Effect of pamidronate administration on bone in patients with acute spinal cord injury

Neuroprotective macromolecular methylprednisolone prodrug nanomedicine prevents glucocorticoid-induced muscle atrophy and osteoporosis in a rat model of spinal cord injury

To address the adverse side effects associated with systemic high-dose methylprednisolone (MP) therapy for acute spinal cord injury (SCI), we have developed a N-2-hydroxypropyl methacrylamide copolymer-based MP prodrug nanomedicine (Nano-MP). Intravenous Nano-MP selectively targeted to the inflamed SCI lesion and significantly improved neuroprotection and functional recovery after acute SCI. In the present study, we comprehensively assessed the potential adverse side effects associated with the treatment in the SCI rat models, including reduced body weight and food intake, impaired glucose metabolism, and reduced musculoskeletal mass and integrity. In contrast to free MP treatment, intravenous Nano-MP after acute SCI not only offered superior neuroprotection and functional recovery but also significantly mitigated or even eliminated the aforementioned adverse side effects. The superior safety features of Nano-MP observed in this study further confirmed the clinical translational potential of Nano-MP as a highly promising drug candidate for better clinical management of patients with acute SCI.

Exoskeletal-Assisted Walking in Veterans With Paralysis: A Randomized Clinical Trial

Importance

Robotic exoskeletons leverage technology that assists people with spinal cord injury (SCI) to walk. The efficacy of home and community exoskeletal use has not been studied in a randomized clinical trial (RCT).

Objective

To examine whether use of a wheelchair plus an exoskeleton compared with use of only a wheelchair led to clinically meaningful net improvements in patient-reported outcomes for mental and physical health.

Design, Setting, and Participants

This RCT of veterans with SCI was conducted at 15 Veterans Affairs medical centers in the US from September 6, 2016, to September 27, 2021. Data analysis was performed from March 10, 2022, to June 20, 2024.

Interventions

Participants were randomized (1:1) to standard of care (SOC) wheelchair use or SOC plus at-will use of a US Food and Drug Administration (FDA)-cleared exoskeletal-assisted walking (EAW) device for 4 months in the home and community.

Main Outcomes and Measures

Two primary outcomes were studied: 4.0-point or greater improvement in the mental component summary score on the Veterans RAND 36-Item Health Survey (MCS/VR-36) and 10% improvement in the total T score of the Spinal Cord Injury-Quality of Life (SCI-QOL) physical and medical health domain and reported as the proportion who achieved clinically meaningful changes. The primary outcomes were measured at baseline, post randomization after advanced EAW training sessions, and at 2 months and 4 months (primary end point) in the intervention period. Device usage, reasons for not using, and adverse events were collected.

Results

A total of 161 veterans with SCI were randomized to the EAW (n = 78) or SOC (n = 83) group; 151 (94%) were male, the median age was 47 (IQR, 35-56) years, and median time since SCI was 7.3 (IQR, 0.5 to 46.5) years. The difference in proportion of successes between the EAW and SOC groups on the MCS/VR-36 (12 of 78 [15.4%] vs 14 of 83 [16.9%]; relative risk, 0.91; 95% CI, 0.45-1.85) and SCI-QOL physical and medical health domain (10 of 78 [12.8%] vs 11 of 83 [13.3%]; relative risk, 0.97; 95% CI, 0.44-2.15) was not statistically different. Device use was lower than expected (mean [SD] distance, 1.53 [0.02] miles per month), primarily due to the FDA-mandated companion being unavailable 43.9% of the time (177 of 403 instances). Two EAW-related foot fractures and 9 unrelated fractures (mostly during wheelchair transfers) were reported.

Conclusions and Relevance

In this RCT of veterans with SCI, the lack of improved outcomes with EAW device use may have been related to the relatively low device usage. Solutions for companion requirements and user-friendly technological adaptations should be considered for improved personal use of these devices.

Trial Registration

ClinicalTrials.gov Identifier: NCT02658656.

Spinal Cord Injury Associated Disease of the Skeleton, an Unresolved Problem with Need for Multimodal Interventions

Spinal cord injury is associated with skeletal unloading, sedentary behavior, decreases in skeletal muscle mass, and exercise intolerance, which results in rapid and severe bone loss. To date, monotherapy with physical interventions such as weight-bearing in standing frames, computer-controlled electrically stimulated cycling and ambulation exercise, and low-intensity vibration are unsuccessful in maintaining bone density after SCI. Strategies to maintain bone density with commonly used osteoporosis medications also fail to provide a significant clinical benefit, potentially due to a unique pathology of bone deterioration in SCI. In this review, the available data is discussed on evaluating and monitoring bone loss, fracture, and physical and pharmacological therapeutic approaches to SCI-associated disease of the skeleton. The treatment of SCI-associated disease of the skeleton, the implications for clinical management, and areas of need are considered for future investigation.

Monthly treatment with romosozumab for 1 year increases bone mineral at the hip, but not the knee, in women with chronic spinal cord injury

Bone loss below the level of neurological lesion is a well-known complication of spinal cord injury (SCI). To date, most research has focused on pharmaceutical intervention using antiresorptives to prevent bone loss during the acute phase of SCI; however, limited research has investigated treatments for established osteoporosis during chronic SCI. Romosozumab, a monoclonal antibody with both antiresorptive and anabolic effects, has demonstrated significant increases in BMD for women with established PMO. Therefore, the purpose of this study was to examine the efficacy of monthly treatment with romosozumab to improve DXA-derived areal BMD at the hip, and CT-derived BMC and strength at the hip and knee in women with chronic SCI and an inability to ambulate. Twelve female participants with chronic SCI were recruited to receive 1 yr of monthly subcutaneous injections of romosozumab (210 mg). DXA and CT scans were taken at baseline, and months 3, 6, and 12 to quantify bone mineral, and finite element (FE) analysis was used to predict bone strength. Longitudinal mixed effects models were employed to determine the impact of treatment on bone properties. After 12 mo of treatment, areal BMD at the lumbar spine and total hip were significantly increased with median changes of 10.2% (IQR: 8.3-15.2%, p<.001) and 4.2% (IQR: 3.4-7.7%, p = .009), respectively. Improvements at the hip were primarily due to increases in trabecular, not cortical, bone and effects were sufficient to significantly increase FE-predicted strength by 20.3% (IQR: 9.5-37.0%, p = .004). Treatment with romosozumab did not lead to any significant improvement in bone mineral at the distal femur or proximal tibia. These findings provide promising results for romosozumab treatment to improve bone mineral and reduce fracture risk at the hip, but not the knee, in women with chronic SCI.

Anti-Siglec-15 Antibody Prevents Marked Bone Loss after Acute Spinal Cord Injury-Induced Immobilization in Rats

Rapid and extensive sublesional bone loss after spinal cord injury (SCI) is a difficult medical problem that has been refractory to available interventions except the antiresorptive agent denosumab (DMAB). While DMAB has shown some efficacy in inhibiting bone loss, its concurrent inhibition of bone formation limits its use. Sialic acid-binding immunoglobulin-like lectin (Siglec)-15 is expressed on the cell surface of mature osteoclasts. Anti-Siglec-15 antibody (Ab) has been shown to inhibit osteoclast maturation and bone resorption while maintaining osteoblast activity, which is distinct from current antiresorptive agents that inhibit the activity of both osteoclasts and osteoblasts. The goal of the present study is to test a Siglec-15 Ab (NP159) as a new treatment option to prevent bone loss in an acute SCI model. To this end, 4-month-old male Wistar rats underwent complete spinal cord transection and were treated with either vehicle or NP159 at 20 mg/kg once every 2 weeks for 8 weeks. SCI results in significant decreases in bone mineral density (BMD, -18.7%), trabecular bone volume (-43.1%), trabecular connectivity (-59.7%), and bone stiffness (-76.3%) at the distal femur. Treatment with NP159 almost completely prevents the aforementioned deterioration of bone after SCI. Blood and histomorphometric analyses revealed that NP159 is able to greatly inhibit bone resorption while maintaining bone formation after acute SCI. In ex vivo cultures of bone marrow cells, NP159 reduces osteoclastogenesis while increasing osteoblastogenesis. In summary, treatment with NP159 almost fully prevents sublesional loss of BMD and metaphysis trabecular bone volume and preserves bone strength in a rat model of acute SCI. Because of its unique ability to reduce osteoclastogenesis and bone resorption while promoting osteoblastogenesis to maintain bone formation, Siglec-15 Ab may hold greater promise as a therapeutic agent, compared with the exclusively antiresorptive or anabolic agents that are currently used, in mitigating the striking bone loss that occurs after SCI or other conditions associated with severe immobilization. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Alteration of Volumetric Bone Mineral Density Parameters in Men with Spinal Cord Injury

