Identification of vertebral fractures in osteoporosis

Osteoporosis is a systemic skeletal disease characterized by reduced bone mass and microarchitectural deterioration. These lead to subsequent increase in bone fragility and susceptibility to low-trauma or atraumatic fractures, most commonly vertebral fractures but also fractures of hip and wrist. These have a significant impact on morbidity, mortality, and health care cost. Studies have demonstrated that the presence of vertebral fractures is an independent and significant predictor of the increased risk for further fractures. The occurrence of a vertebral fracture is often clinically asymptomatic, and many of these fractures, therefore, remain undiagnosed. Recently, a number of techniques have been developed that allow for reliable identification of vertebral fractures on radiographs. The two most widely used methods in clinical research are the semiquantitative assessment of vertebral deformities, which is based on visual evaluation, and the quantitative approach, which is based on different morphometric criteria. In our practice for osteoporosis evaluation we use the Genant semiquantitative approach-an accurate and reproducible method, tested and applied in many clinical studies. The newest generation of fan-beam dual energy X-ray absorptiometry (DXA) systems delivering "high-resolution" lateral spine images offer a potential practical alternative to radiographs for clinical vertebral fracture analysis. The advantages of using DXA over conventional X-ray devices are its minimal radiation exposure and high-speed image acquisition. It also allows combined evaluation of vertebral fracture status and bone mineral density, which could become a standard for patient assessment in osteoporosis.

Trabecular microstructure and surface changes in the greater tuberosity in rotator cuff tears

OBJECTIVE

When planning surgery in patients with rotator cuff tear, strength of bone at the tendon insertion and trabecular bone structure in the greater tuberosity are usually taken into consideration. We investigated radiographic changes in bone structure of the greater tuberosity in rotator cuff tears.

DESIGN

Twenty-two human cadaveric shoulders from subjects ranging from 55 to 75 years of age were obtained. The integrity of the rotator cuff was examined by sonography to determine if it is intact without any tear, or torn partially or completely. The humeral head was sectioned in 3 mm thick coronal slab sections and microradiographed. After digitization of the microradiographs and imaging processing with in-house semi-automated image processing software tools developed using software interfaces on a Sun workstation, the trabecular histomorphometrical structural parameters and connectivity in the greater tuberosity were quantified. The degenerative changes on the surface of the greater tuberosity were interpreted blindly by 2 independent readers.

RESULTS

Among the 22 shoulder specimens, the rotator cuff was found intact in 10 shoulders, partially in 7 and fully torn in 5. Statistically significant loss in apparent trabecular bone volume fraction, number of trabecular nodes, and number of trabecular branches, and a statistically significant increase in apparent trabecular separation and number of trabecular free ends were found in the greater tuberosity of the shoulders with tears. The loss was greater in association with full tear than in partial tear. Thickening of the cortical margin of the enthesis, irregularity of its surface, and calcification beyond the tidemark were observed in 2 (20%) shoulders with intact rotator cuff, in 6 (86%) shoulders with partial tear, and in 5 (100%) shoulders with full tear.

CONCLUSIONS

Rotator cuff tears are associated with degenerative changes on the bone surface and with disuse osteopenia of the greater tuberosity. Aging, degenerative enthesopathy of the supraspinatus tendon, and rotator cuff tears appear closely related.

SHIP-deficient mice are severely osteoporotic due to increased numbers of hyper-resorptive osteoclasts

The hematopoietic-restricted protein Src homology 2-containing inositol-5-phosphatase (SHIP) blunts phosphatidylinositol-3-kinase-initiated signaling by dephosphorylating its major substrate, phosphatidylinositol-3,4,5-trisphosphate. As SHIP(-/-) mice contain increased numbers of osteoclast precursors, that is, macrophages, we examined bones from these animals and found that osteoclast number is increased two-fold. This increased number is due to the prolonged life span of these cells and to hypersensitivity of precursors to macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor-kappa B ligand (RANKL). Similar to pagetic osteoclasts, SHIP(-/-) osteoclasts are enlarged, containing upwards of 100 nuclei, and exhibit enhanced resorptive activity. Moreover, as in Paget disease, serum levels of interleukin-6 are markedly increased in SHIP(-/-) mice. Consistent with accelerated resorptive activity, 3D trabecular volume fraction, trabecular thickness, number and connectivity density of SHIP(-/-) long bones are reduced, resulting in a 22% loss of bone-mineral density and a 49% decrease in fracture energy. Thus, SHIP negatively regulates osteoclast formation and function and the absence of this enzyme results in severe osteoporosis.

Does osteoporosis classification using heel BMD agree across manufacturers?

The lack of standardization in bone mineral density (BMD) measurements is known. Several studies have been carried out to cross-calibrate the axial dual X-ray absorptiometry (DXA) devices. Recently, a number of peripheral DXA (pDXA) densitometers have been introduced. In this study we evaluated the agreement between two heel DXA devices on BMD and T-scores. A total of 99 females aged 21-78 years (ca. 16 per decade) had their non-dominant heel BMD measured using the PIXI (Lunar Inc.) and the Apollo (Norland Medical) pDXA scanners. The mean BMD values were 0.492 and 0.607 g/cm(2) and the mean T-scores using manufacturers' specified reference data were -0.07 and -0.25 for the PIXI and Apollo, respectively. Both the BMD and T-score intermachine relationships were highly correlated but showed significant nonidentity slopes and non-zero offsets. The diagnostic comparison on T-scores resulted in 86% agreement between the instruments (weighted kappa score of 0.550). Normalizing the reference peaks and SDs using this study's young adult population BMD results removed the systematic T-score disagreement. We found that PIXI and Apollo are highly correlated. Differences in BMD values are mainly due to different region of interest (ROI) definitions and additional T-score disagreement reflects the difference in normative databases.

Efficacy of raloxifene on vertebral fracture risk reduction in postmenopausal women with osteoporosis: four-year results from a randomized clinical trial

The Multiple Outcomes of Raloxifene Evaluation trial studied 7705 postmenopausal women with osteoporosis randomized to placebo, or raloxifene 60 or 120 mg/d [JAMA 282(1999): 637]. This report assesses the efficacy of raloxifene on the long-term cumulative incidence new vertebral fractures through 4 yr. New vertebral fractures was assessed from radiographs taken at baseline, yr 2-4. The primary analysis was the cumulative incidence of new vertebral fractures through 4 yr. A posthoc analysis compared the vertebral fracture risk in yr 4 alone with that observed in the first 3 yr. The 4-yr cumulative relative risks (RR) for one or more new vertebral fractures were 0.64 [95% confidence interval (CI) 0.53, 0.76] with raloxifene 60 mg/d and 0.57 (95% CI 0.48, 0.69) with raloxifene 120 mg/d. In yr 4 alone, raloxifene 60 mg/d reduced the new vertebral fracture risk by 39% [RR 0.61 (95% CI 0.43, 0.88)], which was not found to be significantly different from the RR observed in the first 3 yr in both raloxifene groups, irrespective of prevalent fracture status. The nonvertebral fracture risk was not significantly reduced [RR 0.93 (95% CI 0.81, 1.06)]. The safety profile after 4 yr was similar to that observed after 3 yr. Raloxifene 60 and 120 mg/d through 4 yr decreased the cumulative risk of new vertebral fractures in postmenopausal women with osteoporosis. The decreased vertebral fracture risk in yr 4 alone was not different from that observed in the first 3 yr.

The evaluation of a new digital semi-automated system for the radiological assessment of distal radial fractures

OBJECTIVE

To compare intra- and inter-observer variation for measurements of wrist deformity using a manual method of measurement and a semi-automated digital system developed in our department.

DESIGN

Four observers measured radial angle, radial shift, radial length, palmar tilt, and dorsal shift on ten wrist-fracture films using a standardised protocol. Each observer made measurements directly from the radiograph on three occasions, and on a further three occasions digitised images were viewed and measurements made with semi-automated on-screen measurement tools.

RESULTS

Manual measurements took 12 min per case compared with 3 min for the digital system. The digital system resulted in improved intra-observer variation for all measurements and an improvement in inter-observer variation for all measurements except posterior tilt.

CONCLUSION

The new system allows greater precision in assessing fracture reduction and follow-up. Its principal application is in studies that utilise the wrist as a model for fracture healing.

