Bone mineral density correlates strongly with basal metabolic rate in postmenopausal women

BACKGROUND: This study investigated the relationships of bone mineral density (BMD) with body composition, basal metabolic rate (BMR), and fat distribution. METHODS: We measured body mass index (BMI), anthropometrics, and BMD in 345 postmenopausal women and 224 elderly men. Total body fat (TBF), fat distribution, and BMR were assessed using a body composition analyzer. Lumbar spine and proximal femur BMDs were measured with dual-energy X-ray absorptiometry. RESULTS: Lumbar spine BMD was more strongly correlated with BMR (r=0.51, p<0.01) than with lean body mass (r=0.39, p<0.01) and waist hip ratio (r=-0.28, p<0.01) in postmenopausal women. The mean values of BMR in osteoporotic women were significantly lower than those for non-osteoporotic women (p<0.01). The prevalences of osteoporosis at the sites of lumbar spine and proximal femur were 32.1% and 23.3% in the women with BMR<1230 kcal, which were significantly higher than those of osteoporosis (5.4% and 7.7%) at the corresponding sites in the women with BMR> or =1230 kcal (p<0.01). In elderly men, the incidence of osteoporosis at the proximal femur was 29.5% in the subjects with BMR<1390 kcal, significantly higher than that (2.2%) in the subjects with BMR> or =1390 kcal (p<0.01). CONCLUSION: BMR is more closely associated with bone density in elderly persons, at least as compared to TBF, BMI, or lean body mass.     

Bone mineral density after spinal cord injury: a reliable method for knee measurement

OBJECTIVES: To test the interrater reliability of a standardized method to analyze knee bone mineral density (BMD) using dual-energy x-ray absorptiometry (DXA); to compare spine, hip, and knee BMD of people with spinal cord injury (SCI) with able-bodied controls; and to determine the relation between hip BMD and knee BMD in SCI and able-bodied subjects. DESIGN: Criterion standard and masked comparison. SETTING: Primary care university hospital. PARTICIPANTS: A convenience sample of 11 subjects with complete SCI was age and sex matched with 11 able-bodied control subjects. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Four raters analyzed regions of interest according to operational definitions recently developed to standardize the analysis of BMD of the knee. Subjects with chronic SCI and matched controls underwent conventional DXA scans of the spine and hips and "less conventional" scans of the distal femurs and proximal tibias. The relation between hip and knee BMD was analyzed. RESULTS: The knee measurements were highly reliable (femur intraclass correlation coefficient model 2,1 [ICC(2,1)]=.98; tibia ICC(2,1)=.89). Subjects with SCI had lower BMD values than controls at all hip and knee sites (P<.05). Lumbar spine BMD did not differ between groups. Hip BMD was moderately predictive of distal femur BMD (R2=.67), but less correlated with the proximal tibia (R2=.38). CONCLUSIONS: Knee BMD can be reliably analyzed using DXA with this protocol. Subjects with SCI have diminished knee and hip BMD. Low hip BMD is associated with low distal femur BMD.     

Fracture threshold in the femur and tibia of people with spinal cord injury as determined by peripheral quantitative computed tomography

OBJECTIVE: To determine bone traits of the femur and tibia with peripheral quantitative computed tomography (pQCT) that best distinguish between spinal cord injury (SCI) subjects with and without fractures. DESIGN: Cross-sectional study. SETTING: In- and outpatient paraplegic center in Switzerland. PARTICIPANTS: Ninety-nine motor complete SCI subjects (duration of paralysis, 2 mo-49 y), 21 of whom had sustained fractures of the femur or tibia. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Subjects with SCI were questioned about the occurrence, location, and approximate date of fractures to their lower extremities. Trabecular and cortical bone mineral density (BMD), as well as bone geometric properties of distal epiphyses and midshafts of the femur and tibia, were measured by pQCT. RESULTS: Trabecular BMD of the femur and tibia distal epiphyses was found to distinguish best subjects with fractures from those without. Fractures occurred in subjects with trabecular BMD of less than 114 mg/cm 3 and less than 72 mg/cm 3 for the femoral and tibial distal epiphysis, respectively (corresponding to 46% and 29% of mean values of an able-bodied reference group). Approximately 50% of the subjects with chronic SCI (defined as time postinjury >5 y for femur data and >7 y for tibia data) had trabecular BMD values above the fracture threshold in the femur and about one third above the fracture threshold in the tibia. CONCLUSIONS: By using pQCT, it may be possible to identify subjects with SCI who are at risk of sustaining fractures of the femur and tibia through minor trauma.     

