonal antibody to RANKL, has been tested in the treatment of osteoporosis. But the interactions between RANKL, receptor activator of nuclear factor-kappaB (RANK) and osteoprotegerin (OPG) are also involved in immune regulations in addition to bone metabolism. So, blocking RANKL could interplay with immune cells and have systemic effects. Here, we review biological data regarding potential consequences of RANKL blocking on the immune system.