Spinal cord injury (SCI) induces severe losses of trabecular and cortical volumetric bone mineral density (vBMD), which cannot be discriminated with conventional dual-energy X-ray absorptiometry (DXA) analysis. The objectives were to: (i) determine the effects of SCI on areal BMD (aBMD) and vBMD determined by advanced 3D-DXA-based methods at various femoral regions and (ii) model the profiles of 3D-DXA-derived parameters with the time since injury. Eighty adult males with SCI and 25 age-matched able-bodied (AB) controls were enrolled in this study. Trabecular and cortical vBMD, cortical thickness and derived strength parameters were assessed by 3D-SHAPER® software at various femoral subregions. Individuals with SCI had significantly lower integral vBMD, trabecular vBMD, cortical vBMD, cortical thickness and derived bone strength parameters (p < 0.001 for all) in total proximal femur compared with AB controls. These alterations were approximately to the same degree for all three femoral subregions, and the difference between the two groups tended to be greater for cortical vBMD than trabecular vBMD. There were minor differences according to the lesion level (paraplegics vs tetraplegics) for all 3D-DXA-derived parameters. For total proximal femur, the decreasing bone parameters tended to reach a new steady state after 5.1 years for integral vBMD, 7.4 years for trabecular vBMD and 9.2 years for cortical vBMD following SCI. At proximal femur, lower vBMD (integral, cortical and trabecular) and cortical thickness resulted in low estimated bone strength in individuals with SCI. It remains to be demonstrated whether these new parameters are more closely associated with fragility fracture than aBMD.

Zoledronic acid after spinal cord injury mitigates losses in proximal femoral strength independent of ambulation ability

Rapid bone loss can occur after spinal cord injury (SCI) and a standard of care to prevent or treat this phenomenon is an active area of research. Using advanced analysis techniques, this study demonstrates that zoledronic acid, a possible treatment, prevented loss of bone strength at the hip following SCI.

INTRODUCTION

Bone loss below the level of neurological lesion is a well-known complication of spinal cord injury (SCI), and effective preventive treatment for this phenomenon is an active area of research. Zoledronic acid has demonstrated efficacy to attenuate bone loss at the hip after SCI, but previous studies relied on measurements from dual-energy X-ray absorptiometry. The purpose of this investigation was to more thoroughly characterize changes to bone mineral and strength at the proximal femur in individuals receiving zoledronic acid in the acute SCI stage; we also examined the influence of ambulatory ability on bone outcomes.

METHODS

Participants randomized to either zoledronic acid (n = 29) or placebo (n = 30) received computed tomography (CT) scans and ambulatory assessments at baseline and 6 and 12 months following drug infusion. CT-based finite element (FE) modeling was used to predict changes in proximal femoral strength associated with treatment.

RESULTS

After 12 months, FE-predicted bone strength was reduced by a mean (SD) of 9.6 (17.9)% in the zoledronic acid group versus 24.6 (24.5)% in the placebo group (p = 0.007). These differences in strength were explained by reductions in CT measurements of both trabecular (p < 0.001) and cortical (p ≤ 0.021) bone at the femoral neck and trochanteric region. Ambulation ability influenced select trabecular and cortical parameters, but we were unable to detect an impact on FE-predicted bone strength.

CONCLUSION

These findings demonstrate that treatment with zoledronic acid in acute SCI attenuates losses in proximal femoral strength, which may reduce the risk of hip fractures across patients with varying degrees of ambulatory abilities.

The Pathophysiology, Identification and Management of Fracture Risk, Sublesional Osteoporosis and Fracture among Adults with Spinal Cord Injury

BACKGROUND

The prevention of lower extremity fractures and fracture-related morbidity and mortality is a critical component of health services for adults living with chronic spinal cord injury (SCI).

METHODS

Established best practices and guideline recommendations are articulated in recent international consensus documents from the International Society of Clinical Densitometry, the Paralyzed Veterans of America Consortium for Spinal Cord Medicine and the Orthopedic Trauma Association.

RESULTS

This review is a synthesis of the aforementioned consensus documents, which highlight the pathophysiology of lower extremity bone mineral density (BMD) decline after acute SCI. The role and actions treating clinicians should take to screen, diagnose and initiate the appropriate treatment of established low bone mass/osteoporosis of the hip, distal femur or proximal tibia regions associated with moderate or high fracture risk or diagnose and manage a lower extremity fracture among adults with chronic SCI are articulated. Guidance regarding the prescription of dietary calcium, vitamin D supplements, rehabilitation interventions (passive standing, functional electrical stimulation (FES) or neuromuscular electrical stimulation (NMES)) to modify bone mass and/or anti-resorptive drug therapy (Alendronate, Denosumab, or Zoledronic Acid) is provided. In the event of lower extremity fracture, the need for timely orthopedic consultation for fracture diagnosis and interprofessional care following definitive fracture management to prevent health complications (venous thromboembolism, pressure injury, and autonomic dysreflexia) and rehabilitation interventions to return the individual to his/her pre-fracture functional abilities is emphasized.

CONCLUSIONS

Interprofessional care teams should use recent consensus publications to drive sustained practice change to mitigate fracture incidence and fracture-related morbidity and mortality among adults with chronic SCI.

Primary Care in the Spinal Cord Injury Population: Things to Consider in the Ongoing Discussion

Purpose of Review

Spinal cord injury (SCI) creates unique needs that if not recognized and addressed timely can have detrimental effects on the health and quality of life (QOL) of people living with a SCI. Primary preventive health care is shown to decrease morbidity and mortality, yet the SCI population reportedly faces challenges getting access to this care. This area in SCI health care is still largely understudied with no consensus on the ideal way or which health care provider is best to provide primary care for this population.

Findings

Preventive care is generally provided by general primary care providers, but not all primary care providers are trained in recognizing and addressing spinal cord injury-specific needs. SCI providers generally are not trained in addressing all aspects of preventive care. Knowing the recommended preventive care screenings, recognizing and managing specific conditions seen after a SCI, and seamless coordination of care between general practitioners and SCI specialists are some of the interventions to help prevent health complications, decrease morbidity and mortality, improve health outcomes, and promote QOL in this patient population.

Summary

Prioritized focus on preventive care is necessary for a positive impact on the overall health and QOL in this population. Addressing the knowledge gap reported by primary care providers and SCI providers may help increase the probability of SCI patients getting their preventive and specialty care needs addressed. We present a "cheat sheet" of recommendations for the preventive care evaluation of a person living with a SCI.

Bisphosphonates Alleviate Bone Loss in People with Acute Spinal Cord Injury：A Systematic Review and Meta-Analysis

OBJECTIVE

Bone loss is not to be underestimated in people with acute spinal cord injury (SCI). Bisphosphonates can inhibit the bone resorption of osteoclast. To study whether the early application of bisphosphonates can alleviate bone loss after acute SCI, we included 7 randomized controlled trials for meta-analysis.

METHODS

Seven randomized controlled trials were found in literature databases. The percentage change in bone mineral density (BMD) at different sites were primary outcomes and serum bone turnover markers were secondary outcomes. A random-effects model was selected for meta-analysis.

