Osteoporotic Fractures: Diagnosis, Evaluation, and Significance From the International Working Group on DXA Best Practices.

Osteoporotic fractures, also known as fragility fractures, are reflective of compromised bone strength and are associated with significant morbidity and mortality. Such fractures may be clinically silent, and others may present clinically with pain and deformity at the time of the injury. Unfortunately, and even at the time of detection, most individuals sustaining fragility fractures are not identified as having underlying metabolic bone disease and are not evaluated or treated to reduce the incidence of future fractures. A multidisciplinary international working group with representation from international societies dedicated to advancing the care of patients with metabolic bone disease has developed best practice recommendations for the diagnosis and evaluation of individuals with fragility fractures. A comprehensive narrative review was conducted to identify key articles on fragility fractures and their impact on the incidence of further fractures, morbidity, and mortality. This document represents consensus among the supporting societies and harmonizes best practice recommendations consistent with advances in research. A fragility fracture in an adult is an important predictor of future fractures and requires further evaluation and treatment of the underlying osteoporosis. It is important to recognize that most fragility fractures occur in patients with bone mineral density T scores higher than -2.5, and these fractures confirm the presence of skeletal fragility even in the presence of a well-maintained bone mineral density. Fragility fractures require further evaluation with exclusion of contributing factors for osteoporosis and assessment of clinical risk factors for fracture followed by appropriate pharmacological intervention designed to reduce the risk of future fracture. Because most low-trauma vertebral fractures do not present with pain, dedicated vertebral imaging and review of past imaging is useful in identifying fractures in patients at high risk for vertebral fractures. Given the importance of fractures in confirming skeletal fragility and predicting future events, it is recommended that an established classification system be used for fracture identification and reporting.

History of etidronate.

Etidronate is a non-nitrogen-containing bisphosphonate. Because it binds with calcium and inhibits crystal formation and dissolution, it was considered by Procter & Gamble as an additive to toothpaste (to prevent build-up of tartar) and detergent (to bind calcium and increase sudsing in "hard" water). The first clinical use (1968) was for fibrodysplasia ossificans progressiva. The first approved clinical use (1977) was for treatment of Paget's disease of bone. Other approved indications are hypercalcemia of malignancy and heterotopic ossification, with a host of off-label uses (including fibrous dysplasia, periodontal disease, multiple myeloma, neuropathic arthropathy, pulmonary microlithiasis, diabetic retinopathy, bone metastases, melorheostosis, urinary stone disease, periodontal disease, etc.). Unique among bisphosphonates, etidronate (oral therapy) results in hyperphosphatemia, increased tubular reabsorption of phosphorus and increased levels of 1,25-dihydroxyvitamin D. The dose that reduces bone resorption is close to the dose that impairs mineralization; prolonged high-dose use can result in osteomalacia and bone fractures. Intermittent cyclic etidronate for osteoporosis resulted in favorable changes in bone density and histomorphometry (no mineralization defect) as well as a decrease in vertebral fracture rates in postmenopausal women with osteoporosis. Later studies showed similar effects in men with osteoporosis and patients with glucocorticoid-induced osteoporosis. Although its use for osteoporosis has given way to newer bisphosphonates and other agents, because of its unique properties, it remains the bisphosphonate of choice for treatment of heterotopic ossification.

Vertebral Augmentation for Osteoporotic Compression Fractures.

Vertebral augmentation procedures such as vertebroplasty and kyphoplasty were developed to reduce pain and improve quality of life for patients with osteoporotic vertebral compression fractures. However, the use of vertebral augmentation has been debated and questioned since its inception. This article addresses some of these issues.

Dual-energy X-ray absorptiometry diagnostic discordance between Z-scores and T-scores in young adults.

