Osteoporosis: Engelke K

Engelke K, Adams JE, Armbrecht G, Augat P, Bogado CE, Bouxsein ML, Felsenberg D, Ito M, Prevrhal S, Hans DB, Lewiecki EM. · Institute of Medical Physics, University of Erlangen, Germany; Synarc, Hamburg, Germany. <> · J Clin Densitom. · Pubmed #18442757 No free full text.

Abstract: The International Society for Clinical Densitometry (ISCD) has developed Official Positions for the clinical use of dual-energy X-ray absorptiometry (DXA) and non-DXA technologies. While only DXA can be used for diagnostic classification according to criteria established by the World Health Organization, DXA and some other technologies may predict fracture risk and be used to monitor skeletal changes over time. ISCD task forces reviewed the evidence for clinical applications of non-DXA techniques and presented reports with recommendations at the 2007 ISCD Position Development Conference. Here we present the ISCD Official Positions for quantitative computed tomography (QCT) and peripheral QCT (pQCT), with supporting medical evidence, rationale, controversy, and suggestions for further study. QCT is available for bone mineral density measurements at the spine, hip, forearm, and tibia. The ISCD Official Positions presented here focus on QCT of the spine and pQCT of the forearm. Measurements at the hip may have clinical relevance, as this is an important fracture site; however, due to limited medical evidence, definitive advice on its use in clinical practice cannot be provided until more data emerge.

Firoozabadi R, Morshed S, Engelke K, Prevrhal S, Fierlinger A, Miclau T, Genant HK. · Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, California 94143, USA. · J Orthop Trauma. · Pubmed #18753895 No free full text.

Abstract: Fractures of the distal radius are one of the most common injuries presented to orthopaedic surgeons. A variety of treatment options are available for the vast array of fracture patterns. Research that explores bone fragility and fracture healing has led to new treatment modalities. As new products and methods are derived to aid in fracture healing it is essential to develop noninvasive and/or nondestructive techniques to assess structural information about bone. Quantitative assessment of macro-structural characteristics such as geometry, and microstructural features such as relative trabecular volume, trabecular spacing, and connectivity may improve our ability to estimate bone strength. Methods for quantitatively assessing macrostructure include (besides conventional radiographs) dual x-ray absorptiometry (DXA) and computed tomography (CT), particularly volumetric quantitative computed tomography (vQCT). Methods for assessing microstructure of trabecular bone include high resolution computed tomography (hrCT), micro computed tomography (microCT), high resolution magnetic resonance (hrMR), and micro magnetic resonance microMR. Volumetric QCT, hrCT and hrMR are generally applicable in vivo; microCT and microMR are principally applicable in vitro. Clinically, the challenges for bone imaging include balancing the advantages of simple bone densitometry versus the more complex architectural features of bone, or the deeper research requirements versus the broader clinical needs.

Genant HK, Engelke K, Prevrhal S. · University of California, San Francisco, CA, USA. · Rheumatology (Oxford). · Pubmed #18556648 links to  free full text

Abstract: Non-invasive and/or non-destructive techniques can provide structural information about bone, beyond simple bone densitometry. While the latter provides important information about osteoporotic fracture risk, many studies indicate that BMD only partly explains bone strength. Quantitative assessment of macro- and microstructural features may improve our ability to estimate bone strength. Methods for quantitatively assessing macrostructure include (besides conventional radiographs) DXA and CT, particularly volumetric quantitative CT (vQCT). Methods for assessing microstructure of trabecular bone non-invasively and/or non-destructively include high-resolution CT (hrCT), microCT (microCT), high-resolution magnetic resonance (hrMR) and microMR (microMR). vQCT, hrCT and hrMR are generally applicable in vivo; microCT and microMR are principally applicable in vitro. Despite recent progress made with these advanced imaging techniques, certain issues remain. The important balances between spatial resolution and sampling size, or between signal-to-noise and radiation dose or acquisition time, need further consideration, as do the complexity and expense of the methods vs their availability and accessibility. Clinically, the challenges for bone imaging include balancing the advantages of simple bone densitometry vs the more complex architectural features of bone or the deeper research requirements vs the broader clinical needs. The biological differences between the peripheral appendicular skeleton and the central axial skeleton must be further addressed. Finally, the relative merits of these sophisticated imaging techniques must be weighed with respect to their applications as diagnostic procedures, requiring high accuracy or reliability, compared with their monitoring applications, requiring high precision or reproducibility.

Kalpakcioglu BB, Morshed S, Engelke K, Genant HK. · Department of Radiology, University of California at San Francisco, 550 Parnassus Avenue, San Francisco, CA 94143, USA. · J Bone Joint Surg Am. · Pubmed #18292360 No free full text.

Abstract: Research into the molecular and cellular pathways focusing on bone fragility and fracture-healing has led to new potential treatments to aid in fracture-healing. This research has focused on physical as well as biological modes of treatment. As new products and methods are derived, it is essential to develop effective and sensitive noninvasive means by which early changes in the fracture repair process can be detected. Specialized noninvasive and/or nondestructive techniques can provide structural information about local and systemic skeletal health, the propensity to fracture, and the pathophysiology of bone fragility. The methods available to quantitatively assess macrostructure include computed tomography and, particularly, volumetric quantitative computed tomography. Methods for assessing microstructure of trabecular bone include high-resolution computed tomography, microquantitative computed tomography, high-resolution magnetic resonance imaging, and micromagnetic resonance imaging. These new techniques help to illustrate the process of fracture-healing by defining the skeletal response to innovative therapies and assessing biomechanical relationships. This review presents perspectives on the advanced imaging modalities that are currently available and on recent developments that may improve the detection and understanding of bone fragility and fracture-healing.

