Quantitative computed tomography in the evaluation of spinal osteoporosis following spinal cord injury

A moderate spinal contusion injury in rats alters bone turnover both below and above the level of injury with sex-based differences apparent in long-term recovery

Spinal cord injury (SCI) leads to significant sublesional bone loss and high fracture rates. While loss of mechanical loading plays a significant role in SCI-induced bone loss, animal studies have demonstrated mechanical loading alone does not fully account for loss of bone following SCI. Indeed, we have shown that bone loss occurs below the level of an incomplete moderate contusion SCI, despite the resumption of weight-bearing and stepping. As systemic factors could also impact bone after SCI, bone alterations may also be present in bone sites above the level of injury. To examine this, we assessed bone microarchitecture and bone turnover in the supralesional humerus in male and female rats at two different ages following a moderate contusion injury in both sub-chronic (30 days) and chronic (180 days) time points after injury. At the 30-day timepoint, we found that both young and adult male SCI rats had decrements in trabecular bone volume at the supralesional proximal humerus (PH), while female SCI rats were not different from age-matched shams. At the 180-day timepoint, there were no statistical differences between SCI and sham groups, irrespective of age or sex, at the supralesional proximal humerus. At the 30-day timepoint, all SCI rats had lower BFR and higher osteoclast-covered trabecular surfaces in the proximal humerus compared to age-matched sham groups generally matching the pattern of SCI-induced changes in bone turnover seen in the sublesional proximal tibia. However, at the 180-day timepoint, only male SCI rats had lower BFR at the supralesional proximal humerus while female SCI rats had higher or no different BFR than their age-matched counterparts. Overall, this preclinical study demonstrates that a moderate contusion SCI leads to alterations in bone turnover above the level of injury within 30-days of injury; however male SCI rats maintained lower BFR in the supralesional humerus into long-term recovery. These data further highlight that bone loss after SCI is not driven solely by disuse. Additionally, these data allude to potential systemic factors exerting influence on bone following SCI and highlight the need to consider treatments for SCI-induced bone loss that impact both sublesional and systemic factors.

Age-related variations in trunk composition and patterns of regional bone and soft tissue changes in adult Caucasian women by DXA

We explored the regional variations in body composition with advancing age in healthy Caucasian females living in the Mediterranean area. The objectives of this study were to establish body composition values for the trunk in healthy women of a Greek origin and to evaluate the effects of aging on the distribution of truncal bone mass, fat mass (FM) and lean mass (LM). Body composition of the trunk and detailed analysis of its anatomical components-the ribs, the thoracic spine, the lumbar spine and the pelvis, and FM and LM ratios--were calculated in 330 women aged 20-85 years, using DXA. Peak bone mineral density (BMD) of the trunk was attained between ages 30 and 33. The overall truncal BMD reduction with age was 20.7% (p < 0.001). Peak %LM of the trunk was achieved at age 20. The overall reduction of %LM with age for the trunk was 9.8% (p < 0.001). Peak %FM of the trunk was attained between ages 68 and 73, and the overall %FM reduction with age was 2.8% (p > 0.05). Multiple comparative analyses showed that the 51-60 years age group was the landmark age for significant changes of truncal bone mass measures across all age groups (p = 0). For truncal LM and FM metrics, multigroup comparative analysis showed the turning point of significant changes in soft tissue was the 41-50 age bracket (p = 0 and p = 0, respectively). In Greek women, truncal %LM exceeded by far %FM across all ages (p = 0). Our results suggest that aging affects body composition of the trunk in ambulatory healthy women of a Greek origin differently, leading to menopausal loss of bone mass, senior adulthood loss of lean mass, and middle-age storage of fat mass. In adult women, these age-related associations between bone and soft tissue metrics on DXA exams carry implications for the attainment of optimal peak values and shifts in body composition overtime, impacting lifelong skeletal health.

Bone Mineral Density in Adult Patients with Type 1 Diabetes Mellitus Assessed by Both DXA and QCT

Purpose

Bone mineral density (BMD) was measured in uncomplicated young adult patients with type 1 diabetes mellitus (T1DM) and sex- and age-matched controls, using both dual X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) to investigate their diagnostic ability in detecting abnormal values in these patients.

Methods

118 patients with T1DM (65 females, mean age 30.12 ± 8.78 years) and 94 sex- and age-matched controls were studied. BMD was assessed in all participants by DXA and QCT at lumbar spine (LS). Biochemical markers of bone metabolism were also measured.

Results

T1DM was associated with lower BMD at L1-L3 vertebrae measured by both DXA and QCT and lower bone turnover compared to sex- and age-matched controls. In T1DM subjects, QCT detected more patients with abnormal BMD values compared to DXA. BMI and HbA1c levels were the only determinants of BMD. Bone turnover markers were lower in patients with longer duration of diabetes.

