Denosumab increases sublesional bone mass in osteoporotic individuals with recent spinal cord injury

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.

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.

The use of alkaline phosphatase as a bone turnover marker after spinal cord injury: A scoping review of human and animal studies

BACKGROUND

Serum alkaline phosphatase (ALP) is measured as an indicator of bone or liver disease. Bone-specific alkaline phosphatase (B-ALP) is an isoform of ALP found in the bone tissue which can predict fractures and heterotopic ossification.

OBJECTIVE

The aim of this scoping review was to explore the current use of ALP and B-ALP in studies using humans or animal models of SCI, and to identify ways to advance future research using ALP and B-ALP as a bone marker after SCI.

RESULTS

HUMAN STUDIES: 42 studies were included. The evidence regarding changes or differences in ALP levels in individuals with SCI compared to controls is conflicting. For example, a negative correlation between B-ALP and total femur BMD was observed in only one of three studies examining the association. B-ALP seemed to increase after administration of teriparatide, and to decrease after treatment with denosumab. The effects of exercise on ALP and B-ALP levels are heterogeneous and depend on the type of exercise performed. ANIMAL STUDIES: 11 studies were included. There is uncertainty regarding the response of ALP or B-ALP levels after SCI; levels increased after some interventions, including vibration protocols, curcumin supplementation, cycles in electromagnetic field or hyperbaric chamber. Calcitonin or bisphosphonate administration did not affect ALP levels.

CONCLUSION

Researchers are encouraged to measure the bone-specific isoform of ALP rather than total ALP in future studies in humans of animal models of SCI.

Pharmacologic and nonpharmacologic treatment modalities for bone loss in SCI - Proposal for combined approach

Increased risk of bone fracture due to bone mineral density (BMD) loss is a serious consequence of spinal cord injury (SCI). Traditionally, pharmaceutical approaches, such as bisphosphonates, have been prescribed to prevent bone loss. However, there is controversy in the literature regarding efficacy of these medications to mitigate the drastic bone loss following SCI. Individuals with SCI are particularly at risk of osteoporosis because of the lack of ambulation and weight bearing activities. In the past two decades, functional electric stimulation (FES) has allowed for another approach to treat bone loss. FES approaches are expanding into various modalities such as cycling and rowing exercises and show promising outcomes with minimal consequences. In addition, these non-pharmacological treatments can elevate overall physical and mental health. This article provides an overview of efficacy of different treatment options for BMD loss for SCI and advocates for a combined approach be pursued in standard of care.

Denosumab for Prevention of Acute Onset Immobilization-Induced Alterations of Bone Turnover: A Randomized Controlled Trial

Metabolic bone disease is a devastating condition in critically ill patients admitted to an intensive care unit (ICU). We investigated the effects of early administration of the antiresorptive drug denosumab on bone metabolism in previously healthy patients. Fourteen patients with severe intracerebral or subarachnoid hemorrhage were included in a phase 2 trial. Within 72 hours after ICU admission, they were randomized in a 1:1 ratio to receive denosumab 60 mg or placebo subcutaneously. The primary endpoint was group differences in the percentage change of C-terminal telopeptide of type 1 collagen (CTX-1) levels in serum from denosumab/placebo application to 4 weeks thereafter. Changes in serum levels of bone formation markers and urinary calcium excretion were secondary outcome parameters. Regarding serum levels of CTX-1, changes over time averaged -0.45 ng/mL (95% confidence interval [CI] -0.72, -0.18) for the denosumab group and 0.29 ng/mL (95% CI -0.01, 0.58) for the placebo group. The primary endpoint, the group difference in changes between baseline and secondary measurement, adjusted for baseline serum levels and baseline neurological status, averaged -0.74 ng/mL (95% CI -1.14, -0.34; p = 0.002). The group difference in changes between baseline and secondary osteocalcin measurement averaged -5.60 ng/mL (95% CI -11.2, -0.04; p = 0.049). The group difference in averaged change between baseline and secondary measurement of 24-hour urine calcium excretion was significant (-1.77 mmol/L [95% CI -3.48, -0.06; p = 0.044]). No adverse events could be attributed to the study medication. The investigation proved that a single application of denosumab early after admission to an ICU prevents acute immobilization-associated increase in bone resorption among previously healthy individuals. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