RESULTS

There were significant differences in the percentage change in BMD of the lumbar spine, total hip, and femoral neck between the bisphosphonates and control groups, but not in the percentage change in distal femur BMD. Besides, there were no statistically significant differences between the groups in the bone formation marker Procollagen type 1 N propeptide; bisphosphonates were effective in reducing the C-terminal telopeptide at the 6-month follow-up, but not at the 12-month follow-up. Subgroup analysis of the effects of zoledronate showed positive effects on BMD of the lumbar spine, total hip, and femoral neck at the 6-month follow-up and showed positive effects on BMD of the total hip and femoral neck at the 12-month follow-up.

CONCLUSIONS

Bisphosphonates can effectively alleviate the bone loss of the lumbar spine, total hip, and femoral neck in patients with acute SCI, and early application is advocated.

Durability and delayed treatment effects of zoledronic acid on bone loss after spinal cord injury: a randomized, controlled trial

A single infusion of zoledronic acid (ZOL) after acute spinal cord injury (SCI) attenuates bone loss at the hip (proximal femur) and knee (distal femur and proximal tibia) for at least 6 months. The objective of this study was to examine the effects of timing and frequency of ZOL over 2 years. In this double-blind, placebo-controlled trial, we randomized 60 individuals with acute SCI (<120 days of injury) to receive either ZOL 5-mg infusion (n = 30) or placebo (n = 30). After 12 months, groups were again randomized to receive ZOL or placebo, resulting in four treatment groups for year 2: (i) ZOL both years; (ii) ZOL year 1, placebo year 2; (iii) placebo year 1, ZOL year 2; and (iv) placebo both years. Our primary outcome was bone loss at 12 months; compared to placebo, a single infusion of ZOL attenuated bone loss at the proximal femur, where median changes relative to baseline were -1.7% to -2.2% for ZOL versus -11.3% to -12.8% for placebo (p < 0.001). Similarly, the distal femur and proximal tibia showed changes of -4.7% to -9.6% for ZOL versus -8.9% to -23.0% for placebo (p ≤ 0.042). After 24 months, differences were significant at the proximal femur only (-3.2% to -6.0% for ZOL vs. -16.8% to -21.8% for placebo; p ≤ 0.018). Although not statistically significant, median bone density losses suggested some benefit from two annual infusions compared to a single baseline infusion, as well as from a single infusion 12 months after baseline compared to 2 years of placebo; therefore, further investigation in the 12-month to 24-month treatment window is warranted. No unanticipated adverse events associated with drug treatment were observed. In summary, ZOL 5-mg infusion after acute SCI was well-tolerated and may provide an effective therapeutic approach to prevent bone loss in the first few years following SCI. © 2021 American Society for Bone and Mineral Research (ASBMR).

Pharmacological approaches for bone health in persons with spinal cord injury

Spinal cord injury (SCI) results in rapid, marked skeletal deterioration below the level of neurological lesion. Ideally, the most effective therapeutic approach would prevent loss of bone mass and architecture shortly after paralysis. Bisphosphonates preserve bone mineral density at the hip but not at the knee, which is the anatomical site most prone to fracture in the SCI population. Denosumab has recently been reported to prevent bone loss in persons with acute SCI but should be continued for an as yet indeterminate time because discontinuation will result in rapid bone loss. Several other novel approaches to preserving bone at the time of acute SCI should be tested, as well as approaches to reverse bone loss in individuals with chronic SCI.

S1 Guidelines on Bone Impairment in Spinal Cord Injury

During the acute and chronic phase of spinal cord injury (SCI) bone turnover and structure are affected. Bone mineral density of lower limbs is decreased up to 28%-50% below that of age-matched peers at 12-18 mo post injury. Coexisting secondary etiologies of osteoporosis may be present, and during ageing additional loss of bone occurs. All these compose a complex canvas of bone impairment after spinal cord injury and make the therapeutical approach challenging. The risk of fragility fractures is increased after the 2nd decade post SCI affecting the functionality and quality of life of individuals with SCI. Diagnostic flaws, lack of a ranking system to categorize the degree of bone impairment similar to the one of World Health Organization, and evidence-based clinical guidelines for management in SCI requires interdisciplinary cooperation and appropriate planning of future research and interventions. Spinal Cord Section of Hellenic Society of Physical Rehabilitation Medicine convened an expert panel working group on bone and spinal cord injury at the Pan-Hellenic Congress 2018 of PRM in Athens Greece, to establish an evidence-based position statement for bone loss in individuals with SCI of traumatic or non-traumatic etiology. This was reviewed by an International Task Force and used to create S1 Guidelines. This first version S1 guideline will work towards to provide help with prophylactic basic osteoporosis therapy diagnostic and therapeutic decisions in acute and chronic phase and rehabilitation countermeasures against osteoporosis related with spinal cord injury.

The efficacy and safety of bisphosphonate analogs for treatment of osteoporosis after spinal cord injury: a systematic review and meta-analysis of randomized controlled trials

Bisphosphonates can inhibit osteoclast-mediated bone resorption, prevent bone loss, and reduce the risk of osteoporotic fractures. Our meta-analysis of studies shows that early bisphosphonate administration after SCI was safe and beneficial to the BMD of the total hip and lumbar spine at 12 months.

INTRODUCTION

Rapid bone loss in the early stages of spinal cord injury (SCI) leads to an increased risk of osteoporotic fracture. A meta-analysis was conducted to assess the efficacy and safety of bisphosphonates for the treatment of osteoporosis after SCI.

METHODS

A literature search of the PubMed, EMBASE, Cochrane Library, and Web of Science databases identified nine randomized controlled trials with 206 individuals. This meta-analysis was performed using a random-effects model. The primary outcome was the percent change in bone mineral density (BMD) of the total hip, distal femur, and lumbar spine from baseline to 12 months. Bone turnover markers were secondary outcomes. The incidences of adverse events were assessed in order to evaluate safety.

RESULTS

There were significant differences in BMD of the total hip and lumbar spine or serum C-terminal telopeptide between the bisphosphonate and control groups but no difference in adverse events. The percent change in BMD of the distal femur and serum type 1 procollagen N-terminal peptide from baseline to 12 months was not superior in the treatment groups. Osteoclast-mediated bone resorption was inhibited by bisphosphonate administration. Subgroup analyses of participants treated with zoledronate at different sites revealed a beneficial effect on BMD of the total hip and lumbar spine but not the distal femur.

CONCLUSION

Early bisphosphonate administration after SCI was safe and beneficial to the BMD of the total hip and lumbar spine at 12 months.

Administration of Denosumab Preserves Bone Mineral Density at the Knee in Persons With Subacute Spinal Cord Injury: Findings From a Randomized Clinical Trial

Persons with neurologically motor-complete spinal cord injury (SCI) have a marked loss of bone mineral density (BMD) of the long bones of the lower extremities, predisposing them to fragility fractures, especially at the knee. Denosumab, a commercially available human monoclonal IgG antibody to receptor activator of nuclear factor-κB ligand (RANKL), may provide an immunopharmacological solution to the rapid progressive deterioration of sublesional bone after SCI. Twenty-six SCI participants with subacute motor-complete SCI were randomized to receive either denosumab (60 mg) or placebo at baseline (BL), 6, and 12 months. Areal bone mineral density (aBMD) by dual energy x-ray absorptiometry (DXA) at 18 months at the distal femur was the primary outcome and aBMD of the proximal tibia and hip were the secondary outcomes analyzed in 18 of the 26 participants (denosumab, n = 10 and placebo, n = 8). The metrics of peripheral QCT (pQCT) were the exploratory outcomes analyzed in a subsample of the cohort (denosumab, n = 7 and placebo n = 7). The mean aBMD (±95% CI) for the denosumab versus the placebo groups demonstrated a significant group × time interactions for the following regions of interest at BL and 18 months: distal femoral metaphysis = mean aBMD 1.187; 95% CI, 1.074 to 1.300 and mean aBMD 1.202; 95% CI, 1.074 to 1.329 versus mean aBMD 1.162; 95% CI, 0.962 to 1.362 and mean aBMD 0.961; 95% CI, 0.763 to 1.159, respectively (p < 0.001); distal femoral epiphysis = mean aBMD 1.557; 95% CI, 1.437 to 1.675 and mean aBMD 1.570; 95% CI, 1.440 to 1.700 versus mean aBMD 1.565; 95% CI, 1.434 to 1.696 and mean aBMD 1.103; 95% CI, 0.898 to 1.309, respectively (p = 0.002); and proximal tibial epiphysis = mean aBMD 1.071; 95% CI, 0.957 to 1.186 and mean aBMD 1.050; 95% CI, 0.932 to 1.168 versus mean aBMD 0.994; 95% CI, 0.879 to 1.109 and mean aBMD 0.760; 95% CI, 0.601 to 0.919, respectively (p < 0.001). Analysis of pQCT imaging revealed a continued trend toward significantly greater loss in total volumetric BMD (vBMD) and trabecular vBMD at the 4% distal tibia region, with a significant percent loss for total bone mineral content. Thus, at 18 months after acute SCI, our findings show that denosumab maintained aBMD at the knee region, the site of greatest clinical relevance in the SCI population. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