脊髓损伤后大鼠骨代谢和骨密度变化

目的:了解脊髓损伤后不同时期大鼠骨代谢和骨密度的变化。方法:60只SD大鼠按体重随机分为6组,对20只大鼠采用脊髓横断法在第10胸椎段横断脊髓制作完全性脊髓损伤模型,分为脊髓损伤6周和12周组;20只在同水平处切断棘突、椎板制作假手术对照组,分为假手术6周和12周组;另20只分为正常6周和12周对照组。分别在脊髓损伤后6周和12周时处死动物。结果:脊髓损伤6周、12周时,脊髓损伤组血Ca较对照组明显升高(P<0.05),碱性磷酸酶和骨钙素则较对照组无明显变化(P>0.05)。脊髓损伤6周时,股骨近端、远端骨密度(BMD)均较对照组显著降低(P<0.001),损伤12周时,除股骨近端、远端外,中段BM D也明显降低(P<0.05)。L5BMD在SCI6周和SCI12周与对照组比较差异无显著性意义(P>0.05)。结论:脊髓损伤6周时,大鼠骨代谢已发生明显改变,骨量出现明显丢失,12周时骨代谢稍有改善,但股骨骨量丢失持续存在。     

脊髓损伤对大鼠股骨骨密度与生物力学特性的影响

目的探讨脊髓损伤(spinal cord injury, SCI)对大鼠股骨生物力学和骨密度(bone mineral density, BMD)的影响. 方法将40只3月龄大鼠随机分为SCI组和对照组,SCI组于T10椎体处完全切断脊髓,对照组仅行椎板切除术.于术后3,6周分2批处死动物进行股骨骨密度和生物力学测定. 结果术后3周时SCI组大鼠股骨远端BMD较对照组显著下降(P<0.05);术后6周时SCI组股骨近端BMD与对照组比较,下降差异显著(P<0.05);股骨远端BMD较对照组下降差异非常显著(P<0.01);股骨干BMD与对照组相比有降低趋势,但无统计学意义.术后3周时股骨颈最大载荷、最大变形、结构刚度及能量吸收在2组间差异均无统计学意义.术后6周时最大变形、结构刚度和能量吸收均低于对照组(P均<0.05),最大载荷低于对照组,差异具有极显著性意义(P<0.01). 结论脊髓损伤后松质骨骨密度和生物力学性能的降低先于密质骨.脊髓损伤后6周时SCI组股骨松质骨的骨密度及生物力学参数均显著低于对照组,脊髓损伤后6周的大鼠可作为骨质疏松动物模型.     

Femur bone mineral density is independently associated with functional recovery after hip fracture in elderly women

