A wireless acquisition system for monitoring the influence of loads on vertebral column behaviour

This paper presents a wireless acquisition module (WAM). This allows the monitoring of heavy loads influence on vertebral column’s behaviour. Each module makes the electromyography (EMG), to measure the electric potentials on the iliocostalis and longissimus thoracis muscles, and use a dual-axis accelerometer to get the movements of the body, in order to obtain the complete behaviour of the vertebral column. The solution chosen to transmit the body’s measured signals for further processing, is a wireless link working in the 433 MHz ISM band. The acquired information is transmitted with a maximum rate of 40 kbps, a resolution of 9.8 V, and accommodates two analog channels. An analog channel with differential input connected to the electrodes, is used to measure the EMG signal, while the remained channel is used in the patient’s movements measurements. The dimensions of the proposed acquisition system are about 7×5×2 cm, and will help to understand the influence of heavy loads as a risk factors in the vertebral column, such as the scoliosis and lordosis

Studies on Spinal Fusion from Computational Modelling to ‘Smart’ Implants

Low back pain, the worldwide leading cause of disability, is commonly treated with lumbar interbody fusion surgery to address degeneration, instability, deformity, and trauma of the spine. Following fusion surgery, nearly 20% experience complications requiring reoperation while 1 in 3 do not experience a meaningful improvement in pain. Implant subsidence and pseudarthrosis in particular present a multifaceted challenge in the management of a patient’s painful symptoms. Given the diversity of fusion approaches, materials, and instrumentation, further inputs are required across the treatment spectrum to prevent and manage complications. This thesis comprises biomechanical studies on lumbar spinal fusion that provide new insights into spinal fusion surgery from preoperative planning to postoperative monitoring. A computational model, using the finite element method, is developed to quantify the biomechanical impact of temporal ossification on the spine, examining how the fusion mass stiffness affects loads on the implant and subsequent subsidence risk, while bony growth into the endplates affects load-distribution among the surrounding spinal structures. The computational modelling approach is extended to provide biomechanical inputs to surgical decisions regarding posterior fixation. Where a patient is not clinically pre-disposed to subsidence or pseudarthrosis, the results suggest unilateral fixation is a more economical choice than bilateral fixation to stabilise the joint. While finite element modelling can inform pre-surgical planning, effective postoperative monitoring currently remains a clinical challenge. Periodic radiological follow-up to assess bony fusion is subjective and unreliable. This thesis describes the development of a ‘smart’ interbody cage capable of taking direct measurements from the implant for monitoring fusion progression and complication risk. Biomechanical testing of the ‘smart’ implant demonstrated its ability to distinguish between graft and endplate stiffness states. The device is prepared for wireless actualisation by investigating sensor optimisation and telemetry. The results show that near-field communication is a feasible approach for wireless power and data transfer in this setting, notwithstanding further architectural optimisation required, while a combination of strain and pressure sensors will be more mechanically and clinically informative. Further work in computational modelling of the spine and ‘smart’ implants will enable personalised healthcare for low back pain, and the results presented in this thesis are a step in this direction

A go-to-market strategy for vertebral metrics

Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica“A Go-to Market Strategy for Vertebral Metrics” is a project for commercialization of a technology capable of measuring the spatial coordinates of previously marked points. The device has been initially development for spine assessment even though it can be applied in different fields. The strategy for market penetration followed outlines some of these applications but will focus on the original purpose for which de device has been created. Market research analysis has resulted in different target segments ranging from small and medium sized healthcare providers to health club and wellness facilities. The project‟s timeline proposed for the next 6 years will be the following: Product development by NGNS, Innovative Solutions (Developer of Vertebral Metrics current prototype) to be finished in 2012. Sales initiation in Portugal (2013) followed by the product‟s entrance in Spain (2014) and Italy (2015). Commercialization will depend upon the creation of a new company called IHS – Innovative Healthcare Solutions which will manage sales, marketing and financial activities. Product assembly and early technical support will be performed by NGNS. Technical assistance will be, with time, incorporated in IHS and production outsourced, with NGNS maintaining its activity as an R&D partner. Marketing objectives will focus on attracting new customers and establishing partnership with both suppliers and distributors. IHS will have its own sales force in Portugal and depend upon partners for local distribution in other countries. The project depends upon an initial investment of 500 000€ with a payback period of 4 years and 3 months. The return is expected to be 6 times higher than the initial investment after 6 years

Smart implant: the biomechanical testing of instrumented intramedullary nails during simulated callus healing using telemetry for fracture healing monitoring

