Densitometric patterns of spinal cord injury associated bone loss

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

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

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.

Effects of Neurological Disorders on Bone Health

Neurological diseases, particularly in the context of aging, have serious impacts on quality of life and can negatively affect bone health. The brain-bone axis is critically important for skeletal metabolism, sensory innervation, and endocrine cross-talk between these organs. This review discusses current evidence for the cellular and molecular mechanisms by which various neurological disease categories, including autoimmune, developmental, dementia-related, movement, neuromuscular, stroke, trauma, and psychological, impart changes in bone homeostasis and mass, as well as fracture risk. Likewise, how bone may affect neurological function is discussed. Gaining a better understanding of brain-bone interactions, particularly in patients with underlying neurological disorders, may lead to development of novel therapies and discovery of shared risk factors, as well as highlight the need for broad, whole-health clinical approaches toward treatment.

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.

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

BACKGROUND CONTEXT

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

PURPOSE

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

STUDY DESIGN

Review article.

METHODS

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

RESULTS

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

CONCLUSIONS

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

Treadmill training induced lumbar motoneuron dendritic plasticity and behavior recovery in adult rats after a thoracic contusive spinal cord injury

Spinal cord injury (SCI) is devastating, causing sensorimotor impairments and paralysis. Persisting functional limitations on physical activity negatively affect overall health in individuals with SCI. Physical training may improve motor function by affecting cellular and molecular responses of motor pathways in the central nervous system (CNS) after SCI. Although motoneurons form the final common path for motor output from the CNS, little is known concerning the effect of exercise training on spared motoneurons below the level of injury. Here we examined the effect of treadmill training on morphological, trophic, and synaptic changes in the lumbar motoneuron pool and on behavior recovery after a moderate contusive SCI inflicted at the 9th thoracic vertebral level (T9) using an Infinite Horizon (IH, 200 kDyne) impactor. We found that treadmill training significantly improved locomotor function, assessed by Basso-Beattie-Bresnahan (BBB) locomotor rating scale, and reduced foot drops, assessed by grid walking performance, as compared with non-training. Additionally, treadmill training significantly increased the total neurite length per lumbar motoneuron innervating the soleus and tibialis anterior muscles of the hindlimbs as compared to non-training. Moreover, treadmill training significantly increased the expression of a neurotrophin brain-derived neurotrophic factor (BDNF) in the lumbar motoneurons as compared to non-training. Finally, treadmill training significantly increased synaptic density, identified by synaptophysin immunoreactivity, in the lumbar motoneuron pool as compared to non-training. However, the density of serotonergic terminals in the same regions did not show a significant difference between treadmill training and non-training. Thus, our study provides a biological basis for exercise training as an effective medical practice to improve recovery after SCI. Such an effect may be mediated by synaptic plasticity, and neurotrophic modification in the spared lumbar motoneuron pool caudal to a thoracic contusive SCI.

Bone Mineral Density and Biochemical Markers of Bone Turnover during the First Year of Injury in Patients with Spinal Cord Injury

Background

Spinal cord injury (SCI) is associated with bone mass loss that can be complicated by fractures, which result in further disabilities for patients. After a SCI, the body starts losing large amounts of calcium and other minerals in the urine (demineralisation). This study aimed to assess the changes in bone mineral density (BMD) during the 1st year of acute SCI in patients with neurological deficit.

Methods

A total of 95 patients with acute SCI and neurological deficit were evaluated in this prospective study. Haematological investigations such as evaluation of serum calcium, serum phosphate, serum creatinine, and serum alkaline phosphatase (ALP) were carried out. Urinary investigations such as 24-hour urinary creatinine level and excretion of calcium and phosphate in the urine were measured. BMD was measured using dual-energy X-ray absorptiometry scan with Hologic QDR 2000 scanner (Explorer). All of the aforementioned parameters were measured again at 3, 6, and 12 months.

Results

Serum ALP at 1-year follow up was significantly raised (p < 0.05). The BMD at 1-year follow up had statistically significant lower values than the initial BMD at the hip (p < 0.05), proximal tibia (p < 0.00l), and distal tibial epiphysis (p < 0.001). The BMD in motor-complete SCI patients [American Spinal Injury Association (ASIA) grades A and B] had significant lower values than motor-incomplete SCI patients (ASIA C and D) at the hip (p < 0.05) and proximal tibial epiphysis (p < 0.05).

Conclusion

There was a marked decrease in BMD in metaphyseal sites than below the neurological deficit level with maximum decrease at the proximal tibia during the 1st year of SCI. Although the markers of osteoblastic activity did not show much change, the decrease in BMD was influenced by the neurological recovery after SCI.

