A new structural concept in moulded fixed ankle foot orthoses and comparison of the bending stiffness of four constructions.

There are many reasons why a rigid ankle foot orthosis (AFO) may be prescribed. In some cases it is desirable that the rigidity is sufficient to maintain a constant ankle position throughout the gait cycle. There is a need to determine a design of cosmetic, lightweight AFO that provides the necessary stiffness whilst being acceptable to the patient, encouraging continued wear with the resultant benefits. This paper describes an investigation of AFO resistance to dorsiflexion, comparing the stiffness of an AFO with forward trim lines, two designs of reinforced AFOs and an AFO with forward trim lines and an external ankle strap. One reinforced AFO had corrugations moulded in the polypropylene around the ankle, the other had carbon fibre inserts attached to the inside of the polypropylene. The emphasis was on testing the mechanical stiffness of the four AFO designs: the test procedure did not mimic the patterns of AFO loading during gait. Each design was tested in the same manner by the same examiner. The AFO with forward trimlines and an ankle strap displayed similar stiffness to the carbon fibre reinforced AFO and both were stiffer than the other two designs.

Comparison of rocking edge spacing for two common designs of swivel walkers.

Two commonly used designs of swivel walker are the Consort 800 and the ORLAU 1000. This paper examines how the footplate rocking edge spacing varies between these two designs and then considers how lateral stability might be influenced if reduced separation is introduced to facilitate ambulation for less able users. In general it is shown that there should be no obstacles to such variation on the part of an orthotist thereby improving access to these devices and function for disabled individuals.

Population genetics of wolf spiders of fragmented habitat in the wheat belt of New South Wales.

Possible effects of habitat fragmentation on the population genetics of a species of wolf spider (Lycosidae) from remnant Callitris woodland in the wheat belt of central western New South Wales in Australia are examined. Single-strand conformational analysis of mitochondrial cytochrome oxidase (subunit 1) was used to characterize the haplotypes of 295 spiders in six blocks each of four woodland sites. DNA sequences were collected from 119 of these spiders to confirm haplotype scoring, allow phylogeny estimation and permit calculation of sequence-based statistics. Intra-block tests do not suggest widespread effects of fragmentation. Genetic diversity is high in all blocks, with 25 haplotypes being identified. Nucleotide diversity is relatively low, as all of the haplotypes are closely related. One block had a significantly low value for the Ewens/Watterson test of neutrality and one block's value was nearly significantly high. Two blocks had nearly significant values of the Harpending Raggedness Index testing for recent population bottlenecks. No other intrablock tests approach significance. Interpopulation comparisons show significant nonhomogeneity of haplotype frequencies globally and in all pairwise comparisons. Relationships between woodland blocks based on haplotype frequencies are discordant with geographical proximity. Haplotype distribution patterns suggest that population structuring existed prior to fragmentation. We develop two measures of genetic distinctiveness to identify subpopulations of interest for conserving evolutionary processes in a species' regional population. One is based on the sum of pairwise FST values and one on the spatial distribution of genetic variation. High values of the measure suggest a subpopulation might have been recently perturbed and low values that it is relatively undisturbed. The two measures identify different blocks as being of particular interest.

Learning motor control in the upright position: a mechanical engineering approach.

Motor control problems that result from damage to the central nervous system can make it difficult to learn functional activities. Although several therapeutic approaches attempt to address such problems there is little evidence of their efficacy. Targeted Training is a new approach, based on a biomechanical analysis of the problem, which usually relies on specifically designed equipment. This paper describes the underlying theory, the development of functional specifications, the translation of these specifications into an engineering design and the clinical results of applying the equipment. The promotion of head and trunk control provides an example of the process.

A rear support walking frame for severely disabled children with cerebral palsy: initial development.

Ambulation for patients with total body involved cerebral palsy poses greater problems than those encountered in providing reciprocal walking for thoracic lesion paraplegic subjects. Experience with a prototype system showed that an orthosis which controls the movement of the lower limbs, in combination with a walking frame giving anterior support, enables such patients to walk. Despite shortcomings which restricted the use of the system to an indoor environment it provided a sound basis on which to examine walking frames to address the problems which had been identified. A review of these devices showed that the most effective means of achieving this aim is the use of a wheeled walking frame which provides vertical support and truncal alignment via a sprung pantograph mounted to the rear of the patient (rear support walking frames). Trials were conducted with two existing rear support walking frames. These indicated their potential for severely disabled patients, but also identified the need for higher stiffness in the structure and more sensitive control of vertical support to be achieved if effective ambulation in a wider range of environments was to be made possible for the target group. Prototypes based on an existing frame, which took account of the specification requirements, were produced for four new total body involved cerebral palsy patients with the same degree of walking dysfunction. Three of the patients were able to walk in a much wider variety of environments than any patient in the original system. A number of other issues related to transfer and steering were identified as requiring further development.