The Outcomes of Robotic Rehabilitation Assisted Devices Following Spinal Cord Injury and the Prevention of Secondary Associated Complications

Spinal cord injuries (SCIs) have major consequences on the patient’s health and life. Voluntary muscle paralysis caused by spinal cord damage affects the patient’s independence. Following SCI, an irreversible motor and sensory deficit occurs (spasticity, muscle paralysis, atrophy, pain, gait disorders, pain). This pathology has implications on the whole organism: on the osteoarticular, muscular, cardiovascular, respiratory, gastrointestinal, genito-urinary, skin, metabolic disorders, and neuro-psychic systems. The rehabilitation process for a subject having SCIs can be considered complex, since the pathophysiological mechanism and biochemical modifications occurring at the level of spinal cord are not yet fully elucidated. This review aims at evaluating the impact of robotic-assisted rehabilitation in subjects who have suffered SCI, both in terms of regaining mobility as a major dysfunction in patients with SCI, but also in terms of improving overall fitness and cardiovascular function, respiratory function, as well as the gastrointestinal system, bone density and finally the psychosocial issues, based on multiple clinical trials, and pilot studies. The researched literature in the topic revealed that in order to increase the chances of neuro-motor recovery and to obtain satisfactory results, the combination of robotic therapy, a complex recovery treatment and specific medication is one of the best decisions. Furthermore, the use of these exoskeletons facilitates better/greater autonomy for patients, as well as optimal social integration.

Vertebral insufficiency fractures as a cause of autonomic dysreflexia in a patient with chronic tetraplegia: A case report

Context: Osteoporosis is a known complication in spinal cord injury patients and can result in an increased risk of fractures and associated morbidity. Bone demineralization is most common in long bones below the level of injury. The pathogenesis is complex and not fully understood.Findings: We present the case of a 65-year-old male with chronic spinal cord injury who was found to have multiple vertebral compression fractures causing autonomic dysreflexia and new onset spasticity.Conclusion/Clinical Relevance: This case illustrates the need for improved awareness, diagnosis, and prevention for this disease process.

The Effects of Exercise and Activity-Based Physical Therapy on Bone after Spinal Cord Injury

Spinal cord injury (SCI) produces paralysis and a unique form of neurogenic disuse osteoporosis that dramatically increases fracture risk at the distal femur and proximal tibia. This bone loss is driven by heightened bone resorption and near-absent bone formation during the acute post-SCI recovery phase and by a more traditional high-turnover osteopenia that emerges more chronically, which is likely influenced by the continual neural impairment and musculoskeletal unloading. These observations have stimulated interest in specialized exercise or activity-based physical therapy (ABPT) modalities (e.g., neuromuscular or functional electrical stimulation cycling, rowing, or resistance training, as well as other standing, walking, or partial weight-bearing interventions) that reload the paralyzed limbs and promote muscle recovery and use-dependent neuroplasticity. However, only sparse and relatively inconsistent evidence supports the ability of these physical rehabilitation regimens to influence bone metabolism or to increase bone mineral density (BMD) at the most fracture-prone sites in persons with severe SCI. This review discusses the pathophysiology and cellular/molecular mechanisms that influence bone loss after SCI, describes studies evaluating bone turnover and BMD responses to ABPTs during acute versus chronic SCI, identifies factors that may impact the bone responses to ABPT, and provides recommendations to optimize ABPTs for bone recovery.

RNAseq and RNA molecular barcoding reveal differential gene expression in cortical bone following hindlimb unloading in female mice

Disuse-induced bone loss is seen following spinal cord injury, prolonged bed rest, and exposure to microgravity. We performed whole transcriptomic profiling of cortical bone using RNA sequencing (RNAseq) and RNA molecular barcoding (NanoString) on a hindlimb unloading (HLU) mouse model to identify genes whose mRNA transcript abundances change in response to disuse. Eleven-week old female C57BL/6 mice were exposed to ambulatory loading or HLU for 7 days (n = 8/group). Total RNA from marrow-flushed femoral cortical bone was analyzed on HiSeq and NanoString platforms. The expression of several previously reported genes associated with Wnt signaling and metabolism was altered by HLU. Furthermore, the increased abundance of transcripts, such as Pfkfb3 and Mss51, after HLU imply these genes also have roles in the cortical bone’s response to altered mechanical loading. Our study demonstrates that an unbiased approach to assess the whole transcriptomic profile of cortical bone can reveal previously unidentified mechanosensitive genes and may eventually lead to novel targets to prevent disuse-induced osteoporosis.

