Individualized evaluation of lumbar bone mineral density and bone mineral apparent density in children and adolescents

Summary

Lumbar spine bone mineral density (LS-BMD) assessed by dual-energy X-ray absorptiometry (DXA) is used in children to evaluate bone health. LS-BMD results in children are influenced significantly by height and BMI. An adjustment for these parameters may improve the clinical use of the method.

Purpose/Introduction

DXA evaluation is considered useful in children to assess bone health. For this purpose, lumbar spine bone mineral density (LS-BMD) and bone mineral apparent density (LS-BMAD) are often used. The aim of the study was to estimate the effect of height and BMI on LS-BMD and LS-BMAD in children and adolescents and to develop a method to adjust individual results for these factors.

Methods

As part of the National Health and Nutrition Examination Survey (NHANES) study, between the years 2005 and 2010 lumbar DXA scans on randomly selected Americans from 8 to 20 years of age were carried out. From all eligible DXA scans, three major US ethnic groups were evaluated (Non-Hispanic Whites, Non-Hispanic Blacks, and Mexican Americans) for further statistical analysis. The relationship between height as well as BMI for age Z-scores and age-adjusted LS-BMD and LS-BMAD Z-scores was analyzed.

Results

For the statistical analysis, the DXA scans of 1799 non-Hispanic White children (823 females), of 1696 non-Hispanic Black children (817 females), and of 1839 Mexican American children (884 females) were eligible. The statistical analysis showed that taller and heavier children had significantly (p?<?0.001) higher age-adjusted LS-BMD Z-scores than shorter and lighter children. But on LS-BMAD, only BMI and not height had a significant influence.

Conclusions

LS-BMD results in children were influenced significantly by their height and BMI, the LS-BMAD results were only influenced by their BMI. For the first time, the proposed method adjusts LS-BMD and LS-BMAD to BMI. An adjustment of the LS-BMD and LS-BMAD results to these factors might improve the clinical significance of an individual result.

     

Relationships of muscle strength and bone mineral density in ambulatory children with cerebral palsy

Summary  

This work explores the relationships of muscle strength and areal bone mineral density (aBMD) in ambulatory children with cerebral palsy (CP). The knee extensor strength, but not motor function, was related to aBMD. Thus, muscle strength, especially antigravity muscle strength, was more associated with aBMD in these children than motor function.     

Factors influencing metacarpal bone mineral density in adults with cerebral palsy

Several studies have examined bone mineral density (BMD) and related factors in children with cerebral palsy, but there are no such studies of adults with cerebral palsy. We evaluated BMD in 123 institutionalized adults (51 men aged 21–41 years and 72 premenopausal women aged 24–46 years) with cerebral palsy, and examined the associations of BMD with mobility level, use of anticonvulsant drugs, and abnormal calcium metabolism status. Hand radiographs were used to measure BMD of the second metacarpal bone (mBMD). Body weight (kg), height (m), and body mass index (BMI) were recorded. Serum calcium, phosphate, and alkaline phosphatase were measured. Abnormal calcium metabolism, defined as calcium 8.5mg/dl, phosphate 2.6mg/dl, or alkaline phosphatase 260U/l, was identified in 28% of the men and 31% of the women. Multiple regression analysis showed that the use of anticonvulsant drugs was significantly associated with lower mBMD in both sexes. Higher alkaline phosphatase level was significantly associated with lower mBMD in men. Mobility level (ambulation) was significantly associated with higher mBMD in women. Neither age nor BMI correlated with mBMD. Our findings indicated poor bone health status in adults with cerebral palsy and the existence of several factors that could affect bone metabolism in these patients.     

Efficacy of home-based virtual cycling training on bone mineral density in ambulatory children with cerebral palsy

Summary

The 12-week home-based virtual cycling training (hVCT) improved lower limb muscle strength and areal bone mineral density (aBMD) than the control program in children with cerebral palsy (CP). A muscle strengthening program, rather than general physical activity, is more specific in enhancing aBMD for these children. A novel hVCT is an effective and efficient strategy that enhances lower limb bone density in these children.

Introduction

This is the first study to assess the efficacy of a novel hVCT program on bone density for children with spastic CP using a well-designed randomized controlled trial.

