Bone marrow lesions identified by MRI in knee osteoarthritis are associated with locally increased bone mineral density measured by QCT

OBJECTIVE

Bone marrow lesions (BMLs) in the knee are associated with pain and compartment-specific joint space narrowing. However, the correlation of BMLs with bone mineral density (BMD) has rarely been investigated. The aim of the present study was to examine whether BMD in BMLs is altered compared to the surrounding bone.

DESIGN

Thirty-four BMLs detected in osteoarthritis (OA) knees (KL grade 2 and 3) of 26 patients were investigated. A 3D-segmentation was used to determine BML volumes of interest (VOI) and their surrounding bone in MR images. These VOIs were registered to corresponding single-energy QCT images and a BMD analysis was performed. The same VOIs were transferred to control datasets (19 OA patients without BMLs) by an elastic registration, where the BMD analysis was repeated. To account for the dependence of bone marrow composition on BMD measures derived using single-energy QCT, simulations were performed to evaluate how changing fat-water compositions likely occurring with BML development may influence BMD measures and observed BMD differences between patients with and without BMLs. The association between loading in the knee and the occurrence of BMLs was investigated by medial to lateral (M:L) BMD ratios.

RESULTS

BMD was significantly increased at BML locations, even with a fat-to-water conversion rate of 39%. The M:L BMD ratio was significantly increased in bones with medial BMLs.

CONCLUSIONS

BMD was examined exactly at BML locations and surrounding bone using highly accurate segmentation and registration methods. BMD was significantly increased at BML locations (P < 0.05).

CT imaging for the investigation of subchondral bone in knee osteoarthritis

In osteoarthritis, magnetic resonance imaging is the method of choice to image articular cartilage and "bone marrow lesions." However, the calcified cartilage, the subchondral bone plate, and trabecular subchondral bone that are mineralized tissues strongly attenuate X-rays and are therefore potentially accessible for analyses using computed tomography (CT). CT images nicely show osseous cardinal signs of advanced osteoarthritis such as osteophytes, subchondral cysts, and subchondral bone sclerosis. But more importantly, CT can help us to better understand the pathophysiology of knee osteoarthritis from the measurement of the density and structure of subchondral mineralized tissues in vivo. For that purpose, we recently developed dedicated image analysis software called Medical Image Analysis Framework (MIAF)-Knee. In this manuscript, our aims are to present current knowledge on CT imaging of the subchondral bone in knee osteoarthritis and to provide a brief introduction to basic technical aspects of MIAF-Knee as well as preliminary results we obtained in patients with knee osteoarthritis as compared to control subjects.

Short-term in vivo precision of BMD and parameters of trabecular architecture at the distal forearm and tibia

In vivo hr-pQCT precision was determined in 42 postmenopausal women using double baseline measurements from a multicenter trial of odanacatib. Errors, e.g., at the radius below 1.3% for BMD and below 6.3% for trabecular structure, were comparable to single-center results. Motion artifacts remain a challenge, particularly at the forearm.

INTRODUCTION

The short-term in vivo precision of BMD, trabecular bone structure, cortical thickness and porosity of the forearm and tibia was measured by hr-pQCT. Also the effect of image quality on precision was evaluated.

METHODS

In 42 postmenopausal women (age 64.4 ± 6.8 years) out of 214 subjects enrolled in a multi center advanced imaging phase III study of odanacatib (DXA spine or hip T-scores between -1.5 and -3.5), double baseline hr-pQCT (XtremeCT) measurements with repositioning were performed. The standard ultradistal location and a second, more proximally located VOI were measured at the radius and tibia to better assess cortical thickness and porosity. Image analysis and quality grading (grades: perfect, slight artifacts, pronounced artifacts, unacceptable) were performed centrally.

RESULTS

At the radius RMS%CV values varied from 0.7% to 1.3% for BMD and BV/TV and from 5.6% to 6.3% for Tb.Sp, Tb.Th, Tb.N, and cortical porosity. Numerically at the tibia, precision errors were approx. 0.5% lower for BMD and 1% to 2% lower for structural parameters although most differences were insignificant. In the radius but not in the tibia, precision errors for cortical thickness were smaller at the distal compared to the ultradistal location (1% versus 2%).