Fully automated software to monitor wear in prosthetic knees using fluoroscopic images

Total knee arthroplasty is now a widely accepted treatment for late-stage arthritis. Wear of the polyethylene layer in prosthetic knees is a known cause of implant failure. Early detection of wear may allow prediction of device failure. In this paper we describe a fully automated image processing algorithm to measure the minimum tibiofemoral joint space width (mJSW) for monitoring prosthesis wear radiographically. The femoral portion and tibial plate were automatically delineated and mJSW was calculated in each compartment. The software also delineated the tip of the prosthesis pin in order to make a magnification correction. The algorithm was tested with a set of triplicate acquisitions of 18 fluoroscopic knee images. The RMS standard deviation (RMSSD) for the triplicate measurements was calculated as a figure of merit. The RMSSD was 0.077 and 0.087 mm for the lateral and medial compartments. The computer successfully found the minimum JSW for both compartments in all 54 images. A single case (2% of total) required user interaction to correct for an obvious failure to delineate the prosthesis pin. We document a robust and precise tool for quantifying mJSW to monitor prosthesis wear.

Measurement of breast density with dual X-ray absorptiometry: feasibility

Dual x-ray absorptiometry (DXA) was used to quantify breast density with a phantom and with cadaveric breasts. With DXA, percentage of fat correlated with percentage of glandular density of the phantom (r > 0.998) and with density at mammography (r(adjusted) = 0.83). DXA precision (SD) was 0.5% without and 1.1% with breast repositioning. DXA devices can be used to accurately and precisely estimate breast tissue density.

Universal standardization of forearm bone densitometry

As part of an effort to quantify device-dependent differences in forearm bone density, 101 women, aged 20-80 years (approximately 16 women in each age decade), were scanned on six forearm bone densitometers: the Aloka DCS-600EX, the Hologic QDR-4500A, the Lunar PIXI, the Norland pDEXA, the Osteometer DTX-200, and the Pronosco X-posure System. Regression statistics are reported for all similar regions of interest (ROIs). However, comparisons were confounded because of large differences in the ROI size and placement. The number of ROIs reported for a single scan by each device varied from 1 to 12. The correlation coefficients ranged from 0.7 < r < 0.97, with the highest correlation coefficients and lowest SEs for comparisons between the most similar ROIs. Standardized units of bone mineral density are derived for distal (sdBMD), mid-(smBMD), and proximal (spBMD) ROTs that allow for comparable mean bone densities to be derived for patient populations. Five phantoms were scanned and characterized on five of the devices and the precision and mean values were reported. These phantom values will aid in the in vitro cross-calibration between manufacturers to recreate the presented in vivo relationships. Care should be exercised when using these equations for cross-calibrating patient databases or pooling clinical data from different devices because the least significant differences detectable from measurements taken on two different machines can be increased substantially.

Improvement in spine bone density and reduction in risk of vertebral fractures during treatment with antiresorptive drugs

PURPOSE

To estimate how much the improvement in bone mass accounts for the reduction in risk of vertebral fracture that has been observed in randomized trials of antiresorptive treatments for osteoporosis.

METHODS

After a systematic search, we conducted a meta-analysis of 12 trials to describe the relation between improvement in spine bone mineral density and reduction in risk of vertebral fracture in postmenopausal women. We also used logistic models to estimate the proportion of the reduction in risk of vertebral fracture observed with alendronate in the Fracture Intervention Trial that was due to improvement in bone mineral density.

RESULTS

Across the 12 trials, a 1% improvement in spine bone mineral density was associated with a 0.03 decrease (95% confidence interval [CI]: 0.02 to 0.05) in the relative risk (RR) of vertebral fracture. The reductions in risk were greater than predicted from improvement in bone mineral density; for example, the model estimated that treatments predicted to reduce fracture risk by 20% (RR = 0.80), based on improvement in bone mineral density, actually reduce the risk of fracture by about 45% (RR = 0.55). In the Fracture Intervention Trial, improvement in spine bone mineral density explained 16% (95% CI: 11% to 27%) of the reduction in the risk of vertebral fracture with alendronate.

CONCLUSION

Improvement in spine bone mineral density during treatment with antiresorptive drugs accounts for a predictable but small part of the observed reduction in the risk of vertebral fracture.

Perthes lesion (a variant of the Bankart lesion): MR imaging and MR arthrographic findings with surgical correlation

OBJECTIVE

The aim of this study was to evaluate the use of MR imaging in the characterization of the Perthes lesion by correlating MR findings with findings at arthroscopy.

CONCLUSION

The use of a combination of axial and abduction-external rotation position sequences on MR images can be helpful in the diagnosis of a Perthes lesion. A fluid-filled joint with capsular distension, caused by either a large amount of effusion or MR arthrography, was found to be helpful in outlining Perthes lesions. Adding the abduction-external rotation position to the protocol in patients in whom Perthes lesion is suspected will increase diagnostic accuracy and may reveal a Perthes lesion not visible on axial images, as was the case in 50% of the patients in our series.

Fractures before menopause: a red flag for physicians

There is substantial interest in the early identification of women at risk for osteoporotic fractures, so that preventive measures may be instituted early. We examined whether women with a history of fractures before menopause were at an increased risk of fractures after menopause. We obtained information about any lifetime fractures of the hip, arm, spine, wrist, leg, ankle, foot and finger from 9086 ambulatory white women ages 65 years and older participating in the Study of Osteoporotic Fractures. We also measured bone mineral density and recorded history of falls, maternal fracture history, drug use, diet, functional status, and other characteristics commonly associated with osteoporotic fractures. We used proportional hazards models to estimate the effects of fractures that occurred before menopause on the risk of fractures after menopause, in particular those that occurred during the 12 years of study follow-up. The risk of fractures of all types during the study period was greater among women with a premenopausal fracture of any type compared with women without a premenopausal fracture (hazard ratio (HR), 1.33; 95% confidence interval (CI), 1.14-1.56; p<0.001). Adjustment for possible confounders, including bone mineral density, had only a modest effect (HR, 1.25; 95% CI, 1.03-1.50; p<0.02). An increased risk of fracture among women with a premenopausal fracture was also seen after stratification by estrogen use, propensity to fall and maternal fracture history. Premenopausal fractures are therefore a risk factor for subsequent fractures independent of other risk factors for osteoporotic fractures, such as bone mineral density. A fracture history, including fractures before menopause, should be obtained when making decisions about preventive treatments.

In vivo assessment of architecture and micro-finite element analysis derived indices of mechanical properties of trabecular bone in the radius

Measurement of microstructural parameters of trabecular bone noninvasively in vivo is possible with high-resolution magnetic resonance (MR) imaging. These measurements may prove useful in the determination of bone strength and fracture risk, but must be related to other measures of bone properties. In this study in vivo MR imaging was used to derive trabecular bone structure measures and combined with micro-finite element analysis (microFE) to determine the effects of trabecular bone microarchitecture on bone mechanical properties in the distal radius. The subjects were studied in two groups: (I) postmenopausal women with normal bone mineral density (BMD) (n = 22, mean age 58 +/- 7 years) and (II) postmenopausal women with spine or femur BMD -1 SD to -2.5 SD below young normal (n = 37, mean age 62 +/- 11 years). MR images of the distal radius were obtained at 1.5 T, and measures such as apparent trabecular bone volume fraction (App BV/TV), spacing, number and thickness (App TbSp, TbN, TbTh) were derived in regions of interest extending from the joint line to the radial shaft. The high-resolution images were also used in a micro-finite element model to derive the directional Young's moduli (E1, E2 and E3), shear moduli (G12, G23 and G13) and anisotropy ratios such as E1/E3. BMD at the distal radius, lumbar spine and hip were assessed using dual-energy X-ray absorptiometry (DXA). Bone formation was assessed by serum osteocalcin and bone resorption by serum type I collagen C-terminal telopeptide breakdown products (serum CTX) and urinary CTX biochemical markers. The trabecular architecture displayed considerable anisotropy. Measures of BMD such as the ultradistal radial BMD were lower in the osteopenic group (p<0.01). Biochemical markers between the two groups were comparable in value and showed no significant difference between the two groups. App BV/TV, TbTh and TbN were higher, and App TbSp lower, in the normal group than the osteopenic group. All three directional measures of elastic and shear moduli were lower in the osteopenic group compared with the normal group. Anisotropy of trabecular bone microarchitecture, as measured by the ratios of the mean intercept length (MIL) values (MIL1/MIL3, etc.), and the anisotropy in elastic modulus (E1/E3, etc.), were greater in the osteopenic group compared with the normal group. The correlations between the measures of architecture and moduli are higher than those between elastic moduli and BMD. Stepwise multiple regression analysis showed that while App BV/TV is highly correlated with the mechanical properties, additional structural measures do contribute to the improved prediction of the mechanical measures. This study demonstrates the feasibility and potential of using MR imaging with microFE modeling in vivo in the study of osteoporosis.

