Body composition and body mass index measures from 8 to 18 years old in children with cystic fibrosis

BACKGROUND

Historically, body mass index (BMI) >50th percentile has represented optimal nutritional status in children with cystic fibrosis (CF) due to its positive association with lung function. Body composition parameters including fat-free mass index (FFMI) have been suggested as a more physiological nutrition benchmark.

AIMS

(1) describe changes in body composition with age and gender; (2) assess the correlation between measures of nutritional status (FFMI-z, FMI-z, BMI-z) and lung function (forced expiratory volume in one second predicted; FEV1pp).

METHODS

This retrospective, mixed cross-sectional and serial measures study consisted of children with CF (8 to 18 years) attending Sydney Children's Hospital (2007-2020). FFMI and fat mass index (FMI) were taken from biennial dual energy x-ray absorptiometry (DXA) scans. Z-scores were derived using Well's reference population [1]. Repeated measures correlation analyses assessed correlations between FFMI-z, FMI-z, and BMI-z with FEV1pp.

RESULTS

339 DXA reports were analysed from 137 patients. There were slight downwards trends in BMI-z and FMI-z, and an upwards trend in FFMI-z with increasing age and across both genders. Females had higher FMI-z and FFMI-z than males from 12.5 years. There was a weak, positive correlation between FEV1pp and BMI-z (r = 0.14, p = 0.04), and FFMI-z (r = 0.25, p<0.001). FMI-z had no correlation with FEV1pp (r=-0.06, p = 0.41).

CONCLUSION

Deficits in FFMI exist despite increasing trends with age. FFMI-z and BMI-z had a weak, positive correlation with FEV1pp. In contemporary cohorts, nutritional status (reflected by surrogate markers such as FFMI and BMI) may be less influential upon lung function than in previous decades. [1]: Wells, J.C., et al. Body-composition reference data for simple and reference techniques and a 4-component model: a new UK reference child. Am. J. Clin. Nutr.96, 1316-1326 (2012).

Digital panoramic radiography and CBCT as auxiliary tools for detection of low bone mineral density in post-menopausal women: a cross-sectional study

BACKGROUND

Osteoporosis is a chronic, multifactorial skeletal disease that occurs especially in women following a decrease in estrogen levels and decrease in bone mineral density. The aim of this study was to evaluate the relationship between qualitative and quantitative indexes in panoramic radiographs and quantitative indexes in CBCT images with femoral and vertebral BMD in postmenopausal women.

METHODS

This comparative cross-sectional study was performed on postmenopausal women aging 40 to 80 years attending for obtaining either panoramic radiograph or mandibular CBCT scan. Dual energy X-ray absorptiometry (DEXA) was performed from the femur and lumbar vertebra. Quantitative parameters of mental index (MI), panoramic mandibular index (PMI), antegonial index (AI) as well as qualitative parameters of mandibular cortical index (MCI) and trabecular bone pattern (TP) were evaluated in panoramic radiographs. Quantitative parameters computed tomography mandibular index (CTMI), computed tomography index (inferior) [CTI(I)] and computed tomography index (superior) [CTI(S)] were analyzed in CBCT images. Kolmogorov-Smirnov tests and Pearson correlation coefficient were used (α = 0.05).

RESULTS

In individuals with panoramic radiography, statistically significant correlations were observed between MI with vertebral and femoral T-score, AI with vertebral and femoral T-score (except for the right AI with femoral T-score), and TP with vertebral and femoral T-score (p < 0.05). In the group with CBCT scans, the correlations between CTMI with vertebral and femoral T-score, CTI(I) with vertebral and femoral T-score, and CTI(S) with vertebral and femoral T-score were statistically significant (p < 0.05).

CONCLUSIONS

in CBCT images, quantitative indexes of CTMI, CTI(I), and CTI(S), and in panoramic images, quantitative indexes of MI and AI and qualitative index of TP can be used to predict the possibility of osteoporosis in postmenopausal women.

Loss of lower extremity bone mineral density 1 year after denosumab is discontinued in persons with subacute spinal cord injury

Twelve months following discontinuation of denosumab, the percent decrease in mean bone mineral density (BMD) values at the hip and knee regions were similar between both the denosumab and placebo groups. These findings emphasize the need for additional trials to understand the effect of continued administration of denosumab after subacute spinal cord injury (SCI) to avoid this demineralization.

OBJECTIVE

To determine changes in BMD 1 year after denosumab was discontinued in participants with subacute SCI who had drug treatment initiated within 90 days post SCI and continued for 1 year.

