W.D. Spence

The characterisation of gait patterns of people with multiple sclerosis

Background. There are relatively few reports describing gait patterns in multiple sclerosis (MS) and most are confined to the analysis of temporal distance parameters with some assessment of joint range of motion. The aim of this study was to perform a biomechanical characterisation of gait patterns among people with MS across a wide range of severity of ambulatory impairment. Methods. Sixteen patients with MS were recruited for this study. Initially, the spasticity of lower limb muscle groups was measured and ambulatory ability was graded. Patients were then placed in two groups based on the level of severity of ambulatory ability. Kinematic, kinetic and EMG gait data from both MS groups were then compared to a control group of 10 healthy subjects. Results. Patients with MS in both groups were found to walk with reduced gait speed, reduced maximum hip and knee extension, ankle plantarflexion angle and propulsive force compared to the control group. In general, the same gait impairments were found in both MS groups compared to the control group, and were greater for the more severely affected MS patient group. Interpretation. This study highlights typical gait patterns of people with MS and provides an indication of common pathways in the degeneration of ambulatory ability as a consequence of disease progression. This information should enable improved clinical treatment of ambulation, as well as the prescription, or even design, of appropriate assistive devices.

Ultrasound imaging in lower limb prosthetics

The biomechanical interaction between the residual limb and the prosthetic socket determines the quality of fit of the socket in lower limb prosthetics. An understanding of this interaction and the development of quantitative measures to predict the quality of fit of the socket are important for optimal socket design. Finite-element modeling is used widely for biomechanical modeling of the limb/socket interaction and requires information on the internal and external geometry of the residual limb. Volumetric imaging methods such as X-ray computed tomography, magnetic resonance imaging, and ultrasound have been used to obtain residual limb shape information. Of these modalities, ultrasound has been introduced most recently and its development for visualization in prosthetics is the least mature. This paper reviews ultrasound image acquisition and processing methods as they have been applied in lower limb prosthetics.

The potential for actigraphy to be used as an indicator of sitting discomfort.

Objective: A novel technique that uses actigraphy, the study of activity involving the use of body-mounted accelerometers, to detect the discomfort-related movements of a sitting individual has been proposed as a potential indicator of sitting discomfort, and the purpose of this study was to test its validity. Background: Objective measurement of sitting discomfort has always been challenging for researchers. Electromyographic measurements, pressure mapping, and a wide range of other techniques have all been investigated with limited success. Method: The activity monitor’s ability to detect and measure seated movement was assessed, and 12 participants were tested on four different chairs (100-min sessions for each). Results: The activity monitor was able to detect participants’ sitting movements (Pearson coefficients > 0.9). The chairs were shown to have significantly different subjective discomfort ratings, all of which increased over time. The movements detected by the activity monitor also increased significantly with time, and the amount measured was greater in the chairs rated as most uncomfortable. Regression analysis indicated that the actigraphy data were able to account for 29.6% of the variation in perceived discomfort ratings. Conclusion: Actigraphy can reliably detect sitting movements and may be of use in measuring sitting discomfort. Application: Potential applications of this technique exist for seating research in the automotive industry, health care, and office and leisure chairs.

Ambulatory rehabilitation in multiple sclerosis

Multiple sclerosis (MS) is an autoimmunogenic disease involving demyelination within the central nervous system. Many of the typical impairments associated with MS can affect gait patterns. With walking ability being one of the most decisive factors when assessing quality of life and independent living, this review focuses on matters, which are considered of significance for maintaining and supporting ambulation. This article is an attempt to describe current research and available interventions that the caring healthcare professional can avail of and to review the present trends in research to further these available options. Evidence-based rehabilitation techniques are of interest in the care of patients with MS, given the various existing modalities of treatment. In this review, we summarise the primary factors affecting ambulation and highlight available treatment methods. We review studies that have attempted to characterise gait deficits within this patient population. Finally, as ambulatory rehabilitation requires multidisciplinary interventions, we examine approaches, which may serve to support and maintain ambulation within this patient group for as long as possible.