Engelke K, Glüer CC. · Institute of Medical Physics, University of Erlangen, Henkestr. 92, 91056 Erlangen, Germany. · Osteoporos Int. · Pubmed #16821003 No free full text.

Abstract: INTRODUCTION: Bone densitometry is one of the main pillars in the assessment of osteoporosis. The most important modalities are dual x-ray absorptiometry (DXA), quantitative computed tomography (QCT), and quantitative ultrasound (QUS). MATERIALS AND METHODS: For each modality a variety of technical solutions and numerous commercial devices are available and widely used for patient measurements. While the field of bone densitometry may be considered mature, new modalities and devices are being introduced. Consequently, there is a constant need to assess and compare the quality of bone densitometry approaches and devices in a rigorous way. RESULTS: The International Commission on Radiation Units has commissioned a report on bone densitometry to address some of these issues, in particular to provide clear definitions of quantities and units used and to describe parameters and methods that can be used to compare and standardize densitometric equipment and measurements. One of the core chapters of the report summarizes quality and performance measures in bone densitometry. It is divided into four sections: physical performance measures, diagnosis, fracture risk, and monitoring. Here we publish part 1 of this chapter containing the first two sections: physical performance measures and issues in diagnosing osteoporosis. CONCLUSION: Following the international standard (ISO 5725-1), trueness, bias, repeatability, and reproducibility are defined along with terms common to osteoporosis research, such as accuracy and precision. Building on the conceptual definition of osteoporosis, diagnostic criteria are defined and discussed including criteria for reference data. Based on this, clinical performance measures commonly used for the diagnosis of osteoporosis are reviewed and discussed.

Engelke K, Karolczak M, Lutz A, Seibert U, Schaller S, Kalender W. · Institut für Medizinische Physik, Universität Erlangen. · Radiologe. · Pubmed #10218213 No free full text.

Abstract: The strength and fracture resistance of bone is determined by the structure of the trabecular network and the cortical shell. While standard 2D techniques like histomorphometry are inadequate to assess the 3D nature of the trabecular network, isotropic 3D datasets of this network can be acquired with the new imaging modality of microCT. However, so far the quantitative analysis of the generated datasets, in particular the extraction of appropriate parameters describing the bone structure, has not been finally solved. In this article we describe the technology and applications of microCT systems relevant in the field of osteology. The most important technical features of current microCT systems in this context are: 1. A spatial resolution down to 5-10 microns can be achieved. 2. The maximum sample size is related to the desired resolution by a factor of approximately 1000, that is, a resolution of 10 microns limits the maximum sample size to approximately 1 cm. 3. Scan times for microCT systems vary between minutes and hours. Currently five areas for the application of microCT systems in osteology can be identified: 1. The search of parameters characterizing the 3D trabecular structure. 2. The application of finite element models to determine the biochemical competence of the structural parameters. 3. The use of microCT in preclinical trials to study drug effects in small animals. 4. The validation of analysis methods used in high-resolution in-vivo imaging systems. 5. The 3D quantification of modeling and remodeling processes.

Stengel SV, Kemmler W, Pintag R, Beeskow C, Weineck J, Lauber D, Kalender WA, Engelke K. · Institute of Medical Physics, Univ. of Erlangen, Henkestr. 91, 91052 Erlangen, Germany. · J Appl Physiol. · Pubmed #15746294 links to  free full text

Abstract: Physical exercise has a favorable impact on bones, but optimum training strategies are still under discussion. In this study, we compared the effect of slow and fast resistance exercises on various osteodensitometric parameters. Fifty-three postmenopausal women were randomly assigned to a strength training (ST) or a power training group (PT). Both groups carried out a progressive resistance training, a gymnastics session, and a home training over a period of 12 mo. During the resistance training, the ST group used slow and the PT group fast movements; otherwise there were no training differences. All subjects were supplemented with Ca and vitamin D. At baseline and after 12 mo, bone mineral density (BMD) was measured at the lumbar spine, proximal femur, and distal forearm by dual-energy X-ray absorptiometry. We also measured anthropometric data and maximum static strength. Frequency and grade of pain were assessed by questionnaire. After 12 mo, significant between-group differences were observed for BMD at the lumbar spine (P < 0.05) and the total hip (P < 0.05). Whereas the PT group maintained BMD at the spine (+0.7 +/- 2.1%, not significant) and the total hip (0.0 +/- 1.7%, not significant), the ST group lost significantly at both sites (spine: -0.9 +/- 1.9%; P < 0.05; total hip: -1.2 +/- 1.5%; P < 0.01). No significant between-group differences were observed for anthropometric data, maximum strength, BMD of the forearm, or frequency and grade of pain. These findings suggest that power training is more effective than strength training in reducing bone loss in postmenopausal women.

Kemmler W, Wildt L, Engelke K, Pintag R, Pavel M, Bracher B, Weineck J, Kalender W. · Institute of Medical Physics, University of Erlangen, Krankenhausstrasse 12, 91054 Erlangen, Germany. · Eur J Appl Physiol. · Pubmed #14504954 No free full text.