Conclusion

QCT provides a higher sensitivity compared to DXA in detecting abnormal BMD values in patients with uncomplicated T1DM. In these patients, the diabetes-related decreased BMD may be present early, before it is detected by DXA, the clinical gold standard for BMD measurements, and before the presence of any other diabetes complications, stressing the importance of an early intervention for fracture prevention.

Employment of Neuromuscular Electrical Stimulation to Examine Muscle and Bone Qualities after Spinal Cord Injury

(1) Background: Resource intensive imaging tools have been employed to examine muscle and bone qualities after spinal cord injury (SCI). We tested the hypothesis that surface neuromuscular electrical stimulation (NMES) amplitude can be used to examine knee extensor muscle quality, distal femur and proximal tibia bone mineral density (BMD) in persons with SCI. (2) Methods: Seventeen persons (2 women) with chronic SCI participated in three weeks of NMES-resistance training twice weekly of 4 sets of 10 repetitions. Participants were classified according to the current amplitude (>100 mA) and the number of repetitions (>70 reps) of leg extension into greater (n = 8; 1 woman; group A) and lower (n = 9; 1 woman; group B) musculoskeletal qualities. Magnetic resonance imaging, dual energy x-ray absorptiometry, isometric peak torque, Modified Ashworth and Penn spasm frequency scales were conducted. (3) Results: In between group comparisons, current amplitude was lower (38−46%) in group A. Whole (27−32%; p = 0.02), absolute (26−33%, p = 0.02) thigh muscle and absolute knee extensor muscle cross-sectional areas (22−33%, p = 0.04) were greater in group A. Right distal femur (24%; p = 0.08) and proximal tibia (29%; p = 0.03) BMDs were lower in group B, and peak isometric torque (p < 0.01), extensor spasticity scorers (p = 0.04) and muscle spasm scores (p = 0.002) were significantly higher in group A. Regression models revealed that amplitude of current, repetitions and body weight can accurately predict musculoskeletal qualities in persons with SCI. (4) Conclusions: Surface NMES amplitude and repetitions of leg extension differentiated between SCI survivors with greater versus lower musculoskeletal qualities. The study may shed the light on the interplay between muscle and bone in persons with SCI.

Application of Medical Imaging Based on Deep Learning in the Treatment of Lumbar Degenerative Diseases and Osteoporosis with Bone Cement Screws

Objective

To explore the application value of magnetic resonance spectroscopy (MRS) and GSI-energy spectrum electronic computed tomography (CT) medical imaging based on the deep convolutional neural network (CNN) in the treatment of lumbar degenerative disease and osteoporosis.

Methods

There were 56 cases of suspected lumbar degenerative disease and osteoporosis. A group of 56 subjects were examined using 1.5 TMR spectrum (MRS) and dual-energy X-ray absorptiometry (DXA) to collect the lumbar L3 vertebral body fat ratio (FF) and L1~4 vertebral bone mineral density (BMD) value. We divided the subjects into 2 groups with T value -2.5 as the critical point. Set T value > -2.5 as the negative group and T value ≤ -2.5 as the positive group. Pearson's method is used for FF-MRS and BMD correlation analyses. A group of all patients underwent GSI-energy spectrum CT scan, and X-ray bone mineral density (DXA) test results (bone density per unit area) were used as the gold standard to analyze the diagnosis of osteoporosis by the GSI-energy spectrum CT scan method value.

Results

The differences in FF and BMD between the negative group and the positive group were statistically significant (P < 0.01), and there was a highly negative correlation between the average value of FF and BMD. 30 cases were diagnosed as osteoporosis by DXA. The accuracy of GSI-energy spectrum CT medical imaging in diagnosing osteoporosis is 89.30%. The GSI-energy spectrum CT diagnosis of osteoporosis and DXA examination results have good consistency.

Conclusion

Based on the deep convolutional neural network (CNN) MRS technology, GSI-energy spectrum CT medical imaging is used in the clinical diagnosis and treatment of lumbar degenerative lesions and osteoporosis. It has a good advantage in assessing bone quality and has good consistency with DXA examination and has better application value high.

Prevention and management of osteoporosis and osteoporotic fractures in persons with a spinal cord injury or disorder: A systematic scoping review

Objectives: The primary objective was to review the literature regarding methodologies to assess fracture risk, to prevent and treat osteoporosis and to manage osteoporotic fractures in SCI/D.Study Design: Scoping review.Settings/Participants: Human adult subjects with a SCI/D.Outcome measures: Strategies to identify persons with SCI/D at risk for osteoporotic fractures, nonpharmacological and pharmacological therapies for osteoporosis and management of appendicular fractures.Results: 226 articles were included in the scoping review. Risk of osteoporotic fractures in SCI is predicted by a combination of DXA-defined low BMD plus clinical and demographic characteristics. Screening for secondary causes of osteoporosis, in particular hyperparathyroidism, hyperthyroidism, vitamin D insufficiency and hypogonadism, should be considered. Current antiresorptive therapies for treatment of osteoporosis have limited efficacy. Use of surgery to treat fractures has increased and outcomes are good and comparable to conservative treatment in most cases. A common adverse event following fracture was delayed healing.Conclusions: Most of the research in this area is limited by small sample sizes, weak study designs, and significant variation in populations studied. Future research needs to address cohort definition and study design issues.

