Physiological effects of lower extremity functional electrical stimulation in early spinal cord injury: lack of efficacy to prevent bone loss

Effectiveness of FES-supported leg exercise for promotion of paralysed lower limb muscle and bone health-a systematic review

Leg exercises through standing, cycling and walking with/without FES may be used to preserve lower limb muscle and bone health in persons with physical disability due to SCI. This study sought to examine the effectiveness of leg exercises on bone mineral density and muscle cross-sectional area based on their clinical efficacy in persons with SCI. Several literature databases were searched for potential eligible studies from the earliest return date to January 2022. The primary outcome targeted was the change in muscle mass/volume and bone mineral density as measured by CT, MRI and similar devices. Relevant studies indicated that persons with SCI that undertook FES- and frame-supported leg exercise exhibited better improvement in muscle and bone health preservation in comparison to those who were confined to frame-assisted leg exercise only. However, this observation is only valid for exercise initiated early (i.e., within 3 months after injury) and for ≥30 min/day for ≥ thrice a week and for up to 24 months or as long as desired and/or tolerable. Consequently, apart from the positive psychological effects on the users, leg exercise may reduce fracture rate and its effectiveness may be improved if augmented with FES.

Motorless cadence control of standard and low duty cycle-patterned neural stimulation intensity extends muscle-driven cycling output after paralysis

Background

Stimulation-driven exercise is often limited by rapid fatigue of the activated muscles. Selective neural stimulation patterns that decrease activated fiber overlap and/or duty cycle improve cycling exercise duration and intensity. However, unequal outputs from independently activated fiber populations may cause large discrepancies in power production and crank angle velocity among pedal revolutions. Enforcing a constant cadence through feedback control of stimulus levels may address this issue and further improve endurance by targeting a submaximal but higher than steady-state exercise intensity.

Methods

Seven participants with paralysis cycled using standard cadence-controlled stimulation (S-Cont). Four of those participants also cycled with a low duty cycle (carousel) cadence-controlled stimulation scheme (C-Cont). S-Cont and C-Cont patterns were compared with conventional maximal stimulation (S-Max). Outcome measures include total work (W), end power (P_end), power fluctuation (PFI), charge accumulation (Q) and efficiency (η). Physiological measurements of muscle oxygenation (SmO₂) and heart rate were also collected with select participants.

Results

At least one cadence-controlled stimulation pattern (S-Cont or C-Cont) improved P_end over S-Max in all participants and increased W in three participants. Both controlled patterns increased Q and η and reduced PFI compared with S-Max and prior open-loop studies. S-Cont stimulation also delayed declines in SmO2 and increased heart rate in one participant compared with S-Max.

Conclusions

Cadence-controlled selective stimulation improves cycling endurance and increases efficiency over conventional stimulation by incorporating fiber groups only as needed to maintain a desired exercise intensity. Closed-loop carousel stimulation also successfully reduces power fluctuations relative to previous open-loop efforts, which will enable neuroprosthesis recipients to better take advantage of duty cycle reducing patterns.

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.

Selective neural stimulation methods improve cycling exercise performance after spinal cord injury: a case series

BACKGROUND

Exercise after paralysis can help prevent secondary health complications, but achieving adequate exercise volumes and intensities is difficult with loss of motor control. Existing electrical stimulation-driven cycling systems involve the paralyzed musculature but result in rapid force decline and muscle fatigue, limiting their effectiveness. This study explores the effects of selective stimulation patterns delivered through multi-contact nerve cuff electrodes on functional exercise output, with the goal of increasing work performed and power maintained within each bout of exercise.

METHODS

Three people with spinal cord injury and implanted stimulation systems performed cycling trials using conventional (S-Max), low overlap (S-Low), low duty cycle (C-Max), and/or combined low overlap and low duty cycle (C-Low) stimulation patterns. Outcome measures include total work (W), end power (Pend), power fluctuation indices (PFI), charge accumulation (Q), and efficiency (η). Mann-Whitney tests were used for statistical comparisons of W and Pend between a selective pattern and S-Max. Welch's ANOVAs were used to evaluate differences in PFIs among all patterns tested within a participant (n ≥ 90 per stimulation condition).