Abstract: The effect of a single bout of exercise on hormones affecting bone metabolism was studied in 25 early postmenopausal women with osteopenia. The complex training session was performed between 8:00 a.m. and 9:05 a.m. Serum concentrations of dehydroepiandrosterone-sulfate (DHEA-S), total testosterone, free testosterone, 17beta-estradiol, cortisol, human growth hormone (hGH), insulin-like growth factor-I (IGF-I), and insulin-like growth factor binding protein-3 (IGFBP-3) were determined. Blood samples were obtained immediately before (baseline) and after exercise, as well as 2 h and 22 h post-exercise. DHEA-S increased by 10% immediately after exercise and remained increased 2 h later. Testosterone showed no increase immediately after exercise but fell by 21% 2 h post-exercise. Free testosterone was increased by almost 20% immediately after exercise and returned to baseline levels after 2 h. Two hours post-exercise a 20% increase in the estradiol level was measured. Cortisol decreased by 36% during exercise and a further 14% during the next 2 h, a loss higher than the normal diurnal decrease. hGH increased by 80% during exercise and fell 30% under baseline values after 2 h. Even though the assessment period was prolonged to 22 h no significant change could be demonstrated for IGF-I. Serum IGFBP-3 showed a biphasic increase. During the exercise session IGFBP-3 increased by 35%, returned to baseline values 2 h post-exercise and increased again by 40% 22 h post-exercise. In summary, this study showed that a single bout of exercise typically used in osteoporosis prevention programs could have an influence on hormones affecting bone metabolism.

Kemmler W, Engelke K, Weineck J, Hensen J, Kalender WA. · Institute of Medical Physics, University of Erlangen, Germany. · Arch Phys Med Rehabil. · Pubmed #12736880 No free full text.

Abstract: OBJECTIVE: To investigate the effect of a 2-year vigorous, combined high-impact, strength, and endurance training program on bone mineral density (BMD) determined by dual-energy x-ray absorptiometry (DXA), quantitative computed tomography (QCT), and ultrasound in early postmenopausal women with osteopenia. DESIGN: Nonrandomized controlled trial, reporting 1-year data. SETTING: Community. PARTICIPANTS: Early postmenopausal (1-8y postmenopausal) osteopenic women (DXA T score at lumbar spine or total hip between -1 and -2.5 standard deviations). The exercise group (n=59; mean age, 55.1+/-3.4y) and control group (n=41; mean age, 55.9+/-3.1y) were recruited from community registers. INTERVENTION: Fourteen months of exercise training, with 2 joint sessions and 2 additional home training sessions. Exercise and control groups were supplemented individually with calcium and cholecalciferol up to 1500mg of calcium and 500IU of vitamin D per day. MAIN OUTCOMES MEASURES: BMD at the lumbar spine and total hip measured by DXA, isometric maximum strength, and maximal oxygen consumption (VO2max) during a stepwise running test to exhaustion. RESULTS: Bone density increased significantly at the lumbar spine for the exercise group (1.3%, P<.001) and decreased in the control group (-1.2%, P<.01). Differences at the total hip (-0.3%, not significant vs -0.8%, P<.05) and the femoral neck (-0.8%, P<.05 vs -1.8%, P<.001) were nonsignificant. Changes in isometric maximum strength were significant for each region (grip strength, trunk flexors and extensors, hip flexors, leg adductors and abductors, arm flexors and extensors) in the exercise group (11%-39%) compared with nonrelevant changes (-1.1% to 3.9%) in the control group. Between-group differences were significant (P<.01-.001) for all strength parameters. VO2max increased significantly by 11% (P<.001) in the exercise group but decreased in the control group by 4% (P<.05) while showing significant between-group differences. CONCLUSION: High-intensity exercise training can have a positive influence on bone density in early postmenopausal osteopenic women.

von Stengel S, Kemmler W, Mayer S, Engelke K, Klarner A, Kalender WA. · Institut für Medizinische Physik, Friedrich-Alexander Universität Erlangen-Nürnberg. · Dtsch Med Wochenschr. · Pubmed #19603365 No free full text.

Abstract: 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.

Engelke K, Libanati C, Liu Y, Wang H, Austin M, Fuerst T, Stampa B, Timm W, Genant HK. · Synarc Inc, San Francisco, USA. · Bone. · Pubmed #19345291 No free full text.

Abstract: BACKGROUND: Dual-energy X-ray absorptiometry (DXA) allows clinically relevant measurement of bone mineral density (BMD) at central and appendicular skeletal sites, but DXA has a limited ability to assess bone geometry and cannot distinguish between the cortical and trabecular bone compartments. Quantitative computed tomography (QCT) can supplement DXA by enabling geometric and compartmental bone assessments. Whole-body spiral CT scanners are widely available and require only seconds per scan, in contrast to peripheral QCT scanners, which have restricted availability, limited spatial resolution, and require several minutes of scanning time. This study evaluated the accuracy and precision of whole-body spiral CT scanners for quantitatively assessing the distal radius, a common site of non-vertebral osteoporosis-related fractures, and compared the CT-measured densitometric values with those obtained from dual-energy-X-ray absorptiometry. SUBJECTS AND METHODS: A total of 161 postmenopausal women with baseline lumbar spine BMD T-scores between -1.0 and -2.5 underwent left forearm QCT using whole-body spiral CT scanners twice, 1 month apart. QCT volumes of interest were defined and analyzed at 3 specific radial regions: the ultradistal region by using slices at 8, 9, and 10 mm proximal to the ulnar styloid tip; the distal region by a slice 20 mm proximal; and the middle region by a slice 40 mm proximal. BMD, bone mineral content (BMC), volume, and average cortical thickness and circumference were measured. We evaluated QCT accuracy and precision and also report correlations between QCT and DXA for BMD and BMC. RESULTS: Overall accuracy and precision errors for BMD, BMC and volume were consistent with known skeletal QCT technology precision and were generally less than 3%. BMD and BMC assessed by QCT and DXA were correlated (r=0.55 to 0.80). DISCUSSION: Whole-body spiral CT scanners allow densitometric evaluations of the distal radius with good accuracy and very good precision. This original and convenient method provides a tool to further investigate cortical and trabecular bone variables in the peripheral skeleton in osteoporotic patients. These assessments, coupled with evaluation of the effects on cortical and trabecular bone measured in response to therapies for osteoporosis, may advance our understanding of the contributors to non-vertebral fracture occurrence.