Influence of region of interest and bone size on calcaneal BMD: implications for the accuracy of quantitative ultrasound assessments at the calcaneus

There is considerable technological diversity among quantitative ultrasound (QUS) devices used to assess osteoporosis. Because the distance between the transducer and the footplate remains constant, the location of the calcaneus measured will vary with foot size. This study was designed to quantify the variation in bone mineral density (BMD) between a manufacturer's region of interest (ROI_M), which is fixed relative to the footplate, and an anatomical region of interest (ROI_A), which is defined as 20% of calcaneal length. The effect of foot length and width on QUS variables measured using two Food and Drug Administration cleared QUS devices, the Sahara (Hologic) and the Achilles+ (Lunar) was assessed. 26 healthy subjects (12 male and 14 female), aged 22-54 years (35.6+/-10 years) and with foot lengths of 21.5 cm to 29.7 cm (25.1+/-2.3 cm) were recruited. QUS assessments were performed at the right calcaneus. In addition, a Hologic 4500 densitometer was used to measure the BMD of the calcaneus in the ROI_M and ROI_A. The sizes of the ROIs were approximated to the sizes of the transducers of the Sahara and Achilles+ devices. The results showed a significant difference in BMD between the two ROI locations for the Sahara device (BMD 0.642+/-0.135 g cm(-2) vs 0.616+/-0.114 g cm(-2), p=0.014), but no significant difference was found in BMD between the two locations for the Achilles device (BMD 0.661+/-0.120 g cm(-2) vs 0.662+/-0.123 g cm(-2), p=0.818). At the ROI_A, there was a significant difference in BMD between the two QUS devices (p<0.001). The correlation between QUS variables and BMD was slightly higher for the ROI_M (r=0.68-0.79, since this is site-matched) than the ROI_A (r=0.59-0.70) for the Achilles device, while for the Sahara device the correlations were r=0.35-0.40 and r=0.51-0.54, respectively. The smaller ROI of the Sahara device resulted in more than 50% of the subjects having BMD differences of greater than 5% between the ROI_A and the ROI_M, compared with only 20% of the subjects on the Achilles device. ROIs containing cortical bone edge and other soft tissues were found in 58% of cases for the Achilles device and 46% of cases for the Sahara device. The greatest differences occurred in very small and very large feet. Calcaneal length correlated significantly with Sahara speed of sound (SOS), and heel width correlated significantly with Achilles SOS. Heel width also correlated significantly with Sahara broadband ultrasound attenuation (BUA) but not Achilles+ BUA. These results suggest that variation in ROI and bone size might affect the accuracy of QUS measurements, since the calcaneus is heterogeneous both in terms of its external geometry and its internal structure and density.

North American male reference population for speed of sound in bone at multiple skeletal sites

Alternatives to dual-energy X-ray absorptiometry (DXA) have been sought to increase access to low-cost osteoporosis risk assessment. Early quantitative ultrasound (QUS) systems measured speed of sound (SOS) and broadband ultrasound attenuation (BUA) at the calcaneus, and these were demonstrated to be good predictors of hip fracture risk. Recent studies have demonstrated the usefulness of other peripheral sites to assess bone status. The Sunlight Omnisense (Sunlight Medical, Rehovot, Israel) is a portable, inexpensive QUS device capable of multiple-site SOS measurement. To provide a robust male reference database, 588 healthy Caucasian males aged 20-90 yr were recruited from 6 centers across North America. SOS measurements were taken at the distal 1/3 radius, proximal third phalanx, midshaft tibia, and fifth metatarsal. A female reference database has previously been collected at North American sites. The results indicate that SOS in males exhibits an age-related decline beginning in the fifth decade at the radius, phalanx, and metatarsal, whereas the tibial SOS remains nearly constant until the ninth decade. Although females reach a higher-peak SOS than males at most sites, SOS is higher in males at all sites after the sixth decade, as a result of a more gradual decline in SOS. Longitudinal monitoring of healthy men should be performed to confirm these cross-sectional results.

Discrepancy in results between spine and hip scans of a woman with end stage renal disease

Conditions and artifacts such as aortic calcifications, osteophytes, hip prostheses, and metallic objects can affect the results of dual X-ray absorptiometry scans of the spine and hip. Abdominal surgery often entails the use of metal sutures causing subtle artifacts near or over the lumbar spine resulting in inaccurate bone mineral density (BMD) measurements. We herein report a case of a woman whose spine BMD appeared normal while her hip BMD was > -3.5 SDs. Although the abdominal artifacts create some uncertainty in the diagnosis, renal osteodystrophy is suspect owing to the patient's renal history. This case demonstrates the importance of acquiring scans at two or more sites, closely evaluating scans for artifacts, and obtaining the patient's medical history.

Measurement of bone mineral density at the spine and proximal femur by volumetric quantitative computed tomography and dual-energy X-ray absorptiometry in elderly women with and without vertebral fractures

The goal of this study was to determine the effect of vertebral fracture status on trabecular bone mineral density (BMD) measurements obtained in the proximal femur and spine by helical volumetric quantitative computed tomography (vQCT). The study population consisted of 71 Italian women (average age 73 +/- 6) years. This group included 26 subjects with radiographically confirmed atraumatic vertebral fractures and 45 controls. The subjects received helical CT scans of the L1 and L2 vertebral bodies and the hip. The three-dimensional CT images were processed using specialized image analysis algorithms to extract measurements of trabecular, cortical, and integral BMD in the spine and hip. To compare the vQCT results with the most widely used clinical BMD measurement, dual X-ray absorptiometry (DXA) scans of the anteroposterior (AP) spine and proximal femur were also obtained. The difference between the subjects with vertebral fractures and the age-matched controls was computed for each BMD measure. All BMD measurements showed statistically significant differences, which ranged from 7% to 22% between subjects with fractures and controls. Although, given our small sample size, we could not detect statistically significant differences in discriminatory power between BMD techniques, integral BMD of the spine measured by vQCT and DXA tended to show stronger associations with fracture status (0.001 < p < 0.004). Measurements by QCT and DXA at the hip were also associated with vertebral fracture status, although the association of DXA BMD with fracture status was explained largely by differences in body weight between subjects with vertebral fractures and controls.

Three-point Dixon chemical-shift imaging for evaluating articular cartilage defects in the knee joint on a low-field-strength open magnet

OBJECTIVE

The purpose of our study was to assess the value of a modified three-point Dixon MR technique for evaluating articular cartilage defects in the knee joint on a low-field-strength open magnet, correlated with arthroscopy.

SUBJECTS AND METHODS

Twenty consecutive patients who underwent both MR imaging and arthroscopy of the knee joint for suspected internal derangement were examined. A modified three-point Dixon MR sequence with a single radiofrequency echo single-scan method for water and fat separation with correction of the static field inhomogeneities was performed on a 0.35-T open magnet to obtain fat suppression. The MR images were prospectively evaluated for the presence and grade of articular cartilage defects.

RESULTS

Uniform fat suppression was obtained in all patients using the modified three-point Dixon technique. Fifty-nine cartilage abnormalities were identified in 19 patients on the basis of arthroscopy. Forty-seven of 59 arthroscopically proven abnormalities were prospectively detected on MR imaging. Compared with arthroscopy, the overall sensitivity of the modified three-point Dixon technique in detecting cartilage lesions was 80% and the specificity was 73%. Sixty-five percent of the cartilage abnormalities were graded identically on MR imaging and arthroscopy.

CONCLUSION

The modified three-point Dixon sequence is a useful technique for achieving fat suppression in the knee joint on a 0.35-T open magnet. It is a sensitive and specific technique for the assessment of cartilage abnormalities in the knee.