Predicting patient-specific rates of bone loss at fracture-prone sites after spinal cord injury

PURPOSE

People with spinal cord injury (SCI) experience bone loss and have an elevated rate of fracture in the paralysed limbs. The literature suggests an exponential time course of bone loss after SCI, but true rates may vary between patients. We propose systematic evaluation of bone status in the early stages of SCI to identify fast bone losers.

METHOD

A case series of six patients with complete SCI were scanned using peripheral quantitative computed tomography within 5 weeks and at 4, 8 and 12 months post-injury. Bone mineral density (BMD) and bone mineral content (BMC) were measured at fracture-prone sites in the tibia and femur. Patient-specific-predictions (PSP) of expected rates of bone loss were produced by individualising published model equations according to each patient's measured values at baseline. Wilcoxon Signed-Rank tests were used to identify changes between time-points; chi-squared tests for differences between measured and PSP values.

RESULTS

In the lower limbs, mean values decreased significantly between baseline and 8 months post-injury, by 19-31% for trabecular BMD, 21-32% for total BMD, and 9-29% for BMC. Most subjects showed no significant differences between PSP and measured values, but individuals with significantly faster rates of bone loss than predicted should be investigated further.

CONCLUSIONS

There was considerable intersubject variability in rates of bone loss after SCI. Patients showing the fastest bone loss could benefit from continued follow-up and possibly treatment.

Evaluation of bone mineral density in children with perinatal brachial plexus palsy: effectiveness of weight bearing and traditional exercises

PURPOSE

(1) To investigate any evidence of bone mineral density (BMD) changes in children with Perinatal Brachial Plexus Palsy (PBPP). (2) To detect any relationship between these changes and the child age, weight, height, BMI, power index, gender, ethnicity, and the side affected. (3) To determine any possible effects of a designed weight bearing exercise program and the traditional one upon BMD of those children.

STUDY DESIGN

Randomized single blind controlled trial.

METHOD

A convenience sampling strategy was used to obtain 45 children with unilateral PBPP. Their ages ranged from 3 to 10 years. They were randomly divided to three equal groups. Groups were, then, randomly assigned to either interventions [Weight Bearing Exercises Program (WBEP) or Traditional Exercises Program (TEP)] or to the control treatment. Dual Energy X-Ray Absorptiometry (DXA) was used to evaluate BMD for all children at entry and approximately after six months treatment period.

RESULTS

We detected significant low entry level measurements of all BMD parameters of the affected side when compared to that of the unaffected sides (p=0.000). The mean value of the entry level calculated Z score for the affected side of all study children was equal to -1.12 ± 0.327 being in the osteopenic risk range. Furthermore, thirty children (66.7%) recorded less than (-1) Z score being in this risky range. Also, we recorded a significant improvement of all BMD parameters of the affected side after treatment in favor of the WBEP group when compared to that of the control and TEP groups (p=0.02, p=0.03 respectively for the affected both bones BMD parameter).

CONCLUSIONS

BMD is significantly reduced in PBPP children. The retardation of bone accrual increases as the child height and weight decreases and the degree of paralysis increases. WBEP significantly promoted BMD improvement when compared to the TEP.

Bone mineral density in adults disabled through acquired neurological conditions: a review

This article is a review of the changes in bone mineral density (BMD), which occur in a number of acquired neurological conditions resulting in disability. For each of spinal cord injury, stroke, multiple sclerosis, Parkinson's disease, and traumatic brain injury, the following aspects are discussed, where information is available: prevalence of low BMD according to World Health Organization diagnostic categories and recommended diagnostic method, prevalence based on other diagnostic tools, comparison of BMD with a control population, rate of decline of BMD following onset of the neurological condition, factors influencing decline; mechanism of bone loss, and fracture rates. The common risk factors of immobilization and vitamin D deficiency would appear to cross all disability groups, with the most rapid phase of bone loss occurring in the acute and subacute phases of each condition.

An evidence-based review of aging of the body systems following spinal cord injury

STUDY DESIGN

Systematic review.

OBJECTIVE

To systematically review evidence on aging of the body systems after spinal cord injury (SCI).

SETTING

Toronto, Ontario and Vancouver, British Columbia, Canada.

METHODS

Electronic databases (MEDLINE/PubMed, CINAHL, EMBASE and PsycINFO), were searched for studies published between 1980 and 2009. The search was augmented by reviewing the reference lists of relevant papers. Non-intervention studies that were longitudinal or cross-sectional with able-bodied controls that were at minimum matched on chronological age were included for review. Levels of evidence were assigned to the study design using a modified Sackett scale.