Diagnostic criteria for postmenopausal osteoporosis using central dual-energy X-ray absorptiometry (DXA) T-scores have been widely accepted. The validity of these criteria for other populations, including premenopausal women and young men, has not been established. The International Society for Clinical Densitometry (ISCD) recommends using DXA Z-scores, not T-scores, for diagnosis in premenopausal women and men aged 20-49 yr, though studies supporting this position have not been published. We examined diagnostic agreement between DXA-generated T-scores and Z-scores in a cohort of men and women aged 20-49 yr, using 1994 World Health Organization and 2005 ISCD DXA criteria. Four thousand two hundred and seventy-five unique subjects were available for analysis. The agreement between DXA T-scores and Z-scores was moderate (Cohen's kappa: 0.53-0.75). The use of Z-scores resulted in significantly fewer (McNemar's p<0.001) subjects diagnosed with "osteopenia," "low bone mass for age," or "osteoporosis." Thirty-nine percent of Hologic (Hologic, Inc., Bedford, MA) subjects and 30% of Lunar (GE Lunar, GE Madison, WI) subjects diagnosed with "osteoporosis" by T-score were reclassified as either "normal" or "osteopenia" when their Z-score was used. Substitution of DXA Z-scores for T-scores results in significant diagnostic disagreement and significantly fewer persons being diagnosed with low bone mineral density.

Perioperative management of bariatric surgery patients: focus on metabolic bone disease.

Chronic vitamin D deficiency, inadequate calcium intake, and secondary hyperparathyroidism are common in obese individuals, placing them at risk for low bone mass and metabolic bone disease. After bariatric surgery, they are at even higher risk, owing to malabsorption and decreased oral intake. Meticulous preoperative screening, judicious use of vitamin and mineral supplements, addressing modifiable risk factors, and monitoring the absorption of key nutrients postoperatively are essential in preventing metabolic bone disease in bariatric surgery patients.

DXA-generated Z-scores and T-scores may differ substantially and significantly in young adults.

Central dual-energy X-ray absorptiometry (DXA) is the gold standard for non-invasive measurement of bone mineral density (BMD). Using this value and subject demographics, DXA software calculates T-scores and Z-scores. Professional society guidelines for the management of osteoporosis are based on T-scores and Z-scores, rather than on the actual BMD value. Although one expects T-scores and Z-scores to be very similar in young men and women for any given BMD measurement, little literature exists on this issue. Our clinical experience shows that some younger adult individuals (premenopausal women and men younger than 50 yr) have larger than expected difference between their DXA T-score and Z-score. This cross-sectional study evaluates the extent of this discordance between Z-scores and T-scores in a sample of 4275 men and women aged 20-49 yr. All subjects were scanned by central DXA using equipment manufactured by GE Lunar, GE, Madison, WI, or Hologic, Inc., Bedford, MA. Significant differences between Z-scores and T-scores were seen within individuals at the lumbar spine, total hip, femoral neck, and trochanter (p value<0.001) for both DXA systems. Although these differences were less than half a standard deviation (SD) in most instances, the magnitude of difference was substantial at times, being 1 or more SD in up to 11% of cases (range: -1.95 to +1.54 SD). The smallest differences were seen at the total hip and the largest differences were seen at the femoral neck for both technologies. This is in part because there is no single standard Z-score definition, resulting in different methods of calculation across, and even within, DXA manufacturers. Standardization of Z-score definition and method of calculation is indicated. DXA Z-scores should be interpreted with caution in men and women aged 20-50 yr.

Repeat dual-energy X-ray absorptiometry (DXA) resulting from reminder letters for women with a baseline abnormal DXA.

The objective was to assess the effects of reminder letters on women returning for repeat bone density. We queried our clinical data repository to identify all women undergoing dual-energy X-ray absorptiometry (DXA) during the entire 2003 calendar year. Women with abnormal DXAs were entered into a database for reminder letters. The electronic medical record was then reviewed for the presence of the reminder letter and whether any repeat DXA scan was done. Approximately half of the women returned for repeat DXA of this group, approximately one-third were improved, one-third deteriorated, and the remaining were unchanged. We suggest a clinical benchmark of a minimum of 50% of women with abnormal bone density returning for repeat DXA on the same machine at a DXA imaging center should be a quality improvement goal. Further research into exploring why patients do not return for serial DXA and the impact of reminder letters on improving treatment outcomes should be conducted.