Effects of current and discontinued estrogen replacement therapy on hip structural geometry: the study of osteoporotic fractures

It is assumed that estrogen influences bone strength and risk of fractures by affecting bone mineral density (BMD). However, estrogen may influence the mechanical strength of bones by altering the structural geometry in ways that may not be apparent in the density. Repeated dual energy X-ray absorptiometry (DXA) hip scan data were analyzed for bone density and structural geometry in elderly women participating in the Study of Osteoporotic Fractures (SOF). Scans were studied with a hip structural analysis program for the effects of estrogen replacement therapy (ERT) on BMD and structural geometry. Of the 3,964 women with ERT-use data, 588 used ERT at both the start and end of the approximately 3.5-year study, 1,203 had past use which was discontinued by clinic visit 4, and 2,163 women had never used ERT. All groups lost BMD at the femoral neck, but the reduced BMD among users of ERT was entirely due to subperiosteal expansion and not bone loss, whereas both bone loss and expansion occurred in past or nonusers. BMD increased 0.8%/year at the femoral shaft among ERT users but decreased 0.8%/year among nonusers. Section moduli increased at both the neck and shaft among ERT users but remained unchanged in past and nonusers. Current, but not past, use of estrogen therapy in elderly women seems to increase mechanical strength of the proximal femur by improving its geometric properties. These effects are not evident from changes in femoral neck BMD.

Radiographic damage in rheumatoid arthritis correlates with functional disability but not direct medical costs

OBJECTIVE

Few longitudinal data exist on the relationship between radiographic damage and self-reported functional disability and direct medical costs in rheumatoid arthritis (RA). We assessed these relationships.

METHODS

One hundred thirty patients with RA (at time of the first available radiograph, mean age 56.6 yrs, 16.9% male, mean disease duration 16.8 yrs) were followed for up to 13.4 years. Semiannually, they reported on functional disability (0 = no difficulty, 3 = unable to do), global severity (0 = very well, 100 = very poor), pain (0 = no pain, 3 = severe pain), and health services utilization through completion of the Stanford Health Assessment Questionnaire (HAQ). Concurrent hand radiographs were scored for erosions and joint space narrowing using the Genant method and a single score summing both erosions and joint space narrowing for both hands was calculated (0 = no damage, 200 = maximum damage). The univariate association of functional disability, global severity, pain, or direct medical costs with concurrent radiographic damage was assessed through Spearman correlations and hierarchical regression models. The hierarchical models permit exploitation of the between-patient and within-patient variation present in our longitudinal data.

RESULTS

At the time of the first available radiograph, mean (SD) levels of functional disability, global severity, and pain were 1.3 (0.7), 39.4 (21.0), and 1.1 (0.7), respectively. At entry into the study, the average radiograph score was 49.7 and upon leaving the study it was 66.9. Patients were followed an average of 6.7 years, with radiograph scores increasing at an average rate of 2.5 units/yr. The Spearman correlation [95% confidence interval (CI)] between average per-patient radiograph score and average per-patient HAQ disability index, average per-patient global severity, average per-patient pain score, and average per-patient direct medical costs was, respectively, 0.42 (0.26, 0.55), 0.23 (0.06, 0.39), 0.20 (0.03, 0.36), and 0.06 (-0.11, 0.23). The mean slope (95% CI) for disability on radiograph score was 0.0186 (0.0132, 0.0226), for severity on radiographs 0.1889 (0.1295, 0.2498), and for pain on radiographs 0.0057 (0.0027, 0.0084). As an example, over 10 years, a 25 unit (i.e., 50%) increase in radiograph scores would, on average, be associated with a 0.46 unit (i.e., 35%) increase in disability, a 4.72 unit (12%) increase in global severity score, and a 0.14 unit (13%) increase in pain, all expressed on the HAQ scales. There was little association between radiograph score and direct medical costs.

CONCLUSION

A clinically meaningful association exists between radiographic damage and self-reported functional disability, suggesting that interventions that slow radiographic progression may improve the patient's health status. Such a relationship was not observed between radiographic damage and direct medical costs.

Evaluation of a gel-coupled quantitative ultrasound device for bone status assessment

OBJECTIVE

To evaluate a new gel-coupled calcaneal quantitative ultrasound system, Osteospace (Medilink, Montpellier, France), which was designed to assess the status of bone in the calcaneus.

METHODS

The study group consisted of 215 healthy white women aged 20 to 85 years and 51 white women aged 60 to 86 years with osteoporotic fractures. Fifty-two healthy women aged 50 to 85 years were randomly selected from the healthy cohort as the control group. All the women had calcaneal quantitative ultrasonic measurements. The women with osteoporotic fractures and the control group also had proximal femur and lumbar anteroposterior spine bone mineral density measurements using dual X-ray absorptiometry. Bone mineral density was also measured in a subgroup of 54 women at the calcaneus.

RESULTS

There was a significant inverse correlation of broadband ultrasound attenuation and speed of sound with age (P < .001). Short-term measurement precision values expressed as coefficients of variation were 1.72% for broadband ultrasound attenuation and 0.64% for speed of sound, and standardized short-term precision values were 6.09% for broadband ultrasound attenuation and 3.87% for speed of sound. The correlations between the quantitative ultrasonic parameters and calcaneal bone mineral density were 0.69 (P = .0001) for broadband ultrasound attenuation and 0.45 (P = .0008) for speed of sound. Both quantitative ultrasonic parameters and all bone mineral density measurements of the hip and spine differed significantly between the control and osteoporotic fracture groups (P < .01). Age-, weight-, and height-adjusted odds ratios per SD decrease were as follows: broadband ultrasound attenuation, 1.79; speed of sound, 1.83; spine bone mineral density, 2.34; femoral neck bone mineral density, 1.69; and total hip bone mineral density, 1.85. The areas under the receiver operating characteristic curve for quantitative ultrasound parameters and bone mineral density measurements were close, ranging from 0.75 to 0.80.

CONCLUSIONS

This new quantitative ultrasound system can detect age- and menopause-related influences on skeletal status and can discriminate healthy women from those with osteoporotic fractures in a manner comparable with that of bone mineral density measurement by dual X-ray absorptiometry.

Sustained-release sodium fluoride in the treatment of the elderly with established osteoporosis

BACKGROUND

We ascertained the safety and efficacy of fluoride in augmenting spinal bone mass and reducing spinal fractures in older women with established osteoporosis. We compared a combination of sustained-release sodium fluoride, calcium citrate, and cholecalciferol (SR-NaF group) with calcium and cholecalciferol alone (control group).

METHODS

Eighty-five ambulatory women aged 65 years or older with 1 or more nontraumatic vertebral compression fractures were enrolled in a 42-month randomized, double-blind, placebo-controlled trial. Primary outcome measures were vertebral fracture rate, bone mass, and safety.

RESULTS

The vertebral fracture rate determined by means of computer assistance in the SR-NaF group was significantly lower than that in the control group (relative risk [RR], 0.32; 95% confidence interval [CI], 0.14-0.73; P =.007). Results of visual adjudicated inspection also confirmed a significant reduction in fracture rate (RR, 0.40; 95% CI, 0.17-0.95; P =.04). Bone mineral density in L2 through L4 increased significantly from baseline in the SR-NaF group by 5.4% (95% CI, 2.7%-8.2%; P<.001), and by 3.2% in the control group (95% CI, 0.8%-5.6%; P =.01). The between-group differences in bone mineral density were not significant. The femoral neck and total hip bone mineral density remained stable in the SR-NaF group and was not significantly different from that of the control group. There were no significant differences in adverse effects between groups.

CONCLUSION

The SR-NaF group significantly decreased the risk for vertebral fractures and increased spinal bone mass without reducing bone mass at the femoral neck and total hip.