METHODS

Fourteen participants who completed a randomized, double-blinded, placebo-controlled drug trial (parent study: denosumab 60 mg (Prolia, Amgen Inc., n = 8) or placebo (n = 6); administered at baseline, 6, and 12 months) were followed 12 months after the 18 months from baseline primary end point was completed. The BMD of skeletal regions below the SCI at higher risk of fracture was measured [total hip, distal femur epiphysis (DFE), distal femur metaphysis (DFM), and proximal tibia epiphysis (PTE)] by dual energy X-ray absorptiometry.

RESULTS

The percent decreases in mean BMD values at all regions of the hip and knee from 18 to 30 months were similar in both the denosumab and placebo groups. However, at 30 months, the absolute values for mean BMD remained significantly higher in the drug treatment than that of the placebo group at the DFM (p = 0.03), DFE (p = 0.04), and PTE (p = 0.05).

CONCLUSIONS

In persons with SCI who initiated denosumab treatment during the subacute injury phase and maintained treatment for 1 year, the discontinuation of drug resulted in percent loss of mean BMD similar to that of the placebo group, with absolute mean BMD values at the knee regions at the 12-month follow-up visit significantly higher in the drug treatment than those in the placebo group. These data underscore the need to study continued administration of denosumab after subacute SCI to avoid marked demineralization in the sublesional skeleton upon discontinuation of this agent.

Dietary carotenoid intake and osteoporosis: the National Health and Nutrition Examination Survey, 2005-2018

Higher intake of β-carotene and β-cryptoxanthin were associated with lower risk of osteoporosis. A very high intake of lutein + zeaxanthin was also associated with lower risk of osteoporosis. These results support the beneficial role of carotenoids on bone health.

PURPOSE

To examine the associations of α-carotene, β-carotene, β-cryptoxanthin, lycopene, and lutein + zeaxanthin intake with the risk of osteoporosis based on the cross-sectional data from the National Health and Nutrition Examination Survey (NHANES), 2005-2018.

METHODS

This study identified individuals ≥ 50 years old with valid and complete data on carotenoid intake and bone mineral density (BMD). Intake of α-carotene, β-carotene, β-cryptoxanthin, lycopene, and lutein + zeaxanthin was averaged from two 24-h recall interviews. BMD was measured by dual-energy X-ray absorptiometry (DXA) and converted to T-scores; osteoporosis was defined as a T-score ≤  - 2.5. We used logistic regression models to test the associations between carotenoids and osteoporosis, adjusting for factors such as age, sex, race, and education.

RESULTS

Participants were on average 61.9 years of age, with 57.5% identifying as females. Higher quintiles of β-carotene (odds ratio [OR] for quintile 5 vs. 1:0.33; 95% CI: 0.19-0.59; P for trend = 0.010) and β-cryptoxanthin intake (OR for quintile 5 vs. 1:0.61; 95% CI: 0.39-0.97; P for trend = 0.037) were associated with reduced risk of osteoporosis. Similar and marginally significant results for lutein + zeaxanthin intake was found (OR for quintile 5 vs. 1:0.53; 95% CI: 0.30-0.94; P for trend = 0.076). There was no association of α-carotene and lycopene intake with osteoporosis. These associations did not differ by sex (all P_interaction > 0.05).

CONCLUSIONS

Higher β-carotene and β-cryptoxanthin intake was associated with decreased osteoporosis risk. A very high intake of lutein + zeaxanthin was also associated with lower risk of osteoporosis.

DXA2: An Automated Program for Extraction of Dual-Energy X-Ray Absorptiometry Data

INTRODUCTION/BACKGROUND

Since the 1970s imaging devices have been rapidly advancing to provide researchers, clinicians, radiologists, and practitioners greater capabilities to image bone. Today, dual-energy X-ray absorptiometry (DXA) has emerged as the gold standard for the assessment of bone and body composition. Despite recent improvements in DXA image quality and reduced radiation dosages and scan times, the data extraction process has yet to be streamlined. The objective of this study was to design an application to allow DXA users to quickly and accurately transfer DXA report data directly into a user-friendly format.

METHODOLOGY

Initial development of the DXA Data Xtraction Assistant (DXA²) included processing 485 DXA reports from a previous study. Using Python script, numeric data from these DXA reports were converted to .csv files and then merged into one file, effectively compiling and organizing all table data from each report, by participant and visit number. A graphical user interface was then developed and beta tested using multiple DXA manufacturers, models, and software versions. To compare the effectiveness of the DXA² to the current standard of manual extraction, all 485 reports were manually transcribed into Microsoft Excel. The time required per report and the error rates were compared.