Feasibility study on a composite material construction technique for highly stressed components in reciprocal walking orthoses for paraplegic patients.

Reciprocal walking for thoracic level paraplegic patients using reciprocal walking orthoses has become a routine treatment option. Two general design options are currently deployed within an overall treatment regime. Research has shown that one has better walking efficiency but is cosmetically less acceptable to the patient. Design analysis and experimental data have shown that a major factor in improved walking efficiency is the lateral stiffness of the body brace section of the orthosis. This is the area where problems of cosmesis in the more efficient orthosis are perceived because of the employment of metallic structures. The use of composite material structures to achieve shapes which are more closely conforming to the patient is an attractive option. However the brittle nature of these materials makes it unlikely that the requirement for the ductile failure mode will be achieved from a straightforward moulding. A new construction technique has been devised which has the potential to provide a safe failure mode with greater stiffness and lighter weight. This feasibility study has been undertaken to demonstrate its potential so that further work can be justified which will provide sufficient evidence to support a patent application. The successful outcome of the study, in which stiffness was increased by 60 per cent with a weight reduction of 50 per cent and a failure mode comparable with the original metal structure, suggests that further work will enable the dilemma in the choice of orthosis to be resolved.

A review of reciprocal walking systems for paraplegic patients: factors affecting choice and economic justification.

The prescription of treatment systems which include orthoses to enable patients with high level thoracic spinal lesions to walk reciprocally is now widely practised. It remains a clinical option for which the efficacy is frequently called into question. A broad range of experience has now been accumulated with orthoses of this type, and this is reflected in the literature. The indications for prescription and outcomes of treatment have, as a result of the reported research, become clearer. However, the length of time over which the relevant work has been published and the variety of journals in which it has appeared makes it difficult to perceive a coherent message. This review analyses the published work in order to identify the degree to which the therapeutic benefits which can accrue from ambulatory activity produce an economically justified outcome. Provided appropriate supply procedures are observed so that good patient compliance with the treatment is achieved, there is strong evidence that fewer pressure sores and improved independence will occur at a level where real overall cost savings can be made. Factors which affect patient compliance and on which research findings have been published are identified. Comparisons are made between different orthoses with regard to these, so that more informed choice, taking into account preferences of individual patients, can be made by clinicians.

A review of 42 patients of 16 years and over using the ORLAU Parawalker.

A 7 year retrospective review of 42 patients of 16 years or over using the ORLAU Parawalker has been conducted to establish the degree of long-term compliance in using the orthosis on a regular basis. Regular use was defined as putting the orthosis on at least once a week. All subjects had been supplied with an ORLAU Parawalker via the routine supply procedures adopted in Oswestry, and were followed up at regular 6 month intervals as part of the standard treatment regime. The records from routine follow-up were surveyed for those patients who were continuing to use their orthosis to establish age, length of time since supply of orthosis and cause of lesion. Average period of usage is calculated for those still using their orthosis, and for all patients in the study. Of the 42 subjects, 32 were myelomeningocele patients with confirmed absence of innervation of hip extensors and abductors, the remainder being paraplegic patients with traumatic or acquired complete thoracic lesions. Compliance figures were extracted from the results, as were the minimum possible average periods of usage. The respective results were: of the 32 myelomeningocele patients 59.4% continued usage after an average period of 85.5 months, and of the 10 traumatic or acquired lesion patients 60% continued usage after an average period of 24.8 months respectively, which gave a combined compliance of 59.5% after a minimum average 71.1 months of use. The performance or myelomeningocele patients suggests that their additional deformities do not lead to inferior compliance as adults and that a high proportion to continue to walk after adolescence.

Improvement in gait parameters following late intervention in traumatic brain injury: a long-term follow-up report of a single case.