Assessment of bone status using speed of sound at multiple anatomical sites

Studies in vitro and in vivo have shown that quantitative ultrasound (QUS) is a valid tool for the assessment of bone status. Current QUS methods using the transmission technique are limited to one peripheral bone site. A new system, Sunlight Omnisense (Omnisense, Sunlight Medical Ltd., Rehovot, Israel), measures speed of sound (SOS, in m/s) along the surface of the bone based on an axial transmission technique. The Omnisense can measure SOS at several anatomical sites. This study evaluated the SOS at different anatomical sites in a healthy population. A total of 334 adult women from three research centers in the USA and Canada with a mean (+/- SD) age of 48.8 (+/- 17.4) years were enrolled in this study. SOS was measured at the proximal third phalanx, distal one third radius, midshaft tibia, and fifth metatarsal. The mean SOS (+/- SD) values for the phalanx, radius, tibia and metatarsal were 3984 (+/- 221), 4087 (+/- 147), 3893 (+/- 150) and 3690 (+/- 246) m/s, respectively. Each anatomical site SOS was significantly different (p < 0.001) from that of the other sites. SOS at the different anatomical sites was modestly, but significantly, correlated (r = 0.31 to 0.56, p < 0.001). Similar correlation coefficients were obtained for the T scores. The mean T scores for subjects over the age of 60 years were -1.94, -2.01, -0.97 and -1.42 for the phalanx, radius, tibia and metatarsal, respectively. The age of peak SOS and the rate of change thereafter varied with anatomical site, implying that the prevalence of osteopenia and osteoporosis was site-dependent if only one T score cut-off point was used. Comparing individuals, 10% to 17% of patients had T scores that differed by more than a factor of 2 between sites. Weight and age were some of the contributing factors to this heterogeneity. The Omnisense provides an opportunity to assess bone status at different anatomical sites. Whether or not combining measurements from all these anatomical sites will improve osteoporosis management still needs to be determined.

Current methods and advances in bone densitometry

Bone mass is the primary, although not the only, determinant of fracture. Over the past few years a number of noninvasive techniques have been developed to more sensitively quantitate bone mass. These include single and dual photon absorptiometry (SPA and DPA), single and dual X-ray absorptiometry (SXA and DXA) and quantitative computed tomography (QCT). While differing in anatomic sites measured and in their estimates of precision, accuracy, and fracture discrimination, all of these methods provide clinically useful measurements of skeletal status. It is the intent of this review to discuss the pros and cons of these techniques and to present the new applications of ultrasound (US) and magnetic resonance (MRI) in the detection and management of osteoporosis.

MRI of bone marrow in the distal radius: in vivo precision of effective transverse relaxation times

The effective transverse relaxation time T2* is influenced by the presence of trabecular bone, and can potentially provide a measure of bone density as well as bone structure. We determined the in vivo precision of T2* in repeated bone marrow measurements. The T2* measurements of the bone marrow of the distal radius were performed twice within 2 weeks in six healthy young volunteers using a modified water-presaturated 3D Gradient-Recalled Acquisition at Steady State (GRASS) sequence with TE 7, 10, 12, 20, and 30; TR 67; flip angle (FA) 90 degrees. An axial volume covering a length of 5.6 cm in the distal radius was measured. Regions of interest (ROIs) were determined manually and consisted of the entire trabecular bone cross-section extending proximally from the radial subchondral endplate. Reproducibility of T2* and area measurements was expressed as the absolute precision error (standard deviation [SD] in ms or mm2) or as the relative precision error (SD/mean x 100, or coefficient of variation [CV] in %) between the two-point measurements. Short-term precision of T2* and area measurements varied depending on section thickness and location of the ROI in the distal radius. Absolute precision errors for T2* times were between 1.3 and 2.9 ms (relative precision errors 3.8-9.5 %) and for area measurements between 20 and 55 mm2 (relative precision errors 5.1-16.4%). This MR technique for quantitative assessment of trabecular bone density showed reasonable reproducibility in vivo and is a promising future tool for the assessment of osteoporosis.

Structural adaptation to changing skeletal load in the progression toward hip fragility: the study of osteoporotic fractures

Longitudinal, dual-energy X-ray absorptiometry (DXA) hip data from 4187 mostly white, elderly women from the Study of Osteoporotic Fractures were studied with a structural analysis program. Cross-sectional geometry and bone mineral density (BMD) were measured in narrow regions across the femoral neck and proximal shaft We hypothesized that altered skeletal load should stimulate adaptive increases or decreases in the section modulus (bending strength index) and that dimensional details would provide insight into hip fragility. Weight change in the approximately 35 years between scan time points was used as the primary indicator of altered skeletal load. "Static" weight was defined as within 5% of baseline weight, whereas "gain" and 'loss" were those who gained or lost >5%, respectively. In addition, we used a frailty index to better identify those subjects undergoing changing in skeletal loading. Subjects were classified as frail if unable to rise from a chair five times without using arm support. Subjects who were both frail and lost weight (reduced loading) were compared with those who were not frail and either maintained weight (unchanged loading) or gained weight (increased loading). Sixty percent of subjects (n = 2,559) with unchanged loads lost BMD at the neck but not at the shaft, while section moduli increased slightly at both regions. Subjects with increasing load (n = 580) lost neck BMD but gained shaft BMD; section moduli increased markedly at both locations. Those with declining skeletal loads (n = 105) showed the greatest loss of BMD at both neck and shaft; loss at the neck was caused by both increased loss of bone mass and greater subperiosteal expansion; loss in shaft BMD decline was only caused by greater loss of bone mass. This group also showed significant declines in section modulus at both sites. These results support the contention that mechanical homeostasis in the hip is evident in section moduli but not in bone mass or density. The adaptive response to declining skeletal loads, with greater rates of subperiosteal expansion and cortical thinning, may increase fragility beyond that expected from the reduction in section modulus or bone mass alone.

Effect of parathyroid hormone (1-34) on fractures and bone mineral density in postmenopausal women with osteoporosis

BACKGROUND

Once-daily injections of parathyroid hormone or its amino-terminal fragments increase bone formation and bone mass without causing hypercalcemia, but their effects on fractures are unknown.

METHODS

We randomly assigned 1637 postmenopausal women with prior vertebral fractures to receive 20 or 40 microg of parathyroid hormone (1-34) or placebo, administered subcutaneously by the women daily. We obtained vertebral radiographs at base line and at the end of the study (median duration of observation, 21 months) and performed serial measurements of bone mass by dual-energy x-ray absorptiometry.

RESULTS

New vertebral fractures occurred in 14 percent of the women in the placebo group and in 5 percent and 4 percent, respectively, of the women in the 20-microg and 40-microg parathyroid hormone groups; the respective relative risks of fracture in the 20-microg and 40-microg groups, as compared with the placebo group, were 0.35 and 0.31 (95 percent confidence intervals, 0.22 to 0.55 and 0.19 to 0.50). New nonvertebral fragility fractures occurred in 6 percent of the women in the placebo group and in 3 percent of those in each parathyroid hormone group (relative risk, 0.47 and 0.46, respectively [95 percent confidence intervals, 0.25 to 0.88 and 0.25 to 0.861). As compared with placebo, the 20-microg and 40-microg doses of parathyroid hormone increased bone mineral density by 9 and 13 more percentage points in the lumbar spine and by 3 and 6 more percentage points in the femoral neck; the 40-microg dose decreased bone mineral density at the shaft of the radius by 2 more percentage points. Both doses increased total-body bone mineral by 2 to 4 more percentage points than did placebo. Parathyroid hormone had only minor side effects (occasional nausea and headache).

CONCLUSIONS

Treatment of postmenopausal osteoporosis with parathyroid hormone (1-34) decreases the risk of vertebral and nonvertebral fractures; increases vertebral, femoral, and total-body bone mineral density; and is well tolerated. The 40-microg dose increased bone mineral density more than the 20-microg dose but had similar effects on the risk of fracture and was more likely to have side effects.