RESULTS

Manual transcription, by an experienced researcher, took over 10 h with an error rate of 0.6% and average error magnitude of 51%. Data extraction from DXA² took less than 25 min to retrospectively reformat all DXA reports for the DXA² and transcribe all 485 reports with 100% accuracy.

CONCLUSION

The DXA² application automates DXA report data extraction and aggregation for clinical, research, and applied settings and drastically reduces manual data entry time and eliminates transcription errors.

Cystic fibrosis bone disease treatment: Current knowledge and future directions

Bone disease is a frequent complication in adolescents and adults with cystic fibrosis (CF). Early detection and monitoring of bone mineral density and multidisciplinary preventive care are necessary from childhood through adolescence to minimize CF-related bone disease (CFBD) in adult CF patients. Approaches to optimizing bone health include ensuring adequate nutrition, particularly intake of calcium and vitamins D and K, addressing other secondary causes of low bone density such as hypogonadism, encouraging weight bearing exercise, and avoiding bone toxic medications. Of the currently available anti-resorptive or anabolic osteoporosis medications, only bisphosphonates have been studied in individuals with CF. Future studies are needed to better understand the optimal approach for managing CFBD.

No association between osteoporosis and AO classification of distal radius fractures: an observational study of 289 patients

Background

It is mechanically plausible that osteoporosis leads to more severe peripheral fractures, but studies investigating associations between BMD and radiographically verified complexity of distal radius fractures are scarce. This study aims to study the association between osteoporosis, as well as other risk factors for fracture, and the AO classification of distal radius fractures.

Methods

In this observational study, 289 consecutive patients aged ≥40 years with a distal radius fracture were included. Bone mineral density (BMD) of the hips and spine was measured by dual-energy x-ray absorptiometry (DXA), and comorbidities, medication, physical activity, smoking habits, body mass index (BMI), and history of previous fracture were registered. The distal radius fractures were classified according to the Müller AO system (AO) (type B and C regarded as most complex).

Results

Patients with osteoporosis (n = 130) did not have increased odds of a more complex distal radius fracture (type B + C, n = 192)) (n = vs type A (n = 92) (OR 1.1 [95% CI 0.5 to 2.3]) compared to those with osteopenia /normal BMD (n = 159). Patients with AO fracture types A or C had a higher prevalence of osteoporosis than patients with type B fracture.

Conclusions

Distal radius fracture patients with osteoporosis did not sustain more complex fractures than those with osteopenia/normal BMD according to the AO classification system. The AO classification of distal radius fracture cannot be used to decide which patients should be referred to DXA scan and considered for secondary fracture prevention.

Estimating Waist and Hip Circumference from Routine Clinical DXA

INTRODUCTION

Waist circumference and waist:hip ratio have body mass index-independent detrimental effects on health and mortality. Dual-energy X-ray absorptiometry (DXA) scans of the lumbar spine and hip can provide site-specific measures of soft-tissue thickness, and we hypothesized that this could be used to opportunistically estimate body circumference in patients undergoing DXA for osteoporosis assessment.

METHODOLOGY

We assessed the correlation and explained variance (as coefficient of determination, R²) between directly measured body circumference (waist circumference, hip circumference, and waist:hip circumference ratio) with DXA-derived measures of soft tissue thickness (spine DXA tissue thickness, hip DXA tissue thickness, and spine:hip tissue thickness ratio) in 214 women and 96 men (mean age 66.1 and 63.7 yr, respectively) undergoing DXA screening for osteoporosis.

RESULTS

DXA-derived spine tissue thickness explained most of the variance in measured waist circumference (female R² 0.90, male R² 0.88). Explained variance was slightly lower for measured hip circumference (female R² 0.87, male R² 0.76) and waist:hip ratio (female R² 0.68, male R² 0.72). Final models predicted waist circumference with an adjusted R² 0.91, hip circumference with R² 0.86, and waist:hip ratio with R² 0.70.

CONCLUSION

Routine clinical DXA measurements of the spine and hip can be used to estimate body circumference measurements.

Utility of bioimpedance methods for the assessment of fat-free mass in adult outpatients with inflammatory bowel disease

OBJECTIVES

Clinically accessible body composition assessment is required to identify fat-free mass (FFM) depletion, which is common in inflammatory bowel disease (IBD) and poorly correlated with body mass index (BMI). The aim of this study was to compare FFM assessed using bioimpedance spectroscopy (BIS) and multifrequency bioelectrical impedance analysis (MFBIA) with dual energy x-ray absorptiometry (DXA) in adult outpatients with IBD.