RESULTS

Of the 74 studies selected for inclusion, 16 were longitudinal in design. The hypothesis that SCI represents a model for premature aging is supported by a large proportion of level 5 evidence for the cardiovascular and endocrine systems, level 2, 4 and 5 evidence for the musculoskeletal system, and limited level 5 evidence for the immune system. Only a few level 4 and 5 studies for the respiratory system were found. The evidence on the genitourinary system, gastrointestinal system, and for skin and subcutaneous tissues provide level 4 and 5 evidence that premature aging may not be occurring. The evidence on the nervous system does not provide evidence of premature aging as a result of SCI.

CONCLUSIONS

Premature aging appears to occur in some systems after SCI. Additional longitudinal studies are required to confirm these findings.

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.

Five-year longitudinal bone evaluations in individuals with chronic complete spinal cord injury

BACKGROUND/OBJECTIVES

Knowledge of spinal cord injury (SCI) bone changes has been derived primarily through cross-sectional studies, many of which are controvertible. Longitudinal studies are sparse, and long-term longitudinal chronic studies are unavailable. The objective of this study was to provide a clearer perception of chronic longitudinal bone variations in people with complete SCI.

METHODS

Bone status of 31 individuals with chronic, complete SCI was assessed twice using dual-energy xray absorptiometry at an average interval of 5.06 +/- 0.9 years. Because the sample of women was small (4), the primary analyses of change and comparisons of those with paraplegia vs tetraplegia were confined to the male participants.

RESULTS

Spine Z-scores showed a significant increase (P < 0.0001). The average Z-scores, initial and followup, were within the normal range. Hip Z-scores also showed a significant increase (P < 0.0001), and hip bone mineral density (BMD) increased in 48% of the participants. Knee BMD and lower extremity total bone mineral showed significant decreases (P < 0.003 and P < 0.02, respectively), but increases were seen in 33% and 26% at the respective sites. Individuals with tetraplegia had significantly lower values across all regions (P < 0.0001), and changes were significantly different compared with paraplegia (P < 0.0001). Bone values and changes in men vs women, despite the small sample of women, showed highly significant differences (P < 0.003-0.002).

CONCLUSION

Chronic effects of complete SCI do not exclusively result in continued loss of BMD or a static state of lowered BMD; gain in BMD may occur. The nature and magnitude of the effects of complete SCI on BMD vary by site, with sex and level of injury, which has implications for treatment and its assessment.

Alendronate prevents bone loss in patients with acute spinal cord injury: a randomized, double-blind, placebo-controlled study

CONTEXT

Patients who sustain an acute spinal cord injury (SCI) experience rapid dramatic reductions in bone mineral density (BMD), especially marked in sublesional areas and sometimes leading to hypercalcemia and hypercalciuria, as well as increased fracture risk.

OBJECTIVE

In this prospective, double-blind, randomized, placebo-controlled study, we evaluated the hypothesis that oral alendronate administration would preserve BMD when administered soon after acute SCI.

PATIENTS AND INTERVENTION

Thirty-one patients with acute SCI were randomly allocated to receive oral alendronate 70 mg/wk or placebo, within 10 d of acute SCI, for 12 months.

MAIN OUTCOME MEASUREMENTS

At entry and at 3, 6, 12, and 18 months, total body bone density, lumbar and hip BMD, ultrasound of the calcaneus, 24-h urinary calcium, and serum C-telopeptide (betaCTX) were measured.

RESULTS

At study entry, patients in the two groups were well matched for age, gender, severity of neurological deficit, BMD, urinary calcium, and betaCTX. BMD indices declined steadily in the placebo group, and this effect was attenuated significantly by alendronate. After 12 months, there was a 5.3% difference (P<0.001) in total body BMD and a 17.6% difference (P<0.001) in the total hip BMD between the two groups. Alendronate compared with placebo induced significant (P<0.001) reductions in urinary calcium excretion and serum betaCTX. No treatment-related side effects were noted.

CONCLUSIONS

We conclude that alendronate therapy, 70 mg/wk, initiated soon after acute SCI, prevents bone loss and is not associated with side effects.

Effects of spinal cord injury on osteoblastogenesis, osteoclastogenesis and gene expression profiling in osteoblasts in young rats

INTRODUCTION

Spinal cord injury (SCI) causes a significant amount of bone loss in the sublesional area in animals and humans, and this type of bone loss is different from other forms of osteoporosis such as disuse osteoporosis and postmenopausal osteoporosis. However, no data is available on the cellular and molecular changes of osteoblastogenesis and osteoclastogenesis during SCI-induced bone loss.

METHODS

SCI and SHAM rats were used in this study to investigate osteoblastogenesis and osteoclastogenesis in bone-marrow culture. We also measured bone mass and bone histomorphometry, as well as the expression of alkaline phosphatase (ALP), core binding factor alpha1 (Cbfa-1), osterix, receptor activator of NF-kappaB ligand (RANKL) and osteoprotegerin (OPG) in osteoblast-like cells in bone-marrow culture obtained from SCI and SHAM rats.