OBJECTIVE: To evaluate the association between femur bone mineral density (BMD) and functional recovery after hip fracture. DESIGN: Cross-sectional study. SETTING: Rehabilitation hospital in Italy. PARTICIPANTS: A total of 233 of 263 white women with hip fracture consecutively admitted to a rehabilitation hospital. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Patients underwent BMD assessment by dual-energy x-ray absorptiometry (DXA) at the proximal femur (5 sites) on admission. Functional recovery was evaluated by using Barthel Index scores. RESULTS: A positive correlation was found between BMD and Barthel Index scores assessed on both admission and discharge (r range,.16-.24, depending on the site of BMD measurement). Linear multiple regression showed that the association between BMD and Barthel Index score was independent of 10 confounding variables: age, body mass index, fracture type, pressure ulcers, cognitive impairment, neurologic diseases, total lymphocyte count as a nutritional index, time between fracture occurrence and DXA assessment, comorbidity, and surgical procedure. Conversely, no significant associations were found between BMD and the change in Barthel Index score attributable to rehabilitation. CONCLUSIONS: In the study population, femur BMD was an independent predictor of the functional recovery assessed by Barthel Index score after hip fracture, but not of the change in the functional score resulting from rehabilitation.     

Bone mineral and geometric changes through the femur with immobilization due to spinal cord injury

This cross-sectional study describes bone mineral and geometric properties of the midshaft and distal femur in a control population and examines effects of immobilization due to spinal cord injury (SCI) at these skeletal sites. The subject populations were comprised of 118 ambulatory adults (59 men and 59 women) and 246 individuals with SCI (239 men and 7 women); 30 of these were considered to have acute injury (SCI duration <1 year). Bone mineral density (BMD) was assessed at the femoral neck, and midshaft and distal femur by dual energy absorptiometry. Geometric properties, specifically cortical area, polar moment of inertia, and polar section modulus, were estimated at the midshaft from cortical dimensions obtained by concurrent radiography. Reduction in BMD was noted in all femoral regions (27%, 25%, and 43% for femoral neck, midshaft, and distal femur, respectively) compared with controls. In contrast, although endosteal diameter was enlarged, geometric properties were not significantly reduced in the midshaft attributable to the age-related increase in periosteal diameter. These results suggest that simultaneous assessment of bone mineral and geometric properties may improve clinically relevant evaluation of skeletal status.     

Relationship between regional bone density measurements and the time since injury in adults with spinal cord injuries

OBJECTIVES: To determine the bone mineral density (BMD) of the legs, arms, and trunk region of a group of adults with spinal cord injury (SCI) and to determine the relationship between regional BMD values and the time since injury. DESIGN: BMD measurements were determined by total-body, dual-energy x-ray absorptiometry scans and percentage values (percentage-matched BMD), based on manufacturer-supplied normative data for age, sex, body weight, and ethnic group. The relationship between percentage-matched BMD values and time since injury was determined by linear regression analyses. SETTING: Research laboratories in a university setting. PARTICIPANTS: Twenty-nine subjects (21 men, 8 women; mean age, 38.5 y) who had sustained an SCI a mean of 10.6 years earlier (range, 0.6-35.3 y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The relationship between percentage-matched BMD values and the time since injury. RESULTS: There was a significant inverse relationship between percentage-matched BMD leg (r2 = -.76), arm (r2 = -.45), and trunk (r2 = -.38) values and the log of time since injury. CONCLUSION: Despite the varying levels of SCI and other relevant BMD contributing factors, the regional percentage-matched BMD values were significantly inversely related to the log of time since injury.     

脉冲电磁场及阿仑膦酸钠对脊髓损伤大鼠骨质量的影响

目的探讨早期应用脉冲电磁场（PEMFs）和／或阿仑膦酸钠（ALN）对脊髓损伤（SCI）后大鼠骨质量的影响。方法将62只3月龄雌性sD大鼠随机分为5组，其中假手术组仅行椎板切除术，SCI组、SCI＋ALN组、SCI＋PEMFs组及SCI＋PEMFs＋ALN组行脊髓完全横断术，后3组于术后1周时分别给予ALN和／或PEMFs治疗；于术后8周时取材，检测各组大鼠股骨骨密度值、生物力学指标以及胫骨近端骨组织形态计量学等指标。实验所得数据比较采用单因素方差分析及析因分析。结果早期应用ALN和／或PEMFs均可使股骨骨密度、股骨弹性载荷、最大载荷等生物力学指标增高，胫骨近端骨小梁面积百分比也同时增大，骨小梁宽度增加。结论早期应用ALN和／或PEMFs均可抑制SCI后骨量丢失，增强抗骨折能力，阻止胫骨近端微观结构的退变，提示早期应用ALN及PEMFs有助于防治SCI后骨质疏松，但其具体治疗机制还有待进一步研究。     