METHODS

FFM was measured using DXA, BIS, and MFBIA in 40 outpatients with IBD. Paired t tests, Lin and Pearson's correlations, and limits of agreement (LOA) analysis were used to compare FFM_DXA with FFM_BIS and FFM_MFBIA.

RESULTS

Participants (26 men, 24 with Crohn's disease) had a median (IQR) age 39 y (32-50 y) and median (IQR) BMI 24.2 kg/m² (21.9-26.4 kg/m²). Mean FFM_DXA was 51.6 ± 12 kg. FFM_BIS was highly correlated with FFM_DXA (r_p = 0.97; P < 0.001); however, BIS significantly overestimated FFM compared with DXA by a mean 3.4 ± 2.6 kg (P < 0.001) and showed wide 95% LOA (-1.7 to 8.4 kg). FFM_BIS estimations improved when FFM was adjusted for by BMI using Moissl's predictive algorithm, reducing mean bias to 0.1 ± 2 kg (P = 0.858; 95% LOA -3.9 to 4 kg). The bias between FFM_MFBIA and FFM_DXA was 1.3 ± 2 kg (P = 0.002) with 95% LOA -2.6 to 5 kg (n = 28).

CONCLUSION

Unadjusted BIS overestimated FFM in IBD outpatients compared with DXA with poor agreement at an individual level. Adjusting for BMI ameliorated the overestimation. It is suggested for the estimation of FFM in outpatients with IBD that MFBIA or the Moissl algorithm with BIS be used if DXA is unavailable.

Bone health in adolescents with idiopathic scoliosis

AIMS

Idiopathic scoliosis is the most common spinal deformity in adolescents and children. The aetiology of the disease remains unknown. Previous studies have shown a lower bone mineral density in individuals with idiopathic scoliosis, which may contribute to the causation. The aim of the present study was to compare bone health in adolescents with idiopathic scoliosis with controls.

METHODS

We included 78 adolescents with idiopathic scoliosis (57 female patients) at a mean age of 13.7 years (8.5 to 19.6) and 52 age- and sex-matched healthy controls (39 female patients) at a mean age of 13.8 years (9.1 to 17.6). Mean skeletal age, estimated according to the Tanner-Whitehouse 3 system (TW3), was 13.4 years (7.4 to 17.8) for those with idiopathic scoliosis, and 13.1 years (7.4 to 16.5) for the controls. Mean Cobb angle for those with idiopathic scoliosis was 29° (SD 11°). All individuals were scanned with dual energy x-ray absorptiometry (DXA) and peripheral quantitative CT (pQCT) of the left radius and tibia to assess bone density. Statistical analyses were performed with independent-samples t-test, the Mann-Whitney U test, and the chi-squared test.

RESULTS

Compared with controls, adolescents with idiopathic scoliosis had mean lower DXA values in the left femoral neck (0.94 g/cm² (SD 0.14) vs 1.00 g/cm² (SD 0.15)), left total hip (0.94 g/cm² (SD 0.14) vs 1.01 g/cm² (SD 0.17)), L1 to L4 (0.99 g/cm² (SD 0.15) vs 1.06 g/cm² (SD 0.17)) and distal radius (0.35 g/cm² (SD 0.07) vs 0.39 g/cm² (SD 0.08; all p ≤ 0.024), but not in the mid-radius (0.72 g/cm² vs 0.74 g/cm²; p = 0.198, independent t-test) and total body less head (1,559 g (SD 380) vs 1,649 g (SD 492; p = 0.0.247, independent t-test). Compared with controls, adolescents with idiopathic scoliosis had lower trabecular volume bone mineral density (BMD) on pQCT in the distal radius (184.7 mg/cm³ (SD 40.0) vs 201.7 mg/cm³ (SD 46.8); p = 0.029), but not in other parts of the radius or the tibia (p ≥ 0.062, Mann-Whitney U test).

CONCLUSION

In the present study, idiopathic scoliosis patients seemed to have lower BMD at central skeletal sites and less evident differences at peripheral skeletal sites when compared with controls. Cite this article: Bone Joint J 2020;102-B(2):268-272.