CONCLUSIONS

BMD precision errors were lower than those for trabecular architecture and cortical porosity. Motion artifacts remain a challenge, particularly at the forearm. Quality grading remains subjective, and more objective evaluation methods are needed. Precision in the context of a multicenter clinical trial, with centralized training and scan analysis, was comparable to single-center results previously reported.

Exercise and fractures in postmenopausal women: 12-year results of the Erlangen Fitness and Osteoporosis Prevention Study (EFOPS)

This trial is the first exercise study that focuses on fracture incidence as a primary study endpoint. Although we marginally failed to determine significant effects on "overall" fracture risk (p = .074) or rate ratio (p = .095), our findings further increased the evidence that exercise relevantly prevents fractures in the elderly.

INTRODUCTION

The purpose of this study is to determine the effect of strictly supervised long-term exercise training on "overall" fracture incidence and bone mineral density (BMD) in postmenopausal osteopenic women.

METHODS

Eighty-five early postmenopausal (1-8 years), osteopenic women living in the area of Erlangen-Nuremberg, Germany without any medication or diseases affecting bone metabolism were assessed after 12 years of supervised exercise (EG) or unvarying lifestyle (control, CG). Exercisers were encouraged to perform two group sessions/week and two home training sessions/week. Calcium and vitamin D supplementation was provided for both groups. "Overall" fractures were determined by questionnaires and structured interviews. The BMD was assessed at lumbar spine and proximal femur by dual-energy X-ray absorptiometry.

RESULTS

"Overall" fracture risk ratio in the EG was 0.32 (95% confidence interval (CI), 0.08 to 1.05; p = .074), and the rate ratio for "overall" fractures was 0.38 (95% CI, 0.11 to 1.15; p = .095). BMD changes at lumbar spine (EG, -0.8%; 95% CI, 0.8% to -2.7% vs. CG, -4.0%; 95% CI, -2.4% to -5.7%; p = .011) and femoral neck (EG, -3.7%; 95% CI, -2.4% to -5.0% vs. CG, -6.7%; 95% CI, -5.3% to -8.2%; p = .003) significantly differed between both groups.

CONCLUSION

Although we marginally failed to determine significant effects on overall fracture risk or rate ratio, our study increased the body of evidence for the fracture prevention efficiency of exercise programs, with special regard on bone strength (as assessed by bone mineral density measurement). Future studies should focus on subjects more prone to fractures to generate enough statistical power to clearly determine this issue.

An in vivo comparison of hip structure analysis (HSA) with measurements obtained by QCT

SUMMARY

In a population of elderly women, bone cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), section modulus (Z), femoral neck axis length (FNAL), and width measured with hip structure analysis (HSA) on dual-energy x-ray absorptiometry (DXA) images in the femoral neck and trochanteric regions are highly correlated to quantitative computed tomography (QCT) measurements.

INTRODUCTION

HSA is a method of obtaining measurements of proximal femur structure using 2D DXA technology. This study was designed to examine the correlations between HSA measurements and 3D QCT.

METHODS

Forty-one women (mean age, 82.8 ± 2.5 years) were measured using DXA and a 64-slice CT scanner (1 mm slice thickness, 0.29 mm in plane resolution). HSA parameters were calculated at the narrow neck (NN) and trochanteric (IT) regions on the DXA image. These regions were then translated to anatomically equivalent regions on the QCT dataset by co-registering the DXA image and QCT dataset using four DXA images acquired at different angles.

RESULTS

At the NN and IT regions, high linear correlations were measured between HSA and QCT for CSA r = 0.95 and 0.93, CSMI r = 0.94 and 0.93, and Z r = 0.93 and 0.89, respectively. All correlations were highly significant (p < 0.001), but there were differences in slope and offset between the two techniques, at least in part due to differences in calibration between the two techniques. FNAL and width of the bone at the NN and IT regions, physical measurements independent of the calibration, were highly correlated (r = 0.90-0.95, p < 0.001) and had slopes close to 1.0 (range, 0.978 to 1.003).

CONCLUSION

CSA, CSMI, Z, FNAL, and width measured by HSA correlate highly to high-resolution QCT.