Transducers for the determination of the pressure and shear stress distribution at the stump-socket interface of trans-tibial amputees

Abstract Recent developments in prosthetic socket design have created renewed interest in monitoring the stress distribution at the socket—residual limb interface. Although a few devices for measuring pressure can be found in the literature, none are capable of measuring reliably in areas of high curvature, such as the important area at the patellar tendon bar. Furthermore, few devices can record shear stress, thought to be critical in causing tissue damage. In order to address these issues two new transducers have been designed and evaluated. One design allows the simultaneous recording of the normal and shear stresses at various points of the socket walls, while the other is capable of measuring the three components of the force applied on the patellar tendon. The latter design incorporates a feature that permits displacement of the patellar tendon bar, in order to study the effect of various amounts of indentation of the tendon on the stress distribution around the residual limb. Both transducers were calibrated using dead weights and special jigs to ensure accurate loading conditions. Under laboratory bench conditions the normal—shear force transducer showed: 2.03 per cent full scale output (FSO) hysteresis error for shear stress direction, 1.65 per cent FSO for normal direction; 99.56 per cent FSO overall accuracy for shear direction, and within 99.64 per cent FSO for normal direction; and for the patellar tendon transducer 1.53 per cent FSO hysteresis error for shear direction, 1.85 per cent FSO for shear stress direction; 99.65 per cent FSO overall accuracy for shear direction, and 99.58 per cent FSO for normal direction. During an amputee walking trial the transducers showed 92 per cent to 97 per cent repeatability. The two new transducers were used in conjunction with two other types of transducers, previously designed at the University of Strathclyde, in a series of tests on ten trans-tibial amputees. Sample results for walking activities and a summary of maximum stresses recorded are presented.

The patellar tendon bar! Is it a necessary feature?

The purpose of this investigation was to vary the load on the patellar tendon bar and to study the subsequent effect this has on the pattern of the pressure distribution at the stump-socket interface. Ten male subjects from the Southern General Hospital in Glasgow, UK participated in this study. Measuring systems utilising strain gauge and electrohydraulic technologies were designed, developed and constructed to enable pressure measurements to be conducted. One transducer, the patellar tendon (PT) transducer, was attached to the patellar tendon bar of the socket such that the patellar tendon bar was capable of being translated by +/-10 mm towards or away from the tendon. The results of this study showed that the position of the patellar tendon bar had no significant effect on the pressure distribution around the socket indicating that it is an unnecessary feature, which, we propose, may be eliminated during manufacture of a trans-tibial socket.

An investigation of teaching staff members' and parents' views on the current state of adaptive seating technology and provision

Purpose. It is recognized that for children with poor postural control, a comfortable adaptive seating system which provides them with the support needed to maintain a sitting position can be essential for raising their overall level of well being. The purpose of this study was to investigate the views of teaching staff members at special needs schools and of the parents of children who attended these schools on the provision and current technology of seating systems. Method. Two similar questionnaires intended to elicit the views of teaching staff and the parents of children attending these schools were designed and distributed to these groups. Results. Dissatisfaction exists with reliability of these systems and the time it takes for replacement systems to be issued. The perceived importance of adaptive seating role in the user being accepted by peers was found to be statistically different between the two groups. Time spent per day transferring the child to and from seating systems was found to be greater than 1 h for both groups. Conclusion. Scope remains for improvements to be made in adaptive seating provision and technology. Although mainly descriptive, these results could be of use when developing newer systems and improving services.

Automatic segmentation of magnetic resonance images of the trans-femoral residual limb

An automatic algorithm for the extraction of the skin and bone boundaries from axial magnetic resonance images of the residual limb of trans-femoral amputees is presented. The method makes use of K-means clustering and mathematical morphology. Statistical analysis of the results indicates that the computer-generated boundaries compare favourably to those drawn by human observers. The boundaries may be used in biomechanical modelling of the interaction between the residual limb and the prosthetic socket. The limb/socket interface determines the quality of prosthetic fit, therefore knowledge of this interface is important for the improvement of socket design in order to achieve patient comfort and mobility.

The Effect of Impaired Plantar Sensation on Gait in People with Multiple Sclerosis

People with multiple sclerosis (MS) often experience debilitating motor and sensory dysfunction. The aim of this study was to determine whether impaired plantar sensation affects gait patterns in MS patients, as it does in other patient populations such as those with diabetes mellitus. Sixteen patients with MS were recruited and divided into two groups according to their ambulatory ability. Ten healthy subjects made up a control group. Plantar sensation thresholds were measured and kinematic and kinetic gait data were collected for both MS groups and the control group. The MS patients had less sensation than the control group at all plantar sites tested. Gait speed and hip, knee, and ankle joint sagittal plane excursion were significantly lower in both MS groups than in the control group. Braking and push-off ground reaction forces were significantly lower in both MS groups than in the control group, and patients were found to carry the limb through the swing phase using the hip flexors and knee extensors...

Automatic boundary extraction from magnetic resonance images of the residual limb of a trans-femoral amputee

Information about the relative locations of different tissue types in the residual limb is required for biomechanical analysis of the interaction between the limb and the prosthetic socket. An automatic method for the extraction of the boundaries of muscle, fat, and bone from transverse magnetic resonance images of the residual limb of a unilateral trans-femoral amputee is presented. Median filtering is applied for smoothing, segmentation is achieved by k-means clustering, and boundaries are extracted using mathematical morphology.