Prediction of thigh skeletal muscle mass using dual energy x-ray absorptiometry compared to magnetic resonance imaging after spinal cord injury

Objectives: A rapid decline in lean mass (LM), fat-free mass (FFM) and increased intramuscular fat (IMF) predispose persons with spinal cord injury (SCI) to chronic medical conditions including dyslipidemia, insulin resistance, type 2 diabetes mellitus and cardiovascular disease. (1) To determine the relationship between dual energy x ray absorptiometry (DXA) and gold standard magnetic resonance imaging (MRI) LM values; (2) to develop predictive equations based on this relationship for assessing thigh LM in persons with chronic SCI. Study Design: Cross-sectional predicational design. Settings: Clinical research medical center. Participants: Thirty-two men with chronic (>1 y post-injury) motor complete SCI. Methods: Participants completed total body DXA scans to determine thigh LM and were compared to measurements acquired from trans-axial MRI. Outcome measures: MRI was used to measure whole muscle mass (MM_MRI-WM), absolute muscle mass (MM_MRI-ABS) after excluding IMF, and knee extensor muscle mass (MM_MRI-KE). DXA was used to measure thigh LM (LM_DXA) and (FFM_DXA). To predict MM_MRI-KE, LM_DXA was multiplied by 0.52 and yielded LM_DXA-KE. Results: LM_DXA predicted MM_MRI-WM [r²= 0.90, standard error of the estimate (SEE) = 0.23 kg, P < 0.0001] and MM_MRI-ABS (r² = 0.82, SEE = 0.28 kg, P < 0.0001). LM_DXA-KE predicted MM_MRI-KE (r² = 0.78, SEE = 0.16 kg, P < 0.0001). Conclusion: DXA measurements revealed an acceptable agreement with the gold standard MRI and may be a viable alternative for assessing thigh skeletal muscle mass after SCI.

Diagnosis of osteoporotic vertebral fractures in children

Osteoporosis is a generalised disorder of the skeleton with reduced bone density and abnormal bone architecture. It increases bone fragility and renders the individual susceptible to fractures. Fractures of the vertebrae are common osteoporotic fractures. Vertebral fractures may result in scoliosis or kyphosis and, because they may be clinically silent, it is imperative that vertebral fractures are diagnosed in children accurately and at an early stage, so the necessary medical care can be implemented. Traditionally, diagnosis of osteoporotic vertebral fractures has been from lateral spine radiographs; however, a small number of studies have shown that dual energy x-ray absorptiometry is comparable to radiographs for identifying vertebral fractures in children, while allowing reduced radiation exposure. The diagnosis of vertebral fractures from dual energy x-ray absorptiometry is termed vertebral fracture assessment. Existing scoring systems for vertebral fracture assessment in adults have been assessed for use in children, but there is no standardisation and observer reliability is variable. This literature review suggests the need for a semiautomated tool that (compared to the subjective and semiquantitative methods available) will allow more reliable and precise detection of vertebral fractures in children.

Estimating bone mass in children: can bone health index replace dual energy x-ray absorptiometry?

BACKGROUND

Bisphosphonates have been shown to increase metacarpal cortical width. Bone health index is computed from hand radiographs by measuring cortical thickness, width and length of the three middle metacarpals, and may potentially help predict fracture risk in children.

OBJECTIVE

To compare bone health index with bone mineral density as measured from dual energy X-ray absorptiometry scans in patients with and without bisphosphonate treatment.

MATERIALS AND METHODS

Two hundred ninety-three Caucasian patients (mean age: 11.5±3.7 years) were included. We documented absolute values and z-scores for whole-body less head and lumbar spine bone mineral density then correlated these with the bone health index, which were acquired on the same day, in different patient groups, depending on their ethnicity and diagnosis.

RESULTS

Bone health index showed moderate to strong correlation with absolute values for whole-body (r=0.52) and lumbar spine (r=0.70) bone mineral density in those not treated with bisphosphonates and moderate correlation absolute values for whole-body (r=0.54) and lumber spine (r=0.51) bone mineral density for those treated with bisphosphonates. There was weak correlation of z-scores, ranging from r=0.11 to r=0.35 in both groups.

CONCLUSION

The lack of a strong correlation between dual energy X-ray absorptiometry and bone health index suggests that they may be assessing different parameters.

Comparison of femoral strength and fracture risk index derived from DXA-based finite element analysis for stratifying hip fracture risk: A cross-sectional study

BACKGROUND

Dual-energy X-ray absorptiometry (DXA)-based finite element analysis (FEA) has been studied for assessment of hip fracture risk. Femoral strength (FS) is the maximum force that the femur can sustain before its weakest region reaches the yielding limit. Fracture risk index (FRI), which also considers subject-specific impact force, is defined as the ratio of von Mises stress induced by a sideways fall to the bone yield stress over the proximal femur. We compared risk stratification for prior hip fracture using FS and FRI derived from DXA-based FEA.