OBJECTIVE: To evaluate the effect of using an optimally adjusted fixed ankle foot orthosis to control knee pain and promote improvement in gait parameters in a subject with hemiplegia following a traumatic brain injury 11 years previously. DESIGN: This is the report of a single case, using gait laboratory facilities to monitor force alignment relative to the knee and single leg balance time with the subject barefoot. SUBJECT: A 35-year-old woman with a right hemiplegia seen 11 years after onset. INTERVENTION: A polypropylene fixed ankle foot orthosis was supplied to the hemiplegic limb and shoe modifications were made to optimize the position of the ground reaction force relative to the knee during stance phase of gait. This orthosis was used on a daily basis for one year. RESULTS: Knee pain was controlled after three months use of the orthosis. Graphical results of force alignment during stance phase of gait are presented for initial assessment and at one and four years postorthotic supply. A large knee-extending effect was noted on the hemiplegic limb at initial assessment and this was reduced by 67% of its initial value at one year. A compensatory early heel lift was initially noted on the opposite limb and this was reduced by 42% of the initial height at one year. These results were maintained at four years. Right leg standing balance was not initially possible but was recorded as 5 s duration at three months and this was maintained at one and at four years. CONCLUSIONS: The use of an optimally adjusted ankle foot orthosis was effective in controlling knee pain and improving barefoot gait parameters with maintenance of the improvement after use of the orthosis was discontinued. Further research is required to fully establish the potential of this approach in subjects with traumatic brain injury.

The potential for ambulation by severely handicapped cerebral palsy patients.

Whereas walking for paraplegic patients is now a routine clinical option, ambulation for heavily handicapped cerebral palsy patients is less well established. There are good reasons for supposing that therapeutic benefits similar to that achieved with paraplegic patients are possible for this group. However, the biomechanical problems which must be overcome are different and in many ways more difficult to address. The most important factors are identified as appropriate truncal support, control of abduction/adduction, rotation and flexion range at the hip, and of knee flexion. A means of applying these controls is described as being a combination of a walking frame and orthosis. The special walking frame provides adjustable support at thoracic, abdominal and sacral levels and incorporates castor steering and upper limb support. Controls on lower limb movements are applied through a special orthosis which has a readily available variation of specification to accommodate the wide range of conditions met in cerebral palsy. Practical application of a prototype system has shown that it can enable patients to walk unaided. However, in most cases it was used indoors only. Evaluation of the experience in applying the system has enabled the fundamental principles to permit more practical applications to be defined.

The use of the Orthotic Research and Locomotor Assessment Unit (ORLAU) ParaWalker by adult myelomeningocele patients: a seven year retrospective study--preliminary results.

There is a widely accepted perception that whereas many paediatric myelomeningocele patients use walking orthoses effectively, very few continue to ambulate in adult life. A seven-year retrospective review of 31 patients for whom the ORLAU ParaWalker (2) was prescribed in Oswestry showed that there was a 58% adult compliance rate. Of the 18 who continued walking the average age at supply was 11.28 years (range 5 to 24), average age at survey 22.61 yrs. (range 17 to 33) and the average period of use was 11.33 yrs. (range 3 to 16). These results compare surprisingly well with an ORLAU review of adult traumatic lesions who had a compliance rate of 63% and average follow-up of 2.87 years. The ORLAU ParaWalker has been shown to be an efficient form of walking and this is considered an important feature in ensuring that many adults can continue to take advantage of the proven therapeutic benefits of walking. Notwithstanding, the adult compliance rate shown in this study lends strength to the case for a vigorous and efficient walking programme in treating spina bifida children so as to promote the longer term health of the patient.

The influence of orthosis stiffness on paraplegic ambulation and its implications for functional electrical stimulation (FES) walking systems.

This study examines the evidence which supports the importance of maintaining relative abduction for effective reciprocal walking in high level paraplegic patients. In comparisons of orthoses, where this can only be achieved mechanically, those with higher lateral rigidity consistently showed greater levels of walking efficiency. The influence on hybrid systems of functional electrical stimulation (FES) of the gluteal muscles, where the primary function is to maintain abduction, also showed reductions in overall energy cost, reductions in upper limb effort, or both. Examination of the effect of increasing lateral rigidity of a purely mechanical orthosis by 10% showed that significant energy cost reductions were achieved (30% reduction in Physiological Cost Index) for patients with thoracic lesions experienced in reciprocal walking. A review of FES research suggested that for the modern healthcare sector the cost effectiveness of purely mechanical systems make them an attractive means of routinely providing the functional and therapeutic benefits of walking for high level paraplegic patients. In the prevailing climate of strict budgetry control a case is made for concentrating more research resources on improving still further walking efficiency, and resolving the outstanding problems of functionality and cosmesis in such systems for reciprocal walking.