RESULTS

Bone mineral density (BMD) measurement showed serious bone loss in the tibial ephiphyses and metaphyses of SCI rats compared with SHAM rats. In addition, bone histomorphometry analysis of the tibial metaphyses of SCI rats demonstrated that bone microarchitecture in SCI rats deteriorated further than in SHAM rats, and increased eroded surfaces and bone formation rates were observed in SCI rats. The number of osteoclasts that developed from bone marrow of SCI rats at equal density was significantly increased compared with SHAM rats, and the area of the resorption pits formed in the bone marrow culture from SCI rats was significantly greater than SHAM rats, whereas the number of CFU-F and CFU-OB was similar in both groups. RANKL mRNA and protein levels in osteoblast-like cells in culture obtained from SCI rats were significantly higher than those from the SHAM rats, whereas OPG levels decreased slightly. The ratios of RANKL to OPG expression in SCI rats were significantly higher than those in SHAM rats. However, osteogenic gene profiling of Cbfa-1, ALP and osterix in SCI rats remained similar with SHAM rats.

CONCLUSION

These changes favor increased osteoclast activity over osteoblast activity, and may explain, in part, the imbalance in bone formation and resorption following SCI.

Bone mineral density of the hip and knee in children with spinal cord injury

BACKGROUND/OBJECTIVE

To report on the bone mineral density (BMD) of the hip, distal femur, and proximal tibia in children with spinal cord injury (SCI) of at least 1-year duration and before skeletal maturity.

METHODS

BMD values were measured in 28 children (age, 9.6 +/- 2.5 years; range, 5-13 years) using dual-energy x-ray absorptiometry (DEXA) and were analyzed based on sex, injury, and time since injury. The hip values were compared with reported age- and sex-matched values in children without disability. No comparison was made at the knee because normative data were not available.

RESULTS

Average BMD values were 0.48 +/- 0.17 g/cm2 for the total hip, 0.48 +/- 0.17 g/cm2 at the femoral neck, 0.41 +/- 0.17 g/cm2 at the greater trochanter, 0.47 +/- 0.17 g/cm2 at Ward's triangle, 0.38 +/- 0.10 g/ cm2 at the distal femur, and 0.37 +/- 0.07 g/cm2 at the proximal tibia. Trends were observed with respect to sex, level of injury, and time since injury. Z-scores for the femoral neck, greater trochanter, and Ward's triangle were -1.65 +/- 1.02, -1.83 +/- 1.30, and -1.78 +/- 0.78, respectively, representing a 40% lower BMD in comparison with children without disability.

CONCLUSIONS

Children with a SCI seem to have a substantially lower BMD at the hip and knee in comparison with children without disability, placing them at the same risk for lower extremity fractures as adults with SCI, with potentially higher risks as they age given the lack of activity in a period of their life where exercise is essential for optimal bone health.

Bone loss in spinal cord-injured patients: from physiopathology to therapy

STUDY DESIGN

Review article on bone metabolism and therapeutic approach on bone loss in patients with spinal cord injury (SCI).

OBJECTIVE

The first part aims to describe the process of bone demineralization and its effects on bone mass in patients with SCI. The second part describes and discusses the therapeutic approaches to limiting the alteration in bone metabolism related to neurological lesions.

SETTING

Propara Rehabilitation Center, Montpellier, France.

RESULTS

During the first 24 months postinjury, demineralization occurs exclusively in the sublesional areas and predominantly in weight-bearing skeletal sites such as the distal femur and proximal tibia, both of which are trabecular-rich sites. Reduced bone mass, in association with a modified bone matrix property and composition, is very likely at the origin of pathological fractures after minor trauma to which these patients are frequently exposed. Since these fractures may be asymptomatic yet may lead to complications, preventing and managing 'neurological osteoporosis' remains a considerable challenge. Two main approaches are considered: the first consists in applying a mechanical stimulus to the bone tissue by standing, orthotically aided walking or functional electrical stimulation (FES). The second uses medications, particularly antiresorptive drugs such as calcitonin or diphosphonates.

CONCLUSION

To develop well-adapted treatments, a more precise understanding of bone loss etiology is needed. The current rehabilitation programs are based on the idea that the bone physiological changes observed in patients with SCI are due to immobility, but results indicate that alterations inherent to neurological damage may play an even greater role in inducing osteoporosis.

Electrically induced muscle contractions influence bone density decline after spinal cord injury

STUDY DESIGN

Longitudinal repeated-measures; within-subject control.

OBJECTIVE

We examined the extent to which an isometric plantar flexion training protocol attenuates bone loss longitudinally after SCI.

SUMMARY OF BACKGROUND DATA

After spinal cord injury (SCI), bone mineral density (BMD) of paralyzed extremities rapidly declines, likely because of loss of mechanical loading of bone via muscle contractions.