Bone Mineral Density Testing in Spinal Cord Injury: 2019 ISCD Official Position

Spinal cord injury (SCI) causes rapid osteoporosis that is most severe below the level of injury. More than half of those with motor complete SCI will experience an osteoporotic fracture at some point following their injury, with most fractures occurring at the distal femur and proximal tibia. These fractures have devastating consequences, including delayed union or nonunion, cellulitis, skin breakdown, lower extremity amputation, and premature death. Maintaining skeletal integrity and preventing fractures is imperative following SCI to fully benefit from future advances in paralysis cure research and robotic-exoskeletons, brain computer interfaces and other evolving technologies. Clinical care has been previously limited by the lack of consensus derived guidelines or standards regarding dual-energy X-ray absorptiometry-based diagnosis of osteoporosis, fracture risk prediction, or monitoring response to therapies. The International Society of Clinical Densitometry convened a task force to establish Official Positions for bone density assessment by dual-energy X-ray absorptiometry in individuals with SCI of traumatic or nontraumatic etiology. This task force conducted a series of systematic reviews to guide the development of evidence-based position statements that were reviewed by an expert panel at the 2019 Position Development Conference in Kuala Lumpur, Malaysia. The resulting the International Society of Clinical Densitometry Official Positions are intended to inform clinical care and guide the diagnosis of osteoporosis as well as fracture risk management of osteoporosis following SCI.

Hounsfield Units on Lumbar Computed Tomography for Predicting Regional Bone Mineral Density

Objective

Bone mineral density (BMD) is a very important factor in spinal fusion surgery using instrumentation. Our aim was to investigate the utility of Hounsfield units (HU) obtained from preoperative lumbar computed tomography (CT) to predict osteoporosis coupling with data of quantitative computed tomography (QCT) and dual X-ray absorptiometry (DEXA).

Methods

We reviewed 180 patients that underwent both QCT and lumbar CT for spine surgery. HU was retrospectively calculated on the lumbar CT of 503 lumbar vertebrae from L1 to L3. Femur DEXA was performed in all patients and spine DEXA was tested in 120 patients (331 vertebrae). BMD was grouped as osteoporosis (QCT<80mg/cm³, DEXA T score≤-2.5) and non-osteoporosis (QCT≥80mg/cm³, DEXA T score>-2.5) for comparison of HU value.

Results

HU value and BMD showed significant correlations. The optima cut-off value based on QCT was higher than that of DEXA scans which had the best correlation for predicting osteoporosis. ROC curve analysis demonstrated that HU value with QCT of 146 has a sensitivity of 94.3% and a specificity of 87.5% for osteoporosis.

Conclusions

Significant correlation was found between HU measurement and BMD value. These findings provide evidence that HU measurement can be established as a means for predicting osteoporosis before spine fusion surgery with reduced radiation hazard.

Energy and Nutrient Issues in Athletes with Spinal Cord Injury: Are They at Risk for Low Energy Availability?

Low energy availability (LEA) and nutrient intake have been well studied in able-bodied athletes, but there is a lack of research examining these issues amongst athletes with spinal cord injury (SCI). To date, there have been no studies that have examined energy availability (EA) amongst this population. Furthermore, athletes with SCI may experience unique challenges around nutrition that may increase their risk of LEA. This review will evaluate the literature and assess whether this population is at risk for LEA. Due to the limited research on this topic, sedentary individuals with SCI and para athletes were also included in this review. Review of the current literature suggests that athletes with SCI may be at an increased risk for LEA. While research examining EA and risk of LEA in athletes with SCI is lacking, the number of athletes with SCI continues to increase; therefore, further research is warranted to assess nutrient and energy needs and their risk to this population.

The Role of Trunk Musculature in Osteoporotic Vertebral Fractures: Implications for Prediction, Prevention, and Management

This review examines the current evidence for associations between vertebral fractures (VFx), the most common type of fracture in older adults, and trunk muscles, which are intimately tied to spinal loading and function. Individuals with prevalent VFxs have more fat infiltration in the trunk muscles, lower trunk extension strength, and altered muscle activation patterns. However, no longitudinal studies have examined whether assessment of trunk muscle can contribute to prediction of fracture risk. A few studies report that exercise interventions targeting the trunk muscles can reduce the risk of VFx, improve trunk strength and endurance in patients who have had a VFx, and reduce the risk of falling, a common cause of VFx, but the quality of evidence is low. Trunk muscles likely have an important role to play in prediction, prevention, and management of VFx, but additional longitudinal studies and randomized controlled trials are needed to clarify this role.

