Symposium on the Analysis and Management of Gait February 2019

ALLARD AFO on the Analysis & Management of Gait

INTRODUCTIONThe purpose of the Symposium was to stimulate debate and educate in the area of gait analysis and the treatment of drop foot. A broad level of experience and professional diversity was sought from the presenters to enable current practice and methodology to be examined and provide an informal verbal consensus to be achieved from open forum discussions during the last session of the symposium.

HISTORICAL PERSPECTIVE William MunroIn order to provide a context for the meeting, a historical perspective of innovation timelines relating to the advancement of material technologies, biomechanical understanding and where current best practice sits, was examined. Understanding of these areas would therefore inform where the potential for change and where future advancement in clinical practice in this area would be initiated.

THE ALLARD AFO STORY (Product Evolution and Design Considerations) Gunilla StrömA historical perspective was provided on the use of carbon fibre and the influence of Dr Stig Willner and Karl Engdahl, resulting in the awarding of a patent for the ToeOFF® in 1997. Design considerations for a dynamic, lightweight and non – custom device were discussed. The importance of customization to achieve success, and conversely, reasons for material failure, including fatigue and cyclic load were explained. Delamination testing to establish the efficiency of the Allard Carbon Fiber AFO designs was explained.

The importance of Void testing and geometrical shaping and whether 3D printing will have a place in manufacture in the future, were all outlined and discussed within this presentation.

The transition from conventional leather and metal, through to thermoplastic, to the advent of Carbon Fibre within orthotics was highlighted. It was stated that the thought process behind the original design considerations were that (1) it must have the ability to “mimic” the natural movements of the ankle”, (2) must have the ability to influence dynamics, (3) the components should be lightweight and comfortable, (4) allow the possibility of using a patient’s own shoes, in their own size (not upsizing to accommodate the AFO, and not needing to have custom made footwear. See Fig. 1, 2, & 3.

Fig. 1

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Fig. 2 Fig. 3

It was stated that today’s design considerations do stay true to the inherited functionality and seek to optimise the dynamics for different users and the fatigue properties. It was also explained that a recent, independently performed benchmarking exercise to measure the void content present within different well known and internationally available composite AFO products, resulted in the Allard AFO range displaying by far the lowest levels of those products tested (Fig. 4). Void content levels above 1% will have a negative effect on laminate quality, resulting in a reduction in some mechanical properties and thus the propensity for cracks/delamination to occur more rapidly.

What makes Allard Carbon Fibre Unique? Benchmarking – Void Content

Brace Average Void Content (%)

ToeOFF®2.0 0.2BlueROCKER® 0.1Competitor I 2.7Competitor II 2.3Competitor III 2.1Competitor IV 2.6Competitor V 3.0

The areas of solid dark points in the above images indicate “voids”.

ToeOFF®2.0 (0.2% Average Void content)

Competitor V (3.0% Average Void Content)

Fig. 4

Another important part of the design consideration of Allard Carbon Fiber AFO’s is the patient expectation in relation to footwear, pitch and heel height, leading to compliance with the orthosis.

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Why we Use Composite AFO (Experience from RJAH Orthopaedic Hospital, (ORLAU) Oswestry) Robert Freeman

An orthopaedic surgeon’s perspective was outlined, relative to the challenges of surgery and the use of complimentary orthosis and the measurement of outcomes in patients with childhood neuro muscular disorders. It was apparent that some of the goals in clinic were being driven by what the patient’s expectations were, and that compromise between professional imperatives and compliance were very important. Therefore, areas such as walking speed and the ability to achieve lifestyle goals were a major factor in enhancing quality of life.

Focus on Ground Reaction Force (Experience from RJAH Orthopaedic Hospital, (ORLAU) Oswestry) – Tom Woods and Sarah Jarvis

RJAH assessment protocols were described, and the time allocated to their examination process, including utilising 2D Video Vector and determining Ground Reaction Vectors to supplement visual and physical exami¬nation with both barefoot, and with footwear and AFOs was part of their informative presentation. This helped to identify and influence Gait impairments and subsequently drive the goals for Physiotherapy as well as Orthotic and Orthopaedic interventions. Tone was taken into consideration, however adherence to the Modified Ashworth Scale was not felt to be helpful and the experience and intuition of the clinicians was felt to be more beneficial in the determination of what extent tone played in the orthotic management. The main determinants of integrated treatment were to optimise energy consumption, reduce pain, avoid overstretching and limiting deformity. Perceptions of patient and parent expectations were also most important, and the treatment regime should seek to minimisethe cost to the families. Self-image and compliance were also seen as drivers for the use of less visually obvious designs of orthosis. Several case studies were presented to illustrate the ORLAU team’s rationale and support the theories discussed.The use of 2D Video Vector (Fig. 5,6,7 & 8), allows for analysis of what one cannot see, measuring force which equals Mass multiplied by Acceleration, Moment which equals Force multiplied by Distance. It also allows slow motion and comparisons, considering walking speed and cadence.

Which muscles do we use?