阿法骨化醇及二膦酸盐类药物对脊髓损伤患者骨密度的影响

目的探讨阿法骨化醇及二膦酸盐类药物对脊髓损伤患者骨密度的影响。方法分别比较 3 1例口服阿法骨化醇与42例未口服该药的脊髓损伤患者 ,以及 2 2例口服二膦酸盐类药物与 2 4例未口服该药的脊髓损伤患者第 4腰椎和股骨近端及其分区骨密度变化的差异。结果是否口服阿法骨化醇对脊髓损伤患者骨密度的保持无显著影响 ;但口服二膦酸盐类药物患者的股骨近端 (total)骨密度较未口服该药物患者下降少 ,两者的差异具有显著性意义 (P <0 .0 5 )。结论口服二膦酸盐类药物对股骨近端的骨密度变化有保护作用。     

Bone mineral density after bicycle ergometry training

The effect of functional electrical stimulation (FES) cycle ergometry on bone mineral density (BMD) was investigated in six spinal cord injury (SCI) quadriplegic men. Each subject trained three days a week for six months on an FES cycle ergometer. Pretraining and posttraining BMD measurements of the proximal femur were performed using dual photon absorptiometry. Mean pretraining BMD (percent norm) for the femoral neck, Ward triangle, and trochanter were 66.65, 57.43, and 57.67, respectively. After six months of FES cycle ergometry, mean BMD measurements were 66.15, 57.07, and 55.13, respectively. There was no statistically significant difference between the pretraining and posttraining BMD measurements. All subjects were found to have osteoporotic proximal femurs when BMD was expressed as a percent of their age-matched controls. Bone mineral density measurements were subsequently performed on three additional men with SCI who had exercised for three years with the FES cycle ergometry modality. Their mean BMDs were not significantly different from the experimental group. This study demonstrated that six months of FES cycle ergometry did not produce an increase in BMD.     

Relationships between serum adiponectin, leptin, resistin, visfatin levels and bone mineral density, and bone biochemical markers in Chinese men

BACKGROUND: Adiponectin, leptin, resistin, and visfatin, as the main circulating peptides secreted by adipose tissue, are potential contributors to bone metabolism. We investigated whether these serum adipocytokines levels are associated with BMD and bone turnover biochemical markers in 232 Chinese men (20-80 y). METHODS: Serum adiponectin, leptin, resistin, and visfatin levels were determined by ELISA. RESULTS: Leptin had a positively correlation with fat mass, and remained significant after adjustment for age and BMI. There was a significant negative weak correlation between adiponectin and fat mass, and disappear after adjustment for age and BMI. Resistin and visfatin were not significantly correlated with fat mass. In the multiple linear stepwise regression analysis, lean mass and adiponectin, but not leptin, resistin and visfatin, were independent predictors of BMD. The significant positive correlations between adiponectin and bone-specific alkaline phosphatase (BAP), bone cross-linked N-telopeptides of type collagen (NTX) were found, and remained significant after adjustment for age and fat mass. CONCLUSIONS: Adiponectin was an independent predictor of BMD in Chinese men, and positively correlated with bone turnover biochemical markers. It suggested that adiponectin exert a negative effect on bone mass in men.     