Perioperative complications associated with spine surgery in patients with established spinal cord injury

BACKGROUND CONTEXT

Only a small percentage of patients with spinal cord injury (SCI) require consideration for reconstructive surgery after their initial injury. For those who do, perioperative complications can be frequent and significant. There has been very little published literature examining treatment of these patients and essentially nothing to guide the surgeon in perioperative decision making and management.

PURPOSE

To identify some of the common challenges associated with surgery in this patient population and review the literature to highlight the perioperative concerns in patients with chronic SCI.

STUDY DESIGN

Review article.

METHODS

A primary PubMed literature search was performed and reviewed for patients with chronic SCI with emphasis on the complications and difficulties encountered during surgical treatment of patients with chronic SCI.

RESULTS

For those who do proceed with surgery in this patient population, preoperative nutrition, bone density, and skin should be evaluated and optimized. Preoperative inferior vena cava filters should be considered. The integrity of the reconstruction will be extensively challenged. In addition, augmented fixation and bracing should be contemplated.

CONCLUSIONS

Patients with chronic SCI who require spinal reconstruction provide many unique challenges. Indications for surgery must be strong as perioperative complications can be frequent and long-term outcomes unpredictable. Close monitoring for postoperative complications is essential.

Assessment of Bone Mineral Density in Male Patients with Chronic Obstructive Pulmonary Disease by DXA and Quantitative Computed Tomography

The purpose of this study is to identify the prevalence of osteoporosis in male patients with chronic obstructive pulmonary disease (COPD) by dual-energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) and to compare the diagnostic abilities of the above methods. Thirty-seven male patients with established COPD were examined with DXA and standard QCT in lumbar spine, including L1, L2, and L3 vertebrae. T-scores and bone mineral density values were calculated by DXA and QCT method, respectively. Comparative assessment of the findings was performed and statistical analysis was applied. QCT measurements found more COPD patients with impaired bone mineral density compared to DXA, namely, 13 (35.1%) versus 12 (32.4%) patients with osteopenia and 16 (43.2%) versus 9 (16.2%) patients with osteoporosis (p = 0.04). More vertebrae were found with osteoporosis by QCT compared to DXA (p = 0.03). The prevalence of osteoporosis among male patients with COPD is increased and DXA may underestimate this risk. QCT measurements have an improved discriminating ability to identify low BMD compared to DXA measurements because QCT is able to overcome diagnostic pitfalls including aortic calcifications and degenerative spinal osteophytes.

Evaluation of bone mineral loss in patients with chronic traumatic spinal cord injury in Iran

OBJECTIVES

We described the associations between demographic and injury-related factors on bone mineral density (BMD) of the spine and the hip among adult patients with chronic spinal cord injury (SCI).

DESIGN

BMD in spinal and femoral bone sites were assessed. Multivariate analysis was performed to evaluate the relationship between anthropometric and injury-related factors with BMD. Serum level and amount of dietary intake of calcium, phosphor, and 25-hydroxy vitamin D were measured.

SETTING

A referral tertiary rehabilitation center in Iran.

PARTICIPANTS

Patients with SCI who had no previous history of endocrine disorders and were not on specific medications entered the investigation. Those with non-traumatic SCI, pregnant, or with substance dependency were excluded as well.

INTERVENTIONS

No interventions were applied. MAIN STUDY OUTCOME MEASURES: Dual X-ray absorptiometry was performed to estimate BMD. Body mass index was positively associated with higher femoral (P < 0.01, r = 0.56) and hip (P < 0.0001, r = 0.82) BMD only in female participants. The high prevalence of vitamin D deficiency (60%) was noticeable.

RESULTS

Older male patients revealed lower BMD only in spinal vertebrae (P < 0.02, r = -0.21). A significant higher BMD loss in lumbar vertebras in male patients with complete spinal cord lesion (P < 0.009) was detected. Spinal reduction of BMD was more severe when the level of injury was above T6 (P < 0.02).

CONCLUSION

Along with the clarification of age, gender, post injury duration, and the other factors' effect on the BMD in the SCI patients, here we have also shown the noticeable prevalence of the 25-hydoxy vitamin D deficiency in these patients which needs attention.

Bone mineral density in spinal cord injury: an evaluation of the distal femur

Osteoporosis (OP) in spinal cord injury (SCI) patients is a secondary process in which numerous factors are involved. Diagnosing OP and the threshold for fractures in this population, based on bone mineral density (BMD) measured by double energy X-ray absorptiometry (DXA), is still a challenge. The aim of this study was to evaluate bone mineral loss by DXA, its relationship with body composition and fracture incidence, in complete paraplegics patients, compared with aged-matched controls; we include a nonstandard bone site, the distal femur, and describe the technical and practical aspects of this procedure. Twenty-five SCI patients were included in the study and 17 subjects as control group. No prior or recent fractures were observed in X-ray analysis. The BMD of all femoral sites was significantly lower in patients than in controls (femoral neck, total femur, and distal femur); no difference was observed between BMD of the lumbar spine of patients and controls. We found inverse relationship between time of SCI and bone mineral mass only for distal femur BMD. We conclude that the distal femur is a more sensitive bone site for assessing bone loss by DXA, in SCI patients, than the proximal femoral sites.