Methods

Twenty-seven ambulatory children with spastic CP, aged 6–12 years, were randomly assigned to the hVCT group (n?=?13) or control group (n?=?14). Outcome measures—motor function [Gross Motor Function Measure-66 (GMFM-66)], muscle strength (curl up scores and isokinetic torque of knee extensor and flexor muscle) and aBMD of the lumbar and distal femur—were administered before and immediately after the 12-week intervention.

Results

Analysis of covariance results show that the hVCT group had greater distal femur aBMD and isokinetic torques of knee extensor and flexor muscles than the control group at posttreatment (p?<?0.05). However, curl up scores, GMFM-66, and lumbar aBMD at posttreatment did not differ between the two groups.

Conclusions

Analytical findings suggest that the muscle strengthening program is more specific in enhancing bone density for children with CP than general physical activity. Thus, the proposed 12-week hVCT protocol is an effective and efficient strategy for improving lower limb aBMD in these children.     

Pamidronate treatment and posttreatment bone density in children with spastic quadriplegic cerebral palsy.

Little is known about the long-term effects of a course of pamidronate treatment on bone mineral density (BMD) of children with spastic quadriplegic cerebral palsy (SQCP). Nine patients with SQCP who had low bone density and/or history of previous fracture(s) were studied during treatment and more than 1 yr after cyclic pamidronate treatment ended. Over the 12 mo of treatment, spine BMD increases raised average Z-score from -4.0 to -2.8. In the distal femoral metaphysis, BMD increase raised average Z-score from -3.6 to -1.7. Observations posttreatment ranged from 12 to 49 mo. Changes in BMD were variable among individuals. Group spine Z-score an average of 34 mo posttreatment approached pretreatment value. Six of eight patients had final distal femur posttreatment Z-scores the same or better than pretreatment baseline an average of 27.1 mo later. While most but not all gains in BMD were lost over the first 2 yr after treatment, no patient sustained fracture during or after treatment for a cumulative follow-up of more than 27 patient-yr.     

Diagnostic evaluation using whole-body technetium bone scan in children with cerebral palsy and pain

BACKGROUND: Pain in noncommunicative children can be difficult to localize and diagnose. The purpose of this study is to report our experience using a 3-phase whole-body technetium bone scan as a screening tool in identifying the source of persistent pain in children with profound disabilities who cannot communicate. METHODS: We reviewed the medical and imaging records of 45 patients who met the inclusion criteria of the study, which included a diagnosis of spastic quadriplegic cerebral palsy with severe motor and cognitive impairment, persistent pain of more than 1 week in duration with no recognizable source, and a 3-phase whole-body bone scan as part of the pain workup. RESULTS: The study group included 26 females and 19 males with an average age at presentation of 13.5 years (range, 3-20 years). A positive bone scan was seen in 24 patients (53%). The diagnosis and the source of pain were identified in all 24 patients with a positive bone scan, with the bone scan being instrumental in establishing a diagnosis or localization in 22 patients. An orthopaedic diagnosis was not established in the 21 other patients with a negative bone scan. Based on the bone scan results, additional imaging was obtained at the anatomical location indicated. The bone scan was used to establish a diagnosis of fracture in 10 of 24 patients. Other diagnoses included 3 patients with painful internal hardware, 2 with sinusitis, 2 with infections, and 1 with an obstructed kidney. CONCLUSIONS: Whole-body bone scan is a viable imaging option to identify the source of persistent pain in children who are noncommunicative. The bone scan can assist in localizing the source of pain and direct the location for further imaging as needed.     

慢性肾衰竭患者腰椎骨密度测定分析

目的 观察慢性肾衰竭病人骨密度（BMD）值的变化.方法 采用双能X线骨密度测定的方法测定201例慢性肾衰竭病人的1～4腰椎前后位BMD值,并与年龄、性别相匹配的正常人1～4腰椎前后位BMD值进行比较分析.结果 慢性肾衰竭早期（氮质血症期）、肾衰竭期与尿毒症期患者BMD测定值无明显差异（P＞0.05）.慢性肾衰竭患者BMD测定值明显低于正常对照组（P＜0.05）.结论 慢性肾衰竭早期BMD值已明显降低,骨量丢失在慢性肾衰竭出现前已经开始.BMD测定敏感性较高,可以在慢性肾衰竭早期反映患者骨含量变化,是目前早期诊断肾性骨病的较好方法.     