Bone mineral density of vertebrae,proximal femur and os calcis in normal Greek subjects as assessed by dual-energy X-ray absorptiometry: comparison with other populations

Dual energy X-ray absorptiometry (DXA) is an established method for the detection of even small changes in bone mineral density (BMD). It thus allows the earliest possible diagnosis of osteopenia, with consequent prompt estimation of fracture risk. However, for proper evaluation of densitometry results it is essential that a comparison with reference BMD values of normal age- and sex-matched persons from the same population be performed. For this purpose we determined bone density of the L2–L4 vertebrae, the L3 vertebra in the lateral projection, the proximal femur and the os calcis in a cross-sectional study of 168 men and 244 women from the Greek population. The age range of the subjects was 20–80 years. Peak bone mass for both sexes was attained in the 30–35 year age group for the vertebrae and in the 25–30 year age group for the proximal femur and os calcis. Mean annual vertebral bone loss calculated on cross-sectional data ranged from 0.1% to 0.22% for women <50 years and from 1.3% to 1.6% for those >50 years, whereas in men the range was from 0.36% to 0.64% for the whole age spectrum. Regarding femoral neck, the values were 0.3% (women <50 years), 1.2–1.5% (>50 years) and 0.6–0.8% for men. Total bone loss between ages 20 and 70 was 29.5% for the vertebrae and 32% for the femoral neck in women, whereas the values for men were 19.5% and 29% respectively. A positive correlation was observed between bone density, body weight and body height in both sexes. Body mass index correlated significantly with density only in postmenopausal women. Compared with North American, Finnish and German populations, Greek men presented with lower BMD values in the decades above 40 years. Greek women exhibited lower vertebral BMD values than those from the USA, Germany and Japan (50–60 age group), whereas they did not differ from those of Finnish women. However, femoral neck BMD in Greek women was higher than in Japanese women in all age groups.     

低频振动对脊髓损伤继发骨质疏松的影响

目的了解低频振动对脊髓损伤（SCI）继发骨质疏松（OP）大鼠骨代谢和骨质量的影响。方法50只SD大鼠采用脊髓全切横断法在第10胸椎处横断脊髓制作完全性SCI模型,并随机分为SCI6周对照组（SCI6w）、SCI12周对照组（SCI12w）、振动6周组（Vi6w）、振动12周组（Vi12w）和SCI6-12周振动组（Vi6-12w）,每组10只;振动组分别于SCI后第4天（Vi6w组、Vi12w组）、第7周（Vi6-12w组）开始接受振动干预,振动频率20Hz,加速度0.15g,10min/次,2次/d,6d/周,Vi6w组和Vi6-12w组共振动6周,Vi12w组振动12周。分别在振动结束1d后处死动物,进行骨代谢血生化指标、骨密度（BMD）、骨形态计量学和生物力学性能测试。结果Vi6w组大鼠血Ca和股骨近端BMD较对照组改善（P〈0.05）;Vi12w组第5腰椎最大载荷较对照组升高（P〈0.05）;Vi6-12w组大鼠骨代谢和骨质量未见明显变化。结论早期开始的低频振动干预可改善SCI继发OP,但存在部位差异;后期进行的振动干预不能改善SCI继发OP,但可防止其进展。     

Healthy body mass index values often underestimate body fat in men with spinal cord injury

OBJECTIVE: To examine the relation between body mass index (BMI) and adiposity in men with spinal cord injury (SCI). DESIGN: Cross-sectional study. SETTING: Outpatient study in 2 centers in New Zealand. PARTICIPANTS: Nineteen men with traumatic SCI were age-, height-, and weight-matched with 19 able-bodied men. INTERVENTIONS: Not applicable.Main Outcome Measures: BMI (kg/m(2)) and dual-energy x-ray absorptiometry measures of total and regional lean tissue mass and fat mass. RESULTS: Although the groups had similar BMIs, the total lean tissue mass was 8.9kg lower (95% confidence interval [CI], -12.7 to -5.2; P<.001) whereas total fat mass was 7.1kg greater (95% CI, 1.3-12.8; P<.05) in the SCI group. Body fat percentage was 9.4% (95% CI, 3.6-15.1; P<.01) greater in the SCI group. Regional measures showed a similar pattern. Truncal fat mass increased 3.7kg (95% CI, 0.5-6.9; P<.05) in the SCI group compared with controls. CONCLUSIONS: Body fat mass was greater for any given BMI in the SCI group. Many patients with SCI do not appear to be obese, yet they carry large amounts of fat tissue. BMI is widely used to estimate adiposity, but it may underestimate body fat in men with SCI.     