Diagnosis and treatment of osteoporosis in spinal cord injury patients: A literature review

OBJECTIVE

To present an up-to-date literature review of osteoporosis in spinal cord injury (SCI) patients, in view of the seriousness of this complication (with a high risk of fractures) and the complexity of its diagnosis, evaluation and treatment.

METHODS

A Medline search with the following keywords: immobilization osteoporosis, spinal cord injury, bone loss, dual energy X-ray absorptiometry (DEXA), bisphosphonate.

RESULTS

Our analysis of the literature noted a bone metabolism imbalance in SCI patients, with accelerated early bone resorption (particularly during the first 6 months post-injury). Although dual energy X-ray absorptiometry constitutes the "gold standard" diagnostic method, the decrease in bone mineral density only becomes significant 12 months after the injury. Bisphosphonate therapy has proven efficacy. Despite the frequent use of various physical therapies, these methods have not been found to be effective.

CONCLUSION

Although our literature review did not identify any guidelines on the strategy for diagnosing and treating osteoporosis in SCI patients, several findings provide guidance on procedures for early diagnosis and preventive treatment.

Underestimation of bone loss of the spine with posterior-anterior dual-energy X-ray absorptiometry in patients with spinal cord injury

BACKGROUND

Bone mineral density (BMD) of the lumbar spine (L-spine) has been reported to be normal by routine posterior-anterior (PA) bone density imaging in patients with chronic spinal cord injury (SCI).

OBJECTIVE

To determine BMD of the L-spine by PA and lateral (LAT) dual-energy radiographic absorptiometry (DXA) in patients with chronic SCI.

DESIGN

Prospective study.

SETTING

Veterans Affairs Medical Center and a private rehabilitation facility.

METHODS

Measurements of the PA and LAT L-spine and hip were performed in 15 patients with SCI: 9 with tetraplegia and 6 with paraplegia. The DXA (GE Lunar Advance DXA) images were obtained using standard software. Results are reported as mean +/- SD.

RESULTS

The mean age was 35 +/- 15 years (range = 20-62 years), and the duration of injury was 57 +/- 74 months (range = 3-240 months). T- and Z-scores were lower for the LAT L-spine than those for PA L-spine (T-scores L2: -0.7 +/- 1.2 vs. 0.0 +/- 1.4, P < 0.01; L3: -0.9 +/- 1.6 vs. 0.3 +/- 1.3, P < 0.002; L2-L3: -0.8 +/- 1.3 vs. 0.2 1.3 vs. 0.2 +/- P < 0.001; Z-scores Z-0.3 +/- 1.1 vs. 0.2 +/- 1.2, P < 0.05; L3: -0.6 +/- 1.3 vs. 0.5 +/- 1.3, P < 0.01; L2-L3: -0.4 +/- 1.1 vs. 0.4 +/- 1.2, P < 0.005). The T- and Z-scores for the total hip (-1.1 +/- 1.0 and -1.0 +/- 1.0, respectively) and L2-L3 LAT L-spine demonstrated remarkable similarity, whereas the L2-L3 PA L-spine scores were not reduced. Bone mineral density of the LAT L-spine, but not the PA L-spine, was significantly reduced with increasing duration of injury.

CONCLUSIONS

Individuals with SCI may have bone loss of the L-spine that is evident on LAT DXA that may be misdiagnosed by PA DXA, underestimating the potential risk of fracture.

Sublesional spinal vertebral bone mineral density correlates with neurological level and body mass index in individuals with chronic complete spinal cord injuries

STUDY DESIGN

A cross-sectional study.

OBJECTIVE

Our aim was to find out the factors influencing the bone mineral density (BMD) change of sublesional spinal vertebrae in spinal cord injury (SCI) individuals.

SUMMARY OF BACKGROUND DATA

In individuals with SCI, the BMD of sublesional extremities dramatically decreases to fracture threshold because of unloading. In contrast, the BMD of sublesional spinal vertebrae is reported to be preserved. The etiology of the discrepancy is unknown.

METHODS

This study was performed in a university tertiary referral medical center. A total of 62 men with traumatic and neurologically complete SCI attending a special SCI clinic attached to the medical center from 2000 to 2003. Participants were prescreened using lumbosacral roentgenography to rule out heterotopic ossification and early-onset spinal degeneration. The BMD was then evaluated with dual energy radiograph absorptiometry at the thoracic spine and lumbar spine, using anteroposterior and lateral scout images.