Lewiecki EM, Keaveny TM, Kopperdahl DL, Genant HK, Engelke K, Fuerst T, Kivitz A, Davies RY, Fitzpatrick LA. · New Mexico Clinical Research & Osteoporosis Center, 300 Oak Street NE, Albuquerque, New Mexico 87106, USA. · J Clin Endocrinol Metab. · Pubmed #18840641 No free full text.

Abstract: CONTEXT: Bone strength and fracture resistance are determined by bone mineral density (BMD) and structural, mechanical, and geometric properties of bone. DESIGN, SETTING, AND OBJECTIVES: This randomized, double-blind, placebo-controlled outpatient study evaluated effects of once-monthly oral ibandronate on hip and lumbar spine BMD and calculated strength using quantitative computed tomography (QCT) with finite element analysis (FEA) and dual-energy x-ray absorptiometry (DXA) with hip structural analysis (HSA). PARTICIPANTS: Participants were women aged 55-80 yr with BMD T-scores -2.0 or less to -5.0 or greater (n = 93). INTERVENTION: Oral ibandronate 150 mg/month (n = 47) or placebo (n = 46) was administered for 12 months. OUTCOME MEASURES: The primary end point was total hip QCT BMD change from baseline; secondary end points included other QCT BMD sites, FEA, DXA, areal BMD, and HSA. All analyses were exploratory, with post hoc P values. Results: Ibandronate increased integral total hip QCT BMD and DXA areal BMD more than placebo at 12 months (treatment differences: 2.2%, P = 0.005; 2.0%, P = 0.003). FEA-derived hip strength to density ratio and femoral, peripheral, and trabecular strength increased with ibandronate vs. placebo (treatment differences: 4.1%, P < 0.001; 5.9%, P < 0.001; 2.5%, P = 0.011; 3.5%, P = 0.003, respectively). Ibandronate improved vertebral, peripheral, and trabecular strength and anteroposterior bending stiffness vs. placebo [7.1% (P < 0.001), 7.8% (P < 0.001), 5.6% (P = 0.023), and 6.3% (P < 0.001), respectively]. HSA-estimated femoral narrow neck cross-sectional area and moment of inertia and outer diameter increased with ibandronate vs. placebo (respectively 3.6%, P = 0.003; 4.0%, P = 0.052; 2.2%, P = 0.049). CONCLUSIONS: Once-monthly oral Ibandronate for 12 months improved hip and spine BMD measured by QCT and DXA and strength estimated by FEA of QCT scans.

Kemmler W, Engelke K, von Stengel S, Weineck J, Lauber D, Kalender WA. · Institute of Medical Physics, University of Erlangen-Nürnberg, Germany. · J Strength Cond Res. · Pubmed #17313298 No free full text.

Abstract: The purpose of the study was to determine the effect of long-term exercise on coronary heart disease, osteoporotic risk factors, and physical fitness parameters in postmenopausal women. Forty early postmenopausal women (age 55.1 +/- 3.3 years) with no medication or illness affecting bone metabolism exercised (high impact aerobic, multilateral jumps, multi-set resistance exercise) for 50 months (EG), while 28 women (age 55.5 +/- 3.0 years) served as a nontraining control (CG). Both groups were supplemented with calcium and cholecalciferol. Bone mineral density (BMD) was measured at the lumbar spine, hip, and forearm by dual energy x-ray absorptiometry. Blood lipids were determined using serum samples, and body composition was determined using the bioimpedance technique. Further, maximum isometric strength was determined (Schnell M3, Schnell Trainer). The BMD at the lumbar spine (+1.0%, p = 0.037) and the total hip (-0.3%, p = 0.194) were maintained in the EG, while significant (p < 0.001) decreases were observed in the CG (lumbar spine -3.2; total hip -2.3%). Differences between both groups were significant (p < 0.001). Significant differences between EG and CG were also observed, respectively, for total cholesterol (-6.1 vs. +3.5%, p = 0.008), HDL-cholesterol (+14.1 vs. -7.1%, p = 0.007), triglycerides (-10.2 vs. +27.5%, p = 0.002), body fat (-3.3 vs. +1.3%, p = 0.041), and waist-hip-ratio (-3.5 vs. +0.2%, p > 0.001). Maximum isometric strength significantly (p < 0.001) increased in the EG, while strength parameters decreased in the CG (-0.5 to -6.4%). Thus, the study demonstrated that multipurpose high-intensity exercise programs significantly affect relevant menopausal risk factors and, therefore, may be individually considered as an alternative to hormone replacement therapy.

Mastmeyer A, Engelke K, Fuchs C, Kalender WA. · Institute of Medical Physics, University of Erlangen-Nuernberg, Henkestrasse 91, 91052 Erlangen, Germany. · Med Image Anal. · Pubmed #16828329 No free full text.