The Effect of Bisphosphonates on Managing Osteoporosis After Spinal Cord Injury: A Meta-Analysis

BACKGROUND

The increased bone loss after spinal cord injury (SCI) is associated with an increase in the morbidity and mortality of fragility fractures, which can constitute a substantial cost to health care systems. Bisphosphonates (BPs) are now the principal class of medications used for osteoporosis.

OBJECTIVE

To demonstrate the effect of BPs on treating osteoporosis after SCI.

METHODS

A comprehensive search in PubMed, EMBASE, Web of Science and Cochrane Central databases was undertaken for randomized controlled trials (RCTs), exploring the effect of BPs on osteoporosis after SCI. The primary outcome measures were the BMD of different locations, serum bone turnover marker levels, serum biochemistry marker levels and adverse effect (AE) risks. The final search was performed in September 2019. Reporting was carried out according to PRISMA Guidelines.

RESULTS

Six RCTs were included. A total of 147 patients met the inclusion criteria. BPs were found to statistically prevent bone loss in the total hip, femoral neck and trochanter at the 6- and 12-month follow-up points and to increase the BMD of the lumbar spine at the 12-month follow-up time point. BPs had no clear effect on serum PINP or serum calcium levels at the 12-month follow-up time point.

CONCLUSION

BP therapy may prevent bone loss in the lumbar spine and hip when administered early after SCI and has relatively high safety.

A Primary Care Provider's Guide to Bone Health in Spinal Cord-Related Paralysis

Individuals with spinal cord injury/disorder (SCI/D) are at high risk for developing secondary osteoporosis. Bone loss after neurologic injury is multifactorial and is dependent on the time from and extent of neurologic injury. Most bone loss occurs in the first year after complete motor paralysis, and fractures occur most commonly in the distal femur and proximal tibia (paraplegic fracture). The 2019 International Society for Clinical Densitometry Position Statement in SCI establishes that dual-energy X-ray absorptiometry (DXA) can be used to both diagnose osteoporosis and predict lower extremity fracture risk in individuals with SCI/D. Pharmacologic treatments used in primary osteoporosis have mixed results when used for SCI/D-related osteoporosis. Ambulation, standing, and electrical stimulation may be helpful at increasing bone mineral density (BMD) in individuals with SCI/D but do not necessarily correlate with fracture risk reduction. Clinicians caring for individuals with spinal cord-related paralysis must maintain a high index of suspicion for fragility fractures and consider referral for surgical evaluation and management.

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.

Is prophylaxis for osteoporosis indicated after acute spinal cord injury?

Spinal cord injury (SCI)-related osteoporosis is common complication in people with tetraplegia or paraplegia. Studies have shown that sublesional regions are severely demineralized. Loss of bone and sequential fractures are major problems in people with SCI that lead to further immobilization and decreasing quality of life. Despite extensive research mechanisms of this bone impairment are inadequately understood. This article discusses basics of bone metabolism physiopathology along with pharmaceutical prevention and treatment approaches to manage acute SCI-related bone loss.

Evidence-based prevention and treatment of osteoporosis after spinal cord injury: a systematic review

PURPOSE

Spinal cord injury (SCI) results in accelerated bone mineral density (BMD) loss and disorganization of trabecular bone architecture. The mechanisms underlying post-SCI osteoporosis are complex and different from other types of osteoporosis. Findings of studies investigating efficacy of pharmacological or rehabilitative interventions in SCI-related osteoporosis are controversial. The aim of this study was to review the literature pertaining to prevention and evidence-based treatments of SCI-related osteoporosis.

METHODS

In this systematic review, MEDLINE, EMBASE, PubMed, and the Cochrane Library were used to identify papers from 1946 to December 31, 2015. The search strategy involved the following keywords: spinal cord injury, osteoporosis, and bone loss.

RESULTS

Finally, 56 studies were included according to the inclusion criteria. Only 16 randomized controlled trials (involving 368 patients) were found. We found following evidences for effectiveness of bisphosphonates in prevention of BMD loss in acute SCI: very low-quality evidence for clodronate and etidronate, low-quality evidence for alendronate, and moderate-quality evidence for zoledronic acid. Low-quality evidence showed no effectiveness for tiludronate. In chronic SCI cases, we found low-quality evidence for effectiveness of vitamin D₃ analogs combined with 1-alpha vitamin D₂. However, low-quality inconsistent evidence exists for alendronate. For non-pharmacologic interventions, very low-quality evidence exists for effectiveness of standing with or without treadmill walking in acute SCI. Other low-quality evidences indicated that electrical stimulation, tilt-table standing, and ultrasound provide no significant effects. Very low-quality evidence did not show any benefit for low-intensity (3 days per week) cycling with functional electrical stimulator in chronic SCI.

CONCLUSIONS

No recommendations can be made from this review, regarding overall low quality of evidence as a result of high risk of bias, low sample size in most of the studies, and notable heterogeneity in type of intervention, outcome measurement, and duration of treatment. Therefore, future high-quality RCT studies with higher sample sizes and more homogeneity are strongly recommended to provide high-quality evidence and make applicable recommendations for prevention and treatment of SCI-related bone loss.

Dual-energy X-ray absorptiometry and fracture prediction in patients with spinal cord injuries and disorders

Low T-scores at the hip predict incident fractures in persons with a SCI.

INTRODUCTION

Persons with a spinal cord injury (SCI) have substantial morbidity and mortality following osteoporotic fractures. The objective of this study was to determine whether dual-energy X-ray absorptiometry (DXA) measurements predict osteoporotic fractures in this population.

METHODS

A retrospective historical analysis that includes patients (n = 552) with a SCI of at least 2 years duration who had a DXA performed and were in the VA Spinal Cord Disorders Registry from fiscal year (FY) 2002-2012 was performed.

RESULTS

The majority of persons (n = 455, 82%) had a diagnosis of osteoporosis or osteopenia, with almost half having osteoporosis. BMD and T-scores at the lumbar spine were not significantly associated with osteoporotic fractures (p > 0.48) for both. In multivariable analyses, osteopenia (OR = 4.75 95% CI 1.23-17.64) or osteoporosis (OR = 4.31, 95% CI 1.15-16.23) compared with normal BMD was significantly associated with fractures and higher T-scores at the hip were inversely associated with fractures (OR 0.73 (95% CI 0.57-0.92)). There was no significant association of T-scores or World Health Organization (WHO) classification with incident fractures in those with complete SCI (p > 0.15 for both).

CONCLUSION

The majority (over 80%) of individuals with a SCI have osteopenia or osteoporosis. DXA-derived measurements at the hip, but not the lumbar spine, predict fracture risk in persons with a SCI. WHO-derived bone density categories may be useful in classifying fracture risk in persons with a SCI.