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.

Bone and non-contractile soft tissue changes following open kinetic chain resistance training and testosterone treatment in spinal cord injury: an exploratory study

Twenty men with spinal cord injury (SCI) were randomized into two 16-week intervention groups receiving testosterone treatment (TT) or TT combined with resistance training (TT + RT). TT + RT appears to hold the potential to reverse or slow down bone loss following SCI if provided over a longer period.

INTRODUCTION

Persons with SCI experience bone loss below the level of injury. The combined effects of resistance training and TT on bone quality following SCI remain unknown.

METHODS

Men with SCI were randomized into 16-week treatments receiving TT or TT + RT. Magnetic resonance imaging (MRI) of the right lower extremity before participation and post-intervention was used to visualize the proximal, middle, and distal femoral shaft, the quadriceps tendon, and the intermuscular fascia of the quadriceps. For the TT + RT group, MRI microarchitecture techniques were utilized to elucidate trabecular changes around the knee. Individual mixed models were used to estimate effect sizes.

RESULTS

Twenty participants completed the pilot trial. A small effect for yellow marrow in the distal femur was indicated as increases following TT and decreases following TT + RT were observed. Another small effect was observed as the TT + RT group displayed greater increases in intermuscular fascia length than the TT arm. Distal femur trabecular changes for the TT + RT group were generally small in effect (decreased trabecular thickness variability, spacing, and spacing variability; increased network area). Medium effects were generally observed in the proximal tibia (increased plate width, trabecular thickness, and network area; decreased trabecular spacing and spacing variability).

CONCLUSIONS

This pilot suggests longer TT + RT interventions may be a viable rehabilitation technique to combat bone loss following SCI.

CLINICAL TRIAL REGISTRATION

Registered with clinicaltrials.gov : NCT01652040 (07/27/2012).

Abaloparatide treatment increases bone formation, bone density and bone strength without increasing bone resorption in a rat model of hindlimb unloading

Disuse osteoporosis can result from prolonged bed rest, paralysis, casts, braces, fractures and other conditions. Abaloparatide (ABL) is a PTHrP analog that increases bone density and strength by stimulating osteogenesis with limited effects on bone resorption. We examined skeletal responses to abaloparatide in young adult male rats with normal weight-bearing and with hindlimb unloading via a pelvic harness. Rats were allocated to four groups (10-12 per group): normal weight-bearing plus vehicle treatment (CON-VEH), normal weight-bearing plus ABL treatment (CON-ABL), hindlimb-unloading plus vehicle (HLU-VEH), or hindlimb-unloading plus ABL (HLU-ABL). Rats received ABL (25 μg/kg/day, s.c.) or vehicle throughout the 28-day unloading period and were then sacrificed, at which time HLU-VEH rats exhibited reduced bone formation and significant deficits in tibial, femoral, and vertebral bone mass compared with CON-VEH. ABL treatment increased serum osteocalcin in CON and HLU animals while having no effect on the osteoclast marker TRACP-5b. Longitudinal peripheral quantitative computed tomography (pQCT) indicated that ABL increased trabecular and cortical bone mass in the tibia. ABL was also associated with improved trabecular and cortical bone mass and architectural parameters at the femur, tibia, and vertebrae by μCT. Tibial histomorphometry indicated increased trabecular and endocortical bone formation with HLU-ABL versus HLU-VEH and with CON-ABL versus CON-VEH, and ABL was also associated with lower trabecular and endocortical osteoclast surfaces. Vertebral finite element analysis indicated higher ultimate load and stiffness for CON-ABL versus CON-VEH and for HLU-ABL versus HLU-VEH. In summary, ABL was associated with improved trabecular and cortical bone density and architecture in normal weight-bearing and hindlimb-unloaded rats, with higher bone formation and no difference in bone resorption. ABL was also associated with improved bone biomechanical parameters. These results provide rationale for investigating the ability of abaloparatide to prevent or treat disuse osteoporosis in humans.

