Morphometric X-ray Absorptiometry Research Articles

P0894AEFFECTS OF DENOSUMAB ON BONE MINERAL DENSITY AND LOW ENERGY FRACTURES IN KIDNEY TRANSPLANT PATIENTS: SAFE AND EFFECTIVE

Abstract Background and Aims Fractures are a disabling clinical outcome after kidney transplantation (KTx), with incidence 5 to 34 times higher expected in males and females, respectively. Denosumab, a fully human monoclonal antibody that binds to RANKL with high affinity and specificity, blocking the interaction of RANKL with RANK, mimicking the endogenous effects of osteoprotegerina, increase bone mineral density; however, its effects to reduce the risk of vertebral fractures and ameliorate BMD remain undefinite in the KTx. Method Thirteen kidney recipients (aged from 50 to 79 yy, 6.2 + 5.5 (SD) yy after KTx), 6 M and 7 F (all postmenopausal) with nearly normal renal function (creat. 1.1+-0.31 mg/dl), affected by low energy vertebral fractures (21 dorsal and 1 lumbar vertebrae), evaluated by morphometric X-ray absorptiometry (Hologic DQR-4500A), were treated with denosumab (four 60-mg doses of denosumab Q6M) over 24 months. Data for vertebral heights and height ratios (P-A), covering 9 vertebral bodies were obtained, besides the data of vertebral, femural and radius BMD.The immunosuppressive regimen consisted of CNI (TAC or CsA), MMF and 8 out of 13 patients were still taking prednisone. Bone mineral metabolism parameters (whole-PTH, 25OHD3 and alcaline phosphatase) were also evaluated. Results No sides effects were observed, and all Patients concluded the study.After two years of denosumab treatment, we observed a significative reduction of vertebral T-score (from -2.12 +- 0.35 (SE) to -1.67+-0.35; p< .02), while T score of femural and radius did not show significative variation (-1.86+-0.21 versus -1.84+- 0.23 and -3.04+-0.42 versus -3.19+-0.45, respectively). The number of low energy vertebral fractures, basal versus two years control, had increased for only two dorsal vertebral fractures. However, to one of two subjects, with new dorsal vertebral fractures, was administered high dose of methylprednison for a severe kidney reject. No variations were observed in whole-PTH (89.31+-19.9 versus 68.38+-9.8 pg/ml), 25OHD3 (24.02+-2.75 versus 26.67+-2.29 ug/dl) and alcaline phosphatase (78.46+-12.73 versus 56.77+-7.14 UI). Conclusion Treatment with denosumab improve BMD at vertebral site in KTx, despite continuous steroid therapy and reduce the risk of new low energy vertebral fractures

Stature estimation based on vertebral morphometry by dual energy X-rays absorptiometry imaging in Italian females

Anthropological profile in forensic context includes the assessment of parameters as ancestry, sex, age and stature of an individual by the analysis of skeletal remains. Stature can be estimated from decomposed and fully or partially skeletonized remains by means of anatomical or mathematical methods applied on the whole skeleton or single bones. Many authors calculated regression formulae for the living stature estimation by these methods, in particular based on a population similar to the remains recovered. Long bones are commonly used for stature estimation, but, when they are missing, methods involving different parts of the skeleton are needed. In this preliminary study we measured heights of the vertebral bodies in a female Caucasian Italian population, evaluated by images of morphometric X-ray absorptiometry based on dual-energy X-ray absorptiometry in living subjects investigated for routine diagnostic purposes. Thoracic and lumbar segments of the spine were measured and statistical analysis was performed, thus obtaining regression formulae for estimated living stature from thoraco-lumbar spine segments (T<sub>6</sub>-T<sub>12</sub>, L<sub>1</sub>-L<sub>4</sub> and T<sub>6</sub>-L<sub>4</sub>). We propose this method for stature evaluation in physical or forensic anthropology when the spine is available and long bones are missing.

Reliability of vertebral fractures assessment (VFA) in children with osteogenesis imperfecta.