Advanced imaging of the macrostructure and microstructure of bone

Noninvasive and/or nondestructive techniques are capable of providing more macro- or microstructural information about bone than standard bone densitometry. Although the latter provides important information about osteoporotic fracture risk, numerous studies indicate that bone strength is only partially explained by bone mineral density. Quantitative assessment of macro- and microstructural features may improve our ability to estimate bone strength. The methods available for quantitatively assessing macrostructure include (besides conventional radiographs) quantitative computed tomography (QCT) and volumetric quantitative computed tomography (vQCT). Methods for assessing microstructure of trabecular bone noninvasively and/or nondestructively include high-resolution computed tomography (hrCT), micro-computed tomography (muCT), high-resolution magnetic resonance (hrMR), and micromagnetic resonance (muMR). vQCT, hrCT and hrMR are generally applicable in vivo; muCT and muMR are principally applicable in vitro. Although considerable progress has been made in the noninvasive and/or nondestructive imaging of the macro- and microstructure of bone, considerable challenges and dilemmas remain. From a technical perspective, the balance between spatial resolution versus sampling size, or between signal-to-noise versus radiation dose or acquisition time, needs further consideration, as do the trade-offs between the complexity and expense of equipment and the availability and accessibility of the methods. The relative merits of in vitro imaging and its ultrahigh resolution but invasiveness versus those of in vivo imaging and its modest resolution but noninvasiveness also deserve careful attention. From a clinical perspective, the challenges for bone imaging include balancing the relative advantages of simple bone densitometry against the more complex architectural features of bone or, similarly, the deeper research requirements against the broader clinical needs. The considerable potential biological differences between the peripheral appendicular skeleton and the central axial skeleton have to be addressed further. Finally, the relative merits of these sophisticated imaging techniques have to be weighed with respect to their applications as diagnostic procedures requiring high accuracy or reliability on one hand and their monitoring applications requiring high precision or reproducibility on the other.

Classification of osteoporosis based on bone mineral densities

In this article we examine the role of bone mineral density (BMD) in the diagnosis of osteoporosis. Using information from 7671 women in the Study of Osteoporotic Fractures (SOF) with BMD measurements at the proximal femur, lumbar spine, forearm, and calcaneus, we examine three models with differing criteria for the diagnosis of osteoporosis. Model 1 is based on the World Health Organization (WHO) criteria using a T score of -2.5 relative to the manufacturers' young normative data aged 20-29 years, with modifications using information from the Third National Health and Nutrition Examination Survey (NHANES). Model 2 uses a T score of -1 relative to women aged 65 years at the baseline of the SOF population. Model 3 classifies women as osteoporotic if their estimated osteoporotic fracture risk (spine and/or hip) based on age and BMD is above 14.6%. We compare the agreement in osteoporosis classification according to the different BMD measurements for the three models. We also consider whether reporting additional BMD parameters at the femur or forearm improves risk assessment for osteoporotic fractures. We observe that using the WHO criteria with the manufacturers' normative data results in very inconsistent diagnoses. Only 25% of subjects are consistently diagnosed by all of the eight BMD variables. Such inconsistency is reduced by using a common elderly normative population as in model 2, in which case 50% of the subjects are consistently diagnosed as osteoporotic by all of the eight diagnostic methods. Risk-based diagnostic criteria as in model 3 improve consistency substantially to 68%. Combining the results of BMD assessments at more than one region of interest (ROI) from a single scan significantly increases prediction of hip and/or spine fracture risk and elevates the relative risk with increasing number of low BMD subregions. We conclude that standardization of normative data, perhaps referenced to an older population, may be necessary when applying T scores as diagnostic criteria in patient management. A risk-based osteoporosis classification does not depend on the manufacturers' reference data and may be more consistent and efficient for patient diagnosis.

Interleukin-1 receptor antagonist treatment of rheumatoid arthritis patients: Radiologic progression and correlation of Genant/Sharp and Larsen scoring methods

OBJECTIVE

The Genant/Sharp scoring method is a validated radiologic scoring system useful for diagnosing, classifying, and defining specific clinical problems associated with rheumatoid arthritis (RA). The Genant/Sharp scoring method is described, and its level of correlation with the Larsen scoring method is discussed.

METHOD

The Genant/Sharp scoring system evaluates erosion, joint space narrowing (JSN), and a combination of erosion and JSN referred to as the total score. This method was used to determine change in radiographic progression during 2 consecutive 6-month intervals within a multicenter, double-blind, placebo-controlled study of recombinant human interleukin-1 receptor antagonist (IL-1ra) in patients with RA. These results were compared with the results obtained through the Larsen scoring method to determine their correlation.

RESULTS

The Genant/Sharp scoring method showed a moderate correlation with the Larsen scoring method, particularly at baseline, and showed similar treatment trends in a study of IL-1ra in patients with RA.

CONCLUSION

The Genant/Sharp scoring method provides an alternative to the Sharp and Larsen approaches for radiographic assessment in RA.

Structural analysis of high resolution in vitro MR images compared to stained grindings

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.

Automated measurement of radiographic hip joint-space width

Radiographic joint-space narrowing (JSN) is the principle indicator of cartilage loss in osteoarthritis (OA). JSN is usually assessed qualitatively by visual inspection or in clinical research, is measured manually with a graduated handheld lens directly applied to the x-ray film, or from digitized radiographs by hand tracing the joint margins with a mouse. The minimum joint-space width (mJSW) and joint-space area (JSA) are recorded as the indices of OA progression in epidemiological studies and clinical drug trials. We present a computerized method that automatically finds the articular margins of the hip to improve determination of mJSW and JSA. The algorithm requires that three seed points are manually identified on the femoral head and uses three steps to process each digitized hip x-ray. First, a Hough transform finds the center and radius (R) of a circle that approximates the femoral head. Finding R indicates whether magnification differences must be corrected on repeat exams. Second, a gradient algorithm finds the edge of the femoral head and acetabulum. Third, the mid-line of the femoral neck is automatically found and used to define the joint portion (theta) that is assessed for narrowing. theta is fixed for follow-up exams of the same subject. The algorithm was evaluated in three ways to determine its performance characteristics. First, the inter-reader and intra-reader variability for mJSW and JSA associated with the selection of the seed points was found to be negligible (< 1%) compared to the variability associated with manual scoring with a lens or by tracing the joint margins with a mouse. Second, from duplicate hip x-rays of 19 subjects with OA, the Root Mean Square Standard Deviation and coefficient of variation for mJSW and JSA defined by the algorithm was determined to be better than manual techniques by at least a factor of 2. Third, the algorithm correctly identified the joint margin in more than 85% of the 105 cases tested. Automated measures of radiographic hip joint-space narrowing is less subjective than manual methods and may be applicable for monitoring OA progression in clinical research.

A comparison of spinal quantitative computed tomography with dual energy X-ray absorptiometry in European women with vertebral and nonvertebral fractures

Quantitative computed tomography (QCT) was compared to dual X-ray absorptiometry (DXA) measured in the lumbar spine of 508 European women defined as normal without fracture (NoF), or osteoporotic (OP), with either vertebral fracture (VF), or peripheral fracture (PF). The correlations between QCT and DXA BMD measurements were significantly different in normal and in osteoporotic patients, indicating that the two exams do not measure the same bone aspects. According to ROC curves results, QCT Z-scores separate OP from NoF with better sensitivity than all other measurements. A threshold to differentiate OP from NoF was chosen at Z-score = -1 for DXA-BMD and -1.5 for QCT-BMD. VF patients showed a highly significant decrease in BMD by DXA or QCT. PF patients revealed measurements lower than those of normal subjects but greater than those of VF, calling into question the idea of a diffuse osteoporosis causing nonvertebral fractures that is measurable by spinal DXA or QCT. DXA is weakly dependent upon age, and T-score or Z-score are equivalent for evaluating osteoporosis. QCT depends greatly upon age, and Z-score appears to be more efficient.

Vertebral morphometry: a comparison of long-term precision of morphometric X-ray absorptiometry and morphometric radiography in normal and osteoporotic subjects