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonThe purpose of this study is to investigate the effect of loading during long bone fracture healing in-vitro and in-vivo. Fracture healing has until now only been monitored using radiographs and ultrasound. An intramedullary nail instrumented with strain gauges has the potential to monitor loading in-vivo during bone fracture healing. Strain has been previously monitored over time though external fixation devices however there has been no published data about monitoring through a nail. The load carried by a telemetric intramedullary nail during simulated fracture healing is monitored in-vitro with the aid of custom designed jigs, integrated in a biomechanical test frame. Clinically predetermined loading conditions are applied to the construct and synthetic bone composites are used developed to simulate mechanical strength of early to mature osteogenic bone, approximating natural healing processes. Four different synthetic bone composites have been designed and developed to mimic the mechanical properties of granulation tissue, fibrous tissue, cartilaginous tissue and immature bone. Three different generations (GEN I – IIIa) of intramedullary nails were developed and biomechanically tested in-vitro. GEN I and II were purely biomechanical nails that underwent compression, torsional and 4pt bend tests. Different fracture patterns and callus morphology were simulated and tested biomechanically. Circumferential and segmental application of the synthetic materials were applied on the artificial fractured bone instrumented with GEN I. Observations from live animal study provided x-rays from which callus growth patterns were extracted and repeated in-vitro. Cadaveric biomechanical tests and pre-clinical trial of GEN IIIa was conducted. The aim was to repeat the biomechanical tests while at the same time monitoring healing with an instrumented nail implanted in an induced fractured, ovine left hind limb. A loading rig was designed for the in-vivo test. The hypothesis proposed is that forces experienced by an intramedullary nail will progressively decrease as fracture heals. Results from GEN I have shown that strain measurement can be monitored during fracture healing in-vitro. The GEN IIIa nail is yet to be tested in-vivo for the same biomechanical tests for comparison. There is currently no published study on simulating fracture healing with accuracy.Smith & Nephew Plc (S&N) & the Technology Strategy Board (TSB

Vibration transmission through the human spine during physical activity

Osteoporosis causes bone to become fragile. Pharmacological treatments of osteoporosis are burdened with adverse effects and increase bone mineral density (BMD) only between 1% and 15% depending on the drug and time used. Thus non pharmacological treatments are needed to complement pharmacological ones. Physical activity is a non pharmacological treatment of osteoporosis and is essential for maintaining bone health at any age. However, physical activities have been identified to produce a modest improvement of spinal strength or just preserve it. In addition, it is not known how much exercise is optimal and safe for people with spinal osteoporosis. Most research employs conflicting definitions of physical activity and measure the effect of exercise on BMD alone instead of combining it with measurements of three dimensional bone strength. There is the need to offer a technique to measure the effect of physical activity on the overall strength of the spine, not only on its bone mineral content. Vibration transmissibility is a measurement of the mechanical response of a system to vibration expressed as stiffness or damping, thus offering a variable that represents structural strength. It can be employed to measure the mechanical response of the human spine during physical activity by attaching inertial sensors over the spine. However, it has not been employed to characterize the way vibration is transmitted through the osteoporotic spine during physical activity. Understanding the effects of osteoporosis and ageing on vibration transmission is important since such effects are related to the stiffness of the spine and thus very likely to the incidence of vertebral fractures. It is also often recommended that fast walking is beneficial to the bone, yet it is not known if fast walking affects the mechanical response of the spine of people with osteoporosis. The aims of this study were (1) to evaluate the feasibility of employing inertial sensors and a skin correction method to measure vibration transmission through the spine during physical activity (2) to characterize the transmission of vibration in the lumbar and thoracic spines of people with and without osteoporosis during physical activities, (3) to characterize the effect of osteoporosis on vibration transmissibility at levels of the thoracic spine which are known to fracture and (4) to investigate the effects of fast walking on vibration transmissibility. 100 young and healthy and older volunteers with and without osteoporosis were recruited. Participants were asked to perform straight walking, stair negotiation and turning while having inertial sensors attached to the skin over the spinous process of the first sacral (S1), twelfth (T12), eighth (T8) and first thoracic vertebrae (T1). Vibration transmissibility was calculated as the square root of the acceleration of the output (T12 for the lumbar and T1 for the thoracic spine) over the input (S1 for the lumbar and T12 for the thoracic spine) in the frequency spectrum. Vibration transmissibility was corrected for the movement of the skin-sensor interface and for the inclination of the sensor over the spine of every subject. All physical activities were performed at self selected normal and fast walking speeds. Lumbar and thoracic curvatures were determined with an electromagnetic device and BMD was measured through quantitative ultrasound. Skin measurement of transmission of vertical vibration is feasible with the inertial sensors and correction method presented. Vibration transmissibility through the human spine is significantly different between dissimilar physical activities and frequency dependent. Ageing significantly alters the vibration transmissibility of the spine. Osteoporosis has a minimal effect on vibration transmissibility of the spine. The effect of ageing and osteoporosis are frequency dependent. Older lumbar spines may receive greater stimulation than young and healthy ones, whereas older thoracic spines may receive lower stimulation during fast walking. There are significant differences in vibration transmissibility between lumbar and thoracic spines. A percentage of vibration transmission of the lumbar and thoracic spines is determined by their curvatures. This thesis has provided a technique that future research can employ to correlate vibration transmissibility with mechanotransduction signals in bone as well as volumetric bone health measurements and the risk of vertebral fractures. Until then it will be possible to prescribe physical activity taking into account individual capabilities, bone strength and differences in mechanical response between lumbar and thoracic sections