The aim of this study is to evaluate the diagnostic accuracy of vertebral fractures assessment (VFA) in comparison with conventional radiography in identifying vertebral fractures in children and adolescents affected by OI. On 58 patients (33 males, 25 females; age range 1-18 years; 41 children and 17 adolescents) with osteogenesis imperfecta (OI type I, n = 44, OI type III, n = 4; OI type IV, n = 10), lateral spine images by radiographs and by dual-energy X-ray absorptiometry (DXA) were acquired. For vertebral fracture diagnosis, plain radiographs were used as "gold standard" and VFA and morphometric X-ray absorptiometry (MXA) were performed. The visualized vertebrae were 738 (97.9%) by radiographs and 685 (90.9%) by DXA of a total of 754 vertebrae from T4 to L4. VFA and MXA identified, respectively, 129 (74%) and 116 (66%) of the 175 vertebral fractures detected by radiographs. Radiographs identified 36 patients with vertebral fractures, VFA 35 and MXA 41 (6 false positives). On a per vertebra basis, radiographs and VFA had elevated agreement (93.9%; k score 0.81, 95% CI 0.76-0.86), that resulted slightly lower for MXA (90.6%; k score 0.72, 95% CI 0.65-0.78). VFA and MXA demonstrated high sensitivity (95.6 and 94.1 %, respectively) while specificity was 100% for VFA and 90.6% for MXA on a per patient basis; the agreement was excellent for VFA (98.3%; k score 0.96, 95% CI 0.89-1.03) and good for MXA (87.9%; k score 0.73, 95% CI 0.55-0.91). The diagnostic performance parameters resulted better for VFA (sensitivity 95.6%; specificity 100%; PPV 100%; NPV 97.2%), than for MXA (sensitivity 94.1%; specificity 85.4%; PPV 72.7%; NPV 97.2%). The results of our study demonstrate the reliability of VFA for diagnosis of vertebral fractures in children with OI suggesting its use as a more safe and practical alternative to conventional radiography.

SAT0299 Morphometric X-ray absorptiometry in the assessment of vertebral fractures in patients with psoriatic arthritis and their relationship to disease activity and functional ability

BackgroundBone mineral density (BMD) detected by dual energy x-ray absorptiometry (DXA) is a gold standard and powerful predictor of osteoporotic fractures. BMD in patients with psoriatic arthritis (PsA) can be...

Improvements in the management of rheumatic patients from vertebral image obtained through dual-energy X-ray absorptiometry

The diagnosis of asymptomatic vertebral fracture is clinically useful and the identification of new fractures may influences the choice of appropriate therapeutic measures. In order to identify moderate and asymptomatic vertebral deformities in an objective and reproducible manner, vertebral morphometry is performed. This method measures the vertebral body's anterior, middle and posterior heights at the dorsal and lumbar level. Currently this technique is performed on lateral images of the spine obtained through the traditional X-ray method (radiological morphometry or morphometric X-ray radiography, MRX) and, more recently from images obtained through dual-energy X-ray absorptiometry (DXA) machines (visual assessment of X-ray absorptiometry scans or morphometric X-ray absorptiometry, MXA), commonly used to measure bone mineral density. The main advantage of MXA relative to MRX is the lower radiation dose to which the patient is exposed during the exam. In addition, MXA scans offers the advantage of acquiring a single image of thoracic and lumbar spine, without any distortion (e.g.: coning). The most obvious advantage of MXA is the opportunity of obtaining during the same session a bone mineral density evaluation, and digital images that are easily processable, manageable, recordable and comparable for the patient's follow up. A limitation of the MXA technique is the inferior quality of the images, that make often impossible the detection of the vertebral edges, and the impossibility to visualize the upper thoracic vertebral bodies. MXA, despite its intrinsic limitations, when carried out by trained personnel may provide substantial improvements in the management (diagnosis and follow-up) of rheumatic patients.

Vertebral morphometry by X-ray absorptiometry: Which reference data for vertebral heights?