Vertebral morphometry, the quantification of vertebral body shape, has proved a useful tool in the identification and evaluation of osteoporotic vertebral deformities in both epidemiologic surveys and clinical trials. Although conventionally it has been performed on lateral radiographs of the thoracolumbar spine (morphometric radiography, MRX), it may now be accomplished on morphometric X-ray absorptiometry (MXA) scans, acquired on dual-energy X-ray absorptiometry (DXA) machines. In this study the long-term precision of vertebral height measurement using MXA and MRX was directly compared. Initially 24 postmenopausal women were recruited (mean age 67+/-5.8 years): 12 normal subjects (group 1) and 12 with osteoporosis and known vertebral deformities (group 2). Each subject attended for a baseline visit at which they had a MXA examination and lateral thoracic and lumbar radiographs. Twenty-one subjects then returned 1.7+/-0.4 years later (10 subjects from group 1 and 11 from group 2) for a follow-up visit to repeat both the MXA scans and conventional radiographs. The baseline MXA scans and conventional radiographs were each analyzed quantitatively by two observers in a masked fashion, using a standard six-point method. The follow-up images were then analyzed by the same observers. The MRX observers were masked to the baseline analyses, while the MXA observers utilized the manufacturer's 'compare' facility. On all scans and radiographs anterior (Ha), mid (Hm) and posterior (Hp) vertebral heights were measured and wedge (Ha/Hp) and mid-wedge (Hm/Hp) ratios calculated for each vertebral body, ideally from T4 to L4. MRX analyzed 129 of the 130 available vertebrae in group 1 at both visits and 141 of the 143 available in group 2, while MXA analyzed 124 vertebrae in group 1 at both visits and 127 in group 2. Intra- and inter-observer precision errors, particularly in terms of coefficient of variation (CV%), were larger for MXA than for MRX in both normal subjects and those with vertebral deformities. For example, intra-observer precision errors for vertebral height measurement were 0.62 mm (2.9%) for MXA compared with 0.63 mm (2.2%) for MRX in group 1 (normal) subjects and 0.82 mm (4.2%) for MXA compared with 0.85 mm (3.3%) for MRX for group 2 (osteoporosis and vertebral deformities) subjects. Both MXA and MRX inter-observer precision was clearly poorer than the intra-observer precision, a problem associated with any morphometric technique. This was particularly noticeable for MXA; for example, precision of vertebral height measurement in group 1 subjects was 0.62 mm (2.9%) for intra-observer compared with 0.99 mm (4.6%) for inter-observer analyses. MXA and MRX intra- and inter-observer precision was significantly poorer for subjects with vertebral deformities compared with those without, with the CV% for subjects with vertebral deformity approximately 50% greater than that of normal subjects. For example, MRX intra-observer precision for the midwedge ratio was 2.6% for group 1 subjects compared with 3.8% for group 2 subjects. The precision of vertebral height measurement on deformed vertebrae of group 2 subjects was poorer than that for normal vertebrae in the same subjects using both MXA and MRX, as a result of increased variability in point placement. For example, MXA intra-observer precision (RMS SD) for the wedge ratio precision was 0.037 (3.9%) for normal vertebrae compared with 0.060 (6.6%) for deformed vertebrae. We conclude that MXA precision was generally poorer than MRX, although both techniques were adversely affected by the presence of vertebral deformities and the use of more than one observer. Although precision errors for both techniques were substantially smaller than the 20-25% reduction in vertebral height frequently proposed to identify incident deformities, the poorer precision of MXA may lead to an increased risk of erroneous classification of vertebrae as normal or deformed.

Treatment of painful osteoporotic vertebral fractures with percutaneous vertebroplasty or kyphoplasty

Vertebral fracture is the most common complication of osteoporosis. It results in significant mortality and morbidity, including prolonged and intractable pain in a minority of patients. Vertebroplasty and kyphoplasty, procedures that involve percutaneous injection of bone cement into a collapsed vertebra, have recently been introduced for treatment of osteoporotic patients who have prolonged pain (several weeks or longer) following vertebral fracture. To determine the details of the procedures and to gather information on their safety and efficacy, we performed a MEDLINE search using the terms 'vertebroplasty' and 'kyphoplasty.' We reviewed reports of these procedures in patients with osteoporosis. We supplemented the articles found with other papers known to the authors and with presentations at national meetings. Randomized trials of vertebroplasty and kyphoplasty have not been reported. Case reports suggest that these procedures are associated with pain relief in 67% to 100% of cases. Short-term complications, mainly the result of extravasation of cement, include increased pain and damage from heat or pressure to the spinal cord or nerve roots. Proper patient selection and good technique should minimize complications, but rarely, decompressive surgery is needed. Long-term benefits have not yet been shown, but potentially include prevention of recurrent pain at the treated level(s) with both procedures, and, with kyphoplasty, reversal of height loss and spinal deformity, an improved level of function, and avoidance of chronic pain and restriction of internal organs. Possible long-term complications, again not fully evaluated, include local acceleration of bone resorption caused by the treatment itself or by foreign-body reaction at the cement-bone interface, and increased risk of fracture in treated or adjacent vertebrae through changes in mechanical forces. Controlled trials are needed to determine both short-term and long-term safety and efficacy of vertebroplasty and kyphoplasty. Both procedures may be useful for osteoporotic patients who have prolonged pain following acute vertebral fracture. Until there is conclusive evidence for efficacy and long-term safety, these procedures should be done only in carefully selected patients, only by experienced operators with appropriate high-quality imaging equipment, and ideally at centers that are participating in controlled trials.

Is quantitative ultrasound dependent on bone structure? A reflection

Trabecular bone plays a significant role in maintaining bone structural integrity. Its density is a significant determinant of bone strength and fracture risk, but there is still unexplained variance. It has been suggested that the ability to measure structural information will improve the estimation of bone strength and fracture risk. Quantitative ultrasound (QUS) is a mechanical wave that can be influenced by bone structure, in addition to bone mineral density (BMD). This article reviews the evidence in the literature supporting or refuting this assumption. Theoretically, the propagation of QUS is influenced by both structure and density of the medium. QUS measurement in vivo shows weak but significant association with axial BMD. However, the association becomes stronger when measured in vitro. Broadband ultrasound attenuation (BUA) exhibits a nonlinear relationship with density over a large density range. When cubes of cancellous bone are measured in the three orthogonal directions, both BUA and speed of sound (SOS) show significant anisotropy which mirrors mechanical anisotropy. QUS has also been shown to correlate significantly with structural parameters measured by histomorphometry. However, structure remains a significant predictor after adjustment for BMD mainly in bovine samples. Other studies using phantoms of bone samples have also demonstrated that QUS is dependent on structure. There is preliminary indication that fractal dimensions are significantly associated with QUS. The ultimate usefulness of structural dependence of QUS will be in its ability to improve bone strength estimation above and beyond density. There is ample evidence documenting the ability of QUS to predict bone strength in vitro. BMD is a significant predictor of bone strength and the additive value of structure in estimating bone strength is variable. Clinically, ultrasound of the calcaneus is measured in one direction (medio-lateral) and the structural variation in this direction may be limited. Nevertheless, QUS can provide useful additional information to that provided by axial BMD due in part to different precision and accuracy errors and to biological discordance. On the whole one could conclude that ultrasound attenuation is due to structural parameters and these variables are also dependent on density.

Quantitative ultrasound of the tibia depends on both cortical density and thickness

This study investigated whether tibial speed of sound (SOS; SoundScan 2000, Myriad Ultrasound Systems, Israel) reflects not only bone mineral density (BMD) but also tibial cortical thickness, as assessed by dual-energy X-ray absorptiometry (DXA) and Quantitative CT (QCT) at a site-matched location. The secondary focus of the study was how tibial SOS compares with BMD at the spine and the hip, the most widely used locations for densitometry. Twenty-two young normal (N) and 23 postmenopausal women with spinal fractures (Fx) (mean (SD) age 35 (8) and 70 (5) years) underwent quantitative ultrasound (QUS) SOS measurement at the left tibial midshaft. From site-matched QCT scans (three 3-mm slices spaced along the QUS measurement region), BMD and cortical thickness were computed (QCT-cBMD, QCT-cTh). The cortex in the CT images was then subdivided into three concentric and equally spaced bands, and QCT-cBMD was computed separately for each band. DXA was performed at the mid-tibia (TIB BMD), at the spine (SPINE BMD) and the hip (total hip, HIP BMD). Correlation coefficients between parameters were determined with least-square linear fits. Intergroup differences were assessed by analysis of covariance, whose r2 value reflects the percentage variation in the data explained by group assignment. SOS correlated significantly with site-matched parameters (QCT-cBMD, OCT-cTh and TIB BMD, all r = 0.6, p < 0.001), SPINE BMD and HIP BMD (both r = 0.5, p < 0.001). Multiple regression with both QCT-cBMD and QCT-cTh against SOS yielded r = 0.7 with both parameters contributing significantly. For the cortex band subdivision, SOS correlated better with QCT-cBMD in the outermost band of the cortex (r = 0.67) than with the more central bands (r = 0.59 and r = 0.53). Group assignment could best explain SPINE BMD (r2 = 0.62) and HIP BMD (r2 = 0.51). SOS was comparable to TIB BMD (r2 = 0.3 vs. r2 = 0.35).: Our findings suggest that the tibial SOS measurement depends on both the thickness and density of the tibia, but is more strongly influenced by the density of the cortex near the surface than by its interior parts. The power of tibial ultrasound to discriminate between normal and fracture patients was less than that of spinal and femoral DXA BMD and comparable to site-matched DXA BMD.

