We thank the INSPIRE Foundation, UK, for funding these studies.
Neurologically motor complete spinal cord injury (SCI) presents a unique model of bone loss whereby specific regional sites are exposed to a complete loss of voluntary muscle-induced skeletal loading against gravity. This results in a high rate of bone loss, especially in the lower limbs where trabecular bone mass decreases by~50-60% and cortical bone mass decreases by 25-34% before the rate of bone loss slows. These SCI-induced losses that are likely superimposed on continual age-related bone losses, increase the risk of low-impact fragility fracture. The fracture incidence 20 years post SCI is reported to be 4.6% per year. An intervention that effectively prevents, attenuates, or reverses bone loss is therefore highly desirable. We present a case study of an individual with chronic complete SCI, where bone loss has been attenuated following long-term functional electrical stimulation (FES)-rowing training. In this case study, we characterize the ultradistal tibia and ultradistal radius of the FES-rower with chronic complete SCI using high-resolution-peripheral quantitative computed tomography. These data are compared with a group of FESuntrained individuals with chronic complete SCI and to a normative non-SCI cohort. The evidence suggests, albeit from a single individual, that long-term FES-rowing training can attenuate bone loss secondary to chronic complete SCI. Indeed, key FES-rower's bone metrics for the ultradistal tibia more closely resemble normative age-matched values, which may have clinical significance since the majority of fragility fractures in chronic SCI occur in the lower extremities. Neurologically motor complete spinal cord injury (SCI) presents a unique model of bone loss whereby specific regional sites are exposed to a complete loss of voluntary muscle-induced skeletal loading against gravity. The initial loss of bone mineral content is estimated to approach 4% per month in trabecular sites, and 2% per month in cortical sites. Spinal Cord Series and Cases1 Trabecular bone mass is estimated to decrease by 48% of pre-injury values in the femur, reaching a new slower rate of loss by 3 years and 58% in the tibia by 5 years. Cortical bone mass decreases by 34% of pre-injury values in the femur by 5 years, and 25% in the tibia by 7 years.2 These losses are likely superimposed on continual age-related bone loss.3 SCIinduced bone loss often leads to the development of osteoporosis, which increases the risk of low-impact fragility fracture. 4 The fracture incidence 20 years post SCI is reported to be 4.6% per year.5 Thus, even active individuals with complete SCI at age 20 undergoing conventional standard of care have a very high likelihood of sustaining a fragility fracture in their lifetime, markedly affecting quality of life and increasing the risk of mortality. 6 An intervention that effectively prevents, attenuates or reverses bone loss is therefore highly desirable. 7One such intervention under investigation is functional electrical stimulation (FES) rowing. 8 In the present configuration, FES...
Study design: A single case study. Objectives: To compare proximal tibia trabecular bone mineral density (BMD) of a participant with complete spinal cord injury (SCI), long-termed functional electrical stimulation-rowing (FES-R) trained, with previously reported SCI and non-SCI group norms. To estimate lower limb joint contact forces (JCFs) in the FES-R trained participant. Setting: UK University and orthopaedic hospital research centre. Methods: Bilateral proximal tibial trabecular BMD of the FES-R trained participant was measured using peripheral quantitative computerised tomography, and the data were compared with SCI and non-SCI groups. An instrumented four-channel FES-R system was used to measure the lower limb JCFs in the FES-R trained participant. Results: Structurally, proximal tibial trabecular BMD was higher in the FES-R trained participant compared with the SCI group, but was less than the non-SCI group. Furthermore, left (184.7 mg cm À3 ) and right (160.7 mg cm À3 ) BMD were well above the threshold associated with non-traumatic fracture. The knee JCFs were above the threshold known to mediate BMD in SCI, but below threshold at the hip and ankle. Conclusion: As pathological fractures predominate in the distal femur and proximal tibia in chronic SCI patients, the fact that the FES-R trained participant's knee JCFs were above those known to partially prevent bone loss, suggests that FES-R training may provide therapeutic benefit. Although the elevated bilateral proximal tibial BMD of the FES-R participant provides circumstantial evidence of osteogenesis, this single case precludes any statement on the clinical significance. Further investigations are required involving larger numbers and additional channels of FES to increase loading at the hip and ankle. Spinal Cord (2014) 52, S4-S5; doi:10.1038/sc.2014.112 INTRODUCTIONOsteoporosis is a known secondary complication of spinal cord injury (SCI) characterised by low bone mineral density (BMD), which results in a high incidence of pathological fractures in the distal femur and proximal tibia. 1 Physical therapy is one strategy under investigation to mediate bone loss in SCI by increasing muscle-induced skeletal loading. 2 In the SCI model, functional electrical stimulation (FES) is required to activate paralysed muscle. Although the dose-response in the SCI model is unknown, compressive loads of 1-2 times body weight, delivered by FES-induced muscle contractions, have been found to partially prevent bone loss after SCI. 2 The aims of this study were to: (1) compare the lower limb BMD of a participant with long-term FESrowing (FES-R) trained with SCI and non-SCI groups, using peripheral quantitative computerised tomography imaging and (2) establish the magnitude of joint contact forces (JCFs) in the lower limbs of the FES-R trained participant. MATERIALS AND METHODSThe participant for these trials (Table 1), and author of this paper, had been FES-R trained for 48 years as described in reference 3 using quadriceps and hamstring controlled FES-activation. Th...
Potentially, functional electrical stimulation (FES)-assisted exercise may have an important therapeutic role in reducing comorbidities associated with spinal cord injury (SCI). Here, we present an overview of these secondary life-threatening conditions, discuss the rationale behind the development of a hybrid exercise called FES rowing, and describe our experience in developing FES rowing technology. FES rowing and sculling are unique forms of adaptive rowing for those with SCI. The paralyzed leg musculature is activated by multiple channels of electrical pulses delivered via self-adhesive electrodes attached to the skin. The stimulated muscle contractions are synchronized with voluntary rowing movements of the upper limbs. A range of steady-state FES rowing exercise intensities have been demonstrated from 15.2 ± 1.8 mL/kg/min in tetraplegia to 22.9 ±7.1 mL/kg/min in paraplegia. We expect that such high levels may help some to achieve significant reductions in the risks to their health, particularly where a dose-response relationship exists as is the case for cardiovascular disease and Type II diabetes. Furthermore, preliminary results suggest that cyclical forces more than 1.5 times body weight are imposed on the leg long bones which may help to reduce the risk of fragility fractures. We have demonstrated the feasibility of FES rowing on land and water using adapted rowing technology that includes; a fixed stretcher indoor ergometer (adapted Concept 2, Model E), a floating stretcher indoor ergometer (adapted Concept 2 Dynamic), a turbine powered water rowing tank, a custom hydraulic sculling simulator and a single scull (adapted Alden 16). This has involved volunteers with paraplegia and tetraplegia with SCI ranging from C4 to T12 AIS A using at least 4-channels of surface electrical stimulation. FES rowers, with SCI, have competed alongside non-SCI rowers over the Olympic distance of 2000 m at the British Indoor Rowing Championships in 2004, 2005, and 2006 and the World Indoor Rowing Championships in 2006 (CRASH-B's) in Boston, MA, USA. The best 2000 m FES rowing performance to date has been achieved by a 23-year-old male, Tom Aggar T12 AIS A, in 10 min 28 s. Moreover, two of our FES rowers with complete paraplegia have gone on to successfully compete in the Adaptive Rowing arms-only category (AM1x) at the World Rowing Championships and Paralympic Games.
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