The recent improvement in the resolution of dual-energy X-ray absorptiometry (DXA) images enables most vertebral levels to be seen adequately and thus DXA may be a worthwhile alternative to radiologic morphometry for the identification of vertebral fractures (VF). In this multicenter study, we have derived reference data for vertebral heights and their ratios in Italian women using morphometric X-ray absorptiometry (MXA). DXA scans were acquired in 1254 consecutive pre- and postmenopausal women, (mean age 63.7 ± 11.3, range 26-88 yrs), referred to six osteoporosis centers. MXA analysis of these images was performed by the same operator measuring vertebral heights and height ratios from L4 to T4. We calculated measures of central tendency and dispersion of vertebral heights and vertebral ratios using different approaches (mean and standard deviation as well as median and interquartile range of raw data, mean and standard deviation of trimmed data using an iterative algorithm, and mean and standard deviation of not fractured vertebrae). Independently of the approach that we used, all the measures of central tendency were similar, while significant differences were found when compared with reference ranges in other populations. The vertebral heights of our sample at every vertebral level were significantly smaller than both Rea population and the Lunar reference values, even after normalization. Splitting data according to age groups, there was a decrease in the vertebral heights and ratios between the younger and older women. This study demonstrates that reference data for MXA should be population specific and age matched.

Effect of sex, age, and anthropometric parameters on the size and shape of vertebrae in densitometric morphometry. Results of the EPOLOS study

Morphometric densitometry (morphometric X-ray absorptiometry - MXA) allows to identify vertebral fractures, based on the objective measurement of vertebral dimensions. The aim of the study was to assess the effect of sex, age, height, and body mass index (BMI) on selected parameters of vertebral size and shape measured by MXA. A random study sample comprised 829 patients (520 women and 309 men) aged 20 to 79 years, none of whom had been previously treated for osteoporosis. Lateral densitometric scans of the thoracic-lumbar spine (T4-L4) were performed using a fan-beam densitometer. Anterior (Ha), central (Hc), and posterior (Hp) vertebral heights were determined. The analysis included 9632 vertebrae. Higher values of Ha, Hc, and Hp were observed in men (P <0.001). The Ha/Hp ratio from T7 to L3 was lower in men compared with women (P <0.05). The Hc/Hp ratio was lower in T12 to L3 vertebrae in men (P <0.05). Wedging was significantly greater in men in thoracic vertebrae, and significantly lower in L3 and L4 (P <0.05). Concavity was similar in men and women in thoracic vertebrae from T5 to T10. We observed weak and moderate negative correlations between age and vertebral heights, Ha/Hp and Hc/Hp (P <0.001), and a moderate positive correlation between body height and vertebral heights (P <0.001). There were no statistically significant correlations between the body mass index and the remaining variables. Morphometric parameters of vertebrae vary depending on sex and age, which has to be considered when choosing reference groups. Knowledge about the differences in vertebral size and shape may prevent diagnostic errors and bias.

Morphometric vertebral fractures of the lower thoracic and lumbar spine, physical function and quality of life in men

The epidemiology and sequelae of morphometric vertebral fracture (MVF) are poorly documented. We found that MVFs of the lower thoracic and lumbar spine were associated with poor quality of life and impaired physical function in men. We recommend that morphometric X-ray absorptiometry be included in routine requests for bone densitometry. Vertebral fractures are sentinel events for osteoporosis. We aimed to compare quality of life and physical function in men with and without MVF. Using morphometric X-ray absorptiometry (T10-L4), MVFs were identified in a random sample of men aged 20-93 years. Moderate and severe wedge, biconcave or compression deformities (>25% reduction in any vertebral height) were classified as MVFs. Of 1,147 men, MVFs were identified in 64. No MVFs were detected for men in their twenties. Prevalence was 1.5% for 30-39 years, 1.4% 40-49 years, 3.2% 50-59 years, 4.7% 60-69 years, 10.0% 70-79 years and 14.6% 80+ years. Among 555 men aged 60+ years, those with MVFs were twice as likely to have quality of life scores in the lowest tertile (age-adjusted OR = 2.35, 95%CI 1.24-4.45). MVFs were associated with lower mean age-adjusted physical activity scores [11.3 (95%CI 9.0-13.8) vs 14.0 (13.2-14.9), P = 0.04] and longer mean age-adjusted 'Up-&-Go' times [9.5 (8.9, 10.1) vs 8.9 (8.8, 9.1) s, P = 0.06]. Despite most men being unaware of their condition, MVFs were associated with poor quality of life and impaired physical function. We recommend that morphometric X-ray absorptiometry be included in routine requests for bone densitometry because detection of MVFs has important implications for osteoporosis management in men.