Standardization of bone mineral density at femoral neck, trochanter and Ward's triangle

The International Committee for Standards in Bone Measurement (ICSBM) has published standardization formulas for total hip bone mineral density (BMD). In many applications, however, BMD of hip subregions, such as femoral neck (FN), trochanter (TR), and Ward's triangle (WT), are commonly measured. This paper addresses whether the standardization formulas for total hip BMD can be adequately used for hip subregions. We used data from 100 healthy women, from 20 to 80 years old, who had hip BMD measured in both the total hip and hip subregions by a Hologic QDR 2000, a Lunar DPX, and a Norland XR26 Mark II. The same women were used by ICSBM for the standardization of total hip BMD. In addition, we used data of 3139 patients from a clinical trial to validate our results. We derived standardization formulas for FN, TR, and WT using the same statistical method as that used for total hip BMD. We applied both total hip calibration formulas and subregion-specific formulas to the data and compared the corresponding effect. We found that the total hip calibration formulas can partially reduce BMD differences between the Hologic and Lunar as well as the Lunar and Norland scanners in hip subregions, but increase differences between the Hologic and Norland scanners. The subregion calibration formulas are most appropriate for calibrating subregion BMD values and their absolute changes, and should be adopted. Standardization is unnecessary for BMD percentage changes in our clinical trial data.

Multisite bone ultrasound measurement on North American female reference population

The Sunlight Omnisense is a portable quantitative ultrasound device that measures speed of sound (SOS) at multiple skeletal sites and therefore has the potential to provide a more complete assessment of an individual's overall fracture risk than single-site measurements such as the calcaneus. To provide a robust normative female database, 545 healthy Caucasian women ages 20-90 were recruited at five centers across North America. SOS measurements were obtained from the distal one-third radius, proximal third phalanx, midshaft tibia, and fifth metatarsal. The results demonstrate that peak SOS occurs around the age of 40, with maximum mean values of 4161, 3928, 3786, and 4092 m/s seen at the radius, tibia, metatarsal, and phalanx, respectively. Maximal rate of decline of SOS was seen in the decade following menopause (-12.4, -9.2, -12.1, and -18.8 m/s at the radius, tibia, metatarsal, and phalanx, respectively). Reproducibility between successive measurements indicates high precision, with standardized coefficients of variance ranging between 1.5 and 4.5%. Greatest precision was seen at the metatarsal. Further work is required to clarify the biologic significance of multisite SOS measurements and their use in the assessment of fracture risk.

In vivo assessment of trabecular bone structure using fractal analysis of distal radius radiographs

Our purpose in this study was (i) to measure trabecular bone structure using fractal analysis of distal radius radiographs in subjects with and without osteoporotic hip fractures, and (ii) to compare these measures with bone mineral density (BMD) as well as with measures of trabecular bone structure derived from high resolution magnetic resonance (MR) images. Distal radius radiographs were obtained using semi-industrial films (55 kVp, 400 mAs) in 30 postmenopausal patients, who had suffered osteoporotic hip fractures (74.8+/-8.2 years) in the last 24 months and 27 postmenopausal age-matched (74.6+/-6.6 yr) normal volunteers. Radiographs were digitized at 50 microm. A Fourier power spectrum-based fractal dimension (FD) characterizing the trabecular pattern was measured in a region of interest proximal to the joint line. The fractal dimension was calculated over two spatial frequency (f) ranges: FD1 was calculated over 0.5<log(f)<l.0, FD2 over the higher range 1.0<log(f)<1.5. Trabecular BMD in the radius was obtained using peripheral quantitative computed tomography (pQCT) (Stratec GmbH, Germany). In addition BMD of the proximal femur was determined using dual x-ray absorptiometry (DXA) (QDR 2000, Hologic, MA). In a subset of patients (16 controls and 18 with hip fractures), high resolution MR imaging of the distal radius (spatial resolution of 156 x 156 x 500 microm) was used to obtain measures analogous to bone histomorphometry. There were significant differences (p<0.05) between the fracture and nonfracture groups in the total femur BMD (13%), trabecular BMD in the distal radius (4%), and the fractal dimension in the radiographs (FD2) (3%). The correlations between FD2 and the total femur BMD as well as trabecular bone BMD in the distal radius were -0.48 (p<0.006) and -0.22 (p<0.33); respectively; FD1 increased with BMD and showed lower correlations. FD2 showed good correlations with App. Tb.N (-0.71) and App. Tb.Sp (0.69) (p<0.01), moderate correlation with App BV/TV (-0.53) (p<0.05), and no significant correlation with App. Tb.Th. The correlations between structural measures and FD1 showed the inverse trend and were typically lower. The odds ratios for a hip fracture were 2.44 for total femur BMD, 1.5 for trabecular BMD (radius), and 1.5 for FD2, respectively. In summary, the fractal measures derived from radiographs of the radius show differences between subjects with and without hip fractures, the predictive power of measures in the distal radius are comparable to radial trabecular BMD but lower than that of total hip BMD.

Measurement of endometrial thickness at US in multicenter drug trials: value of central quality assurance reading

PURPOSE

To assess the value of central quality assurance (QA) reading of transvaginal ultrasonographic (US) images obtained to measure endometrial thickness and to assess image quality.

MATERIALS AND METHODS

Results of 2,000 US examinations performed in 1,000 subjects during one of two multicenter drug trials were evaluated. Endometrial thickness was measured at the study site; images were then sent to the QA center, where an experienced sonologist evaluated endometrial thickness and image quality.

RESULTS

In 360 (18%) of the 2,000 examinations, image quality was insufficient for central QA reading. Repeat examinations were requested, and suggestions for improvement in technique were provided. In 349 (97%) of the 360 examinations, repeat US images were of acceptable quality. In 99 (5%) of the 1,989 examinations in which endometrial thickness was measured, central measurement of thickness differed by more than 2 mm from that of the site. In a group (n = 300) that was followed up for 1 year, requests for repeat US examinations decreased from 24% at baseline to 11% at 1 year.

CONCLUSION

Central QA reading provides a consistent evaluation of endometrial thickness on US images obtained in multicenter drug trials and helps to ensure the acquisition of high-quality transvaginal US images. It further leads to demonstrable improvement in site performance.

Estimation of wrist fracture load using phalangeal speed of sound: an in vitro study

This study aimed to evaluate the ability of speed of sound (SOS) measured at the phalanges to estimate simulated wrist fracture load and stress. SOS was measured along the proximal phalanges of the second, third and fourth fingers using an ultrasound (US) system operating in axial transmission mode. The bone mineral density (BMD) of the radius and the phalanges was also measured with quantitative computed tomography (QCT) and dual x-ray absorptiometry (DXA), and the combined cortical thickness (CCT) of the phalanges was measured from hand radiographs. After the measurements were completed, the radius was excised from the cadaver, embedded in polymethylmethacrylate and tested to failure on a servohydraulic testing machine. The configuration of the radius was chosen to simulate a fall onto the hand. Linear regression analysis showed a highly significant correlation between SOS (r = 0.76-0.94, p < 0.001), CCT (r = 0.86-0.90, p < 0.001) and BMD (r = 0.92-0.96, p < 0.0001) in the three proximal phalanges measured. SOS, BMD and CCT were significant predictors of fracture load (r = 0.60-0.69, p < 0.03) and stress (r = 0.65-0.77, p < 0.02). Cortical area and bone mineral content (BMC) of the radius were consistently higher predictors of fracture load (r = 0.76-0.82, p < 0.01 for area and r = 0.78-0.88, p < 0.01 for BMC) than BMD. The correlation of BMC and area was poorer with fracture stress. In a step-wise regression analysis using both phalangeal BMD and SOS, only SOS remained a significant predictor of fracture stress. In forward stepwise regression analysis, both cortical area and SOS were entered into the regression model to estimate fracture load. Only SOS remained significant in the model for estimating fracture stress. Phalangeal BMD was only entered in the combined model with the cortical area at the 4% site (r = 0.84, p = 0.002). Phalangeal SOS is a useful parameter in the assessment of bone status of the radius.