The case for lateral stiffness in walking orthoses for paraplegic patients.

The provision of walking for paraplegic patients has therapeutic benefits but must be at a low energy cost. Although claims have been made regarding the need for high lateral stiffness in any orthosis targeted at this group, much of the supporting evidence was confusing. This paper presents the theoretical reasoning behind this claim and reviews recent evidence that would appear to support it.

Improvement in walking performance of children with cerebral palsy: preliminary results.

The effect of four to six months use of ankle-foot orthoses (AFOs) and balance training was determined for six children with cerebral palsy. The six consecutively referred patients had spastic diplegia or hemiplegia, with hyperextension of the knee, and had accurate voluntary control of the trunk and hips. Fixed AFOs were adjusted to control the position of the ground reaction force in relation to the knees. Balance training was targeted to the knees. All children showed a decrease in the magnitude of the knee-extending moment arm toward normal when barefoot. Improvement was noted in foot-ground contact for three children and of stance-phase posture for three. These improvements were not related to range of motion or speed, and a motor learning effect is proposed. The value of monitoring the moment arm is emphasised.

The Edinburgh-ORLAU prosthetic system to provide reciprocal locomotion in children and adults with complete transverse lower limb deficiency.

A novel prosthetic system to provide reciprocal locomotion in children and adults with complete transverse lower limb deficiency is described. This is based on the hip joints from the ORLAU ParaWalker, a system with a proven record of success in the orthotic management of paraplegic patients. The fitting of the prototype system to an eight year old girl is described. This experience shows that the orthotic principles of the ParaWalker, which provides reciprocal locomotion for the paraplegic, is equally applicable to the prosthetic situation. Developments are therefore continuing to improve the design and to enable further fittings.

A microcomputer-based video vector system for clinical gait analysis.

A microcomputer-based video vector system has been developed to display the resultant ground reaction force vector on a television image of the subject in real-time. For each television field the force platform signals are acquired and processed and the resultant force vector superimposed on the video image of the walking subject. The force platform results are stored on disc and the composite video signals recorded on video tape for further analysis. The system is easy to set up and use and the results can be readily interpreted. The external moments produced at the joint centers by the ground reaction forces can be observed visually and, if required, quantification of the external moments can be achieved following data collection. The spatial resolution of the system is 0.342% vertically and 0.156% horizontally. The force vector visualization technique has routine applications in orthotics and prosthetics. It is also a useful technique for the teaching of biomechanics.

Instrumentation used in clinical gait studies: a review.

This paper reviews the currently available instrumentation used for gait studies and discusses the clinical suitability of the various methods of recording gait parameters. Most of the presently available motion analysis systems appear to be more suited to research than to the routine clinical situation. However the video vector visualization technique appears to be the most useful clinically since it produces a real time display, is simple to operate and interpretation of the data is easier than other systems available. Some further development of the video vector visualization system is necessary to improve its accuracy and to produce quantitative information.

A review of the fundamental design problems of providing ambulation for paraplegic patients.

Walking for paraplegics with complete mid-thoracic lesions is now becoming a clinically viable reality. However, much of the literature in this field overstates the achievements and masks the difficulties that patients may encounter. This paper highlights Independence, Energy Cost, Cosmesis, Reliability and Cost as the five areas of prime interest involved in the design compromise for any walking system and urges that all relevant information for any system should be readily available to prescribers. Currently available walking systems are briefly considered.

Dynamics of reciprocal gait of adult paraplegics using the Para Walker (Hip Guidance Orthosis).

Force plate studies with nine adult traumatic complete paraplegics with lesion at thoracic level have shown that, unlike children walking in the Oswestry Hip Guidance Orthosis (Para Walker) system, they have to apply extra stabilizing forces through the crutches for safe walking. These forces are described and are attributed to an increased crutch force applied to prevent lateral deformation of the orthosis in stance phase.