METHODS

Six individuals with complete paralysis began a 3-year unilateral plantar flexor muscle activation program within 4.5 months after SCI. The opposite limb served as a control. Compliance with recommended dose was > 80%. Tibia compressive force was > 140% of body weight.

RESULTS

Bilateral hip and untrained tibia BMD declined significantly over the course of the training. Lumbar spine BMD showed minimal change. Percent decline in BMD (from the baseline condition) for the trained tibia (approximately 10%) was significantly less than the untrained tibia (approximately 25%) (P < 0.05). Trained limb percent decline in BMD remained steady over the first 1.5 years of the study (P < 0.05).

CONCLUSIONS

Compressive loads of approximately 1 to 2 times body weight, induced by muscle contractions, partially prevent the loss of BMD after SCI. Future studies should establish dose-response curves for attenuation of bone loss after SCI.

Body weight supported treadmill training in acute spinal cord injury: impact on muscle and bone

DESIGN

Longitudinal prospective case series.

OBJECTIVE

To evaluate the impact of early introduction post-spinal cord injury (SCI) of twice-weekly body-weight supported treadmill training (BWSTT) on muscle and bone.

SETTING

Centre for Health Promotion and Rehabilitation, McMaster University, Canada.

METHODS

Five individuals who had sustained traumatic SCI within 2-6 months participated in the study. Bone mineral densities (BMD) of proximal femur, distal femur, proximal tibia and lumbar spine were measured before and after training, as well as muscle cross-sectional area (CSA), BMD and bone geometry at mid-femur and proximal tibia. Serum osteocalcin and urinary deoxypyridinoline were measured at baseline, and after 24 and 48 sessions of training.

RESULTS

All participants experienced increased muscle CSAs, ranging from 3.8 to 56.9%. Reductions in BMD were evident in all participants at almost all lower limb sites after training, ranging in magnitude from -1.2 to -26.7%. Lumbar spine BMD changes ranged from 0.2 to -7.4%. No consistent changes were observed in bone geometry. BWSTT did not alter the expected pattern of change in bone biochemical markers over time. The individual with the greatest improvement in ambulatory ability demonstrated the smallest reduction in lower limb BMD. Conversely, the individual who completed the fewest BWSTT sessions demonstrated the greatest reductions in BMD.

CONCLUSIONS

Twice-weekly BWSTT appeared to partially reverse muscle atrophy after SCI, but did not prevent bone loss. Larger, controlled trials should evaluate whether relative preservation of bone loss occurs with regular BWSTT following acute SCI.

SPONSORSHIP

Ontario Neurotrauma Foundation.

Osteoporosis after spinal cord injury

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

Implantable FES system for upright mobility and bladder and bowel function for individuals with spinal cord injury

STUDY DESIGN

Postintervention.

OBJECTIVES

To determine the effectiveness of the Praxis multifunctional implantable functional electrical stimulation (FES) system (Neopraxis Pty. Ltd, Lane Cove, NSW, Australia) to provide standing and stepping ability and bladder and bowel management for individuals with motor complete thoracic level spinal cord injuries (SCI).

SETTING

Pediatric orthopedic hospital specializing in SCI.

SUBJECTS

Three males, ages 17 and 21 years, with motor-complete thoracic level SCI and intact lower motor neurons to the muscles targeted for stimulation.

METHODS

Each subject was successfully implanted with the Praxis FES system. All three subjects received electrodes for upright mobility and the first two subjects received additional electrodes for stimulated bladder and bowel management. Following training, subjects were evaluated in their ability to use FES for nine mobility activities. Acute and chronic experiments of the effect of stimulation on bowel and bladder function were also performed.

RESULTS

All three subjects could independently stand up from the wheelchair and could walk at least 6 m using a swing through gait pattern. Two subjects were able to independently perform swing through gait for 6 min and one subject was able to independently ascend and descend stairs. Suppression of reflex bladder contractions by neuromodulation (subject 1) and stimulated contractions of the rectum (subject 2) were observed in acute experiments. When stimulation was applied over the course of several weeks, a positive effect on bowel function was measured. Stimulated bladder contractions were not achieved.

CONCLUSION

The feasibility of using the Praxis FES system for upright mobility and aiding aspects of bladder and bowel function was demonstrated with three subjects with thoracic level SCI.

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

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

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

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

The course of bone mineral density and biochemical markers of bone turnover in early postmenopausal spinal cord-lesioned females

STUDY DESIGN

A prospective observational study.

OBJECTIVE

To evaluate bone mineral density (BMD) and biochemical markers of bone turnover in spinal cord-lesioned females in the early postmenopausal period.

SETTING

Clinic for Spinal Cord Injuries, H:S Rigshospitalet, Denmark.