RESULTS

At least one selective pattern significantly (p < 0.05) increased W and Pend over S-Max in each participant. All selective patterns also reduced Q and increased η compared with S-Max for all participants. C-Max significantly (p < 0.01) increased PFI, indicating a decrease in ride smoothness with low duty cycle patterns.

CONCLUSIONS

Selective stimulation patterns can increase work performed and power sustained by paralyzed muscles prior to fatigue with increased stimulation efficiency. While still effective, low duty cycle patterns can cause inconsistent power outputs each pedal stroke, but this can be managed by utilizing optimized stimulation levels. Increasing work and sustained power each exercise session has the potential to ultimately improve the physiological benefits of stimulation-driven exercise.

Tibiofemoral forces during FES rowing in individuals with spinal cord injury

The purpose of this study is to determine the tibiofemoral forces during functional electrical stimulation (FES) rowing in individuals with spinal cord injury (SCI). We analysed the motion of five participants with SCI during FES rowing, with simultaneous measurements of (i) three-dimensional marker trajectories, (ii) foot reaction forces (FRFs), (iii) ergometer handle forces, and (iv) timestamps for electrical stimulation of the quadriceps and hamstrings muscles. We created full-body musculoskeletal models in OpenSim to determine subject-specific tibiofemoral forces during FES rowing. The peak magnitudes of tibiofemoral forces averaged over five participants with SCI were 2.43 ± 0.39 BW and 2.25 ± 0.71 BW for the left and right legs, respectively. The peak magnitudes of FRFs were 0.19 ± 0.04 BW in each leg. The peak magnitude of handle forces was 0.47 ± 0.19 BW. Peak tibiofemoral force was associated with peak FRF (magnitudes, R² = 0.56, p = 0.013) and peak handle force (magnitudes, R² = 0.54, p = 0.016). The ratios of peak magnitude of tibiofemoral force to peak magnitude of FRF were 12.9 ± 1.9 (left) and 11.6 ± 2.4 (right), and to peak magnitude of handle force were 5.7 ± 2.3 (left) and 4.9 ± 0.9 (right). This work lays the foundation for developing a direct exercise intensity metric for bone mechanical stimulus at the knee during rehabilitation exercises. Clinical Significance: Knowledge of tibiofemoral forces from exercises such as FES rowing may provide clinicians the ability to personalize rehabilitation protocols to ensure that an SCI patient is receiving the minimum dose of mechanical stimulus necessary to maintain bone health.

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.

Effects of FES-Rowing Exercise on the Time-Dependent Changes in Bone Microarchitecture After Spinal Cord Injury: A Cross-Sectional Investigation

Disuse osteoporosis is a serious, secondary consequence of spinal cord injury (SCI). Numerous pharmacological and exercise therapies have been implemented to mitigate bone loss after SCI. However, these therapies have not been shown to improve bone density, potentially because of insufficient duration and magnitude of loading and/or inability of imaging modalities to capture changes in bone microarchitecture. In this cross‐sectional study, we evaluated bone microstructure of the distal tibia and radius using HR‐pQCT in men with SCI (N = 13) who regularly trained with functional electrical stimulation‐ (FES‐) rowing. We aimed to determine whether the amount of FES‐rowing (total distance rowed and peak foot force) and/or time since injury (TSI) predict bone loss after SCI. We assessed volumetric density of the total, cortical, and trabecular compartments, cortical thickness, and trabecular thickness. Using linear regression analysis, we found that TSI was not associated with any of the tibial bone metrics. In fact, none of the variables (TSI, total distance rowed, and peak foot force) independently predicted bone loss. Using stepwise regression, when all three variables were considered together, we found a strong prediction for trabecular microstructure (trabecular vBMD: R² = 0.53; p = 0.06; trabecular thickness: R² = 0.72; p < 0.01), but not cortical bone metrics. In particular, trabecular vBMD and thickness were negatively associated with TSI and positively associated with distance rowed. Foot force contributed markedly less to trabecular bone than distance rowed or TSI. Our results suggest that regular FES‐rowing may have the capacity to alter the time‐dependent bone negative effects of SCI on trabecular bone density and microstructure. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

Epidural stimulation with locomotor training improves body composition in individuals with cervical or upper thoracic motor complete spinal cord injury: A series of case studies

CONTEXT

Four individuals with motor complete SCI with an implanted epidural stimulator who were enrolled in another study were assessed for cardiovascular fitness, metabolic function and body composition at four time points before, during, and after task specific training. Following 80 locomotor training sessions, a 16-electrode array was surgically placed on the dura (L1-S1 cord segments) to allow for electrical stimulation. After implantation individuals received 160 sessions of task specific training with epidural stimulation (stand and step).