RESULTS

The mean age was 27.3 +/- 8.3 years and mean injury duration was 11.7 +/- 6.8 years. Lumbar spine BMD did not increase or decrease significantly after SCI. Lumbar spine BMD correlated significantly with body mass index. Thoracic and lumbar spine BMDs were significantly higher if the injury level was below T6. There were no correlations with postinjury duration, age of the subject, or level of physical activity.

CONCLUSION

In men with chronic complete SCI, the long-term sublesional spinal vertebrae BMDs are significantly lower if injury levels are at T6 or above, suggesting the role of neurologic control on bone metabolism.

A longitudinal Raman microspectroscopic study of osteoporosis induced by spinal cord injury

INTRODUCTION

A longitudinal study was established to investigate bone compositional information in spinal cord injury (SCI) rat model.

METHODS

Raman spectroscopy was applied to detect the distal femur and humeri of SCI, sham-operated (SO), and age-matched control (CON) male Sprague-Dawley (SD) rats at first, second, third, and fifth weeks after surgery. One-way ANOVA and Tukey's HSD post hoc multiple comparison tests were used to analyze the longitudinal data of mineral to matrix ratio and carbonate substitution.

RESULTS

Relative mineral decrease was found in SCI group by more than 20% in femur and approximately 12% in humeri compared with CON group. No significant changes in carbonate substitution were observed.

CONCLUSIONS

Severe bone loss in the early stage of SCI was confirmed by a continuous decrease of the mineral to collagen matrix ratio. The decrease in the humeri suggested hormone level variations might participate in the etiology of SCI-induced osteoporosis.

Dual-energy X-ray absorptiometry overestimates bone mineral density of the lumbar spine in persons with spinal cord injury

BACKGROUND

Bone mineral density (BMD) of the lumbar spine (L-spine) has been reported to be normal or increased in persons with chronic spinal cord injury (SCI).

OBJECTIVE

To determine BMD of the L-spine by dual-energy X-ray absorptiometry (DXA) and quantitative computerized tomography (qCT) in men with chronic SCI compared with able-bodied controls.

DESIGN

Cross-sectional, comparative study.

SETTING

Clinical research unit, Veterans Affairs Medical Center, Bronx, NY, USA and Kessler Institute of Rehabilitation, West Orange, NJ, USA.

METHODS

Measurements of the L-spine were made in 20 men with SCI and compared with 15 able-bodied controls. The DXA images were acquired on a GE Lunar DPX-IQ. The qCT images of the L-spine were acquired on a Picker Q series computerized tomographic scanner.

RESULTS

The mean ages for the SCI and control groups were 44+/-13 vs 42+/-9 years, and the duration of injury of the group with SCI was 14+/-11 years. There were no significant differences between the SCI and control groups for L-spine DXA BMD (1.391+/-0.210 vs 1.315+/-0.178 g/m(2)) or for L-spine DXA T-score (1.471+/-1.794 vs 0.782+/-1.481). L-spine qCT BMD was significantly lower in the SCI compared with the control group (1.296+/-0.416 vs 1.572+/-0.382 g/m(2), P=0.05); the T-score approached significance (-1.838+/-1.366 vs -0.963+/-1.227, P=0.059). Subjects with moderate degenerative joint disease (DJD) had significantly higher T-scores by DXA than those without or with mild DJD.

CONCLUSION

Individuals with SCI who have moderate to severe DJD may have bone loss of the L-spine that may be underestimated by DXA, reducing awareness of the risk of fracture.

Does standing protect bone density in patients with chronic spinal cord injury?

BACKGROUND/OBJECTIVE

To compare the t-scores of proximal femur and lumbar spine of patients with spinal cord injury (SCI) with different levels of weight bearing.

METHODS

Cross-sectional study comparing 3 groups of patients with SCI: patients with daily standing times of more than 1 hour, patients with daily standing times of less than 1 hour, and nonstanding patients. Seventy-one patients with chronic SCI were recruited. They were assigned to 1 of 3 groups according to their reported daily standing time. The bone density of lumbar and proximal femoral regions was measured with dual-energy x-ray absorptiometry.

RESULTS

The 3 groups were similar in terms of demographics and clinical variables. No significant difference was found among the mean t-scores of lumbar and proximal femoral regions of the groups. However, the patients in the group that stood more than 1 hour daily had a slight tendency to have higher t-scores than those in the control group.

CONCLUSIONS

There was no significant difference among the 3 groups. However, standing might be partially helpful in protecting the bone density in SCI by opposing the effects of immobilization.