High bone mineral apparent density in children with X-linked hypophosphatemia

Summary

Bone mineral apparent density (BMAD) in children with X-linked hypophosphatemia (XLH) was evaluated, as they are unlikely to have extra-skeletal ossifications contributing to the elevated bone mineral density of the spine in adult patients. Children with XLH also had significantly higher BMAD of the spine compared to femoral neck.

Introduction

BMAD obtained by dual-energy X-ray absorptiometry scans in children with XLH was evaluated, as they are unlikely to have the extra-skeletal ossifications contributing to the elevated bone mineral density of the spine in adult patients.

Methods

A total of 15 children with biochemically and genetically verified XLH were recruited. Anthropometric measurements were performed, and to correct for the short stature (small bones), the BMAD of the spine and the femoral neck was evaluated.

Results

Z-scores of BMAD of the spine (mean (95 % CI); 2.0 (1.3–2.7); p?<?0.001) were significantly elevated compared to reference children. Z-scores of the femoral neck (1.0 (?0.0 to 2.1); p?=?0.059) tended to be elevated. Spine Z-scores were significantly higher than the Z-scores of the femoral neck, (paired t test, p?=?0.02). BMAD of the spine was evaluated according to the Molgaard’s approach; XLH children had normal bone size of the spine for age due to a normal sitting height Z-score of ?0.4 (?1.0 to 0.1); p?=?0.1. Z-scores of bone mineral content (BMC) of the spine for bone area were elevated (1.4 (0.8–2.1); p?<?0.001). No reference data were available to allow evaluation of the BMAD of the femoral neck by the Molgaard's approach.

Conclusions

Children with XLH have an increased BMAD and a high BMC for bone area at the lumbar spine, and this was due to causes other than extra-skeletal ossifications and corrected for bone size. The BMAD of the spine was significantly higher compared to the femoral neck.     

Bisphosphonates in children with hypercalciuria and reduced bone mineral density

Previous studies have demonstrated reduced bone mineral density (BMD) and biochemical changes of excessive bone resorption in some patients with idiopathic hypercalciuria (IH). Consequently, bisphosphonates have been successfully employed in research animals and adults with IH and reduced BMD. We evaluated the effect of treatment with bisphosphonates in seven patients ages 10–16 years with persistent IH and reduced BMD. In five children, preceding traditional therapy failed. All children received oral alendronate and one also IV Zoledronic acid for 6–18 (median 9.0, mean 10.7) months. With treatment, BMD Z scores in the lumbar spine improved from −2.0 ± 0.3 to −0.8 ± 0.8 (p = 0.002) and in the femoral neck from −1.8 ± 0.4 to −0.7 ± 0.9 (p = 0.01); urine N-telopeptides/creatinine decreased from 372 ± 289 to 72 ± 39 nmol/mmol (p = 0.05) and calcium/creatinine from 0.29 ± 0.12 to 0.13 ± 0.06 mg/mg (p = 0.009). Height Z scores, normal at baseline in all, remained unaffected, and no new stones or fractures were documented throughout the treatment period. Serum creatinine, electrolytes, calcium, phosphorus and parathyroid hormone remained normal as well. In summary, in children with IH and decreased BMD, treatment with bisphosphonates normalized urine calcium excretion, eliminated urinary symptoms, and significantly improved reduced BMD. These short-term beneficial effects indicate the need for larger prospective studies on the potential of bisphosphonates to serve as a new tool in treating children with IH and reduced BMD.     

定量CT腰椎骨密度测量的低剂量研究

目的通过临床验证多排螺旋定量悦栽腰椎低剂量扫描参数,制定最佳的低剂量多排螺旋 QCT腰椎扫描协议。资料与方法选取住院拟进行腰椎手术,术前行常规多排螺旋悦栽平扫和腰椎 匝悦栽检查的30位患者。其中男：0例,女20例;年龄48耀79岁,平均年龄63.97依8.66岁。分两次 采集常规250皂粤和50皂粤两组腰椎加校准体模QCT容积数据,将两组L2-L4容积数据传至骨密度 工作站进行骨密度（Bone Mineral DensiLy )测量。应用统计软件杂孕杂杂15. 0进行统计分析。结果250 皂粤组与50皂粤组L2、L3、蕴4平均BMD值无差异（孕>0. 05 )两组三椎体总平均BMD值无差异（责跃 0. 05 )250 mA 组辐射剂量 DLP 值为 229. 06 土 12. 35 mGy cm。0 mA 组 DLP 值为 45. 78 ±2. 48 mGy 糟皂。结论多排螺旋定量QCT腰椎低剂量扫描技术能够保证BMD测量准确性,同时使患者的受辐射 剂量比常规多排螺旋CT腰椎扫描大幅度降低     