OUTCOME MEASURES

Dual-energy X-ray absorptiometry (DXA), resting metabolic rate and peak oxygen consumption (VO₂peak) were measured before locomotor training, after locomotor training but before epidural stimulator implant, at mid-locomotor training with spinal cord epidural stimulation (scES) and after locomotor training with scES.

FINDINGS

Participants showed increases in lean body mass with decreases on percentage of body fat, particularly android body fat, and android/gynoid ratio from baseline to post training; resting metabolic rate and VO₂peak also show increases that are of clinical relevance in this population.

CONCLUSIONS

Task specific training combined with epidural stimulation has the potential to show improvements in cardiovascular fitness and body composition in individuals with cervical or upper thoracic motor complete SCI.

Musculoskeletal Health in the Context of Spinal Cord Injury

PURPOSE OF REVIEW

This review assembles recent understanding of the profound loss of muscle and bone in spinal cord injury (SCI). It is important to try to understand these changes, and the context in which they occur, because of their impact on the wellbeing of SC-injured individuals, and the urgent need for viable preventative therapies.

RECENT FINDINGS

Recent research provides new understanding of the effects of age and systemic factors on the response of bone to loading, of relevance to attempts to provide load therapy for bone in SCI. The rapidly growing dataset describing the biochemical crosstalk between bone and muscle, and the cell and molecular biology of myokines signalling to bone and osteokines regulating muscle metabolism and mass, is reviewed. The ways in which this crosstalk may be altered in SCI is summarised. Therapeutic approaches to the catabolic changes in muscle and bone in SCI require a holistic understanding of their unique mechanical and biochemical context.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Fabrication and in vitro biological properties of piezoelectric bioceramics for bone regeneration

The piezoelectric effect of biological piezoelectric materials promotes bone growth. However, the material should be subjected to stress before it can produce an electric charge that promotes bone repair and reconstruction conducive to fracture healing. A novel method for in vitro experimentation of biological piezoelectric materials with physiological load is presented. A dynamic loading device that can simulate the force of human motion and provide periodic load to piezoelectric materials when co-cultured with cells was designed to obtain a realistic expression of piezoelectric effect on bone repair. Hydroxyapatite (HA)/barium titanate (BaTiO₃) composite materials were fabricated by slip casting, and their piezoelectric properties were obtained by polarization. The d₃₃ of HA/BaTiO₃ piezoelectric ceramics after polarization was 1.3 pC/N to 6.8 pC/N with BaTiO₃ content ranging from 80% to 100%. The in vitro biological properties of piezoelectric bioceramics with and without cycle loading were investigated. When HA/BaTiO₃ piezoelectric bioceramics were affected by cycle loading, the piezoelectric effect of BaTiO₃ promoted the growth of osteoblasts and interaction with HA, which was better than the effect of HA alone. The best biocompatibility and bone-inducing activity were demonstrated by the 10%HA/90%BaTiO₃ piezoelectric ceramics.

Does early exercise attenuate muscle atrophy or bone loss after spinal cord injury?

OBJECTIVES

To systematically identify and assess the evidence on the efficacy of exercise initiated early after traumatic spinal cord injury (SCI).

METHODS

A comprehensive search (Any-2014) of eleven databases identified studies evaluating exercise interventions initiated within 12 weeks after SCI on muscle and bone loss in paralyzed limbs and comparing with standard care or immobilization. Two reviewers assessed methodological quality. One reviewer extracted data and critiqued results according to the Spinal Cord Injury Rehabilitation Evidence body of evidence framework.

RESULTS

A total of 2811 titles were screened. Eleven studies were included: five randomized controlled trials, four cohort studies and two within-subject control studies. All provided level II evidence with a moderate risk of bias. Two studies found significant positive effects of high-load FES-resisted stance on physiological measures of muscle. Three reported positive effects of 3 months of Functional Electrical Stimulation (FES) on muscle size. Two studies found positive effects of 6-month body-weight supported treadmill training or FES on trabecular bone using pQCT.