Effect of block-periodized exercise training on bone and coronary heart disease risk factors in early post-menopausal women: a randomized controlled study

The purpose of this 12 month randomized exercise intervention was to determine the effect of a block-periodized multipurpose exercise program on bone mineral density (BMD) and parameters of the metabolic syndrome (MetS) in early post-menopausal women. Eighty-five subjects (52.3 ± 2.4 years) living in the area of Erlangen (Germany) were randomly assigned into an exercise (EG, n=43) or a wellness-control group (CG: n=42). The EG performed a periodized multipurpose exercise program with 4-6-week blocks of high-intensity bone-specific exercise intermitted by 10-12 weeks of exercise dedicated to increase endurance and reduce cardiac and metabolic risk factors. The CG performed a low-volume/low-intensity "wellness" program to increase well-being. After 12 months, significant exercise effects were observed for the lumbar spine (LS) BMD as assessed by quantitative computed tomography [total BMD (EG: -0.3 ± 2.1% vs CG: -2.1 ± 2.2%, P=0.015); trabecular BMD (EG: -0.7 ± 3.4% vs CG: -4.7 ± 4.9%, P=0.001) and dual-energy x-ray absorptiometry (DXA) (EG: -0.1 ± 2.2% vs CG: -2.0 ± 2.0%, P=0.002)]. However, no significant effects were observed for total hip BMD as assessed by DXA (P=0.152). Although all MetS parameters were favorably affected among the EG, only the effect for waist circumference was significant. In summary, short periods of bone-specific intervention embedded in longer periods of exercises dedicated to improve cardiovascular and metabolic risk factors positively affected BMD at the LS.

Effects of whole body vibration on bone mineral density and falls: results of the randomized controlled ELVIS study with postmenopausal women

We determined whether the effect of exercise on bone mineral density (BMD) and falls can be enhanced by whole body vibration (WBV). In summary, the multi-purpose exercise training was effective to increase lumbar BMD but added WBV did not enhance this effect. However, falls were lowest in the exercise program combined with WBV.

INTRODUCTION

WBV is a new approach to reduce the risk of osteoporotic fractures. In the "Erlangen Longitudinal Vibration Study" (ELVIS), we investigated whether WBV enhances the effect of multifunctional exercise on BMD and falls.

METHODS

One hundred fifty-one postmenopausal women (68.5 ± 3.1 years) were randomly assigned to a: (1) conventional training group (TG); (2) conventional training group including vibration (TGV); and (3) wellness control group (CG). TG conducted an exercise program consisting of 20 min dancing aerobics, 5 min balance training, 20 min functional gymnastics, and 15 min dynamic leg-strength training on vibration plates (without vibration) twice a week. TGV performed an identical exercise regimen with vibration (25-35 Hz) during the leg-strengthening sequence. CG performed a low-intensity wellness program. BMD was measured at the hip and lumbar spine at baseline and follow-up using the DXA method. Falls were recorded daily via the calendar method.

RESULTS

After 18 months, an increase in BMD at the lumbar spine was observed in both training groups (TGV: +1.5% vs. TG: +2.1%). The difference between the TG and the CG (1.7%) was significant. At the hip no changes were determined in either group. The fall frequency was significantly lower in TGV (0.7 falls/person) compared with CG (1.5), whereas the difference between TG (0.96) and CG was not significant.

CONCLUSIONS

A multifunctional training program had a positive impact on lumbar BMD. The application of vibration did not enhance these effects. However, only the training including WBV affected the number of falls significantly.

Denosumab improves density and strength parameters as measured by QCT of the radius in postmenopausal women with low bone mineral density

BACKGROUND

Bone strength is determined by both cortical and trabecular bone compartments and can be evaluated radiologically through measurement of bone density and geometry. Quantitative computed tomography (QCT) separately assesses cortical and trabecular bone reliably at various sites, including the distal radius where there is a gradation of cortical and trabecular bone. We evaluated the effect of denosumab, a fully human monoclonal antibody that inhibits RANK ligand, on distal radius QCT in women with low bone mass to assess the impact of this novel therapy separately on trabecular and cortical bone.

METHODS

Postmenopausal women (n=332) with spine areal bone mineral density (BMD) T-scores between -1.0 and -2.5 received denosumab 60 mg or placebo every 6 months during the 24-month study. QCT measurements along the distal radius were made using a whole-body computed tomography scanner and were used to determine the percentage change from baseline in volumetric BMD; volumetric bone mineral content (BMC); cortical thickness; volume; circumference; and density-weighted polar moment of inertia (PMI), a derived index of bone strength.