Disuse in adult male rats attenuates the bone anabolic response to a therapeutic dose of parathyroid hormone

Intermittent treatment with parathyroid hormone (PTH) increases bone formation and prevents bone loss in hindlimb-unloaded (HLU) rats. However, the mechanisms of action of PTH are incompletely known. To explore possible interactions between weight bearing and PTH, we treated 6-mo-old weight-bearing and HLU rats with a human therapeutic dose (1 microg.kg(-1).day(-1)) of human PTH(1-34) (hPTH). Cortical and cancellous bone formation was measured in tibia at the diaphysis proximal to the tibia-fibula synostosis and at the proximal metaphysis, respectively. Two weeks of hindlimb unloading resulted in a dramatic decrease in the rate of bone formation at both skeletal sites, which was prevented by PTH treatment at the cancellous site only. In contrast, PTH treatment increased cortical as well as cancellous bone formation in weight-bearing rats. Two-way ANOVA revealed that hPTH and HLU had independent and opposite effects on all histomorphometric indexes of bone formation [mineral apposition rate (MAR), double-labeled perimeter (dLPm), and bone formation rate (BFR)] at both skeletal sites. The bone anabolic effects of weight bearing and hPTH on dLPm and BFR at the cortical site were additive, as were the effects on MAR at the cancellous site. In contrast, weight bearing and hPTH resulted in synergistic increases in cortical bone MAR and cancellous bone dLPm and BFR. We conclude that weight bearing and PTH act cooperatively to increase bone formation by resulting in site-specific additive and synergistic increases in indexes of osteoblast number and activity, suggesting that weight-bearing exercise targeted to osteopenic skeletal sites may improve the efficacy of PTH therapy for osteoporosis.

Osteoporosis after spinal cord injury

Osteoporosis is a known consequence of spinal cord injury (SCI) and occurs in almost every SCI patient. It manifests itself as an increase in the incidence of lower extremity fractures. The pattern of bone loss seen in SCI patients is different from that usually encountered with endocrine disorders and disuse osteoporosis. In general, there is no demineralization in supralesional areas following SCI. Several factors appear to have a major influence on bone mass in SCI individuals, such as the degree of the injury, muscle spasticity, age, sex and duration after injury. At the lumbar spine, bone demineralization remains relatively low compared to that of the long bones in the sublesional area. A new steady state level between bone resorption and formation is reestablished about 2 years after SCI. SCI may not only cause bone loss, but also alter bone structure and microstructure. Trabecular bone is more affected than cortical bone in the SCI population. Numerous clinical series have reported a high incidence ranging from 1 to 34% of lower extremity fractures in SCI patients. The pathogenesis of osteoporosis after SCI remains complex and perplexing. Disuse may play an important role in the pathogenesis of osteoporosis, but neural factors also appear to be important. SCI also leads to impaired calcium and phosphate metabolism and the parathyroid hormone (PTH)-vitamin D axis. Pharmacologic intervention for osteoporosis after SCI includes calcium, phosphate, vitamin D, calcitonin and biphosphonates. However, the concomitant prescription of bone-active drugs for the prevention and treatment of osteoporosis remains low, despite the availability of effective therapies. Functional stimulated exercises may contribute to the prevention of bone loss to some extent. In addition, many unanswered questions remain about the pathogenesis of osteoporosis and its clinical management.

Densitometric and quantitative ultrasound measurements and laboratory investigations in wheelchair-bound patients

Skeletal status and laboratory investigations may be influenced by immobilization. Thirty-six wheelchair-bound subjects and 19 age-matched controls were evaluated using measurements of bone mineral density (BMD) at the calcaneus and forearm (PIXI, Madison, WI), amplitude-dependent speed of sound at the hand phalanges (quantitative ultrasound-DBM Sonic 1200, IGEA, Modena, Italy), carboxyterminal telopeptide of type I collagen and bone alkaline phosphatase. In the whole group and in the males, bone mineral density values were significantly lower in comparison with controls (calcaneus, forearm) and in females only for calcaneus. The duration of the disease significantly influenced the calcaneal bone mineral density data. Bone alkaline phosphatase was significantly lower in the patients than in the controls. Bone resorption had a negative influence on forearm BMD. Generally, skeletal and laboratory results were not affected by duration of the disease or reason for immobilization. In conclusion, in wheelchair-bound subjects, the skeletal status was affected and bone formation was depressed.

Bone loss and muscle atrophy in spinal cord injury: epidemiology, fracture prediction, and rehabilitation strategies

Individuals with spinal cord injury (SCI) often experience bone loss and muscle atrophy. Muscle atrophy can result in reduced metabolic rate and increase the risk of metabolic disorders. Sublesional osteoporosis predisposes individuals with SCI to an increased risk of low-trauma fracture. Fractures in people with SCI have been reported during transfers from bed to chair, and while being turned in bed. The bone loss and muscle atrophy that occur after SCI are substantial and may be influenced by factors such as completeness of injury or time postinjury. A number of interventions, including standing, electrically stimulated cycling or resistance training, and walking exercises have been explored with the aim of reducing bone loss and/or increasing bone mass and muscle mass in individuals with SCI. Exercise with electrical stimulation appears to increase muscle mass and/or prevent atrophy, but studies investigating its effect on bone are conflicting. Several methodological limitations in exercise studies with individuals with SCI to date limit our ability to confirm the utility of exercise for improving skeletal status. The impact of standing or walking exercises on muscle and bone has not been well established. Future research should carefully consider the study design, skeletal measurement sites, and the measurement techniques used in order to facilitate sound conclusions.