Spinal fusion and computer methods : an FEA study into ovine lumbar vertebrae fusion.

Spinal fusion is a surgery undertaken to relieve pain or degeneration in the spine. This involves the fixing together of two or more vertebrae and the promotion of bone growth to fuse the vertebrae together. Diagnosis time for spinal fusion surgery averages 4 months and the economic costs of lost productivity are significant. The ability to measure the process of spinal fusion in real time would have the potential to reduce the diagnosis time by half as the fusion mass created during the spinal fusion healing process is strong enough to support normal activities before it becomes visible on medical imaging methods. Implantable sensors would allow for the loads through the spine to be measured, allowing doctors to give their patients a shorter recovery plan based on how their spine is fusing. Sheep are an ideal analogue for human spinal implant development as they have a spine structure that closely matches the human spine, and thus spinal implants can be tested on sheep for verification of design to ensure that human trials have a higher likelihood of success. A large research gap found was the lack of sheep models that allow the virtual prototyping of spine implants before an animal study is required. This thesis discusses the construction of such a model from CT imaging to CAD to the construction of an FEA model. The FEA model considers the effect of material strength changes in the bone healing zones (fusion mass) and how load transference though the spine is affected. The model shows that with gradual increase in bone strength and stiffness, strain through the pedicle rods is reduced. This thesis also discusses the development of methods to measure stiffness changes on fused sheep spines. The mechanical testing apparatus was partially verified by testing sheep spines subjected to simulated spinal fusion

Book of Abstracts 15th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering and 3rd Conference on Imaging and Visualization

In this edition, the two events will run together as a single conference, highlighting the strong connection with the Taylor & Francis journals: Computer Methods in Biomechanics and Biomedical Engineering (John Middleton and Christopher Jacobs, Eds.) and Computer Methods in Biomechanics and Biomedical Engineering: Imaging and Visualization (JoãoManuel R.S. Tavares, Ed.). The conference has become a major international meeting on computational biomechanics, imaging andvisualization. In this edition, the main program includes 212 presentations. In addition, sixteen renowned researchers will give plenary keynotes, addressing current challenges in computational biomechanics and biomedical imaging. In Lisbon, for the first time, a session dedicated to award the winner of the Best Paper in CMBBE Journal will take place. We believe that CMBBE2018 will have a strong impact on the development of computational biomechanics and biomedical imaging and visualization, identifying emerging areas of research and promoting the collaboration and networking between participants. This impact is evidenced through the well-known research groups, commercial companies and scientific organizations, who continue to support and sponsor the CMBBE meeting series. In fact, the conference is enriched with five workshops on specific scientific topics and commercial software.info:eu-repo/semantics/draf

Combined musculoskeletal and finite element modelling of the lumbar spine and lower limbs

Bone health deterioration is a major public health issue increasing the risk of fragility fracture with a substantial associated psychosocioeconomic impact. In the lumbar spine, physical deconditioning associated with ageing and chronic pain is a potential promoter of bone structural degradation. General guidelines for the limitation of bone loss and the management of pain have been issued, prescribing a healthy lifestyle and a minimum level of physical activity. However, there is no specific recommendation regarding targeted activities that can effectively maintain lumbar spine bone health in populations at risk. The aim of this thesis was to develop a new predictive computational modelling framework for the study of bone structural adaptation to healthy and pathological conditions in the lumbar spine. The approach is based on the combination of a musculoskeletal model of the lumbar spine and lower limbs with structural finite element models of the lumbar vertebrae. These models are built with bone and muscle geometries derived from healthy individuals. Based on daily living activities, musculoskeletal simulations provide physiological loading conditions to the finite element models. Cortical and trabecular bone are modelled with shell and truss elements whose thicknesses and radii are adapted to withstand the physiological mechanical environment using a strain driven optimisation algorithm. This modelling framework allows to generate healthy bone architecture when a loading envelope representative of a healthy lifestyle is applied to the vertebrae, and identify influential activities. Prediction of bone remodelling under altered loading scenarios characteristic of lumbar pathologies can also be achieved. The modelling approach developed in this thesis is a powerful tool for the investigation of bone remodelling in the lumbar spine. Preliminary results indicate that locomotion activities are insufficient to maintain lumbar spine bone health. Specific recommendations to limit the effect of physical deconditioning related to muscle weakening back pain are suggested. The approach is also promising for the investigation of other lumbar pathologies such as age related osteoporosis and scoliosis.Open Acces