Abstract: We have developed a new hierarchical 3D technique to segment the vertebral bodies in order to measure bone mineral density (BMD) with high trueness and precision in volumetric CT datasets. The hierarchical approach starts with a coarse separation of the individual vertebrae, applies a variety of techniques to segment the vertebral bodies with increasing detail and ends with the definition of an anatomic coordinate system for each vertebral body, relative to which up to 41 trabecular and cortical volumes of interest are positioned. In a pre-segmentation step constraints consisting of Boolean combinations of simple geometric shapes are determined that enclose each individual vertebral body. Bound by these constraints viscous deformable models are used to segment the main shape of the vertebral bodies. Volume growing and morphological operations then capture the fine details of the bone-soft tissue interface. In the volumes of interest bone mineral density and content are determined. In addition, in the segmented vertebral bodies geometric parameters such as volume or the length of the main axes of inertia can be measured. Intra- and inter-operator precision errors of the segmentation procedure were analyzed using existing clinical patient datasets. Results for segmented volume, BMD, and coordinate system position were below 2.0%, 0.6%, and 0.7%, respectively. Trueness was analyzed using phantom scans. The bias of the segmented volume was below 4%; for BMD it was below 1.5%. The long-term goal of this work is improved fracture prediction and patient monitoring in the field of osteoporosis. A true 3D segmentation also enables an accurate measurement of geometrical parameters that may augment the clinical value of a pure BMD analysis.

Kemmler W, Roloff I, Baumann H, Schöffl V, Weineck J, Kalender W, Engelke K. · Institute of Medical Physics, University of Erlangen, Germany. · Int J Sports Med. · Pubmed #16586335 No free full text.

Abstract: A low body mass index is considered essential for high performance in rock climbing; however its effect on bone may be negative. In this study we compared the BMD of competitive male rock climbers (n = 20) and age- and BMI-matched non-training controls (n = 11). Subjects with any medication or illness affecting bone metabolism or a family history of osteoporosis were not included in the analysis. Total body BMD was measured by dual-energy X-ray absorptiometry. Quantitative computed tomographic scans were made from the femoral neck and the lumbar spine. Dietary intake was assessed by a 5-day protocol. BMD of the TB-scan was significantly higher in the climbers group for all sub-regions except the skull (p = 0.191) and the lower extremities (p = 0.079). Trabecular and cortical BMD of the LS were significantly higher (p = 0.036 and p = 0.004) in the climbers. The same was true for total (p = 0.005) and cortical (p = 0.002) BMD of the FN. Trabecular BMD (p = 0.054), CSA (p < 0.343) and cortical thickness (p = 0.065) of the FN was non-significantly higher for the climbers. Our study indicates that the effect of climbing on bone parameters PER SE is not detrimental in elite male athletes. Contrarily climbers demonstrated significantly higher BMD values at all loaded regions without "steal effects" at skeletal sites with low mechanical impact. Although we determined a moderately negative effect of low BMI on BMD we could not decide whether a low BMI value should be used as an exclusion criterion in high level climbing competitions as practized by the Austrian Sportclimbing Organization.

Kemmler W, Engelke K, Baumann H, Beeskow C, von Stengel S, Weineck J, Kalender WA. · Institute of Medical Physics, University of Erlangen, Henkestrasse 91, 91052, Erlangen, Germany. · Eur J Appl Physiol. · Pubmed #16307280 No free full text.

Abstract: The aim of our study was to compare long distance runners to body mass index (BMI)- and age-matched healthy controls with respect to bone parameters at all relevant loaded and nonloaded skeletal sites. Furthermore, we assessed the effect of running volume on bone parameters. Twenty elite male runners (21.1 km<1:15 h; volume >75 km/week/year) participated in the study (RG), 11 age- and BMI-matched male subjects (28+/-5 years) served as nontraining controls (CG). Subjects with any medication or illness affecting bone metabolism or with a family history of osteoporosis were not included. Bone parameters at various sites (total body, lumbar spine, femoral neck/hip, calcaneus) were measured by dual energy X-ray (DXA), quantitative computed tomography and quantitative ultrasound. Body composition was assessed via DXA and bioimpedance analysis; nutritional parameters were determined by 5-day dietary protocols. Training variables were assessed by questionnaires. Compared with nontraining controls runners had significantly higher BMD at all loaded sites (calcaneus, lower limbs, femoral neck, pelvis, and trabecular lumbar spine). BMD at nonloaded sites (ribs, upper limbs, and skull) was slightly but not significantly higher in the runners. We observed a low (r=0.30), nonsignificant association between training volume (km/week/year) and trabecular BMD of the femoral neck, which disappeared after adjusting for age, BMI, and body fat in this group of highly trained male runners. The effect of long distance running per se on bone parameters is not deleterious.

Engelke K, Kemmler W, Lauber D, Beeskow C, Pintag R, Kalender WA. · Institute of Medical Physics, University of Erlangen, Henkestrasse 91, 91054, Erlangen, Germany, · Osteoporos Int. · Pubmed #16096715 No free full text.

Abstract: It is an important aim in the prevention of osteoporosis to stop or decelerate bone loss during the early postmenopausal years. Here we report on results of the 3-year EFOPS exercise trial in osteopenic women. The exercise strategy emphasized low-volume high-resistance strength training and high-impact aerobics. Forty-eight fully compliant women (55.1+/-3.3 years) with no medication or illness affecting bone metabolism participated in the exercise group (EG); 30 women (55.5+/-3.0 years) served as non-training controls (CG). At baseline there were no significant between-group differences with respect to physical fitness, bone mineral density, pain and nutritional status. The training consisted of two group training and two home training sessions per week. The study participants of both groups were individually supplemented with calcium and vitamin D (cholecalciferol). Bone mineral density (BMD) was measured by DXA at the lumbar spine, proximal femur and distal forearm and by QCT at the lumbar spine. Speed of sound and broadband ultrasound attenuation were determined at the calcaneus by quantitative ultrasound (QUS). Pain frequency and intensity at different skeletal sites were assessed via questionnaire. After 38 months, the following within-group changes were measured: DXA lumbar spine, EG: 0.8% n.s.; CG: -3.3% P<0.001; QCT trabecular ROI, EG: 1.1% n.s; CG: -7.7% P<0.001; QCT cortical ROI, EG: 5.3% P<0.001; CG: -2.6% P<0.001; DXA total hip: EG: -0.2% n.s; CG -1.9%, P<0.001; DXA distal forearm, EG: -2.8% P<0.001; CG: -3.8% P<0.001; BUA, EG: -0.3% n.s; CG -5.4% P<0.001; SOS, EG: 0.3% n.s; CG -1.0% P<0.001. At year 3 between-group differences relative to the exercise group were: DXA lumbar spine: 4.1% P<0.001; QCT trabecular ROI: 8.8% P<0.001; QCT cortical ROI: 7.9% P<0.001; DXA total hip: 2.1%, P<0.001; DXA distal forearm: 1.0% n.s.; BUA: 5.8% P<0.05; SOS: 1.3% P<0.001. Pain frequency and intensity in the spine significantly decreased in the exercise group and increased in the control group, while no between-group differences were detected in the main joints. In summary, over a period of 3 years our low-volume/high-intensity exercise program was successful to maintain bone mineral density at the spine, hip and calcaneus, but not at the forearm.