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

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

Mice with sclerostin gene deletion are resistant to the severe sublesional bone loss induced by spinal cord injury

Bone loss after spinal cord injury (SCI) is rapid, severe, and refractory to interventions studied to date. Mice with sclerostin gene deletion are resistant to the severe sublesional bone loss induced by SCI, further indicating pharmacological inhibition of sclerostin may represent a promising novel approach to this challenging medical problem.

INTRODUCTION

The bone loss secondary to spinal cord injury (SCI) is associated with several unique pathological features, including the permanent immobilization, neurological dysfunction, and systemic hormonal alternations. It remains unclear how these complex pathophysiological changes are linked to molecular alterations that influence bone metabolism in SCI. Sclerostin is a key negative regulator of bone formation and bone mass. We hypothesized that sclerostin could function as a major mediator of bone loss following SCI.

METHODS

To test this hypothesis, 10-week-old female sclerostin knockout (SOST KO) and wild type (WT) mice underwent complete spinal cord transection or laminectomy (Sham).

RESULTS

At 8 weeks after SCI, substantial loss of bone mineral density was observed at the distal femur and proximal tibia in WT mice but not in SOST KO mice. By μCT, trabecular bone volume of the distal femur was markedly decreased by 64 % in WT mice after SCI. In striking contrast, there was no significant reduction of bone volume in SOST KO/SCI mice compared with SOST KO/sham. Histomorphometric analysis of trabecular bone revealed that the significant reduction in bone formation rate following SCI was observed in WT mice but not in SOST KO mice. Moreover, SCI did not alter osteoblastogenesis of marrow stromal cells in SOST KO mice.

CONCLUSION

Our findings demonstrate that SOST KO mice were protected from the major sublesional bone loss that invariably follows SCI. The evidence indicates that sclerostin is an important mediator of the marked sublesional bone loss after SCI, and that pharmacological inhibition of sclerostin may represent a promising novel approach to this challenging clinical problem.

Risk factors for osteoporotic fractures in persons with spinal cord injuries and disorders

Clinical risk factors for fracture were explored among Veterans with a spinal cord injury. At the end of 11 years of follow-up, the absolute risk of fracture was approximately 20 %. Among the clinical and SCI-related factors explored, a prior history of fracture was strongly associated with incident fracture.

INTRODUCTION

Few studies to date have comprehensively addressed clinical risk factors for fracture in persons with spinal cord injury (SCI). The purpose of this study was to identify risk factors for incident osteoporotic fractures in persons with a SCI that can be easily determined at the point of care.

METHODS

The Veteran's Affairs Spinal Cord Dysfunction Registry, a national database of persons with a SCI, was used to examine clinical and SCI-related risk factors for fracture. Incident fractures were identified in a cohort of persons with chronic SCI, defined as SCI present for at least 2 years. Cox regression models were used to estimate the risk of incident fractures.

RESULTS

There were 22,516 persons with chronic SCI included in the cohort with 3365 incident fractures. The mean observational follow-up time for the overall sample was 6.2 years (median 6.0, IQR 2.9-11.0). The mean observational follow-up time for the fracture group was 3.9 years (median 3.3, IQR 1.4-6.1) and 6.7 years (median 6.7, IQR 3.1-11.0) for the nonfracture group. By the end of the study, which included predominantly older Veterans with a SCI observed for a relatively short period of time, the absolute (i.e., cumulative hazard) for incident fractures was 0.17 (95%CI 0.14-0.21). In multivariable analysis, factors associated with an increased risk of fracture included White race, traumatic etiology of SCI, paraplegia, complete extent of SCI, longer duration of SCI, use of anticonvulsants and opioids, prevalent fractures, and higher Charlson Comorbidity Indices. Women aged 50 and older were also at higher risk of sustaining an incident fracture at any time during the 11-year follow-up period.

CONCLUSIONS

There are multiple clinical and SCI-related risk factors which can be used to predict fracture in persons with a SCI. Clinicians should be particularly concerned about incident fracture risk in persons with a SCI who have had a previous fracture.

Training Persons with Spinal Cord Injury to Ambulate Using a Powered Exoskeleton

Powered exoskeletons have become available for overground ambulation in persons with paralyses due to spinal cord injury (SCI) who have intact upper extremity function and are able to maintain upright balance using forearm crutches. To ambulate in an exoskeleton, the user must acquire the ability to maintain balance while standing, sitting and appropriate weight shifting with each step. This can be a challenging task for those with deficits in sensation and proprioception in their lower extremities. This manuscript describes screening criteria and a training program developed at the James J. Peters VA Medical Center, Bronx, NY to teach users the skills needed to utilize these devices in institutional, home or community environments. Before training can begin, potential users are screened for appropriate range of motion of the hip, knee and ankle joints. Persons with SCI are at an increased risk of sustaining lower extremity fractures, even with minimal strain or trauma, therefore a bone mineral density assessment is performed to reduce the risk of fracture. Also, as part of screening, a physical examination is performed in order to identify additional health-related contraindications. Once the person has successfully passed all screening requirements, they are cleared to begin the training program. The device is properly adjusted to fit the user. A series of static and dynamic balance tasks are taught and performed by the user before learning to walk. The person is taught to ambulate in various environments ranging from indoor level surfaces to outdoors over uneven or changing surfaces. Once skilled enough to be a candidate for home use with the exoskeleton, the user is then required to designate a companion-walker who will train alongside them. Together, the pair must demonstrate the ability to perform various advanced tasks in order to be permitted to use the exoskeleton in their home/community environment.

Zoledronic Acid Treatment After Acute Spinal Cord Injury: Results of a Randomized, Placebo-Controlled Pilot Trial

OBJECTIVE

To determine the effect of intravenous zoledronic acid 5 mg on the extent and course of bone loss after spinal cord injury (SCI).

DESIGN

Double-blind, randomized, placebo-controlled parallel-group trial.

SETTING

Acute in-patient, tertiary-care rehabilitation hospital.

PARTICIPANTS

Convenience sample of 17 in-patients with SCI <12 weeks before randomization; American Spinal Injury Association Impairment scale A, B, or C and medically stable. Twelve patients were evaluated at the primary endpoint at 6 months.

METHODS

Patients meeting study criteria were randomly assigned to zoledronic acid 5 mg or matching placebo. Dual x-ray absorptiometry scan and serum for bone markers (type 1 procollagen amino-terminal propeptide, bone-specific alkaline phosphatase, collagen type 1 cross-linked C-telopeptide) were obtained at baseline and after 3 months, 6 months, and the every 6 months for up to 2 years.

MAIN OUTCOME MEASURES

The primary endpoint was change in bone mineral density (BMD) at the total hip after 6 months; secondary endpoints were changes in BMD at other skeletal sites and changes in levels of serum bone markers.

RESULTS

The group treated with zoledronic acid had a smaller decrease in BMD at 6 months at the total hip than the placebo group (right: -2.2 ± 3.4% versus -8.6 ± 3.5%, respectively, P = .03; left: -3.7 ± 1.0% versus -12.3 ± 6.9%, P = .03). Differences in BMD at the femoral neck were similar (right: -5.1 ± 6.5% versus -20.0 ± 6.4%, P = .01; left: -1.1 ± 3.5% versus -11.1 ± 7.4%, P = .02) with larger bone loss and smaller between group differences at the knee. Zoledronic acid resulted in a decrease in serum levels of both formation and resorption markers.

CONCLUSIONS

Zoledronic acid is effective at mitigating bone loss after SCI. Duration of efficacy and activity at different skeletal sites may differ from that observed in able-bodied individuals and needs further study.