Influence of orthopaedic metal and high-density detection on body composition as assessed by dual-energy X-ray absorptiometry

We examined the influence of orthopaedic material and computerized high-density detection (HDD) on analysis of bone mass and soft tissue composition performed by dual-energy X-ray absorptiometry (DXA). Measurements of total and regional bone area, bone mineral content (BMC), areal bone mineral density (BMD), lean tissue mass (LTM) and fat tissue mass (FTM) were made using a Norland XR-26 DXA scanner with dynamically changing samarium filtration. Twenty-one subjects who were free of metal implants were measured without and with a Biomet femoral prosthesis (titanium) placed on the proximal part of the femoral region. Twenty-one women with an endogenous prosthesis in the proximal femur were measured once. Analyses of tissue composition were performed without and with HDD using software provided by the manufacturer. Measurements were considerably affected by exogenous metal with overestimation of LTM and underestimation of FTM and bone area. BMC and BMD were over- or underestimated depending on the anatomical region. Enabling the HDD mode, values of bone area and tissue mass came closer to the expected values (–metal/–HDD) but were in general still significantly different from these. For the total body, the following significant changes were found after application of metal (+metal/–HDD vs. +metal/+HDD, mean values): bone area –19·8% vs. –6·9%, BMC +1·1% vs. –2·1%, BMD +26·5% vs. +4·7%, LTM +12·4% vs. +3·7%, FTM –15·8% vs. –7·0%. A similar pattern of change in tissue composition and bone area was found for the subregions of the body. Changes in tissue composition after HDD were similar in subjects with exogenous and endogenous metal, indicating that the experimental model was appropriate. In conclusion, measurements of tissue composition were substantially influenced by orthopaedic metal. HDD partly corrected for the artefacts induced by the metal.     

Dual-energy digital radiography in the assessment of bone mechanical properties

At present, bone fragility and fracture risk are estimated with bone mineral density (BMD), measured by dual-energy x-ray absorptiometry (DXA). It is known that DXA-based BMD (BMD(DXA)) has a relationship with mechanical characteristics of bone. Dual-energy digital radiography (DEDR) has also been shown to be a potential method to determine BMD, but the ability of DEDR-based BMD (BMD(DEDR)) to predict bone mechanical properties is not yet known. In this study, we investigated the ability of BMD(DEDR) to predict the mechanical characteristics of bone. Reindeer femora (N = 50) were imaged at two different energies (79 and 100 kV(p)) using a clinical digital radiography system. BMD was determined in four regions from these images using the DXA calculation principle. Femora were mechanically tested using axial loading configuration. Mechanical parameters were correlated with the BMD(DEDR) and BMD(DXA) of the femoral neck (FNBMD(DEDR) and FNBMD(DXA)). FNBMD(DEDR) and FNBMD(DXA) both correlated moderately with mechanical parameters. The highest correlations were found with maximal load (r = 0.53 and r = 0.65, p < 0.01, respectively). No statistically significant differences were found between the correlation coefficients when comparing the FNBMD(DEDR) or FNBMD(DXA) values and mechanical parameters. The correlation coefficient between BMD(DEDR) and BMD(DXA) varied between r = 0.56 and 0.86 (p < 0.01) in different regions of the upper femur. In conclusion, BMD(DEDR) predicts the mechanical parameters of reindeer bone with similar accuracy as BMD(DXA).     