影响绝经后女性腰椎骨密度的相关因素研究

目的寻找绝经后女性腰椎骨密度(lumbar spine bone mineral density,LSBMD)的独立相关因素。方法调查212例绝经后女性的伴随疾病,并检测LSBMD、骨代谢、血生化和性激素等指标,筛选绝经后女性LSBMD的独立相关因素。结果绝经后女性LSBMD的独立相关因素包括骨钙素(β=-0.003,P0.01)、体质量指数(β=0.021,P0.01)、慢性阻塞性肺疾病(chronic obstructive pulmonary disease,COPD)(β=-0.153,P0.01)和尿酸(β=0.001,P0.05)。结论积极防治COPD,降低血清骨钙素水平,维持合理的尿酸和体质量指数,可能是提高绝经后女性LSBMD的有效方法。     

Evaluation of bone mineral density after instrumented lumbar fusion with computed tomography

BACKGROUND CONTEXTComputed tomography (CT) measurement of Hounsfield Units (HU) has been described as a tool for assessing BMD. For surgeons considering a revision lumbar fusion, knowledge of the BMD of the UIV is of value for surgical planning. However, the presence of metal artifact from instrumentation presents a potential confounder, and prior studies have not validated measurements of HU in this setting.PURPOSETo determine if HU can be measured reliably at the supra-adjacent and upper instrumented levels of a lumbar fusion.STUDY DESIGNRetrospective observational cohortPATIENT SAMPLEConsecutive series of patients who had lumbar CT scans after an instrumented posterior lumbar fusion.OUTCOME MEASURESHounsfield Units at the upper instrumented vertebra and levels proximal.METHODSWe analysed pre- and postoperative CT scans of 50 patients who underwent L2 and distal instrumented lumbar fusion whose scans were no greater than 1 year apart, obtaining HU measurements of analogous axial cuts at the upper instrumented level (immediately caudal to the halo of the pedicle screw), as well as additional control levels above the construct.RESULTSThe HU at the pre-and postoperative UIV exhibited a strong correlation (r=0.917, p<.001), as did one (r=0.887, p<.001) and two (r=0.853, p<.001) levels above the UIV. There were significant but predictable reductions in the postoperative HU compared to preoperative at one (-9.0±26.2) and two (-12.2±30.2) levels above the UIV, as well as T12 (-13.9±42.2). There was no significant difference in HU at the UIV (4.6±34.1).CONCLUSIONSPostoperative HU at the UIV was strongly correlated with and not significantly different from the preoperative HU. Although the HU in the vertebrae proximal to the UIV were slightly lower postoperatively, this change was predictable using a correction factor.     

正常人腰椎正位骨密度测量结果分析

目的 了解正常人腰椎正位骨密度变化，为建立北京地区骨密度正常参考值提供依据。方法 应用Norland XR-36型双能X线骨密度仪（DEXA）对北京地区20－89岁正常人进行腰椎正位骨密度测定，按5岁一个年龄组进行统计分析。结果 L2－L4峰值分布在男性25－29岁，女性30－34岁，男女之间峰值差异无显性（P＞0．05）。55岁以后同年龄组两性间BMD差异显（P＜0．01）。女性从45－50岁组，男性从60－64岁组开始骨量丢失明显加快，男性在70－84岁BMD保持稳定，并有上升趋势。结论 妇女绝经前4－5年椎骨骨量就已出现明显的丢失；在临床扫描分析时，对异常高密区加以删除，可对腰椎骨密度状况得出更真实的评价。     