Zoledronic acid administration failed to prevent bone loss at the knee in persons with acute spinal cord injury: an observational cohort study

After acute spinal cord injury (SCI), rapid depletion of the sublesional skeleton occurs, particularly at the distal femur and proximal tibia. Subsequently, fragility fractures of the knee may occur. We determined the efficacy of zoledronic acid to prevent sublesional bone mineral density (BMD) loss at 6 and 12 months after acute SCI. Thirteen subjects with acute motor-complete SCI were prospectively studied: 6 patients received zoledronic acid (5 mg) and 7 subjects did not receive the drug (controls). Zoledronic acid was administered intravenously within 16 weeks of acute injury. Areal BMD was performed by dual energy X-ray absorptiometry at baseline, 6, and 12 months after administration of drug. The treatment group demonstrated sparing of BMD at the total hip at month 6 (p < 0.0006) and at month 12 (p < 0.01). In contrast to the findings at the hip, the treatment group had a greater loss of BMD compared to the control group at the distal femur and proximal tibia at month 6 (-7.9% ± 3.4 vs.-2.7% ± 5.0, respectively, p = 0.054; and -10.5% ± 6.4 vs. -4.8% ± 6.8, respectively, p = NS) and at month 12 (-18.5% ± 3.9 vs. -8.4% ± 7.2, respectively, p = 0.01; and -20.4% ± 8.8 vs.-7.9% ± 12.3, respectively, p = 0.06). A single dose of zoledronic acid administered soon after acute SCI reduced the %BMD loss at the hip, but appeared to have no effect to prevent %BMD loss at the knee, the site where fracture risk is greatest in persons with SCI.

Osteoporosis in individuals with spinal cord injury

The pathophysiology, clinical considerations, and relevant experimental findings with regard to osteoporosis in individuals with spinal cord injury (SCI) will be discussed. The bone loss that occurs acutely after more neurologically motor complete SCI is unique for its sublesional skeletal distribution and rate, at certain skeletal sites approaching 1% of bone mineral density per week, and its resistance to currently available treatments. The areas of high bone loss include the distal femur, proximal tibia, and more distal boney sites. Evidence from a study performed in monozygotic twins discordant for SCI indicates that sublesional bone loss in the twin with SCI increases for several decades, strongly suggesting that the heightened net bone loss after SCI may persist for an extended period of time. The increased frequency of fragility fracture after paralysis will be discussed, and a few risk factors for such fractures after SCI will be examined. Because vitamin D deficiency, regardless of disability, is a relevant consideration for bone health, as well as an easily reversible condition, the increased prevalence of and treatment target values for vitamin D in this deficiency state in the SCI population will be reviewed. Pharmacological and mechanical approaches to preserving bone integrity in persons with acute and chronic SCI will be reviewed, with emphasis placed on efficacy and practicality. Emerging osteoanabolic agents that improve functioning of WNT/β-catenin signaling after paralysis will be introduced as therapeutic interventions that may hold promise.

Possible way to reduce fracture rates in patients with traumatic spinal cord injury?

Lower extremity fractures in men with spinal cord injury (SCI) are a major problem. The use of thiazide diuretics, a simple and safe intervention, may be effective in reducing the risk of fracture in patients with traumatic SCI. Furthermore, thiazide diuretics have an added benefit of reducing kidney stone formation.

Mortality after lower extremity fractures in men with spinal cord injury

In the United States, there are over 200,000 men with spinal cord injuries (SCIs) who are at risk for lower limb fractures. The risk of mortality after fractures in SCI is unknown. This was a population-based, cohort study of all male veterans (mean age 54.1; range, 20.3-100.5 years) with a traumatic SCI of at least 2 years' duration enrolled in the Veterans Affairs (VA) Spinal Cord Dysfunction Registry from FY2002 to FY2010 to determine the association between lower extremity fractures and mortality. Mortality for up to 5 years was determined. The lower extremity fracture rate was 2.14 per 100 patient-years at risk for at least one fracture. In unadjusted models and in models adjusted for demographic, SCI-related factors, healthcare use, and comorbidities, there was a significant association between incident lower extremity fracture and increased mortality (hazard ratio [HR], 1.38; 95% confidence interval [CI], 1.17-1.63; HR, 1.36; 95% CI, 1.15-1.61, respectively). In complete SCI, the hazard of death after lower extremity fracture was also increased (unadjusted model: HR, 1.46; 95% CI, 1.13-1.89; adjusted model: HR, 1.32; 95% CI, 1.02-1.71). In fully-adjusted models, the association of incident lower extremity fracture with increased mortality was substantially greater in older men (age ≥50 years) for the entire cohort (HR, 3.42; 95% CI, 2.75-4.25) and for those with complete SCI (HR, 3.13; 95% CI, 2.19-4.45), compared to younger men (age <50 years) (entire cohort: HR, 1.42; 95% CI, 0.94-2.14; complete SCI: HR, 1.71; 95% CI, 0.98-3.01). Every additional point in the Charlson comorbidity index was associated with a 10% increase in the hazard of death in models involving the entire cohort (HR, 1.11; 95% CI, 1.09-1.13) and also in models limited to men with complete SCI (HR, 1.10; 95% CI, 1.06-1.15). These data support the concept that both the fracture itself and underlying comorbidities are drivers of death in men with SCI.

Effectiveness of bisphosphonate analogues and functional electrical stimulation on attenuating post-injury osteoporosis in spinal cord injury patients- a systematic review and meta-analysis

BACKGROUND

Various pharmacologic and non-pharmacologic approaches have been applied to reduce sublesional bone loss after spinal cord injury (SCI), and the results are inconsistent across the studies. The objective of this meta-analysis was to investigate whether the two most-studied interventions, bisphosphonate analogues and functional electrical stimulation (FES), could effectively decrease bone mineral density (BMD) attenuation and/or restore lost BMD in the SCI population.

METHODS

Randomized controlled trials, quasi-experimental studies, and prospective follow-up studies employing bisphosphonates or FES to treat post-SCI osteoporosis were identified in PubMed and Scopus. The primary outcome was the percentage of BMD change from baseline measured by dual-energy X-ray absorptiometry (DEXA) or computed tomography (CT). Data were extracted from four points: the 3rd, 6th, 12th, and 18th month after intervention.

RESULTS

A total of 19 studies were included in the analysis and involved 364 patients and 14 healthy individuals. Acute SCI participants treated with bisphosphonate therapy demonstrated a trend toward less bone loss than participants who received placebos or usual care. A significant difference in BMD decline was noted between both groups at the 3rd and 12th month post-medication. The subgroup analysis failed to show the superiority of intravenous bisphosphonate over oral administration. Regarding FES training, chronic SCI patients had 5.96% (95% CI, 2.08% to 9.84%), 7.21% (95%CI, 1.79% to 12.62%), and 9.56% (95% CI, 2.86% to 16.26%) increases in BMD at the 3rd, 6th, and 12th months post-treatment, respectively. The studies employing FES ≥ 5 days per week were likely to have better effectiveness than studies using FES ≤ 3 days per week.

CONCLUSIONS

Our meta-analysis indicated bisphosphonate administration early following SCI effectively attenuated sublesional bone loss. FES intervention for chronic SCI patients could significantly increase sublesional BMD near the site of maximal mechanical loading.

Male osteoporosis

Osteoporosis is now recognized as a major threat to health in aging men. Morbidity and mortality, particularly following hip fracture, are substantial. Although trabecular bone loss starts in early adulthood, loss of cortical bone only seems to occur from midlife onwards. Declining bioavailable estradiol levels plays an integral role in male age-associated bone loss. Both pharmacologic and supportive care interventions are important for optimal care in men at an increased fracture risk.