Regular Tai Chi Chuan exercise may retard bone loss in postmenopausal women: A case-control study

OBJECTIVE: To evaluate the potential benefits of regular Tai Chi Chuan exercise on the weight-bearing bones of postmenopausal women. DESIGN: Case-control study. SETTING: University medical school in Hong Kong. PARTICIPANTS: Postmenopausal women (age range, 50-59y), including 17 self-selected regular Tai Chi Chuan exercisers (TCE) with over 4 years of regular exercise, and 17 age- and gender-matched nonexercising controls (CON). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Bone mineral density (BMD) in the lumbar spine and proximal femur was measured at baseline and at follow-up 12 months later by using dual-energy x-ray absorptiometry (DXA) and in the distal tibia using multislice peripheral quantitative computed tomography (pQCT). RESULTS: Baseline results showed that the TCE group had significantly higher BMD (10.1%-14.8%, all P<.05) than the CON group in the lumbar spine, proximal femur, and the ultradistal tibia. The follow-up measurements showed generalized bone loss in both groups. Although both DXA and pQCT measurements revealed decelerated rates of bone loss in the TCE group, only the more sensitive pQCT showed significantly reduced rate of bone loss in trabecular BMD of the ultradistal tibia (TCE vs CON: -1.10%+/-1.26% vs -2.18%+/-1.60%, P<.05) and of cortical BMD of the distal tibial diaphysis (TCE vs CON: -0.90%+/-1.36% vs -1.86%+/-0.93%, P<.05). CONCLUSION: This is the first case-control study to show that regular Tai Chi Chuan exercise may help retard bone loss in the weight-bearing bones of postmenopausal women.     

Electrical stimulation: can it increase muscle strength and reverse osteopenia in spinal cord injured individuals?

OBJECTIVE: To study the extent to which atrophy of muscle and progressive weakening of the long bones after spinal cord injury (SCI) can be reversed by functional electrical stimulation (FES) and resistance training. DESIGN: A within-subject, contralateral limb, and matching design. SETTING: Research laboratories in university settings. PARTICIPANTS: Fourteen patients with SCI (C5 to T5) and 14 control subjects volunteered for this study. INTERVENTIONS: The left quadriceps were stimulated to contract against an isokinetic load (resisted) while the right quadriceps contracted against gravity (unresisted) for 1 hour a day, 5 days a week, for 24 weeks. MAIN OUTCOME MEASURES: Bone mineral density (BMD) of the distal femur, proximal tibia, and mid-tibia obtained by dual energy x-ray absorptiometry, and torque (strength). RESULTS: Initially, the BMD of SCI subjects was lower than that of controls. After training, the distal femur and proximal tibia had recovered nearly 30% of the bone lost, compared with the controls. There was no difference in the mid-tibia or between the sides at any level. There was a large strength gain, with the rate of increase being substantially greater on the resisted side. CONCLUSION: Osteopenia of the distal femur and proximal tibia and the loss of strength of the quadriceps can be partly reversed by regular FES-assisted training.     

Estimation of geometric properties of cortical bone in spinal cord injury

OBJECTIVE: To evaluate structural and geometrical properties of the tibia shaft in subjects with spinal cord injury (SCI) and subjects without SCI and to estimate the potential usefulness of a multimodal approach to diagnosing osteoporosis in SCI. DESIGN: A cross-sectional study of randomly selected SCI and non-SCI subjects. METHODS: Measurements of bone geometric indices by computed tomography, and calculated bending stiffness with a biomechanical testing method. SETTING: An SCI center hospital. SUBJECTS: Ten men without known orthopedic or neurologic impairments (controls), 10 men with SCI who had a history of lower extremity pathologic fracture since SCI, and 10 men with SCI who had never had lower extremity pathologic fracture. RESULTS: Analysis of geometric and structural indices of subjects' tibias found a significant difference in all geometric indices between controls and the SCI subjects with pathologic fracture history. Between the controls and the SCI subjects with no fracture history, however, differences were found only in cross-sectional area and calculated bending stiffness. CONCLUSION: Structural analysis of leg bone, combined with measurement of bone density, may improve the ability to assess fracture risk in patients with SCI.