CONCLUSION

We found consistent evidence of positive effects of early exercise on muscle, possibly related to load intensity of the protocol. However, the heterogeneity of interventions and outcomes makes this determination speculative. Evidence for the effectiveness of early exercise on bone is scant and confined to measures of trabecular bone mineral density via pQCT. Transparent reporting of methods and variability of data, combined with standardization of valid and sensitive measures of muscle atrophy and bone loss, could facilitate future meta-analysis on this topic.

Early exercise after spinal cord injury ('Switch-On'): study protocol for a randomised controlled trial

Background

Spinal cord injury (SCI) leads to a profound muscular atrophy, bone loss and bone fragility. While there is evidence that exercising paralysed muscles may lead to reversal of muscle atrophy in the chronic period after SCI, there is little evidence that exercise can prevent muscle changes early after injury. Moreover, whether exercise can prevent bone loss and microarchitectural decay is not clear.

Methods/Design

A multi-centre, parallel group, assessor-blinded randomised controlled trial will be conducted. Fifty participants with acute spinal cord injury will be recruited from four SCI units in Australia and New Zealand. Participants will be stratified by site and AIS status and randomised to an experimental or control group. Experimental participants will receive a 12-week programme of functional electrical stimulation (FES)-assisted cycling. Control participants will receive a 12-week programme of passive cycling. The primary outcome is muscle cross-sectional area of the thigh and calf measured using magnetic resonance images (MRI) of the leg. Secondary outcomes include serum biomarkers of SCI osteoporosis (sclerostin, P1NP and β-CTX), markers of immune function (IL-6, IL-10, FGF2, INF-γ, TNF-α), neurological function, body composition, depression and quality of life. Leg MRIs will be measured by a single blinded assessor based in Melbourne. Serum samples will be analysed in a central laboratory. All other characteristics will be measured at baseline and 12 weeks by blinded and trained assessors at each site. The first participant was randomised on 27 November 2012.

Discussion

The results of this trial will determine the relative effectiveness of a 12-week programme of FES-assisted cycling versus passive cycling in preventing muscle atrophy and maintaining skeletal integrity after spinal cord injury.

Trial registration

ACTRN12611001079932 (18 October 2011)

The effects of electrical stimulation on body composition and metabolic profile after spinal cord injury--Part II

Diet and exercise are cornerstones in the management of obesity and associated metabolic complications, including insulin resistance, type 2 diabetes, and disturbances in the lipid profile. However, the role of exercise in managing body composition adaptations and metabolic disorders after spinal cord injury (SCI) is not well established. The current review summarizes evidence about the efficacy of using neuromuscular electrical stimulation or functional electrical stimulation in exercising the paralytic lower extremities to improve body composition and metabolic profile after SCI. There are a number of trials that investigated the effects on muscle cross-sectional area, fat-free mass, and glucose/lipid metabolism. The duration of the intervention in these trials varied from 6 weeks to 24 months. Training frequency ranged from 2 to 5 days/week. Most studies documented significant increases in muscle size but no noticeable changes in adipose tissue. While increases in skeletal muscle size after twice weekly training were greater than those trials that used 3 or 5 days/week, other factors such as differences in the training mode, i.e. resistance versus cycling exercise and pattern of muscle activation may be responsible for this observation. Loading to evoke muscle hypertrophy is a key component in neuromuscular training after SCI. The overall effects on lean mass were modest and did not exceed 10% and the effects of training on trunk or pelvic muscles remain unestablished. Most studies reported improvement in glucose metabolism with the enhancement of insulin sensitivity being the major factor following training. The effect on lipid profile is unclear and warrants further investigation.