Bone disease in thalassemia: a frequent and still unresolved problem.

Adults with β thalassemia major frequently have low BMD, fractures, and bone pain. The purpose of this study was to determine the prevalence of low BMD, fractures, and bone pain in all thalassemia syndromes in childhood, adolescence, and adulthood, associations of BMD with fractures and bone pain, and etiology of bone disease in thalassemia. Patients of all thalassemia syndromes in the Thalassemia Clinical Research Network, ≥6 yr of age, with no preexisting medical condition affecting bone mass or requiring steroids, participated. We measured spine and femur BMD and whole body BMC by DXA and assessed vertebral abnormalities by morphometric X-ray absorptiometry (MXA). Medical history by interview and review of medical records, physical examinations, and blood and urine collections were performed. Three hundred sixty-one subjects, 49% male, with a mean age of 23.2 yr (range, 6.1–75 yr), were studied. Spine and femur BMD Z-scores < −2 occurred in 46% and 25% of participants, respectively. Greater age, lower weight, hypogonadism, and increased bone turnover were strong independent predictors of low bone mass regardless of thalassemia syndrome. Peak bone mass was suboptimal. Thirty-six percent of patients had a history of fractures, and 34% reported bone pain. BMD was negatively associated with fractures but not with bone pain. Nine percent of participants had uniformly decreased height of several vertebrae by MXA, which was associated with the use of iron chelator deferoxamine before 6 yr of age. In patients with thalassemia, low BMD and fractures occur frequently and independently of the particular syndrome. Peak bone mass is suboptimal. Low BMD is associated with hypogonadism, increased bone turnover, and an increased risk for fractures.

Comment on: Comparing morphometric X-ray absorptiometry and radiography in defining vertebral wedge fractures in patients with ankylosing spondylitis

OBJECTIVE To compare the level of agreement of quantitative morphometry of the vertebrae on lateral views of the spine using conventional X-ray and using a dual X-ray absorptiometry device (DXA) in determining the degree of wedging of vertebrae in patients with ankylosing spondylitis (AS). METHODS Thirty patients with AS underwent DXA to acquire single-energy morphometric X-ray absorptiometry (MXA) scans and conventional lateral radiography (MRX) of the thoracic and lumbar spine. Vertebral anterior and posterior heights were measured and the anterior/posterior (AP)-ratio was calculated. We analysed the level of agreement for vertebral wedging between MRX and MXA on the patient level and on the vertebral level, using average AP-ratios per patient, and per vertebra, as well as dichotomized AP-ratios (above or below cut-off levels that are commonly used to identify fractures). RESULTS Per-patient analysis showed good agreement between both methods in the whole spine [intraclass correlation coefficient (ICC) = 0.64], as well as in the thoracic (ICC = 0.66) and lumbar spine (ICC = 0.62) separately. Analysis on individual vertebrae showed differences in agreement dependent on which part of the spine was measured. The ICC on all vertebrae was 0.71, 0.76 in the lumbar and 0.43 in the thoracic vertebrae. If AP-ratios were translated into fractures (yes vs no) using different cut off levels for a fracture (AP-ratios 0.75, 0.80 or 0.85) between-method agreement became fair to good (kappa 0.26-0.35 in the thoracic and 0.47-0.80 in the lumbar vertebrae). Differences in classifications were in both directions and in all vertebral fractures according to the Genant definition. In this study with a prevalence of 5% of vertebral fractures, the positive predicted value (PPV) was 39% and the negative predicted value (NPV) was 97%. CONCLUSION Although the agreement between MRX and MXA in measuring global vertebral wedging, expressed as (mean) AP-ratio, was good, the reliability of both measures to assess wedging at the vertebral level was highly variable, ranging from fair to very good agreement, dependent on the level. If fracture studies are performed with either of both the methods, the results of wedging at the individual vertebral level cannot be generalized to the other method, except for wedging <0.75 at the lumbar spine. However, as the NPV was high, DXA could be of clinical value to select patients for further evaluation by X-ray to assess vertebral fractures as a sign of bone failure.