Dried plum mitigates spinal cord injury-induced bone loss in mice

Spinal cord injury (SCI) is accompanied by rapid loss of bone and increased risk of low impact fractures. Current pharmacological treatment approaches have proven to be relatively ineffective in preventing or treating bone loss after SCI. Dietary supplementation with dried plum (DP) has been shown to have dramatic effects on bone in various other disease models. In this study, we tested the efficacy of DP in preventing bone loss after SCI and restoring bone that has already been lost in response to SCI. Male C57BL/6J mice (3-month-old) underwent SCI and were fed a diet containing 25% DP by weight or a control diet for up to 4 weeks to assess whether DP can prevent bone loss. To determine whether DP could restore bone already lost due to SCI, mice were put on a control diet for 2 weeks (to allow bone loss) and then shifted to a DP supplemented diet for an additional 2 weeks. The skeletal responses to SCI and dietary supplementation with DP were assessed using microCT analysis, bone histomorphometry and strength testing. Dietary supplementation with DP completely prevented the loss of bone and bone strength induced by SCI in acutely injured mice. DP also could restore a fraction of the bone lost and attenuate the loss of bone strength after SCI. These results suggest that dietary supplementation with DP or factors derived from DP may prove to be an effective treatment for the loss of bone in patients with SCI.

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.

Spinal Cord Injury as a Model of Bone-Muscle Interactions: Therapeutic Implications From in vitro and in vivo Studies

Spinal cord injuries (SCIs) represent a variety of conditions related to the damage of the spinal cord with consequent musculoskeletal repercussions. The bone and muscle tissues share several catabolic pathways that lead to variable degrees of disability in SCI patients. In this review article, we provide a comprehensive characterization of the available treatment options targeting the skeleton and the bone in the setting of SCI. Among the pharmacological intervention, bisphosphonates, anti-sclerostin monoclonal antibodies, hydrogen sulfide, parathyroid hormone, and RANKL pathway inhibitors represent valuable options for treating bone alterations. Loss phenomena at the level of the muscle can be counteracted with testosterone, anabolic-androgenic steroids, and selective androgen receptor modulators. Exercise and physical therapy are valuable strategies to increase bone and muscle mass. Nutritional interventions could enhance SCI treatment, particularly in the setting of synergistic and multidisciplinary interventions, but there are no specific guidelines available to date. The development of multidisciplinary recommendations is required for a proper clinical management of SCI patients.

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.

Off-label uses of denosumab in metabolic bone diseases

Denosumab (Dmab), a monoclonal antibody against the receptor activator of nuclear factor-κB (RANK) ligand (RANKL) which substantially suppresses osteoclast activity, has been approved for the treatment of common metabolic bone diseases, including postmenopausal osteoporosis, male osteoporosis, and glucocorticoid-induced osteoporosis, in which the pathway of the RANK/RANKL/osteoprotegerin is dysregulated. However, the imbalance of RANKL/RANK/osteoprotegerin is also implicated in the pathogenesis of several other rare metabolic bone diseases, including Juvenile Paget disease, fibrous dysplasia, Hajdu Cheney syndrome and Langerhans cell histiocytosis, thus rendering Dmab a potential treatment option for these diseases. Dmab has been also administered off-label in selected patients (e.g., with Paget's disease, osteogenesis imperfecta, aneurysmal bone cysts) due to contraindications or unresponsiveness to standard treatment, such as bisphosphonates. Moreover, Dmab was administered to improve hypercalcemia induced by various diseases, including primary hyperparathyroidism, tuberculosis and immobilization. The aim of this review is to summarize existing evidence on off-label uses of Dmab in metabolic bone diseases and provide opinion for or against its use, which should be always considered on an individual basis.

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.

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.

Prophylactic treatment of osteoporosis after SCI: promising research, but not yet indicated

In persons with spinal cord injury (SCI), osteoporosis and associated fragility fractures are a prevalent phenomenon with clinically meaningful morbidity and mortality. Prevention of osteoporosis utilizing both physical modalities and pharmacological therapies is an area of high-clinical importance. In our perspective, the current body of research cannot provide clear guidance on prophylactic interventions to prevent osteoporosis specifically to stratify SCI subjects to their risk for fragility fractures. Without this critical research, clinicians cannot weigh the risk versus benefits of interventions, such as bisphosphonates, which is not a benign treatment. Other treatments such as physical modalities provide little risk and have other therapeutic benefit. This perspective is an argument that the current research does not indicate prophylactic pharmacological intervention to prevent osteoporosis in the SCI population.