RESULTS

Denosumab treatment significantly increased total BMD and BMC along the radius (proximal, distal, and ultradistal sections). At 24 months, the ultradistal region had the greatest percentage increase in total BMD (4.7% [95% CI, 3.6-5.7]; P<0.001) and total BMC (5.7% [95% CI, 4.8-6.6]; P<0.001) over placebo. When cortical and trabecular bone at the proximal and distal regions were separately assessed, cortical bone had significant (P<0.001) increases in BMD, BMC, and thickness, and trabecular bone had a significant increase in BMD relative to placebo (P<0.05). Bone strength, estimated by density-weighted PMI, significantly increased compared with placebo after 6 months of treatment, with the largest percentage increase occurring at 24 months in the ultradistal region (6.6% [95% CI, 5.6-7.6]; P<0.0001).

CONCLUSIONS

QCT measurements demonstrated that denosumab significantly increased BMD, BMC, and PMI along the radius over 24 months. Additionally, denosumab prevented the decrease in QCT-measured cortical thickness observed in the placebo group. These data extend the evidence from previous dual-energy X-ray absorptiometry studies for a positive effect of denosumab on both the cortical and trabecular bone compartments and propose a possible mechanism for the reduction in fracture risk achieved with denosumab therapy.

Effect of whole-body vibration on neuromuscular performance and body composition for females 65 years and older: a randomized-controlled trial

We examined whether the effect of multipurpose exercise can be enhanced by whole-body vibration (WBV). One hundred and fifty-one post-menopausal women (68.5 ± 3.1 years) were randomly assigned to three groups: (1) a training group (TG); (2) training including vibration (VTG); and (3) a wellness control group (CG). TG and VTG performed the same training program twice weekly (60 min), consisting of aerobic and strength exercises, with the only difference that leg strength exercises (15 min) were performed with (VTG) or without (TG) vibration. CG performed a low-intensity "wellness" program. At baseline and after 18 months, body composition was determined using dual-X-ray-absorptiometry. Maximum isometric strength was determined for the legs and the trunk region. Leg power was measured by countermovement jumps using a force-measuring plate. In the TG lean body mass, total body fat, and abdominal fat were favorably affected, but no additive effects were generated by the vibration stimulus. However, concerning muscle strength and power, there was a tendency in favor of the VTG. Only vibration training resulted in a significant increase of leg and trunk flexion strength compared with CG. In summary, WBV embedded in a multipurpose exercise program showed minor additive effects on body composition and neuromuscular performance.

[Effect of whole body vibration exercise on osteoporotic risk factors]

BACKGROUND AND OBJECTIVE

Whole body vibration (WBV) training is a new approach which is currently discussed in the context of reducing the risk of osteoporotic fractures. The study was undertaken to determine the effect of one-year WBV exercise on bone mineral density (BMD) and the number of falls.

METHODS

151 postmenopausal women (68.5 +/- 3.1 years) were randomly assigned to three groups: (1) conventional (multifunctional) training (TG); (2) multifunctional training including WBV (VTG); (3) wellness-control group (CG). The training groups performed multifunctional training twice weekly (60 min; dancing aerobics, balance training, functional strength training). In the last 15 min of each session, leg strength exercises on vibration platforms were performed. The plates were switched on only in the VTG. The CG performed a low intensity gymnastic and relaxation programme (4 x 10 sessions of 60 min). BMD was measured at the hip and lumbar spine at baseline and after 12 months with the DXA method. Falls were recorded daily with the calendar method in a fall log.

RESULTS

An increase in BMD at the lumbar spine was measured after one year in both training groups (VTG: + 1.17 +/- 2.4 % vs. TG: + 1.73 +/- 2.4 %). The difference between the TG and the CG was significant (p < .05). Regarding the hip region a loss was noted in the CG (- 0.9 +/- 2.5), whereas the BMD stayed stable in the training groups (TG: - 0.3 %; VTG: + 0.1 %). The fall rate was significantly lower in VTG compared to CG (0.43 falls/person/year (VTG) vs. 1.14 (CG).

CONCLUSION

The multifunctional training resulted in a gain of BMD at the lumbar spine. Vibration training did not enhance the effect on bone but significantly reduced falls.