Vertebral morphometry: current methods and recent advances

Vertebral fractures are the hallmark of osteoporosis and are associated with increased morbility and mortality. Because a majority of vertebral fractures often occur in absence of specific trauma and are asymptomatic, their identification is radiographic. The two most widely used methods to determine the severity of vertebral fractures are the visual semiquantitative (SQ) assessment and the morphometric quantitative approach, involving the measurements of vertebral body heights. The measurements may be made on conventional spinal radiographs (MRX: morphometric X-ray radiography) or on images obtained from dual X-ray absorptiometry (DXA) scans (MXA: morphometric X-ray absorptiometry).The availability of a rapid, low-dose method for assessment of vertebral fractures, using advanced fan-beam DXA devices, provides a practical method for integrated assessment of BMD and vertebral fracture status. The visual or morphometric assessment of lateral DXA spine images may have a potential role for use as a prescreening tool, excluding normal subjects prior to performing conventional radiographs.

Morphometric dual-energy roentgen absorptiometry in follow-up of scoliosis

Taking pictures of the spine with Morphometric X-ray Absorptiometry (DXA) leads to a radiation dose of just 1% of conventional X-ray. Purpose of this study was to evaluate if DXA is a suitable method for sufficient measuring of the scoliosis angle. We examined 20 patients with scolioses I. Control-pictures were made with conventional X-rays and compared to those made by DXA, measuring of scoliosis angle was performed by the method of Lippmann/Cobb. The difference between both methods was -10.5% DXA to conventional X-ray-each angle examined on DXA was smaller. It is possible to measure scolioses I on DXA.

The relationship of an Asian-specific screening tool for osteoporosis to vertebral deformity and osteoporosis

An Asian-specific screening tool for osteoporosis, the so-called OSTA index, was devised and is likely to be helpful in determining which postmenopausal women need bone mineral density (BMD) measurement. Besides BMD, prevalent vertebral fracture is a strong risk factor for future fractures. However, the relationship of the OSTA index to prevalent vertebral fractures is currently unknown. In this study, we evaluated the performance of the OSTA index in elderly Thai women and assessed the relationship of the index to prevalent vertebral deformities. Subjects consisted of 741 healthy Thai elderly women. BMD was measured by DEXA and T-score <or=2.5 SD is defined as osteoporosis. Prevalent vertebral deformities were determined by morphometric X-ray absorptiometry. OSTA index >-1 is classified as having low risk of osteoporosis, -1 to -4 as intermediate risk and, <-4 as high risk. Data were expressed as mean +/- SD. The mean age and body weight of subjects were 67 +/- 4.8 years and 57.8 +/- 8.7 kg, respectively. The area under the ROC curve for OSTA index to identify osteoporosis at femoral neck and lumbar spine was 0.80 and 0.72, respectively. Femoral neck osteoporosis was found in 40.4%, 6.3%, and 2.4% of subjects with high-risk, intermediate-risk, and low-risk OSTA indexes, respectively. With regard to vertebral deformities, the area under the ROC curve relating OSTA index to vertebral deformities was 0.70 (P < 0.001). The prevalence of vertebral deformities in according to the OSTA index was 19.2% in the high-risk, 7.9% in the intermediate-risk, and 2.8% in the low-risk group. We concluded that the OSTA index can be of assistance in the selection of postmenopausal women for BMD measurement. In addition, this index may be helpful in the identification of postmenopausal women with vertebral deformity and those who need antifracture treatments.