Combination Therapy With Zoledronic Acid and FES-Row Training Mitigates Bone Loss in Paralyzed Legs: Results of a Randomized Comparative Clinical Trial

Spinal cord injury (SCI) results in rapid, severe osteoporosis and an increased risk of lower extremity fractures. Despite the medical complications associated with these fractures, there is no standard of care to prevent osteoporotic fractures following SCI. Functional electrical stimulation- (FES-) assisted rowing is a promising intervention to improve bone health in SCI because of its ability to generate a muscular contraction in conjunction with mechanical loading of the lower extremity long bones. Combination therapy consisting of FES-rowing plus zoledronic acid (ZA) may be a superior treatment via inhibition of bone resorption and stimulation of new bone formation. We studied participants enrolled in a randomized clinical trial comparing FES-rowing alone with FES-rowing plus ZA to improve bone health in SCI. Volumetric CT scans at the distal femur and proximal tibial metaphyses were performed. Bone geometric properties (cortical thickness index [CTI], cortical compressive strength index [CSI], buckling ratio [BR], bending strength index) and mineral (cortical bone volume [CBV], cortical bone mineral density, cortical bone mineral content) indices were determined. In models adjusting for baseline values, we found that the CBV (p = 0.05 to 0.006), the CTI (p = 0.009), and the BR (p = 0.001) at both the distal femoral and proximal tibial metaphyses were greater in the ZA plus rowing group compared with the rowing-only group. Similarly, there was a significant positive association between the total rowing work completed and the BR at the proximal tibia (p = 0.05). A subgroup analysis of the rowing-only arm showed that gains in the CSI at the tibial metaphysis varied in a dose-dependent fashion based on the total amount of exercise performed (p = 0.009). These findings demonstrate that the osteogenic response to FES-rowing is dose-dependent. Combination therapy with ZA and FES-row training has therapeutic potential to improve bone quality, and perhaps reduce fracture risk at the most common fracture site following SCI. © 2019 The Authors. JBMR Plus Published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

Effects of Curcumin on Bone Loss and Biochemical Markers of Bone Turnover in Patients with Spinal Cord Injury

BACKGROUND

Osteoporosis is one of the most common problems of patients with spinal cord injuries (SCIs). The current study aimed to evaluate the antiosteoporotic effects of curcumin on densitometry parameters and biomarkers of bone turnovers among patients with SCI.

MATERIALS AND METHODS

The current controlled clinical trial was conducted among 100 patients with SCI referred to an outpatient clinic of rehabilitation in Ilam City, Iran, in 2013-2015. The intervention group received 110/mg/kg/day curcumin for 6 months and the control group received placebo. Bone mineral density (BMD) was measured in all patients. The level of procollagen type I N-terminal propeptide, serum carboxy-terminal telopeptide of type I collagen, osteocalcin, and bone-specific alkaline phosphates were compared before and after study.

RESULTS

BMD indicators of lumbar, femoral neck, and total hip in the control group significantly decreased compared with the beginning of study. However, in the curcumin group, a significant increase was observed in BMD indicators of lumbar, femoral neck, and hip at the end of study compared with the beginning. There was also a significant difference between interventional and control groups for the mean BMD of femoral neck and hip at the end of study (0.718 ± 0.002 g/cm² vs. 0.712 ± 0.003 g/cm² and 0.742 ± 0.031 g/cm² vs. 0.692 ± 0.016 g/cm², respectively).

CONCLUSIONS

Curcumin, via modulation of densitometry indices and bone resorption markers, showed inhibitory effects on the process of osteoporosis. Treatment with curcumin was significantly associated with a decrease in the osteoporosis progression and bone turnover markers of patients with SCI after 6 months.

Analysis of the evolution of cortical and trabecular bone compartments in the proximal femur after spinal cord injury by 3D-DXA

Marked trabecular and cortical bone loss was observed at the proximal femur short-term after spinal cord injury (SCI). 3D-DXA provided measurement of vBMD evolution at both femoral compartments and cortical thinning, thereby suggesting that this technique could be useful for bone analysis in these patients.

INTRODUCTION

SCI is associated with a marked increase in bone loss and risk of osteoporosis development short-term after injury. 3D-DXA is a new imaging analysis technique providing 3D analysis of the cortical and trabecular bone from DXA scans. The aim of this study was to assess the evolution of trabecular macrostructure and cortical bone using 3D-DXA in patients with recent SCI followed over 12 months.