MATERIAL

In all, 18 early postmenopausal females with spinal cord lesions (SCL) of more than 2 years duration were recruited. In total, 11 completed the study.

METHODS

Using dual energy X-ray absorption, BMD of the lumbar spine, femoral neck, trochanter and proximal tibia was measured every 6 months for 30 months. Biochemical markers of bone turnover in blood and urine were collected at the same time points.

RESULTS

A significant increase in markers of bone formation in the blood was found and markers of bone resorption in urine tended to increase. BMD values changed insignificantly but for all regions decreased, except the lumbar spine.

CONCLUSION

An accelerated bone turnover occurs in early postmenopausal SCL females. At the same time, we showed an insignificant decrease in BMD data from the lower extremity.

Changes in osteoprotegerin/RANKL system, bone mineral density, and bone biochemicals markers in patients with recent spinal cord injury

This study analyzed the temporal and regional variations in bone loss and explored bone cell activities via biochemical markers during an extended follow-up in patients with spinal cord injury (SCI). In parallel, the possible role of the osteoprotegerin (OPG)/RANKL system in disuse osteoporosis was investigated. Seven male patients with acute and complete SCI (31.3 +/- 9.5 years) and 12 able-bodied (AB) men (26.9 +/- 4.2 years) participated in the study. Measurements were performed 16, 24, 36, 48, and 71 weeks after injury. At week 16, marked calcium homeostasis disturbance and a concomitant increase in bone resorption markers were observed, reflecting an intense bone degradation process. Resorption activity decreased continuously with time. Contrasting with the great rise in the resorption markers, the bone formation markers showed little variation. During the period of investigation, a loss in bone mineral density (BMD) was demonstrated for the total body (-4.3%), pelvis (-15.7%) and lower limbs (-15.2%), whereas BMD did not change at the lumbar spine, upper limbs, or skull. At all stages, SCI patients had lower serum RANKL levels and higher serum OPG levels than did AB controls, but no significant variation with time was observed for either cytokine. These findings suggest that bone resorption persisted long after SCI and specifically affected BMD at sublesional sites. The marked modification of serum OPG/RANKL levels in SCI patients suggests that this system is affected, in disuse osteoporosis. However, the precise biologic role of the OPG/RANKL system in the bone tissue of SCI patients has yet to be determined.

Musculoskeletal changes in women with spinal cord injury: a twin study

Bone mineral density (BMD), bone geometry, and muscle cross-sectional area (CSA) were investigated in two sets of monozygotic female twins, where one of each pair had sustained a spinal cord injury (SCI). Twin pair 1 (TP1) and twin pair 2 (TP2) were 32 and 47 yr old and were 7 and greater than 20 yr postinjury, respectively. BMD was measured using dual-energy X-ray absorptiometry. Computed tomography was used to measure volumetric BMD, bone geometry, and muscle CSA of the thigh and calf. For the SCI twin of TP1, BMDs of hip, distal femur, proximal tibia, and spine were 59.5, 46.6, 53.1, and 93.3%, respectively, of values of the noninjured twin. For TP2, corresponding values in the SCI twin were 36.2, 35.9, 39.2, and 62.2%, respectively, of the non-SCI twin. Average muscle CSAs of the SCI twins were 31.2+/-2.3% and 31.0+/-6.1% of the values for their non-SCI twin, indicating that muscle CSAs were reduced by 70%. Among the SCI twins, volumetric BMDs were 83.4+/-2.4% and 87.0+/-3.45% of the non-SCI twins' values. Moments of inertia in the SCI twins ranged from 62.4 to 97.9% of the non-SCI twins' values at mid-femur and calf. This study reveals that in addition to the declines in muscle CSA and BMD, important changes in bone geometry occur in women after SCI.

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

OBJECTIVE

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

DESIGN

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

RESULTS

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

CONCLUSIONS

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

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

OBJECTIVES

To determine the bone mineral density (BMD) of the legs, arms, and trunk region of a group of adults with spinal cord injury (SCI) and to determine the relationship between regional BMD values and the time since injury.

DESIGN

BMD measurements were determined by total-body, dual-energy x-ray absorptiometry scans and percentage values (percentage-matched BMD), based on manufacturer-supplied normative data for age, sex, body weight, and ethnic group. The relationship between percentage-matched BMD values and time since injury was determined by linear regression analyses.

SETTING

Research laboratories in a university setting.

PARTICIPANTS

Twenty-nine subjects (21 men, 8 women; mean age, 38.5 y) who had sustained an SCI a mean of 10.6 years earlier (range, 0.6-35.3 y).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The relationship between percentage-matched BMD values and the time since injury.

RESULTS

There was a significant inverse relationship between percentage-matched BMD leg (r2 = -.76), arm (r2 = -.45), and trunk (r2 = -.38) values and the log of time since injury.