Whole-Body Electromyostimulation to Fight Osteopenia in Elderly Females: The Randomized Controlled Training and Electrostimulation Trial (TEST-III)

Whole-body electromyostimulation (WB-EMS) has been shown to be effective in increasing muscle strength and mass in elderly women. Because of the interaction of muscles and bones, these adaptions might be related to changes in bone parameters. 76 community-living osteopenic women 70 years and older were randomly assigned to either a WB-EMS group (n = 38) or a control group (CG: n = 38). The WB-EMS group performed 3 sessions every 14 days for one year while the CG performed gymnastics containing identical exercises without EMS. Primary study endpoints were bone mineral density (BMD) at lumbar spine (LS) and total hip (thip) as assessed by DXA. After 54 weeks of intervention, borderline nonsignificant intergroup differences were determined for LS-BMD (WB-EMS: 0.6 ± 2.5% versus CG -0.7 ± 2.5%, P = .051) but not for thip-BMD (WB-EMS: -1.1 ± 1.9% versus CG: -0.8 ± 2.3%, P = .771). With respect to secondary endpoints, there was a gain in lean body mass (LBM) of 1.5% (P = .006) and an increase in grip strength of 8.4% (P = .000) in the WB-EMS group compared to CG. WB-EMS effects on bone are less pronounced than previously reported effects on muscle mass. However, for subjects unable or unwilling to perform intense exercise programs, WB-EMS may be an option for maintaining BMD at the LS.

Effects of electromyostimulation on muscle and bone in men with acute traumatic spinal cord injury: A randomized clinical trial

OBJECTIVE

To study the effect of 14 weeks of electromyostimulation (EMS) training (47 minutes/day, 5 days/week) on both muscle and bone loss prevention in persons with recent, complete spinal cord injury (SCI).

DESIGN

Prospective, experimental, controlled, single-blind randomized trial with external blind evaluation by third parties.

METHODS

Eight men with recent SCI (8 weeks from injury; ASIA Impairment Scale (AIS) "A") were randomized into the intervention or the control groups. Cross-sectional area of the quadriceps femoris (QF) muscle was quantified using magnetic resonance imaging. Bone mineral density changes were assessed with a dual-energy X-ray absorptiometry. Several bone biomarkers (i.e. total testosterone, cortisol, growth hormone, insulin-growth factor I, osteocalcin, serum type I collagen C-telopeptide), lipid, and lipoprotein profiles were quantified. A standard oral glucose tolerance test was performed before and after the 14-week training. All analyses were conducted at the beginning and after the intervention.

RESULTS

The intervention group showed a significant increase in QF muscle size when compared with the control group. Bone losses were similar in both groups. Basal levels of bone biomarkers did not change over time. Changes in lipid and lipoprotein were similar in both groups. Glucose and insulin peaks moved forward after the training in the intervention group.

CONCLUSIONS

This study indicates that skeletal muscle of patients with complete SCI retains the ability to grow in response to a longitudinal EMS training, while bone does not respond to similar external stimulus. Increases in muscle mass might have induced improvements in whole body insulin-induced glucose uptake.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Effect of chronic activity-based therapy on bone mineral density and bone turnover in persons with spinal cord injury

PURPOSE

Osteoporosis is a severe complication of spinal cord injury (SCI). Many exercise modalities are used to slow bone loss, yet their efficacy is equivocal. This study examined the effect of activity-based therapy (ABT) targeting the lower extremities on bone health in individuals with SCI.

METHODS

Thirteen men and women with SCI (age and injury duration = 29.7 ± 7.8 and 1.9 ± 2.7 years) underwent 6 months of ABT. At baseline and after 3 and 6 months of training, blood samples were obtained to assess bone formation (serum procollagen type 1 N propeptide (PINP) and bone resorption (serum C-terminal telopeptide of type I collagen (CTX), and participants underwent dual-energy X-ray absorptiometry scans to obtain total body and regional estimates of bone mineral density (BMD).

RESULTS

Results demonstrated significant increases (p < 0.05) in spine BMD (+4.8 %; 1.27 ± 0.22-1.33 ± 0.24 g/cm(2)) and decreases (p < 0.01) in total hip BMD (-6.1 %; 0.98 ± 0.18-0.91 ± 0.16 g/cm(2)) from 0 to 6 months of training. BMD at the bilateral distal femur (-7.5 to -11.0 %) and proximal tibia (- 8.0 to -11.2 %) declined but was not different (p > 0.05) versus baseline. Neither PINP nor CTX was altered (p > 0.05) with training.

CONCLUSIONS

Chronic activity-based therapy did not reverse bone loss typically observed soon after injury, yet reductions in BMD were less than the expected magnitude of decline in lower extremity BMD in persons with recent SCI.