METHODS

The study cohort included women aged ≥65years undergoing baseline hip DXA, with femoral neck T-scores <-1 and no osteoporosis treatment; 324 cases had prior hip fracture and 655 controls had no prior fracture. Using anonymized DXA hip scans, we measured FS and FRI. Separate multivariable logistic regression models were used to estimate odds ratios (ORs), c-statistics and their 95% confidence intervals (95% CIs) for the association of hip fracture with FS and FRI.

RESULTS

Increased hip fracture risk was associated with lower FS (OR per SD 1.36, 95% CI: 1.15, 1.62) and higher FRI (OR per SD 1.99, 95% CI: 1.63, 2.43) after adjusting for Fracture Risk Assessment Tool (FRAX) hip fracture probability computed with bone mineral density (BMD). The c-statistic for the model containing FS (0.69; 95% CI: 0.65, 0.72) was lower than the c-statistic for the model with FRI (0.77; 95% CI: 0.74, 0.80) or femoral neck BMD (0.74; 95% CI: 0.71, 0.77; all P<0.05).

CONCLUSIONS

FS and FRI were independently associated with hip fracture, but there were differences in performance characteristics.

Risk factors for poor bone health in primary mitochondrial disease

INTRODUCTION

Primary mitochondrial disease is caused by either mitochondrial or nuclear DNA mutations that impact the function of the mitochondrial respiratory chain. Individuals with mitochondrial disorders have comorbid conditions that may increase their risk for poor bone health. The objective of this retrospective electronic medical record (EMR) review was to examine risk factors for poor bone health in children and adults with primary mitochondrial disease.

METHODS

Eighty individuals with confirmed clinical and genetic diagnoses of primary mitochondrial disease at the Children's Hospital of Philadelphia (CHOP) were included in this study. Risk factors and bone health outcomes were collected systematically, including: anthropometrics (low BMI), risk-conferring co-morbidities and medications, vitamin D status, nutrition, immobility, fracture history, and, where available, dual energy x-ray absorptiometry (DXA) bone mineral density (BMD) results.

RESULTS

Of patients 73% (n = 58) had at least one risk factor and 30% (n = 24) had four or more risk factors for poor bone health. The median number of risk factors per participant was 2, with an interquartile interval (IQI 0-4). In the subset of the cohort who were known to have sustained any lifetime fracture (n = 11), a total of 16 fractures were reported, six of which were fragility fractures, indicative of a clinically significant decrease in bone strength.

CONCLUSIONS

The prevalence of risk factors for poor bone health in primary mitochondrial disease is high. As part of supportive care, practitioners should address modifiable risk factors to optimize bone health, and have a low threshold to evaluate clinical symptoms that could suggest occult fragility fracture.

Bone loss at the distal femur and proximal tibia in persons with spinal cord injury: imaging approaches, risk of fracture, and potential treatment options

Persons with spinal cord injury (SCI) undergo immediate unloading of the skeleton and, as a result, have severe bone loss below the level of lesion associated with increased risk of long-bone fractures. The pattern of bone loss in individuals with SCI differs from other forms of secondary osteoporosis because the skeleton above the level of lesion remains unaffected, while marked bone loss occurs in the regions of neurological impairment. Striking demineralization of the trabecular epiphyses of the distal femur (supracondylar) and proximal tibia occurs, with the knee region being highly vulnerable to fracture because many accidents occur while sitting in a wheelchair, making the knee region the first point of contact to any applied force. To quantify bone mineral density (BMD) at the knee, dual energy x-ray absorptiometry (DXA) and/or computed tomography (CT) bone densitometry are routinely employed in the clinical and research settings. A detailed review of imaging methods to acquire and quantify BMD at the distal femur and proximal tibia has not been performed to date but, if available, would serve as a reference for clinicians and researchers. This article will discuss the risk of fracture at the knee in persons with SCI, imaging methods to acquire and quantify BMD at the distal femur and proximal tibia, and treatment options available for prophylaxis against or reversal of osteoporosis in individuals with SCI.