Comparing morphometric X-ray absorptiometry and radiography in defining vertebral wedge fractures in patients with ankylosing spondylitis

To compare the level of agreement of quantitative morphometry of the vertebrae on lateral views of the spine using conventional X-ray and using a dual X-ray absorptiometry device (DXA) in determining the degree of wedging of vertebrae in patients with ankylosing spondylitis (AS). Thirty patients with AS underwent DXA to acquire single-energy morphometric X-ray absorptiometry (MXA) scans and conventional lateral radiography (MRX) of the thoracic and lumbar spine. Vertebral anterior and posterior heights were measured and the anterior/posterior (AP)-ratio was calculated. We analysed the level of agreement for vertebral wedging between MRX and MXA on the patient level and on the vertebral level, using average AP-ratios per patient, and per vertebra, as well as dichotomized AP-ratios (above or below cut-off levels that are commonly used to identify fractures). Per-patient analysis showed good agreement between both methods in the whole spine [intraclass correlation coefficient (ICC) = 0.64], as well as in the thoracic (ICC = 0.66) and lumbar spine (ICC = 0.62) separately. Analysis on individual vertebrae showed differences in agreement dependent on which part of the spine was measured. The ICC on all vertebrae was 0.71, 0.76 in the lumbar and 0.43 in the thoracic vertebrae. If AP-ratios were translated into fractures (yes vs no) using different cut off levels for a fracture (AP-ratios 0.75, 0.80 or 0.85) between-method agreement became fair to good (kappa 0.26-0.35 in the thoracic and 0.47-0.80 in the lumbar vertebrae). Differences in classifications were in both directions and in all vertebral fractures according to the Genant definition. In this study with a prevalence of 5% of vertebral fractures, the positive predicted value (PPV) was 39% and the negative predicted value (NPV) was 97%. Although the agreement between MRX and MXA in measuring global vertebral wedging, expressed as (mean) AP-ratio, was good, the reliability of both measures to assess wedging at the vertebral level was highly variable, ranging from fair to very good agreement, dependent on the level. If fracture studies are performed with either of both the methods, the results of wedging at the individual vertebral level cannot be generalized to the other method, except for wedging <0.75 at the lumbar spine. However, as the NPV was high, DXA could be of clinical value to select patients for further evaluation by X-ray to assess vertebral fractures as a sign of bone failure.

A cohort study of the effect of endogenous estrogen on spine fracture risk and bone structure in elderly women and an assessment of its diagnostic usefulness

The decline in endogenous estrogen concentration after menopause is associated with accelerated bone loss. However, effects in older women remain controversial and the usefulness of estrogen status as a predictor of spine fracture has not been assessed. Therefore, we undertook a prospective cohort study of 1350 women mean age 75 years in order to study the role of endogenous estrogen concentration on the risk of morphometric X-ray absorptiometry (MXA)-defined vertebral deformity and atraumatic clinical spine fracture and the association of endogenous estrogen with bone structure. At 5 years 70 patients (5.2%) had sustained ≥ 1 incident spine fracture. The fracture group had significantly lower concentrations of baseline free estradiol index (FEI) median (IQ range) (0.38 (0.22–0.60) vs. 0.49 (0.29–0.84) pmol/nmol, p = 0.009). The patients in the lowest tertile of FEI (FEI < 0.35) had twice the risk of sustaining a clinical vertebral fracture compared to those subjects in the highest tertile (FEI > 0.68) (HR 2.18: 95% CI 1.11–4.28). A low FEI was associated with an increased risk of a vertebral deformity over the 5-year study (OR 1.77: 95% CI 1.02–3.07) for the lowest compared to highest tertile. A low baseline FEI was associated with lower baseline QUS heel bone structure and DXA hip bone structure at 12 months and with deterioration in QUS heel bone structure 5 years later. The effect size of the FEI in predicting spine fracture was similar to the effect size for DXA BMD and heel QUS, probably because of the beneficial effect of the FEI on bone structure. The data suggest that the estrogen effect on reducing spine fracture is at least in part due to an effect on bone structure and its measurement does not significantly improve fracture prediction.