Zoledronic acid improves bone mineral density in pediatric spinal cord injury

Spinal cord injury (SCI) is associated with rapid and sustained bone loss and increase risk of fracture. Disuse is the primary cause for bone loss, although neural and hormonal changes may also contribute via different mechanisms. Bisphosphonates are used widely to treat osteoporosis in adults and are used increasingly for primary and secondary osteoporosis in children. Current data are insufficient to recommend routine use of bisphosphonates for fracture prevention in adult patients post-SCI and there are no available data in pediatric SCI. We report a 12-year-old boy with non-traumatic SCI who was treated with six monthly zoledronic acid (0.05 mg/kg/dose) for 18 months. The patient (AA) was diagnosed with transverse myelitis at 8.1 years of age, resulting in ventilator-dependent incomplete C3 tetraplegia. Following a fragility fracture to the surgical neck of the right humerus at 9.5 years of age, he was started on zoledronic acid. Bone turnover decreased and bone densitometry data (dual-energy X-ray absorptiometry [DXA] and peripheral quantitative computed tomography [pQCT]) showed improvement in metaphyseal and diaphyseal bone mineral content (BMC), volumetric bone mineral density (vBMD), and size, after 18 months of treatment. In the growing skeleton post-SCI, zoledronic acid potentially increases vertebral and long-bone strength by preserving trabecular bone (increased BMC and vBMD) and increasing cortical vBMD and cross-sectional area (CSA).

31st g. Heiner sell lectureship: secondary medical consequences of spinal cord injury

Persons with spinal cord injury (SCI) have secondary medical consequences of paralysis and/or the consequences of extreme inactivity. The metabolic changes that result from reduced activity include insulin resistance with carbohydrate disorders and dyslipidemia. A higher prevalence of coronary artery calcification was found in persons with SCI than that in matched able-bodied controls. A depression in anabolic hormones, circulating testosterone and growth hormone, has been described. Adverse soft tissue body composition changes of increased adiposity and reduced skeletal muscle are appreciated. Immobilization is the cause for sublesional disuse osteoporosis with an associated increased risk of fragility fracture. Bowel dysmotility affects all segments of the gastrointestinal tract, with an interest in better defining and addressing gastroesophageal reflux disease and difficulty with evacuation. Developing and testing more effective approaches to cleanse the bowel for elective colonoscopy are being evaluated. The extent of respiratory dysfunction depends on the level and completeness of SCI. Individuals with higher spinal lesions have both restrictive and obstructive airway disease. Pharmacological approaches and expiratory muscle training are being studied as interventions to improve pulmonary function and cough strength with the objective of reducing pulmonary complications. Persons with spinal lesions above the 6th thoracic level lack both cardiac and peripheral vascular mechanisms to maintain blood pressure, and they are frequently hypotensive, with even worse hypotension with upright posture. Persistent and/or orthostatic hypotension may predispose those with SCI to cognitive impairments. The safety and efficacy of anti-hypotensive agents to normalize blood pressure in persons with higher level cord lesions is being investigated.

Advances in the rehabilitation management of acute spinal cord injury

Aggressive assessment and management of the secondary complications in the hours and days following spinal cord injury (SCI) leads to restoration of function in patients through intervention by a team of rehabilitation professionals. The recent certification of SCI physicians, newly validated assessments of impairment and function measures, and international databases agreed upon by SCI experts should lead to documentation of improved rehabilitation care. This chapter highlights recent advances in assessment and treatment based on evidence-based classification of literature reviews and expert opinion in the acute phase of SCI. A number of these reviews are the product of the Consortium for Spinal Cord Medicine, which offers clinical practice guidelines for healthcare professionals. Recognition of and early intervention for problems such as bradycardia, orthostatic hypotension, deep vein thrombosis/pulmonary embolism, and early ventilatory failure will be addressed although other chapters may discuss some issues in greater detail. Early assessment and intervention for neurogenic bladder and bowel function has proven effective in the prevention of renal failure and uncontrolled incontinence. Attention to overuse and disuse with training and advanced technology such as functional electrical stimulation have reduced pain and disability associated with upper extremity deterioration and improved physical fitness. Topics such as chronic pain, spasticity, sexual dysfunction, and pressure sores will be covered in more detail in additional chapters. However, the comprehensive and integrated rehabilitation by specialized SCI teams of physicians, nurses, therapists, social workers, and psychologists immediately following SCI has become the standard of care throughout the world.

Bone remodeling and calcium homeostasis in patients with spinal cord injury: a review

Patients with spinal cord injury exhibit early and acute bone loss with the major functional consequence being a high incidence of pathological fractures. The bone status of these patients is generally investigated by dual-energy x-ray absorptiometry, but this technique does not reveal the pathophysiological mechanism underlying the bone loss. Bone cell activity can be indirectly evaluated by noninvasive techniques, including measurement of specific biochemical markers of bone formation (such as osteocalcin or bone-alkaline phosphatase) and resorption (such as procollagen type I N- or C-terminal propeptide). The bone loss in spinal cord injury is clearly due to an uncoupling of bone remodeling in favor of bone resorption, which starts just after the injury and peaks at about 1 to 4 months. Beyond 6 months, bone resorption activity decreases progressively but remains elevated for many years after injury. Conversely, bone formation is less affected. Antiresorptive treatment induces an early and acute reduction in bone resorption markers. Level of injury and health-related complications do not seem to be implicated in the intensity of bone resorption. During the acute phase, the hypercalcemic status is associated with the suppression of parathyroid hormone and vitamin D metabolites. The high sensitivity of these markers after treatment suggests that they can be used for monitoring treatment efficacy and patient compliance. The concomitant use of bone markers and dual-energy x-ray absorptiometry may improve the physician's ability to detect patients at risk of severe bone loss and subsequent fractures.

Treatments for osteoporosis in people with a disability

The morbidity from osteoporotic fractures for people with a disability is considerable because of the increased risk of medical complications, loss of independence and mobility, and prolonged hospitalization. The frequency with which low bone mineral density occurs in people with a disability is now well recognized, and professionals have a greater awareness of the need to investigate bone mineral density levels with a view to preventing fragility fractures. After patients with osteoporosis are identified, the challenge is to treat them appropriately. This article reviews the physical and pharmacologic measures that have been researched in the prevention and treatment of low bone mineral density in people with a disability.

Intensive electrical stimulation attenuates femoral bone loss in acute spinal cord injury

OBJECTIVE

To determine whether intensive electrical stimulation (ES) can reduce femoral bone mineral density (BMD) loss in acute spinal cord injury (SCI).

DESIGN

Randomized controlled trial.

SETTING

Inpatient rehabilitation hospital.

PARTICIPANTS

Twenty-six subjects with C4 to T12 American Spinal Injury Association Impairment Scale A or B SCI less than 12 weeks postinjury.

METHODS

The control group received usual rehabilitative care and the intervention group received usual care plus 1 hour of ES over the quadriceps 5 days per week for 6 weeks.

MAIN OUTCOME MEASUREMENTS

Outcome measurements were collected at baseline, postintervention (interim), and 3 months postinjury (follow-up), and included dual energy x-ray absorptiometry, serum osteocalcin (OC), and urinary N-telopeptide (NTx).

RESULTS

In the control group, there was increasing BMD loss with distance from the spine (lumbar -1.88%, hip -12.25%, distal femur -15.15%, proximal tibia -17.40%). This trend was attenuated over the distal femur in the ES group (lumbar -1.29%, hip -14.45%, distal femur -7.40%, proximal tibia -12.31%). NTx increased over the 3 assessments in controls ([mean ± standard deviation] 115.00 ± 34.10, 154.86 ± 70.41, and 171.33 ± 75.8 nmol/mmol creatinine) compared with the ES group (160.56 ± 140.06, 216.71 ± 128.40, and 154.67 ± 69.12 nmol/mmol creatinine)-all of which were elevated compared with the reference range, and the differences between the 2 groups were not significant. Osteocalcin levels markedly decreased in the control group (12.90 ± 7.30, 24.00 ± 4.29, and 6.40 ± 7.28 μg/L) to subnormal levels, and remained stable and in the normal range in the ES group (13.80 ± 7.64, 11.86 ± 6.77, and 14.80 ± 12.91 μg/L), although differences between the groups were not significant.

CONCLUSIONS

Lower extremity BMD loss increases with distance from the spine. An intensive lower extremity ES program may attenuate BMD loss locally after acute motor complete SCI, although it is unknown whether these benefits are maintained in the long term.