High dose compressive loads attenuate bone mineral loss in humans with spinal cord injury

People with spinal cord injury (SCI) lose bone and muscle integrity after their injury. Early doses of stress, applied through electrically induced muscle contractions, preserved bone density at high-risk sites. Appropriately prescribed stress early after the injury may be an important consideration to prevent bone loss after SCI.

INTRODUCTION

Skeletal muscle force can deliver high compressive loads to bones of people with spinal cord injury (SCI). The effective osteogenic dose of load for the distal femur, a chief site of fracture, is unknown. The purpose of this study is to compare three doses of bone compressive loads at the distal femur in individuals with complete SCI who receive a novel stand training intervention.

METHODS

Seven participants performed unilateral quadriceps stimulation in supported stance [150% body weight (BW) compressive load-"High Dose" while opposite leg received 40% BW-"Low Dose"]. Five participants stood passively without applying quadriceps electrical stimulation to either leg (40% BW load-"Low Dose"). Fifteen participants performed no standing (0% BW load-"Untrained") and 14 individuals without SCI provided normative data. Participants underwent bone mineral density (BMD) assessment between one and six times over a 3-year training protocol.

RESULTS

BMD for the High Dose group significantly exceeded BMD for both the Low Dose and the Untrained groups (p < 0.05). No significant difference existed between the Low Dose and Untrained groups (p > 0.05), indicating that BMD for participants performing passive stance did not differ from individuals who performed no standing. High-resolution CT imaging of one High Dose participant revealed 86% higher BMD and 67% higher trabecular width in the High Dose limb.

CONCLUSION

Over 3 years of training, 150% BW compressive load in upright stance significantly attenuated BMD decline when compared to passive standing or to no standing. High-resolution CT indicated that trabecular architecture was preserved by the 150% BW dose of load.

Time-course response in serum markers of bone turnover to a single-bout of electrical stimulation in patients with recent spinal cord injury

The objective of the present repeat-measures study was to determine whether plasma serum levels of testosterone, cortisol, osteocalcin or type I collagen C-telopeptide (CT) are acutely affected following an electro-myostimulation (EMS) bout, and their relation to bone mineral density and muscle mass. Ten men with recent (8 weeks) thoracic spinal cord injury (SCI) (ASIA A) and 10 age-matched able-bodied (AB) men performed one EMS bout on the quadriceps femoris muscle. Blood samples were drawn at basal condition, immediately after EMS, and 15 min, 30 min, 24 h and 48 h post-EMS. Muscle cross-sectional area was measured by magnetic resonance imaging. Bone mineral density (BMD) was determined by dual-energy X-ray absorptiometry. In the SCI group, a significant decrease in testosterone, cortisol and CT together with a significant increase in testosterone/cortisol ratio and osteocalcin/CT ratio was observed after EMS. For the AB subjects, only testosterone and CT decreased significantly following EMS. Muscle size was only related to testosterone/cortisol ratio in the SCI sample (R = 0.659, p < 0.05), whereas BMD did not show any relation to any biomarker. Acute EMS in recent spinal cord injured men seems to induce positive effects on bone turnover biomarkers, and anabolic and catabolic hormones.

Advances in the rehabilitation management of acute spinal cord injury

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

Spinal cord injury and physical activity: preservation of the body

SETTING

Spinal cord injury (SCI) causes devastating loss of function and can result in serious secondary complications. Although significant advances are being made to develop cellular and molecular therapies to promote regeneration, it is important to optimize physical interventions.

OBJECTIVES

The objective of this review was to examine the evidence for the effects of physical rehabilitation strategies on health and fitness, and maintenance of target systems below the level of injury (for example, muscle, bone, circulation).

RESULTS

Exercise appears to be a potent means of achieving these goals, using a variety of strategies.

CONCLUSION

Physical rehabilitation after SCI needs to move beyond the goal of maximizing independence to focus on maintenance of optimum health and fitness as well as maintenance of target system function below the level of injury. Issues requiring further investigation include identification of the optimum dosage of interventions to achieve specific goals, for example, prevention of muscle atrophy and osteoporosis, and development and validation of simple clinical measures to monitor the changes in body composition. Adoption of a classification system for physical interventions and standardized outcome measures would facilitate large-scale observational studies to identify the critical variables contributing to better outcomes.

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

OBJECTIVE

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

DESIGN

Randomized controlled trial.

SETTING

Inpatient rehabilitation hospital.