Relationships between lumbar inter-vertebral kinematics and paraspinal myoelectric activity during sagittal flexion: a quantitative fluoroscopy and surface electromyography study

Introduction. Previous investigations that have attempted to relate mechanical parameters to NSLBP groups are often contradictory of each other, and currently clear mechanical markers for LBP remain elusive. In order to move forward in this area, it may be necessary to take a step back, and improve understanding of ‘normal’ spinal biomechanics (i.e. in low back pain free populations). Indeed, Peach et al. (1998) stated “By knowing what is “normal” and what is “abnormal” it may be possible to provide objective evaluation of rehabilitation protocols, and possibly classify different low back pathologies” (Peach et al. 1998). Therefore, an improved understanding of biomechanical behaviours in groups of back pain free people is desirable, particularly at an inter-vertebral level, an area where clear knowledge gaps still exist. Control of the spine during voluntary movement requires finely-tuned coordination of numerous trunk muscles. This dynamic control is believed to be achieved via communication between three sub-systems, the passive (vertebrae, discs and ligaments), the active (muscles and tendons) and the control (central and peripheral nervous system) systems. Investigating the interplay between these sub-systems however is difficult, as the spine is a complex structure with a hidden kinematic chain. Quantitative fluoroscopy (QF) is an imaging technology capable of measuring continuous spinal kinematics at the inter-vertebral level, and surface electromyography (sEMG) provides a non-invasive means of objectively quantifying muscle activity. This study used QF and sEMG technologies concurrently to investigate relationships between and amongst lumbar kinematic (QF determined) and muscle activity (sEMG determined) variables, during weight-bearing active forward flexion. This was the first time such technologies have been combined to investigate the biomechanics of the lumbar spine in vivo. An improved understanding of normal lumbar kinematic and myoelectric behaviour, will assist in the interpretation of what is abnormal in terms of inter-vertebral spinal mechanics. Methods. Contemporaneous lumbar sEMG and QF motion sequences were recorded during controlled active flexion of 60° in 20 males with no history of low back pain in the previous year. Electrodes were placed adjacent to the spinous processes of T9, L2 and L5 bilaterally, to record the myoelectric activity of the thoracic and lumbar erector spinae (TES and LES) and lumbar multifidus (LMU) respectively. QF was used concurrently to measure the maximum inter-vertebral rotation during flexion (IV-RoMmax) and initial attainment rate for the inter-vertebral levels between L2 and S1, as well as each participant’s lordotic angle. The sEMG amplitude data were expressed as a percentage of a sub-maximal voluntary contraction (sMVC). Ratios were calculated between the mean sEMG amplitudes of all three muscles examined. Each flexion cycle was also divided into five epochs, and the changes in mean sEMG amplitude between epochs were calculated. This was repeated to determine changes between all epochs for each muscle group. Relationships between IV-RoMmax and all other kinematic, morphological (i.e. lordosis) and muscle activity variables were determined using correlation coefficients, and simple linear regression was used to determine the effects of any significant relationships. The reliability and agreement of the IV-RoMmax, initial attainment rate, and normalised RMS sEMG measurements were also assessed. Results. The reliability and agreement of IV-RoMmax, initial attainment rate and sEMG amplitude measurements were high. There were significant correlations between the IV-RoMmax at specific levels and the IV-RoMmax at other lumbar motion segments (r = -0.64 to 0.65), lordosis (r = -0.52 to 0.54), initial attainment rate (-0.64 to 0.73), sEMG amplitude ratios (r = -0.53) and sEMG amplitude changes (r = -0.48 to 0.59). Simple linear regression analysis of all significant relationships showed that these variables predict between 18% and 42% of the variance in IV-RoMmax. Conclusion. The study found moderately strong relationships between kinematic, morphological and muscle activity amplitude variables and the IV-RoMmax of lumbar motion segments. The effects of individual parameters, when combined, may be important when such inter-vertebral levels are considered to be sources of pain generation or targets for therapy. This is an important consideration for future non-specific low back pain (NSLBP) research, as any attempts to associate these parameters with low back pain (LBP), should also now take in to account the normal biomechanical behaviour of an individual’s lumbar spine. Indeed, consideration should be given to the interactions that exists between such parameters, and they should not be considered in isolation. Multivariate investigations in larger samples are warranted to determine the relative independent contribution of these variables to the IV-RoMmax