Low bone mineral density and fractures are highly prevalent in pediatric patients with spinal muscular atrophy regardless of disease severity

Patients with Spinal Muscular Atrophy (SMA) are at risk for poor bone health. The prevalence of fractures, low areal bone mineral density (aBMD; Z-score ≤-2.0) of the lateral distal femur and of osteoporosis by SMA subtype is not known. We aimed to describe the natural history of bone health in patients with SMA prior to bisphosphonate treatment. We reviewed data from 85 eligible patients with SMA ages 12 months to 18 years, seen at a single institution between January 2005 and July 2016. Fracture history was reported at annual clinic visits. aBMD was obtained from dual energy x-ray absorptiometry scans of the lumbar spine, total body, and lateral distal femur. 85% of patients had aBMD Z-scores ≤-2.0 SD and were progressively lower with worsening SMA severity. Longitudinal aBMD Z-scores of the lateral distal femur decreased with age. Fractures occurred in 38% (32/85) of patients with the femur being the most common location (25 of 57 fractures). Thirteen percent of patients fulfilled criteria for osteoporosis. Low aBMD and femur fractures are highly prevalent in all SMA subtypes from a young age; however, few patients met the criteria for osteoporosis. Poor bone health may be an under-recognized comorbidity of SMA.

Diagnostic accuracy of DXA compared to conventional spine radiographs for the detection of vertebral fractures in children

OBJECTIVES

In children, radiography is performed to diagnose vertebral fractures and dual energy x-ray absorptiometry (DXA) to assess bone density. In adults, DXA assesses both. We aimed to establish whether DXA can replace spine radiographs in assessment of paediatric vertebral fractures.

METHODS

Prospectively, lateral spine radiographs and lateral spine DXA of 250 children performed on the same day were independently scored by three radiologists using the simplified algorithm-based qualitative technique and blinded to results of the other modality. Consensus radiograph read and second read of 100 random images were performed. Diagnostic accuracy, inter/intraobserver and intermodality agreements, patient/carer experience and radiation dose were assessed.

RESULTS

Average sensitivity and specificity (95 % confidence interval) in diagnosing one or more vertebral fractures requiring treatment was 70 % (58-82 %) and 97 % (94-100 %) respectively for DXA and 74 % (55-93 %) and 96 % (95-98 %) for radiographs. Fleiss' kappa for interobserver and average kappa for intraobserver reliability were 0.371 and 0.631 respectively for DXA and 0.418 and 0.621 for radiographs. Average effective dose was 41.9 μSv for DXA and 232.7 μSv for radiographs. Image quality was similar.

CONCLUSION

Given comparable image quality and non-inferior diagnostic accuracy, lateral spine DXA should replace conventional radiographs for assessment of vertebral fractures in children.

KEY POINTS

• Vertebral fracture diagnostic accuracy of lateral spine DXA is non-inferior to radiographs. • The rate of unreadable vertebrae for DXA is lower than for radiographs. • Effective dose of DXA is significantly lower than radiographs. • Children prefer DXA to radiographs. • Given the above, DXA should replace radiographs for paediatric vertebral fracture assessment.

Preoperative Periarticular Knee Bone Mineral Density in Osteoarthritic Patients Undergoing TKA

BACKGROUND

Preoperative periarticular bone quality is affected by joint loading. The purpose of this study was to determine the periarticular bone mineral density of the knee joint of patients undergoing total knee arthroplasty, and whether the location of the load-bearing axis correlates with the measured bone mineral density.

MATERIALS AND METHODS

The bone mineral densities of the medial and lateral femoral condyles and the medial and lateral tibial condyles were analyzed in consecutive 116 osteoarthritic patients (130 knees) by dual energy x-ray absorptiometry.

RESULTS

The median bone mineral density values in the condyles were 1.138 in femoral medial, 0.767 in femoral lateral, 1.056 in tibial medial, and 0.714 in tibial lateral. The medial condyles showed significantly higher bone mineral densities than the lateral condyles in both the femur and tibia. In addition, the femoral medial showed significantly higher bone mineral density levels than the tibial medial, and the femoral lateral condyle had higher bone mineral density levels than the tibial lateral. The bone mineral density Medial/Lateral ratio was significantly negatively correlated with the location (tibial medial edge 0%, lateral edge 100%) of the load-bearing axis in the femur and tibia.

CONCLUSION

Preoperative bone mineral density values may provide against the changes in bone mineral density after total knee arthroplasty by reflecting the correlation with joint loading axis. These results help explain why total knee arthroplasty has such good long-term clinical outcomes with a low frequency of component loosening and periarticular fractures despite a high degree of postoperative bone loss.

Preoperative Bone Mineral Density and Bone Turnover in Women Before Primary Knee Arthroplasty

PURPOSE

The preoperative prevalence of osteoporosis and/or osteopenia and overall bone quality in prospective total knee arthroplasty (TKA) patients may affect the postoperative outcome after prosthetic insertion into the bone. The purpose of this study is to determine the baseline bone mineral density (BMD) and bone turnover in preoperative, female, primary TKA patients.