Kemmler W, von Stengel S, Weineck J, Lauber D, Kalender W, Engelke K. · Institute of Medical Physics, University of Erlangen, Krankenhausstr. 12, 91054 Erlangen, Germany. · Med Sci Sports Exerc. · Pubmed #15692313 No free full text.

Abstract: PURPOSE: To determine the impact of multipurpose exercise training on bone, body composition, blood lipids, physical fitness, and menopausal symptoms in early postmenopausal women with osteopenia. METHODS: Forty-eight fully compliant (more than two sessions per week for 38 months) women (55.1 +/- 3.3 yr) without any medication or illness affecting bone metabolism took part in the exercise training (EG); 30 women (55.5 +/- 3.0 yr) served as the nontraining control group (CG). Both groups were individually supplemented with calcium and vitamin D. Bone mineral density (BMD) at various sites (lumbar spine, hip, forearm, calcaneus) was measured by dual x-ray absorptiometry (DXA) and quantitative ultrasound (QUS). Maximal isometric and dynamic strength, maximal oxygen consumption (VO(2max)), CHD risk factors (blood lipids, body composition), and menopausal symptoms were determined. RESULTS: After 38 months, significant differences between EG and CG were observed for the BMD at the lumbar spine (0.7% vs -3.0%) and the femoral neck (-0.7% vs -2.6%), body composition (waist circumference, waist-to-hip ratio), blood lipids (total cholesterol, triglycerides), and menopausal symptoms (insomnia, migraines, mood changes). Maximal isometric strength increased significantly by 10-36% in the EG, whereas, with one exception, changes in the CG were all negative. One-repetition maximum increased significantly at all sites measured (15-43%, P < 0.001). VO(2max) of the EG increased throughout the study with a significant 13.9 +/- 15.6% net increase after 3 yr. No significant changes after 3 yr could be observed in the CG. CONCLUSIONS: Our mixed high-intensity exercise program effectively compensates for most negative changes related to the menopausal transition.

Kemmler W, Weineck J, Kalender WA, Engelke K. · Institute of Medical Physics, University of Erlangen, Germany. · J Musculoskelet Neuronal Interact. · Pubmed #15615501 links to  free full text

Abstract: CONTEXT: Although the positive effect of well-designed exercise regimes on bone mineral density (BMD) is established the osteo-anabolic relevance of habitual physical activity and non-athletic exercise is still under discussion. OBJECTIVE: To determine the effects of habitual physical activity, non-athletic exercise muscle strength, VO2max and anthropometric parameters on BMD in early post-menopausal women. DESIGN: Cross-sectional study. METHODS: 150 early postmenopausal women (55.5+/-3.4 years), which were free of diseases or medication affecting bone metabolism and had no athletic history were investigated. The influence of weight, body composition, physical activity, isometric strength, VO2max, and nutritional intake on BMD was measured at multiple sites using different techniques. Further bone markers (Osteocalcin, CTX) were determined. Activity and weight-bearing activity were assessed by questionnaire. Maximum strength was measured isometrically. Aerobic capacity was measured with an spirometric system in a stepwise treadmill test and dietary intake was monitored over 5 days. RESULTS: Slight relationships between physical activity, exercise, muscle strength and VO2max with bone parameters were determined by univariate analysis. After adjusting for confounding variables in a stepwise regression analysis, significant relationships with BMD measured at the hip or the spine could no longer be detected for physical activity, exercise, and physical fitness (strength indices, VO2max). The same was true for osteocalcin and CTX. Arm strength explained 4.5% of the variation of forearm BMD (DXA). At the calcaneal site, osteogenic exercise was significantly related to the quantitative ultrasound index (r2 = 0.27). CONCLUSION: The isolated effect of habitual physical activity, unspecific exercise participation, and muscle strength on bone parameters is rather low in (early-) postmenopausal women. CLINICAL RELEVANCE: Women at risk should take specific exercise programs into consideration rather than to increasing the amount of habitual physical activity.