The clinical utility of measured kyphosis as a predictor of the presence of vertebral deformities

Meaured spinal kyphosis, as a predictor of prevalent and incident vertebral deformity, was examined in older women (>70 years) and found to not have sufficient sensitivity or specificity to justify its use as a predictor of present or future vertebral deformity risk. Kyphosis may be attributable to vertebral deformity and was investigated as a clinical tool for predicting the presence and future risk of vertebral deformity. Kyphosis was measured in 434 women aged 70 years or older and the kyphosis index (KI) calculated. Prevalent and incident vertebral deformities were assessed by morphometric X-ray absorptiometry (MXA). The predictive value of KI was examined. Severity of kyphosis was categorised by tertile of KI; 65% of anterior thoracic deformities occurred in the 33% of subjects in the highest (most kyphotic) tertile. Using this tertile as a predictor of anterior thoracic deformity, the probability for a positive test rose from 14% for the whole population to 28% and for a negative test the probability fell to 8%. For any spinal deformity the highest tertile of KI increased the probability of a positive test from 34% to 42% and reduced the probability for a negative test to 30%. The incidence of new deformities was 6% over 4 years; a high KI tertile did not increase the probability of any vertebral deformity. Severe kyphosis does not increase the probability of detection of a prevalent or incident spinal deformity sufficiently to make it a useful method of selecting patients for further evaluation of spinal deformity.

Bone Disease in Long-term Renal Transplant Recipients with Severe Osteopenia: A Cross-sectional Study

Fracture is a disabling clinical outcome after transplantation, but there is little histopathological information on long-term renal recipients with severe osteopenia. Twenty kidney recipients (8.3+/-1.9 years after transplantation), 13 males and 7 females (five postmenopausal) with nearly normal renal function, affected by severe osteopenia (T-score: males= -4.9+/-0.28; females= -5.08+/-0.47) underwent bone biopsy and morphometric X-ray absorptiometry to evaluate vertebral fractures. Histopathological diagnosis was osteoporosis-osteopenia in seven patients, osteitis fibrosa in six, prevalent osteomalacic lesion in six, and "normal" bone in one patient. Significant increases in osteoid volume (OV/BV), osteoid surface, osteoblastic surface (ObS/BS) and osteoid thickness were observed. OV/BV and Obs/BS ratios were inversely correlated to cumulative doses of MPRED (r2=0.85 P<.0001 for both ratios), whereas age, sex, time after transplantation, iPTH levels, and cumulative cyclosporine A dose were not related to osteoblastic indices. Osteoclast surface was slightly increased. Widened mineralization lag times were observed, with normalcy of the bone formation rate. Half of the patients showed fractured vertebrae. No differences in T scores were found when patients were subdivided into groups "with" or "without" vertebral fractures. A higher prevalence of fractures was observed in patients with osteoporosis-osteopenia compared to other osteopathies (P<0.02). No relationships between bone volume versus T-scores were observed. In long-term renal transplant recipients, severe osteopenia does not predict osteoporosis alone. The main abnormality we found was an increase in osteoblastic activity with a slight mineralization defect. The heterogeneous bone illness we observed would suggest performing bone biopsy in these patients.

Morphometric X-ray absorptiometry in the assessment of vertebral fractures in renal transplant patients

Bone mineral density (BMD) is widely employed to evaluate the risk of fractures, but more than mineral content is bone quality that accounts for bone strength. In fact, occasionally, subjects with normal or only mildly reduced BMD also experience pathologic fractures. In metabolic bone disease, like renal transplantation, the agreement between fractures and BMD is less predictable. We assessed the prevalence of vertebral fractures by means of a new, DEXA-based method (morphometric absorptiometry, MXA) and compared its concordance with the two mostly employed radiological techniques (Visual semi-quantitative, SQ, and morphometric radiography, MRX) in an asymptomatic population of transplanted patients. Moreover, the association of bone fractures with low BMD values was examined. Fifty-three renal transplant patients underwent spinal radiographs and BMD measurements by DEXA. In order to obtain a morphometric assessment, a lateral DEXA scan was performed. Patients with vertebral fracture were 17/53 (32%) with both SQ and MRX, and 12/53 (23%) with MXA (chi(2) = n.s.). A single fracture was detected in 9/53 patients (17%) with SQ and MRX, and in 4/53 (7.5%) with MXA; multiple fractures were 8/53 (15%) with any technique. With SQ as the standard reference, predictive indexes were excellent with MRX (invariably 100%) and quite good with MXA (sensitivity 70.6%; specificity 100%). Of the total of 689 vertebrae, 49 were fractured with SQ, 54 with MRX and 41 with MXA. Mild deformities were present in 21 (SQ), 26 (MRX) and 13 (MXA) vertebral bodies, respectively, while moderate-severe deformities were 28 with any technique. Again, with SQ as standard reference, predictive indexes were good (MRX: sensitivity 100%, specificity 99.2%; MXA: sensitivity 83.7%, specificity 100%). When we classified patients according to BMD T-score values, SQ and MRX recognized fractures in 4/18 normal (22%), 10/22 osteopenic (45%) and 3/13 osteoporotic (23%). With MXA 3/18 (17%) normal, 6/22 (27%) osteopenic and 3/13 (23%) osteoporotic were fractured. The lower performance of MXA was very likely due to the poor quality of images from the upper thoracic spine of obese subjects. Prevalence of vertebral fractures in renal transplant patients is quite high and randomly associated with reduced BMD. A surveillance of the spine by Rx, implemented with vertebral morphometry, is therefore warranted to recognize the disease. (MXA is a reliable alternative technique, especially in more severely affected individuals.) MXA, although less sensitive than the conventional techniques because of possible technical biases, is very specific, and can be proposed for follow-up purposes in this population of patients.