Uses and misuses of quantitative ultrasonography in managing osteoporosis.

Quantitative ultrasonography is attractive as a test for osteoporosis, being precise, radiation-free, portable, and inexpensive, but it is still no substitute for the gold-standard test, dual-energy x-ray absorptiometry (DXA). At present, it cannot be used to diagnose osteoporosis or to monitor the effects of medications on bone density. As more data become available, however, it may play a larger role. A thorough understanding of the utility and limitations of this test is necessary for using it effectively in clinical practice.

Vertebral fracture assessment: the 2005 ISCD Official Positions.

Vertebral Fracture Assessment (VFA) is a low radiation method for imaging the thoraco-lumbar spine using bone densitometers. VFA can easily be performed at the time of bone mineral density (BMD) measurement, allowing integration of BMD and vertebral fracture information into clinical patient care. As VFA is a relatively new procedure, it has received limited study and heretofore has not had widespread clinical application. Consequently, the International Society for Clinical Densitometry (ISCD) considered the following VFA issues at the 2005 Position Development Conference: (1) indications for VFA; (2) methodology for the diagnosis of vertebral fractures using VFA; and (3) indications for additional imaging after VFA. The ISCD Official Positions with respect to the above issues, as well as the rationale and evidence used to derive these positions, are presented here.

Three-dimensional texture analysis of cancellous bone cores evaluated at clinical CT resolutions.

The objective of this study was to determine if three-dimensional (3D) Haralick co-occurrence texture measures calculated from low-resolution CT images of trabecular bone correlate with 3D structural indices measured from high-resolution CT images. Thirty-three cubical regions of trabecular bone from human calcanei were analyzed using images obtained from a micro-computed tomography (micro-CT) scanner. 3D measures of bone architecture were calculated. The original images were then subsampled by factors of 5, 10, 15, and 20, and 3D texture features were calculated for each set of subsampled images. Linear regression models showed that co-occurrence texture features were significantly correlated with structural indices. Over 90% of the variation in three different structural indices was explained in two-variable regression models using texture features as predictors when the voxel side length was reduced by a factor of 10. Texture features calculated from clinical images may increase our ability to obtain trabecular bone architectural information when high-resolution images are unobtainable.

DXA scanning to diagnose osteoporosis: do you know what the results mean?

Dual-energy x-ray absorptiometry (DXA) provides useful information about osteoporosis and fracture risk that, combined with other risk factors for osteoporosis, helps guide therapy. However, DXA is operator-dependent, making it imperative to refer patients to sites where the operators are experienced in this technology.

Imaging of spinal stenosis.

Imaging has an important role in the diagnosis of canal and neuroforaminal stenosis when correlated with clinical symptoms. MR and CT myelography have the best correlation because of multiplanar reformatting. Special techniques to load the spine such as an upright MR increase sensitivity in detecting canal stenosis.

Body composition changes in cachectic patients receiving home parenteral nutrition.