Kemmler W, Lauber D, Weineck J, Hensen J, Kalender W, Engelke K. · Institute of Medical Physics, University of Erlangen, Krankenhausstrasse 12, 91054 Erlangen, Germany. · Arch Intern Med. · Pubmed #15159265 links to  free full text

Abstract: BACKGROUND: Growing evidence indicates that physical exercise can prevent at least some of the negative effects on health associated with early menopause. Here we determine the effects of intense exercise on physical fitness, bone mineral density (BMD), back pain, and blood lipids in early postmenopausal women. METHODS: The study population comprised 50 fully compliant women, with no medication or illness affecting bone metabolism, who exercised over 26 months (exercise group [EG]), and 33 women who served as a nontraining control group (CG). Two group training sessions per week and 2 home training sessions per week were performed in the EG. Both groups were individually supplemented with calcium and cholecalciferol. Physical fitness was determined by maximum strength and cardiovascular performance. Bone mineral density was measured at the lumbar spine (dual-energy x-ray absorptiometry [DXA] and quantitative computed tomography [QCT]), the proximal femur (DXA), and the forearm (DXA). In serum samples taken from a subset of the study participants, we determined bone formation (serum osteocalcin) and resorption (serum cross-links) markers as well as blood lipid levels. Vasomotor symptoms related to menopause and pain were also assessed. RESULTS: After 26 months, significant exercise effects determined as percentage changes compared with baseline were observed for physical fitness (isometric strength: trunk extensors [EG +36.5% vs CG +1.7%], trunk flexors [EG +39.3% vs CG -0.4%], and maximum oxygen consumption [EG +12.4% vs CG -2.3%]); BMD (lumbar spine [DXA L1-L4, EG +0.7% vs CG -2.3%], QCT L1-L3 trabecular region of interest [EG +0.4% vs CG -6.6%], QCT L1-L3 cortical region of interest [EG +3.1% vs CG -1.7%], and total hip [DXA, EG -0.3% vs CG -1.7%]); serum levels (total cholesterol [EG -5.0% vs CG +4.1%] and triglycerides [EG -14.2% vs CG +23.2%]); and pain indexes at the spine. CONCLUSION: General purpose exercise programs with special emphasis on bone density can significantly improve strength and endurance and reduce bone loss, back pain, and lipid levels in osteopenic women in their critical early postmenopausal years.

Kemmler W, Engelke K, Lauber D, Weineck J, Hensen J, Kalender WA. · Institute of Medical Physics, University of Erlangen, Krankenhausstr. 12, 91054 Erlangen, Germany. · Med Sci Sports Exerc. · Pubmed #12471325 No free full text.

Abstract: PURPOSE: To determine the effect of an intense exercise training on physical fitness, coronary heart disease (CHD), bone mineral density (BMD), and parameters related to quality of life in early postmenopausal women with osteopenia. METHODS: Fifty-nine fully compliant women (55.1 +/- 3.4 yr) without any medication or illness affecting bone metabolism took part in intensive exercise training (>2 sessions per week); 41 women served as nontraining control. Both groups received calcium and vitamin D (cholecalciferol) up to a maximum of 1500 mg x d(-1) calcium and 500 IU x d(-1) vitamin D. Bone density of the lumbar spine and hip (DXA Hologic QDR 4500), maximum isometric and dynamic strength (Schnell M3, Schnell-Trainer), VO2max (ZAN 600), and quality of life parameters including vasomotor symptoms related to menopause were measured at baseline and after 14 months. RESULTS: After 14 months, there were significant differences between exercise and control groups concerning changes of bone density (LS exercise: +1.3%, P < 0.001 vs control: -1.2%, P < 0.001), maximum isometric strength (exercise: +11 to +32% (P < 0.001) vs control: -1.1 to +3.9%), VO2max (exercise: +11% (P < 0.001) vs control: -4% (P < 0.05)), and quality of life parameters (e.g., lower back pain). Dynamic strength (1RM tests) at four exercises, which was assessed in the exercise group only, increased significantly by 15-43% (all P < 0.001). CONCLUSION: The intense exercise training program presented here was effective in improving strength, endurance, quality of life parameters, and even BMD in women in their critical early postmenopausal years.

Alenfeld FE, Engelke K, Schmidt D, Brezger M, Diessel E, Felsenberg D. · Department of Radiology and Nuclear Medicine, Klinikum Benjamin Franklin, Freie Universität Berlin, Hindenburgdamm 30, 12200 Berlin, Germany. · Br J Radiol. · Pubmed #12466255 links to  free full text

Abstract: Quantitative ultrasound for the assessment of skeletal status is an evolving method in the diagnosis of osteoporosis. In this cross-sectional study we investigated the diagnostic agreement between the Sahara bone sonometer and the Achilles+ with respect to broadband ultrasound attenuation (BUA), speed of sound (SOS) and stiffness/quantitative ultrasound index (QUI). 309 healthy females without diseases or medications known to influence bone metabolism (with the exception of oestrogen) were recruited at two participating centers (Erlangen and Berlin). 33% of subjects were taking oestrogens. There was no significant difference in BUA, SOS, and stiffness/QUI between oestrogen and non-oestrogen takers. In vivo precision (expressed as root mean square coefficient of variation) was calculated from two repeat measurements and analyzed in both centres. Mean values were 1.57% (BUA Achilles+), 3.64% (BUA Sahara), 0.35% (SOS Achilles+), 0.39% (SOS Sahara), 2.22% (stiffness Achilles+) and 3.04% (QUI Sahara). Between the two devices we observed a strong correlation for SOS (r=0.89, p<0.01) and stiffness/QUI (r=0.83, p<0.01), and a moderate correlation for BUA (r=0.68, p<0.01). All parameters were moderately negatively associated with age (r=-0.38 to -0.48; p<0.01 for all correlations). Kappa (kappa) scores used to report diagnostic agreement were calculated for tertiles and "equivalent T-scores". The tertiles divide the cohort on both scanners into the same number of subjects above and below a given T-score. Diagnostic agreement using tertiles was poor to moderate (kappa< or =0.51). Diagnostic agreement using equivalent T-score agreement, again, was poor to moderate for BUA but fair to good for SOS and stiffness/QUI (0.59< or =kappa< or =0.73). We conclude that diagnostic agreement between the two devices is at best comparable to the agreement of a dual X-ray absorptiometry measurement using the same densitometer at two different skeletal sites. It is therefore insufficient to compare directly two measurements of an individual patient on both ultrasound devices. Standardization of quantitative ultrasound is very much needed.