PARTICIPANTS

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

METHODS

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

MAIN OUTCOME MEASUREMENTS

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

RESULTS

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

CONCLUSIONS

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

Screening and habituation of functional electrical stimulation-leg cycle ergometry for individuals with spinal cord injury: a pilot study

OBJECTIVES

To document the screening process and develop the habituation procedures prior to commencing a functional electrical stimulation leg cycle ergometry (FES-LCE) exercise program for individuals with spinal cord injury (SCI).

DESIGN

This was a prospective descriptive study of screening and habituation for FES-LCE exercise for people with chronic SCI (injury duration longer than one year).

SETTING

: Tertiary rehabilitation center.

PARTICIPANTS

Thirteen subjects with SCI (mean years since injury, 7; mean age, 34.8 years; injury range, C4-T10; 7 males).

MAIN OUTCOME MEASURES

Time to attain target cycle speed for 30 continuous minutes.

RESULTS

Six of the 13 subjects were not eligible to start the FES-LCE habituation program because of previous fragility fracture, excessive spasticity, pain, autonomic dysreflexia, or lack of electrical stimulation response because of lower motor neuron damage in individuals with low thoracic injuries (T11-12). Time to attain target cycle speed for 30 continuous minutes ranged from 30 to 779 minutes (1-31 training sessions).

CONCLUSIONS

Almost half of the individuals interested in participating in the FES-LCE exercise program did not pass the screening phase. Although the habituation phase was time-consuming for most of the participants who were able to use the FES-LCE, all reported few adverse effects to using the device once they completed this phase of training.

Non-pharmacological treatment and prevention of bone loss after spinal cord injury: a systematic review

OBJECTIVE

Review the literature on non-pharmacological prevention and treatment of osteoporosis after spinal cord injury (SCI).

METHODS

PubMed, EMBASE and the Cochrane Controlled Trials Register were searched. All identified papers were read by title, abstract and full-length article when relevant. Hand search of the articles' sources identified additional papers. For included studies, the level of evidence was determined.

RESULTS

No studies conclusively showed an effective intervention. However, there are few randomized controlled trials (RCTs), and those that exist assess interventions and outcome measures that could be improved. Five studies on weight-bearing early post-injury are conflicting, but standing or walking may help retain bone mineral. In the chronic phase, there was no effect of weight bearing (12 studies). One study found that an early commencement of sports after SCI improved bone mineral, and the longer the period of athletic career, the higher the (leg) bone mineral. Early after SCI, there may be some effects of electrical stimulation (ES) (five studies). Chronic-phase ES studies vary (14 studies, including mixed periods after injury), but improvement is seen with longer period of training, or higher frequency or stimulus intensity. Improvements correspond to trabecular bone in the distal femur or proximal tibia. Impact vibration and pulsed electromagnetic fields may have some positive effects, whereas pulsed ultrasound does not. Six studies on the influence of spasticity show inconsistent results.

CONCLUSIONS

Bone mineral should be measured around the knee; the length and intensity of the treatment should be sufficiently long and high, respectively, and should commence early after SCI. If bone mineral is to remain, the stimulation has to be possibly continued for long term. In addition, RCTs are necessary.

Application of epidemiology to change health policy: defining age-related thresholds of bone mineral density for primary prevention of fracture

In Australia, benefits for antifracture therapies have been available for patients with osteoporosis and a prior fracture. No benefits were available to those with no prior fracture. We aimed to define, in women with no prior fracture, age-related thresholds of bone mineral density (BMD) associated with fracture risk equivalent to that of women with prior fracture and osteoporosis. A case-control study of women (> or =50 yr) was conducted, including 291 fracture cases and 823 controls. BMD was measured at the proximal femur and posterior anterior (PA) spine. A fracture risk score (FRS) for the group with no prior fracture was calculated with discriminant analysis. The thresholds for equivalent fracture risk between those with no prior fracture and those with prior fracture were assessed using logistic regression. Increasing the FRS to +0.98 in women with no prior fracture resulted in equivalent odds of sustaining a fracture to those with prior fracture and osteoporosis. The corresponding T-score thresholds at the spine were -4.6 at 50 yr, -3.9 at 60 yr, -3.1 at 70 yr, and -2.4 at 80 yr. The femoral neck T-score thresholds were lower by 0.5 standard deviation. The high-risk individuals defined by this study should be considered for primary fracture prevention therapy.