Transmission of low-intensity vibration through the axial skeleton of persons with spinal cord injury as a potential intervention for preservation of bone quantity and quality

BACKGROUND/OBJECTIVE

Persons with spinal cord injury (SCI) develop marked bone loss from paralysis and immobilization. Low-intensity vibration (LIV) has shown to be associated with improvement in bone mineral density in post-menopausal women and children with cerebral palsy. We investigated the transmissibility of LIV through the axial skeleton of persons with SCI as an initial approach to determine whether LIV may be used as a clinical modality to preserve skeletal integrity.

METHODS

Transmission of a plantar-based LIV signal (0.27 +/- 0.11 g; 34 Hz) from the feet through the axial skeleton was evaluated as a function of tilt-table angle (15, 30, and 45 degrees) in seven non-ambulatory subjects with SCI and ten able-bodied controls. Three SCI and five control subjects were also tested at 0.44 +/- 0.18 g and 34 Hz. Transmission was measured using accelerometers affixed to a bite-bar to determine the percentage of LIV signal transmitted through the body.

RESULTS

The SCI group transmitted 25, 34, and 43% of the LIV signal, and the control group transmitted 28, 45, and 57% to the cranium at tilt angles of 15, 30, and 45 degrees, respectively. No significant differences were noted between groups at any of the three angles of tilt.

CONCLUSION

SCI and control groups demonstrated equivalent transmission of LIV, with greater signal transmission observed at steeper angles of tilt. This work supports the possibility of the utility of LIV as a means to deliver mechanical signals in a form of therapeutic intervention to prevent/reverse skeletal fragility in the SCI population.

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.

Nandrolone slows hindlimb bone loss in a rat model of bone loss due to denervation

Nandrolone is an anabolic steroid that has been demonstrated to reduce the loss of bone and muscle from hindlimb unweighting and to slow muscle atrophy after nerve transection. To determine whether nandrolone has the ability to protect bone against loss due to disuse after denervation, male rats underwent sciatic nerve transaction, followed 28 days later by treatment with nandrolone or vehicle for 28 days. Bone mineral density (BMD) was determined 28 days later or 56 days after nerve transection. Denervation led to reductions in BMD of 7% and 12% for femur and tibia, respectively. Nandrolone preserved 80% and 60% of BMD in femur and tibia, respectively, demonstrating that nandrolone administration significantly reduced loss of BMD from denervation. This study offers a potential novel pharmacological strategy for use of nandrolone to reduce bone loss in severe disuse- and denervation-related bone loss, such as that which occurs after spinal cord injury.

Acute suppression of bone turnover with calcium infusion in persons with spinal cord injury

BACKGROUND

Some people with chronic spinal cord injury (SCI) have low vitamin D levels and secondary hyperparathyroidism.

OBJECTIVE

To determine whether, and to what extent, an acute calcium infusion decreased levels of N-telopeptide (NTx), a marker of osteoclastic activity, in individuals with chronic SCI.

STUDY DESIGN

Case series.

SUBJECTS

Eight men with chronic SCI. A relatively low serum 25 hydroxyvitamin D concentration (25[OH]D < or =20 ng/mL) and/or a high parathyroid hormone (PTH) (>55 pg/mL) was a prerequisite for study inclusion.

METHODS

Calcium gluconate bolus 0.025 mmol elemental calcium/kg over 20 minutes followed by a constant infusion of 0.025 mmol/kg per hour for 6 hours was infused; blood samples were collected every 2 hours for measurement of serum total calcium, creatinine, NTx, and PTH.

RESULTS

All results are expressed as means (+/- SDs). Baseline serum 25-hydroxyvitamin D level was 14.5 +/- 3.5 ng/mL (range: 10.2-19.6 ng/mL); PTH, 70 +/- 25 pg/mL (range: 37-100 pg/mL); and NTx, 21 +/- 7 nM bone collagen equivalents (BCE) (range: 14-34 nM). At 2, 4, and 6 hours after the calcium infusion, serum calcium rose from 9.3 +/- 0.2 to 10.8 +/- 0.9, 10.5 +/- 0.8, and 10.6 +/- 0.6 mg/d; PTH was suppressed from 70 +/- 25 pg/mL to 18 +/- 12, 16 +/- 9, and 15 +/- 9 pg/mL, respectively; NTx fell from 21 +/- 8 nM BCE to 17 +/- 5, 12 +/- 4, and 12 +/- 3 nM BCE, respectively.

CONCLUSIONS

Serum NTx is a marker for bone collagen catabolism, and its reduction suggests that bone turnover was decreased. A relative deficiency of vitamin D associated with chronically elevated levels of PTH would be expected to increase bone turnover and to worsen the bone loss associated with immobilization.

Bisphosphonate use in acute and chronic spinal cord injury: a systematic review

BACKGROUND/OBJECTIVE

Bone density loss occurs rapidly after traumatic spinal cord injury (SCI) and is associated with low-energy fractures below the level of injury, commonly occurring around the knee. Bisphosphonates have been tested as potential agents to prevent bone loss after SCI, but no guidelines exist for clinical use of bisphosphonates in these patients. The objective of this study was to systematically review and evaluate evidence quality in studies of bisphosphonate use in patients with post-treatment follow-up of sublesional bone mineral density.

METHODS

Literature search in MEDLINE/PubMed and ISI database using key words bisphosphonates, spinal cord injury, quadriplegia, paraplegia, and tetraplegia.

RESULTS

The search identified 6 experimental studies and 1 quasi-experimental study of bisphosphonate therapy in patients with acute and chronic SCI. The studies were small and of fair or poor quality, and none included fracture outcomes. Mild attenuation of bone density loss with acute administration of bisphosphonates after SCI was found at some measurement sites but was not always maintained during follow-up.

CONCLUSIONS

Data were insufficient to recommend routine use of bisphosphonates for fracture prevention in these patients. Current studies are limited by heterogeneity of patient populations and outcome measures. Uniform bone density measurement sites with rigorous quality control and compliance monitoring are needed to improve reliability of outcomes. Future studies should address specific populations (acute or chronic SCI) and should assess fracture outcomes.

Bone steady-state is established at reduced bone strength after spinal cord injury: a longitudinal study using peripheral quantitative computed tomography (pQCT)

Spinal cord injury (SCI) is associated with a marked and rapid sublesional bone loss. So far, reports about the time course of adaptive changes in bone mass and structure in people with chronic and complete SCI are conflicting. Both, a continuous decline of bone parameters throughout the chronic phase of immobilisation as well as stabilisation of bone status on a low level have been documented. In our recently published cross-sectional study we suggested that subjects with a complete SCI reach a new bone steady-state in the paralysed limbs after extensive bone loss was complete. In addition, we described a time loss curve for each measured bone mineral density and geometry parameter and calculated its individual time to reach steady-state (tsteady-state). The aim of the present study was to test the findings of our cross-sectional study in a longitudinal design. Thirty-nine male subjects of the original cross-sectional study with complete SCI and paralysis duration between 0.9 and 34 years were included. Two follow-up pQCT measurements at 15 and 30 months after baseline measurement were performed at the distal epiphyses and mid shafts of the femur, tibia and radius. From the epiphyseal scans, bone mass, trabecular and total BMD were calculated. From the shaft scans, bone mass and cortical BMD, total and cortical cross-sectional areas and cortical thickness were determined. Repeated measures ANOVAs were performed with bone data at baseline, after 15 months and 30 months. Analyses were performed including only subjects with a lesion duration > or =t(steady-state) for each particular bone parameter. Bone parameters of tibial and femoral epi- and diaphyses were found to show no statistically significant differences between the three time points. Relative changes in bone parameters were small and ranged from -1.72% to +0.51% in the femur and from -1.67% to +0.42% in the tibia within 30 months of monitoring. Our data confirm the temporal limitation of the bone loss after complete SCI with stabilisation of BMD and geometric properties on a lower level-a finding of clinical importance considering the treatment strategies of bone loss after SCI with respect to lesion duration.