Morphometric X-ray absorptiometry: reference data for vertebral dimensions in a population-based sample of young danish men

To determine reference values for vertebral heights in healthy young Danish males using morphometric X-ray absorptiometry (MXA). A population-based study group of 487 males aged between 20 and 30 years (mean 25 years) from the county of Funen, Denmark, were recruited. Using a Hologic QDR 4500 (dual energy X-ray absorptiometry) DXA-scanner, MXA scans covering the vertebrae from T4 to L4 were acquired for each subject. Anterior (Ha), middle (Hm), and posterior (Hp) heights of the thoracic (T4-T12) and lumbar (L1-L4) vertebral bodies were measured. Moreover, wedge, mid-wedge, crush I, and crush II ratios were calculated. No correlation between vertebral dimensions and crush indices on the one hand and age or weight on the other were found. Body height, however, correlated significantly with the cumulated vertebral heights. Reference data for vertebral dimensions, wedge, mid-wedge, crush I, and crush II are tabulated. The anterior, middle, and posterior heights of the vertebral bodies of T4 to L4 can be measured reproducible with MXA. In young men, the cumulative vertebral heights correlated with body height but not with age. Moreover, the wedge and crush indices were unrelated of both age and height.

Incidence of vertebral deformities in 255 female rheumatoid arthritis patients measured by morphometric X-ray absorptiometry.

To date, no studies have been published on incident deformities in patients with rheumatoid arthritis (RA). Morphometric X-ray absorptiometry (MXA) is an alternative to conventional X-rays for identifying vertebral deformities. The aim of the present study was to describe the incidence of vertebral deformities in 255 female RA patients measured by MXA, and the relationship between incident deformities and clinical and demographic variables. MXA is still under evaluation for its ability to identify deformities, so we explored four different cut-off thresholds including fixed percentage reduction and the principle of least significant change (LSC). MXA (T4-L4) and BMD (L2-L4 and total hip; Lunar Expert) were performed on 255 patients (mean age 54.3, range 29.2-70.8 years) at baseline and after a mean period of 2.3 years. MXA scans were analyzed pairwise by the same trained technician, and incident deformities calculated applying LSC with a 99.9% and 99.99% confidence limit, and a fixed reduction of 20% and 25% for anterior, middle or posterior heights. Long term precision (%CV) of height measurements for all vertebrae combined (T4-L4) were 4.8, 4.8 and 4.4, respectively. Frequency and distribution of incident deformities varied from 39 deformities in 33 patients (fixed 20% reduction) to 17 deformities in 15 patients (fixed 25% reduction), and quality control analyses revealed a high number of presumed false deformities. Incidence per 100 patient years varied from 2.9 to 6.7 deformities according to method, and was comparable to those obtained from intervention studies in corticosteroid-induced osteoporosis. Patients with incident deformities were significantly older, had lower BMD, higher disability and more often a previous non-vertebral fractures than those without incident deformities Incident deformities by MXA need further evaluation in secondary osteoporosis. It seems, however, that older patients with previous limb fractures and low BMD are especially prone to this complication.