Engelke K, Süss C, Kalender WA. · Institute of Medical Physics, University of Erlangen, Krankenhausstrasse 12, 91054 Erlangen, Germany. · Eur Radiol. · Pubmed #11702138 No free full text.

Abstract: The analysis of bone structure in vivo is an important goal in osteoporosis, because the determination of bone mineral density alone is insufficient to predict whether an individual patient will eventually suffer an osteoporotic fracture or not. An additional structural analysis may significantly improve the statistical assessment of fracture risk. In this study we present a method to generate realistic although enlarged 3D phantoms of trabecular bone. These phantoms are useful in characterizing the potential of in vivo imaging procedures for the analysis of bone structure and to verify textural or structural analysis methods applied to these images. Our phantoms are based on a real trabecular bone specimen that was converted to a plastic model using the technique of stereolithography. The trabecular network is modeled by hydroxyapatite. Limitations of the stereolithographic process prevent the generation of exact 1:1 replicas of the real bone. A histomorphometric analysis of microCT scans of the phantoms showed that an excellent replication of the bone structure could be achieved in phantoms enlarged by a factor of 2.5 with "trabecular" hydroxyapatite concentrations up to 400 mg/cm3. In order to demonstrate the usefulness of our phantoms, we investigated one of them with various thin-slice CT protocols using clinical single- and multi-slice spiral CT scanners. The enlargement of the phantoms limits their use on high spatial resolution CT scanners (resolution >20 lp/cm). The limited hydroxyapatite concentration requires enhanced exposure rates for the phantoms scans to offset the larger impact of noise due to the lower contrast in the phantoms.

Engelke K, Hahn M, Takada M, Vogel M, Ouyang X, Delling G, Genant HK. · Institute of Medical Physics, University of Erlangen, Germany. · Calcif Tissue Int. · Pubmed #11351500 No free full text.

Abstract: The recent advancement of high resolution magnetic resonance imaging has opened up new avenues for the determination of structural characteristics of the trabecular network, which may significantly improve the diagnosis of osteoporosis. An analysis of the calcaneus in healthy women has shown similar age-related changes when comparing structural parameters in high resolution MR images and BMD as measured by DXA [1]. Here we undertook an in vitro study to further compare structural measurements in MR images with those from stained grindings. A 3D gradient echo sequence on a 1.5 T scanner was used to obtain four contiguous sagittal MR images with a slice thickness of 1 mm and an in plane pixel size of 195 microns. Twenty-one stained grindings with a slice thickness of 1 micron each were obtained from a 3 mm thick slab of the same volume investigated by MR. The stack of stained grindings was also used to simulate the influence of variations in slice thickness and in plane resolution. Results for structural parameters derived from the high resolution MR images differed considerably from those derived from the stained grindings because the MR images are heavily influenced by partial volume artifacts. This finding was supported by simulations which also revealed that even at a slice thickness of 500 microns and an in plane pixel size of 13 microns, accurate results could not be obtained when a histomorphometric type analysis was applied. Results also depended strongly on the segmentation method. However, contrary to the stained grindings, images averaged over several slices reveal the three-dimensional network character of the trabecular structure. New efforts should be undertaken to develop analysis strategies that are more adequate for in vivo high resolution images instead of using analysis techniques applied in classical histomorphometry.

Prevrhal S, Engelke K, Kalender WA. · Institute of Medical Physics, University of Erlangen, Germany. · Phys Med Biol. · Pubmed #10211808 No free full text.

Abstract: In this study we analysed the accuracy of computed tomography (CT) measurements in assessing cortical bone. We determined the dependency of thickness and density measurements on the true width and density of the cortex and on the spatial resolution in the CT images using two optimized segmentation methods. As a secondary goal, we assessed the ability of CT to reflect small changes in cortical thickness. Two different bone-mimicking phantoms with varying cortical thickness were scanned with single-slice CT on a Somatom Plus 4 scanner. Images were reconstructed with both a standard and a high-resolution convolution kernel. Two special operator-independent segmentation methods were used to automatically detect the edges of the cortical shell. We measured cortical thickness and density and compared the phantom measurements with theoretical computations by simulating a cross-sectional shape of the cortical shell. Based on the simulations, we calculated CT's power to detect small changes in cortical thickness. Simulations and phantom measurements were in very good agreement. Cortical thickness could be measured with an error of less than 10% if the true thickness was larger than 0.9 (0.7) mm for the standard (high-resolution) kernel which is close to the full width at half maximum (FWHM) of the point spread functions for these kernels and our scanner. Density measurements yielded errors of less than 10% for true cortical thickness values above two to three times the FWHM corresponding to 2.5 (2) mm in our case. The simulations showed that a 10% change in cortical width would not be detected with satisfying probability in bones with a cortical shell thinner than 1.2 mm. An accurate determination of the cortical thickness is limited to bones with a thickness higher than the FWHM of the scanner's point spread function. Therefore, the use of a high-resolution reconstruction kernel is crucial. Cortical bone mineral density can only be measured accurately in bones two to three times thicker than this number. In thinner bones, the measured density becomes dependent on the thickness. Changes in cortical thickness can only be assessed if the change is rather large or if the measured bone has sufficient thickness. Therefore, assessing density or thickness of the vertebral shell by CT should be treated with caution.