CONCLUSION

Despite the varying levels of SCI and other relevant BMD contributing factors, the regional percentage-matched BMD values were significantly inversely related to the log of time since injury.

Bone status in multiple sclerosis: beyond corticosteroids

The aim of this study was to determine the possible factors affecting bone mineral density (BMD) in multiple sclerosis (MS). In this cross-sectional study, 65 clinically definite MS patients and 72 comparable controls were prospectively evaluated. To assess bone mineral metabolism in MS, the BMD of the lumbar spine and hip (femoral neck, trochanter and total) was measured by dual-energy X-ray absorptiometry, and serum vitamin D and parathyroid hormone levels and biochemical markers of bone turnover were also evaluated. MS patients had significantly lower BMD values than the control group at all measurement sites. There was a significant correlation between the disease duration and BMD values at the trochanter in women with MS. A correlation between femoral BMD values and functional status in women was also detected. There was no relationship between bone biochemical markers and BMD, except a negative correlation between bone alkaline phosphatase and trochanter BMD. Both disability and disease duration have an influence on BMD of the MS patients, whereas no significant correlation between glucocorticoid use and BMD was observed.

Vieillissement chez les blessés médullaires

OBJECTIVE

Literature review of the data on aging with spinal cord injury.

METHOD

Interrogation on Medline using the following keywords: aging, spinal cord injuries, paraplegia, quadriplegia, mortality, morbidity, quality of life, survival, health status.

RESULTS

The expectation of life of the spinal cord injury patients improved even though it remains even lower than that of the general population. The effects of aging add to the specific complications which are numerous and alter almost every function. Respiratory complications became the first cause of death especially for tetraplegics. Urinary and cutaneous complications remain important as well as osteo-articular pathologies (particular upper limbs) whose consequences can be serious on the functional capacities. Studies on the quality of life show that adaptation to the handicap is done in a continuous way and a long time after the initial phase of rehabilitation. They underline the importance of professional resources, psychological reactions and previous experiences of the spinal cord injury patients in appreciating the quality of life after the traumatism.

CONCLUSION

The specificities of the aging of the spinal cord injury patients require to be well known and underline the importance and the necessity of an adequate and specific follow-up. On a more general plan, they imply a reflection on the strategies of initial rehabilitation, not to compromise the future of these spinal cord injury patients.

Intensive exercise may preserve bone mass of the upper limbs in spinal cord injured males but does not retard demineralisation of the lower body

STUDY DESIGN

Cross-sectional study comparing a group of active spinal cord injured (SCI) males carefully matched for age, height, and weight with active able-bodied male controls.

OBJECTIVES

To compare bone mass of the total body, upper and lower limbs, hip, and spine regions in active SCI and able-bodied individuals.

SETTING

Outpatient study undertaken in two centres in New Zealand.

METHODS

Dual energy X-ray absorptiometry (DEXA) scanning was used to determine bone mass. Questionnaires were used to ascertain total time spent in weekly physical activity for each individual. The criterion for entry into the study was regular participation in physical activity of more than 60 min per week, over and above that required for rehabilitation.

RESULTS

Seventeen SCI and their able-bodied controls met our required activity criterion. Bone mineral density (BMD) values of the total body and hip regions were significantly lower in the SCI group than in their controls (P=0.0001). Leg BMD and bone mineral content (BMC) were also significantly lower in the SCI group (P=0.0001). By contrast, lumbar spine BMD and arm BMD and BMC did not differ between the SCI and control groups. Arm BMD and BMC were greater (not significant) than the reference norms (LUNAR database) for both groups.

CONCLUSION

Intensive exercise regimens may contribute to preservation of arm bone mass in SCI males, but does not prevent demineralisation in the lower body.

Supralesional and sublesional bone mineral density in spinal cord-injured patients

This study was performed to evaluate supra- and sublesional bone mineral density (BMD) in spinal cord-injured (SCI) patients after 1 year postinjury, and to correlate the BMD to the neurological level; to correlate the sublesional demineralization to functional parameters (duration postinjury, duration of the initial bedrest); and to assess the role of classic methods of prevention such as walking or standing. Thirty-one SCI patients, all male, were studied vs. 31 controls (age matched). The mean age of the population was 36 years (range 18-60 years). Eleven were tetraplegic and 20 were paraplegic. Twenty-six patients dysplayed a complete motor lesion. The BMD was measured by dual-photon absorptiometry on the lumbar spine and on the femoral neck, and the bone mineral content (BMC) on whole-body scans. Particular attention was paid to the distal femur and proximal tibia upper third. Blood samples and urine samples included phosphocalcic parameters, with determination of urinary hydroxyproline and deoxypyridinoline. SCI patients showed a decrease of sublesional BMD of 41% in comparison with controls. This loss of bone mass is higher at the distal femur (-52%) and proximal tibia (-70%), which are the most common sites of fracture. The degree of demineralization for the lumbar spine, the pelvis, and the lower limbs is independent of the neurological level. The duration of acute posttraumatic immobilization (mean 43.3 days) and the time postinjury increase the loss of bone mass for lower limbs (p = 0.04) and particularly for the proximal tibia (p = 0.02). The study of biomechanical stress (i.e., standing, walking, sitting) does not influence the sublesional BMC. This study underlines the major role of the neurological lesion on the decrease of sublesional BMC in SCI patients and the absence of influence of biomechanical stress.