METHODS

Sixteen males with recent SCI (< 3 months since injury) and without antiosteoporotic treatment were included. Clinical assessment, bone mineral density (BMD) measurements by DXA, and 3D-DXA evaluation at proximal femur (analyzing the integral, trabecular and cortical volumetric BMD [vBMD] and cortical thickness) were performed at baseline and at 6 and 12 months of follow-up.

RESULTS

vBMD significantly decreased at integral, trabecular, and cortical compartments at 6 months (- 8.8, - 11.6, and - 2.4%), with a further decrease at 12 months, resulting in an overall decrease of - 16.6, - 21.9, and - 5.0%, respectively. Cortical thickness also decreased at 6 and 12 months (- 8.0 and - 11.4%), with the maximal decrease being observed during the first 6 months. The mean BMD losses by DXA at femoral neck and total femur were - 17.7 and - 21.1%, at 12 months, respectively.

CONCLUSIONS

Marked trabecular and cortical bone loss was observed at the proximal femur short-term after SCI. 3D-DXA measured vBMD evolution at both femoral compartments and cortical thinning, providing better knowledge of their differential contributory role to bone strength and probably of the effect of therapy in these patients.

Use of bone turnover markers in postmenopausal osteoporosis

Bone turnover comprises two processes: the removal of old bone (resorption) and the laying down of new bone (formation). N-terminal propeptide of type I procollagen (PINP) and C-telopeptide of type I collagen (CTX-I) are markers of bone formation and resorption, respectively, that are recommended for clinical use. Bone turnover markers can be measured on several occasions in one individual with good precision. However, these markers are subject to several sources of variability, including feeding (resorption decreases) and recent fracture (all markers increase for several months). Bone turnover markers are not used for diagnosis of osteoporosis and do not improve prediction of bone loss or fracture within an individual. In untreated women, very high bone turnover marker concentrations suggest secondary causes of high bone turnover (eg, bone metastases or multiple myeloma). In people with osteoporosis, bone turnover markers might be useful to assess the response to anabolic and antiresorptive therapies, to assess compliance to therapy, or to indicate possible secondary osteoporosis. Much remains to be learnt about how bone turnover markers can be used to monitor the effect of stopping bisphosphonate therapy (eg, to identify a threshold above which restarting therapy should be considered). More studies are needed to investigate the use of bone turnover markers for assessment of the bone safety of new medications.

Effect of recent spinal cord injury on the OPG/RANKL system and its relationship with bone loss and the response to denosumab therapy

There is marked bone loss after spinal cord injury (SCI); however, its pathogenesis and clinical management remain unclear. The increased circulating levels of receptor activator of nuclear factor kB ligand (RANKL) associated with bone loss shortly after SCI and the prevention of bone loss with denosumab treatment suggest a contributory role of RANKL in SCI-induced osteoporosis.

INTRODUCTION

Bone turnover and bone loss are markedly increased shortly after SCI. However, the pathogenesis and clinical management of this process remain unclear, especially the role of the osteoprotegerin (OPG)/RANKL system in this disorder. The aim of this study was to analyze serum levels of OPG and RANKL in bone loss associated with recent SCI and the effect of denosumab treatment on these mediators.

METHODS

Twenty-three males with recent complete SCI were prospectively included. Serum OPG and RANKL levels, bone turnover markers (PINP, bone ALP, CTX), and bone mineral density (BMD) were assessed at baseline, at 6 months of follow-up, prior to initiating denosumab, and 6 months after treatment. The results were compared with a healthy control group.

RESULTS

At baseline, SCI patients showed higher RANKL levels vs. controls which were correlated with days-since-SCI and total hip BMD loss at 6 months. OPG levels were similar to controls at baseline. After denosumab treatment, OPG showed no changes, whereas RANKL levels became undetectable in 67% of patients. Patients with undetectable RANKL during treatment showed better response in femoral BMD and bone markers vs. patients with detectable RANKL at 6 months of denosumab. Increased parathormone (PTH) levels during treatment were negatively correlated with RANKL changes.

CONCLUSIONS

RANKL levels are increased after SCI and related to BMD loss at the proximal femur, becoming undetectable after denosumab treatment. The effect of denosumab on preventing sublesional bone loss, especially in patients with undetectable levels during treatment, suggests a contributory role of RANKL in this process.

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.