High-volume FES-cycling partially reverses bone loss in people with chronic spinal cord injury

Spinal cord injury (SCI) leads to severe bone loss in the paralysed limbs and to a resulting increased fracture risk thereof. Since long bone fractures can lead to comorbidities and a reduction in quality of life, it is important to improve bone strength in people with chronic SCI. In this prospective longitudinal cohort study, we investigated whether functional electrical stimulation (FES) induced high-volume cycle training can partially reverse the loss of bone substance in the legs after chronic complete SCI. Eleven participants with motor-sensory complete SCI (mean age 41.9+/-7.5 years; 11.0+/-7.1 years post injury) were recruited. After an initial phase of 14+/-7 weeks of FES muscle conditioning, participants performed on average 3.7+/-0.6 FES-cycling sessions per week, of 58+/-5 min each, over 12 months at each individual's highest power output. Bone and muscle parameters were investigated in the legs by means of peripheral quantitative computed tomography before the muscle conditioning (t1), and after six (t2) and 12 months (t3) of high-volume FES-cycle training. After 12 months of FES-cycling, trabecular and total bone mineral density (BMD) as well as total cross-sectional area in the distal femoral epiphysis increased significantly by 14.4+/-21.1%, 7.0+/-10.8% and 1.2+/-1.5%, respectively. Bone parameters in the femoral shaft showed small but significant decreases, with a reduction of 0.4+/-0.4% in cortical BMD, 1.8+/-3.0% in bone mineral content, and 1.5+/-2.1% in cortical thickness. These decreases mainly occurred between t1 and t2. No significant changes were found in any of the measured bone parameters in the tibia. Muscle CSA at the thigh increased significantly by 35.5+/-18.3%, while fat CSA at the shank decreased by 16.7+/-12.3%. Our results indicate that high-volume FES-cycle training leads to site-specific skeletal changes in the paralysed limbs, with an increase in bone parameters at the actively loaded distal femur but not the passively loaded tibia. Thus, we conclude that high-volume FES-induced cycle training has clinical relevance as it can partially reverse bone loss and thus may reduce fracture risk at this fracture prone site.

Functional electrical stimulation cycling improves body composition, metabolic and neural factors in persons with spinal cord injury

Persons with spinal cord injury (SCI) are at a heightened risk of developing type II diabetes and cardiovascular disease. The purpose of this investigation was to conduct an analysis of metabolic, body composition, and neurological factors before and after 10 weeks of functional electrical stimulation (FES) cycling in persons with SCI. Eighteen individuals with SCI received FES cycling 2-3 times per week for 10 weeks. Body composition was analyzed by dual X-ray absorptiometry. The American Spinal Injury Association (ASIA) neurological classification of SCI test battery was used to assess motor and sensory function. An oral glucose tolerance (OGTT) and insulin-response test was performed to assess blood glucose control. Additional metabolic variables including plasma cholesterol (total-C, HDL-C, LDL-C), triglyceride, and inflammatory markers (IL-6, TNF-alpha, and CRP) were also measured. Total FES cycling power and work done increased with training. Lean muscle mass also increased, whereas, bone and adipose mass did not change. The ASIA motor and sensory scores for the lower extremity significantly increased with training. Blood glucose and insulin levels were lower following the OGTT after 10 weeks of training. Triglyceride levels did not change following training. However, levels of IL-6, TNF-alpha, and CRP were all significantly reduced.

Prevention and Treatment of Bone Loss after a Spinal Cord Injury: A Systematic Review

Preserving and maintaining bone mass after a spinal cord injury (SCI) is crucial to decrease the risk of fragility or low trauma fractures- significant health events that occur as a result of minimal trauma such as falling during transfers or from a standing height or less. There is an increased risk for low trauma fractures after a SCI especially in the lower extremity. Therefore, purpose of this systematic review was to appraise the literature to provide clinical guidance for the optimization of bone health after SCI. The key research questions focused on prevention of acute bone loss and effective treatment of established low bone mass with long-standing SCI (≥ 1year). We report moderate evidence for the treatment of bone loss using pharmacology; however, non-pharmacological evidence for preventing and treating bone loss is limited.