腰椎各椎体骨密度的分析

目的分析腰椎各椎体骨密度（ＢＭＤ）的差异。方法对１２１４例在我科进行骨密度检查的２０～８９岁人群,男性３９０例,女性８２４例,除外各种器质性内分泌、消化系统及肿瘤等疾病,用双能Ｘ线骨密度仪（ＤＥＸＡ）测量腰椎ＢＭＤ,通过计算机分析比较各椎体ＢＭＤ值的差异与相互关系,用ＥＸＣＥＬ软件做统计学分析,计数资料进行配对ｔ检验。结果ＢＭＤ值以Ｌ１最低,Ｌ４最高,Ｌ１－２与Ｌ２－４ＢＭＤ女性在４０岁以上有显著差异（Ｐ＜０．００１）,男性在６０岁以上（Ｐ＜０．０５）,８０岁以后无明显差异,女性５０岁以后骨丢失明显快于男性。结论腰椎各椎体ＢＭＤ存在差异,尤以女性明显,其差异与增龄造成的腰椎退行性变的干扰有关     

Longitudinal study of bone mineral density in children with idiopathic hypercalciuria

Children with idiopathic hypercalciuria (IH) may have a reduced bone mineral density (BMD), which could impact on bone health in adulthood. There is currently no strong evidence for a preferred treatment of such children. The aim of our study was to evaluate the BMD z-score before and after treating children and adolescents with IH with potassium citrate and thiazides. The study consisted of a historical cohort of 80 pediatric patients who were evaluated between October 1989 and November 2010. Bone scanning and densitometry measurements were made with dual-emission X-ray absorptiometry. Lumbar-spine BMD (g/cm²) and BMD z-score were evaluated before and after treatment. The t test and Mann–Whitney U test were used for statistical analysis. Forty-three boys and 37 girls were followed for a median time of 6.0 years. Median calcium excretion before and after treatment was 5.0 and 2.6 mg/kg/24 h, respectively. The BMD z-score changed significantly from −0.763 ± 0.954 (mean ± SD) to −0.537 ± 0.898 (p < 0.0001) before and after treatment, respectively. The BMD z-score of the patients improved with treatment, suggesting a beneficial effect and potential need for treatment. However, the lack of a control group points to the need for future studies to corroborate this outcome.     

腰椎间盘突出症与腰椎骨密度的相关性研究

目的 研究腰椎间盘突出症(lambar disc herniation,LDH)与骨质疏松(osteoporosis,OP)的相关性,探讨腰椎间盘突出症对骨密度的影响.方法 选取腰椎间盘突出症组患者82例,对照组健康体检人群41例,利用定量CT(quantitative computed tomography,QCT)测定其骨密度(bone mineral density,BMD),分析比较两组的骨密度值.并对腰椎间盘突出症组患者病程:≤1年与＞1年,腹肌肌力≤3级与≥4级骨密度值变化进行比较分析.结果 腰椎间盘突出症组患者的骨密度值较对照组低,骨量减少者在腰椎间盘突出症组中的构成比较对照组高,但差异均无统计学意义(P>0.05).其病程、腹肌肌力对腰椎间盘突出症组患者骨密度值变化的影响无统计学差异(P>0.05).结论 腰椎间盘突出症对骨密度有一定的影响,但两者的关系不显著,腰椎间盘突出症并非骨质疏松的独立影响因素.     

The relationship between tight hamstrings and lumbar hypolordosis in children with cerebral palsy

STUDY DESIGN: Retrospective clinical and radiographic review. OBJECTIVE: To assess the influence of tight hamstrings on the sagittal alignment of the thoracic and lumbar spine in children with cerebral palsy. SUMMARY OF BACKGROUND DATA: It is postulated that tight hamstrings may produce a hypolordosis of the lumbar spine. The abnormal sagittal contour of the spine may lead to increased stresses in the lumbar spine and subsequent pain and disability. This is of special concern in children with cerebral palsy who often have shortened spastic hamstring muscles. METHODS: Twenty-one patients were evaluated, with a mean age of 9.4 years. Standing and sitting lateral spine films were obtained and the lumbar lordosis and thoracic kyphosis were measured using the Cobb method. The popliteal angle was measured to assess hamstring tightness, such that a large popliteal angle indicates tight hamstrings. RESULTS: We found a statistically significant correlation between the sitting lumbar curve and popliteal angle (Pearson correlation value -0.77, P < 0.01). As the popliteal angle increased, the amount of lumbar lordosis decreased. This correlation was less significant when the patient was standing (Pearson correlation value -0.59). CONCLUSION: This study demonstrates that there is a correlation between tight hamstrings, as measured by the popliteal angle, and decreasing lumbar lordosis, especially when sitting.