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.

Effect of alendronate on bone mineral density in spinal cord injury patients: a pilot study

STUDY DESIGN

Prospective, randomised controlled trial.

OBJECTIVE

To evaluate the effect of alendronate on bone mineral density in chronic spinal cord injury (SCI) patients.

SETTING

University-based rehabilitation centre in São Paulo, Brazil.

METHODS

A total of 19 chronic SCI patients were evaluated, divided into a control group and an experimental group. Control group patients received 1000 mg of calcium daily, and experimental group patients received 1000 mg of calcium plus 10 mg of alendronate daily. The study duration was 6 months. In all, 12 densitometric parameters were analysed using whole-body dual-energy X-ray absorptiometry at baseline and after 6 months.

RESULTS

The experimental group presented increases in nine densitometric parameters, although statistical significance was attained in only two of those parameters. In the control group, an increase was observed in only one parameter, whereas the remaining 11 presented either no alteration or a decrease.

CONCLUSION

The use of alendronate had a positive effect on bone mineral density in SCI patients and therefore represents a potential tool for prevention and treatment of osteoporosis in this population.

Aging with spinal cord injury

The years after SCI may be associated with acceleration of the aging process because of diminished physiologic reserves and increased demands on functioning body systems. Clinicians with expertise in the treatment and prevention of SCI-specific secondary complications need to collaborate with gerontologists and primary care specialists and need to invest in the training of future physicians to ensure a continuum of accessible, cost-effective, and high-quality care that meets the changing needs of the SCI population. Managed care payers often do not adequately cover long-term disability needs to prevent secondary SCI-specific complications. In this era of increasing accountability, evidence-based clinical practice guidelines are needed to document scientific evidence and professional consensus to effectively diagnose, treat, and manage clinical conditions; to reduce unnecessary testing and procedures; and to improve patient outcomes. Longitudinal research is needed to minimize cohort effects that contribute to misinterpretation of cross-sectional findings as representative of long-term changes in health and functioning. However, longitudinal studies confound chronologic age, time since injury, and environmental change. Thus, time-sequential research, which controls for such confounding effects, is essential, as is research on the effects of gender,culture, and ethnicity. If we consider how much progress has been made over the past 50 years with respect to SCI mortality related to infectious disease, we can expect to achieve even greater progress against the effects of aging in the next 50 years. Recent developments in molecular biology regarding growth and neuro-trophic factors are bringing us closer to the goal of repairing the damaged spinal cord. The challenge remains for rehabilitation professionals to provide the most comprehensive and holistic approach to long-term follow-up, with an emphasis on health promotion and disease prevention, to postpone functional decline and enhance QOL.

Recursos fisioterapêuticos na prevenção da perda da densidade mineral óssea com lesão medular

Este trabalho é uma revisão bibliográfica sobre os tratamentos fisioterápicos destinados a prevenção, estabilização ou lentificação da perda da densidade mineral óssea em pacientes portadores de lesão medular. Foram encontrados poucos trabalhos que se destinaram aos tratamentos fisioterápicos para desmineralização óssea. Em relação aos tipos de tratamentos encontrados foram: estimulação elétrica funcional, estimulação elétrica funcional com bicicleta ergométrica, ortostatismo e deambulação. Estes tratamentos são bastante questionáveis não tendo um consenso na metodologia, apresentando muitas controvérsias em relação à eficácia dos tratamentos, que serão discutidos no decorrer deste trabalho.

Bone density loss after spinal cord injury: elite paraplegic basketball players vs. paraplegic sedentary persons

OBJECTIVE

To compare the bone mineral density of elite paraplegic basketball players with the values obtained from their paraplegic sedentary counterparts.

DESIGN

A total of 17 male paraplegic basketball players and 17 male paraplegic sedentary persons were included in the study. Bone mineral densities of the distal third of radius of the dominant arm, L2-L4 spine, and trochanters, Ward's triangles, and the femoral necks of both hips were measured.

RESULTS

The densities of trochanters, Ward's triangles, and the femoral necks were found to be decreased in both groups, with no significant difference between them. The densities of lumbar and radial regions were found to be increased in both groups. Radial density was significantly higher in paraplegic basketball players than in paraplegic sedentary patients, whereas the groups were not significantly different for lumbar density.

CONCLUSIONS

Wheelchair basketball in spinal cord-injured patients was associated with greater bone density in distal radius compared with sedentary paraplegics. However, it was not associated with greater density below the injury level.

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.

Imaging modalities in the assessment of osteoporosis

Imaging can be helpful in the diagnosis and treatment of osteoporosis. Several imaging modalities have become available to assess bone mass in the peripheral, axial, or entire skeleton. The basic principles, indications, and limitations of each imaging method are presented.