BACKGROUND: The purpose of this study was to evaluate the initial body compositional changes experienced by malnourished patients requiring home parenteral nutrition (HPN) for repletion. METHODS: Eight patients were prospectively studied for 3 months. Body composition was determined by dual-energy X-ray absorptiometry (DXA), and a comprehensive nutrition assessment was performed including body weight, visceral proteins, triceps skinfold (TSF), midupper arm circumference (MUAC), midupper arm muscle circumference (MUAMC), body mass index (BMI), delayed hypersensitivity skin tests (DHST), and diet history. RESULTS: Body composition measured by DXA showed an increase in (mean +/- SD) total fat from 5770 +/- 2805 to 10581 +/- 1980 g (p < .001) and bone mineral content from 2155 +/- 429 to 2190 +/- 443 g (p = .047). Lean soft tissue remained unchanged. Body weight and BMI increased from 47.7 +/- 6.6 to 53.6 +/- 8.2 kg (p = .006) and from 16.6 +/- 1.5 to 18.6 +/- 1.5 kg/m2 (p = .005), respectively. TSF increased from 6.3 +/- 3.1 to 10.4 +/- 4.0 mm (p < .001), and MUAMC remained stable. There was a significant improvement in transferrin from 191 +/- 82 to 326 +/- 128 mg/dL (p = .043), and a trend toward improvement in albumin and DHST. Body weight was highly correlated with DXA weight at baseline (r = .997; 95% confidence interval [CI], 0.98 to 1.00; p < .001) and at 3 months (r = .988; 95% CI, 0.93 to 1.00; p <.001). TSF correlated with total fat as measured by DXA at baseline (r = .839; 95% CI, 0.33 to 0.97; p = .009) but not at 3 months (r = .693; 95% CI, -0.02 to 0.94; p = .057). MUAMC correlated with lean soft tissue measured by DXA both at baseline (r = .739; 95% CI 0.07 to 0.95; p = .036) and at 3 months (r = .870; 95% CI, 0.43 to 0.98; p = .005). Physical activity, on a subjective scale of 1 (low activity) to 3 (high activity), improved over the 3-month period from 1.3 +/- 0.5 to 2.2 +/- 0.8 (p = .031). CONCLUSIONS: Initial weight gain experienced by malnourished HPN patients is primarily fat. Bone mineral content increases, but lean soft tissue does not change. Overall nutritional status is improved as exhibited by significant improvements in body weight and serum transferrin and a trend toward improvement in albumin and delayed hypersensitivity skin tests.

In vitro stability of FRA spacers with integrated crossed screws for anterior lumbar interbody fusion.

STUDY DESIGN: Mechanical testing of human lumbar functional spine units was carried out after instrumenting the disc space with femoral ring allografts (FRAs) with and without integrated crossed anterior screws applied into the adjacent bodies. OBJECTIVES: To assess the stability of FRA construct with and without the integrated crossed anterior screws and to compare that with the intact specimen. SUMMARY OF BACKGROUND DATA: Most modern methods of achieving anterior lumbar intervertebral fusion rely on the use of interbody spacers to restore and maintain intervertebral height, overall alignment, and stability while facilitating arthrodesis. The FRAs have the advantage of biologic compatibility but may not have enough stability when used as stand-alone devices. FRA spacers alone are less stiff in torsion and extension compared with other instrumented constructs. Increased motion could lead to higher failure rates because of graft migration and pseudarthrosis. This makes the use of supplementary anterior or posterior fixation necessary. The current authors hypothesized that the addition of anterior integrated crossed screws applied through the FRA spacer into the adjacent vertebral bodies would increase the stability of the FRA spacer in extension and torsion in the absence of further posterior instrumentation. METHODS: Seven fresh-frozen human cadaveric lumbar spine functional spine units were tested applying cantilever bending moments in flexion, lateral bending, torsion, and extension. The specimens were tested in the following sequence: intact, with FRA spacer alone and with FRA spacer and integrated crossed screws. The stiffness of each construct was then compared with the intact specimen. Specimens with obvious deformity on radiographs or dual-energy radiograph absorptiometry t score values <-1.2 were excluded. RESULTS: The addition of the integrated crossed metal screw system improved the stiffness of the construct by 53% over the intact (P = 0.02) and by 31% over the FRA alone in extension (P = 0.01), whereas it improved the stiffness by 40% over the intact (P = 0.03) and by 18% over the FRA alone in torsion (P = 0.21). The crossed screw system did not improve the stiffness compared with intact in either flexion or lateral bending modes. CONCLUSIONS: Although there is a trend toward improved stability of the FRA spacers in torsion with the addition of the metal screws, this is not statistically significant. The integrated crossed anterior metal screw system significantly improves the stability of the FRA spacers in extension when used for anterior lumbar interbody fusion.