METHODS

We prospectively measured the lumbar spine and hip BMDs using dual-energy X-ray absorptiometry (DEXA) scans in a cohort of 119 knees (107 patients) one day before surgery. We also assessed bone turnover using urinary levels of N-telopeptide (NTX), a type I collagen crosslinker, normalized to creatinine.

RESULTS

The prevalence of osteoporosis by DEXA scan (T-score ≤ -2.5) among the TKAs was 12% in the spine and 10% in the hip. Eighty-three knees (70%) had osteopenia or osteoporosis of either the spine or hip. The mean T-score of the spine was -0.7 (SD 1.6), which is within normal limits, and of the hip was -1.2 (SD 1.0), which is defined as osteopenia. The mean Z-scores of 0.9 (SD 1.4) in the spine and 0.6 (SD 0.9) in the hip were positive. The median urinary NTX/creatinine ratio was elevated at 58.1 (interquartile range: 13.7 to 188.4).

CONCLUSION

Based on Z-scores, the TKA patients had higher spine and hip BMDs than the age-matched general population. Elevated NTX levels may suggest a systemic or local abnormal bone turnover. Further study is needed to determine whether such turnover, as a type of patient-related medical systemic disorder, affects postoperative clinical outcomes.

Evaluation of epicardial adipose tissue in familial partial lipodystrophy

BACKGROUND

Dunnigan type Familial Partial Lipodystrophy (FPLD) is characterized by loss of subcutaneous fat from the limbs and excessive accumulation on the visceral adipose tissue (VAT). Affected individuals have insulin resistance (IR), diabetes, dyslipidemia and early cardiovascular (CV) events, due to their imbalanced distribution of total body fat (TBF). Epicardial adipose tissue (EAT) is correlated with VAT. Hence, EAT could be a new index of cardiac and visceral adiposity with great potential as a marker of CV risk in FPLD.

OBJECTIVE

Compare EAT in FPLD patients versus healthy controls. Moreover, we aimed to verify if EFT is related to anthropometrical (ATPM) and Dual-Energy X-ray Absorptiometry (DEXA) measures, as well as laboratory blood findings. We postulated that FPLD patients have enlarged EAT.

METHODS

This is an observational, cross-sectional study. Six patients with a confirmed mutation in the LMNA gene for FPLD were enrolled in the study. Six sex, age and BMI-matched healthy controls were also selected. EFT was measured by transthoracic echocardiography (ECHO). All participants had body fat distribution evaluated by ATPM and by DEXA measures. Fasting blood samples were obtained for biochemical profiles and also for leptin measurements.

RESULTS

Median EFT was significantly higher in the FPLD group than in matched controls (6.0 ± 3.6 mm vs. 0.0 ± 2.04 mm; p = 0.0306). Additionally, FPLD patients had lower leptin values. There was no significant correlation between EAT and ATPM and DEXA measurements, nor laboratory findings.

CONCLUSIONS

This study demonstrates, for the first time, that EAT measured by ECHO is increased in FPLD patients, compared to healthy controls. However, it failed to prove a significant relation neither between EAT and DEXA, ATPM or laboratory variables analyzed.

Resulting Shifts in Percentile and Standard Placements after Comparison of the BOD POD and DXA

The purpose of this study was to determine the validity of the BOD POD® when compared to the DXA and if placement on a percentile chart and standard table is affected by any differences between the two measures. A total of 244 (27.7 ± 10.8 yrs, 77.3 ± 16.1 kg, 171.4 ± 10.1 cm, 26.31 ± 5.42 BMI) males and females between the ages of 18 and 52 were recruited to participate in this study. The participant's body fat percentage (%BF) was tested in random order on the BOD POD® and DXA during a 30-minute session following manufacturer's guidelines and procedures. Dependent t-test indicated the %BF measured by the BOD POD® (23.4% ± 12.8) was significantly lower when compared to the DXA (29.5% ± 12.1), p = .001. The Pearson's Product moment correlation was 0.95 (p = .001), indicating a very strong relationship between the two instruments. Using estimates of %BF from the BOD POD® also resulted in more favorable shifts on a percentile chart and standard table. Since a high correlation was evident between the two, the BOD POD® can be used as an instrument to track %BF changes over time during a diet and/or exercise intervention. However, caution should be made when classifying %BF with percentile charts or standard tables using the BOD POD® %BF estimates.