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

OBJECTIVE

To study the extent to which atrophy of muscle and progressive weakening of the long bones after spinal cord injury (SCI) can be reversed by functional electrical stimulation (FES) and resistance training.

DESIGN

A within-subject, contralateral limb, and matching design.

SETTING

Research laboratories in university settings.

PARTICIPANTS

Fourteen patients with SCI (C5 to T5) and 14 control subjects volunteered for this study.

INTERVENTIONS

The left quadriceps were stimulated to contract against an isokinetic load (resisted) while the right quadriceps contracted against gravity (unresisted) for 1 hour a day, 5 days a week, for 24 weeks.

MAIN OUTCOME MEASURES

Bone mineral density (BMD) of the distal femur, proximal tibia, and mid-tibia obtained by dual energy x-ray absorptiometry, and torque (strength).

RESULTS

Initially, the BMD of SCI subjects was lower than that of controls. After training, the distal femur and proximal tibia had recovered nearly 30% of the bone lost, compared with the controls. There was no difference in the mid-tibia or between the sides at any level. There was a large strength gain, with the rate of increase being substantially greater on the resisted side.

CONCLUSION

Osteopenia of the distal femur and proximal tibia and the loss of strength of the quadriceps can be partly reversed by regular FES-assisted training.

Intravenous pamidronate attenuates bone density loss after acute spinal cord injury

OBJECTIVE

To compare the effects of a 6-month treatment with intravenous pamidronate (30-mg infusion once per month) to conventional rehabilitation without pamidronate on bone density of the spine and leg bones and on the excretion rate of N-telopeptide, a urinary marker of bone catabolism, in acutely spinal cord injured patients.

DESIGN

A nonrandomized control trial in which 24 spinal cord injured subjects entered the study within 6 weeks of their injury. Fourteen subjects received pamidronate; 10 did not.

OUTCOME MEASURES

Bone density measurements by dual x-ray absorptiometry were performed before the initial treatment (within 6 weeks of the injury) and at 3, 6, and 12 months postinjury and was the primary efficacy parameter. Urine for N-telopeptide levels was the secondary efficacy parameter.

RESULTS

After acute spinal cord injury, patients treated with intravenous pamidronate had significantly less bone density loss compared with those who did not receive pamidronate (parametric ANOVA, p<.02). Also, ambulatory subjects had significantly less bone density loss over the study period (p<.05) than nonambulatory subjects. In general, a high excretion level of the urinary bone-breakdown product N-telopeptide was found before intravenous pamidronate treatment, followed by a dramatic reduction in excretion after pamidronate treatment. Ambulatory subjects excreted significantly less N-telopeptide than motor-complete subjects at all time points.

CONCLUSION

Intravenous pamidronate treatment and ambulatory ability in the first 6 months after an acute spinal cord injury prevents bone density loss.

Bone mineral density and indexes of bone metabolism in spinal cord injury

We evaluated the pattern of osteoporosis after spinal cord injury, determined the time-frame of the changes, and elucidated the relationship among parathyroid hormone levels, biochemical markers of bone formation, and the pattern of bone mass loss. We included 176 subjects with spinal cord injury and 62 subjects without spinal cord injury as controls in the study. Bone mineral density of the spine and the proximal femur was measured. The participants' age, level of injury, and length of time since injury were compared with the nonspinal cord-injured controls and with each other. Serum levels of calcium, calcitonin, biochemical markers of bone formation, and parathyroid hormone were determined. Our results revealed that bone mineral density of the proximal femur declined and reached fracture threshold at one to five years after injury. The decline was detected at 12 months after injury in all age groups. Spinal bone mineral density neither declined significantly nor reached fracture threshold. Parathyroid hormone levels declined before the end of the first year postinjury and increased at one to nine years postinjury in the 20- to 39-year age group. The increase correlated with the initial decline of bone mineral density of the proximal femur. Our studies in spinal cord-injured subjects revealed a pattern of osteoporosis similar to age and parathyroid dysfunction-related osteoporosis. No other correlation was detected between indexes of bone metabolism and bone mineral density measurements.