Fig. 5

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Where should the GRV be?

Fig. 6

Moments

Force (FGRV) × Distance (dGRV) = Force (FQUADS) × Distance (dQUADS)

Fig. 7

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Fig. 8

ORLAU use four steps to problem solve (Fig. 9):Step 1 - Define the problem

Step 2 - Determine Causal relationships

Step 3 - Identify effective solutions

Step 4 - Implement and track solutions

Fig. 9

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Aims of this discussion:• Develop and understanding of shank angle

• Describe the determinants of shank angle

• Reflect on the significance of shank angle

• Explore effects upon knee joint kinematics

• Examine the effects of changing angular velocity (∆V)

• Relate ∆V to tissue stress and load management

The Importance of Shank Angle (Experience from Preston Specialist Mobility Center) Tom Ramsay and Gordon Steel

Fig. 10

The focus of this section (Fig. 10) related to the challenge of understanding the mechanics behind the determination of shank angle. A description of the elements of tuning in the Elaine Owen style was presented. The benefits and limitations of these elements were described in terms of AFO design, footwear pitch, rockers and the everyday elements of uneven ground, slopes and stairs (both up and down), physiological influences, such as growth and spasticity. The presentation considered the effects of changing velocity, and how this related to tissue stress and load management.

The key question of ‘Understanding the relationship between pitch, pitch location and shank angle’ was described. A Vicon 3D system was used to evaluate the wedge location (internal / external) as well as changes to the wedge configuration in terms of both length and height, whilst maintaining constant angulation. Each condition was then assessed for all wedge angles between 10 and 3 degrees. The common themes that emanated from research results were ‘Known wedge position configuration did not result in the predicted shank angle’. No condition resulted in 1:1 ratio. Every reduction in the wedge length / height resulted in deleterious effect in the shank inclination angle, making it clear that the ‘Effect Wedge’ was in fact the dominating element. (Fig. 11)

The underlying maths exposed as a pattern (Fig. 12) that this can be used by the clinician on a daily basis to prescribe the effective wedge height, if they simply multiply the length measured from behind the ground contact point (5th MT Head) by the desired degree value, then they can have the confidence that they have a more accurate starting point in relation to pitch and tuning.

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Fig. 11

Fig. 12

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A description of the first Law of Thermodynamics was described - “Energy can neither be created nor destroyed but can only be transformed from one to another” was followed by the determinants of Gait (Ref: Perry and Gage). Fig. 13

And then a description of angular velocity and managing the relative centre of gravity and understanding muscle action was developed. The conclusion on this topic was “lots of boring maths summarised very, very succinctly”.

Determinants of Gait (Perry & Gage)

• Stance stability

• Swing clearance

• Appropriate pre-positioning of the foot

• Adequate step length

• Energy efficiencyFig. 13

Paediatric Patients (Real Life Practices at East Lancashire NHS Trust, Blackburn) Emma Loader & Graham Nuttall

Several case studies were presented in the use of carbon fibre orthosis in the treatment of paediatric patients. The rationale for prescription criteria, aims of treatment and the percentage of paediatric referrals and their outcomes are described in Figs 14, 15 & 16.

Paediatric patients and ToeOFF®

• 73 Patients supplied (10% of all paediatric referrals)• Ages 3–16

Fig. 14

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Aims of ToeOFF® at ELHT

• Gain heel strike• Encourage ground clearance and swing phase• Aid proprioception• Dynamically maintain muscle length• Aid knee extension and reduce excessive knee flexion

• Encourage 3 rockers of gait• Encourage hip extension• Energy consumption• Increase compliance

Thought processes• We do not supply ToeOFF® for age 3 and under• Mindful not to replace active movement / power as can result in atrophy• No orthosis will give power• Use as a gait training aid• “Energy cannot be created of destroyed, it can only be changed from one

form to another” - Einstein

It was interesting to note that the independent cases presented by Blackburn mirrored the findings of RJAH (ORLAU).

Fig. 15

Fig. 16

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Impact of Orthotic in Paediatric Partial Foot Amputation:A Case Study - Joshua Young

The impact of orthotic prescription in paediatric partial foot amputation was described, utilising carbon fibre ankle foot orthoses. This stimulated debate on techniques for integrating the Toe Off Principle with toe filler sockets, their manufacture and the balance of the foot to deliver optimum foot mechanics and cosmetic footwear choice, culminating with efficient energy consumption and three rocker gait. The case study concluded that improvements in walking speed, community activity levels and physical function were achievable in changing a child with bilateral forefoot amputations from foot orthoses to ankle-foot orthoses.

Figures 17 and 18 highlight the patient parameters and biomechanical considerations in the management of PFA. Prior to this study, very little information on outcomes in children with PFA was available and there remains a need for further work. The presentation was based on an article published in the Journal of Prosthetics and Orthotics:

Young J. Impact of Orthotic Prescription in Paediatric Partial Foot Amputation. J Prosthetics Ortho. 2018;1. Available from: http://insights.ovid.com/crossref?an=00008526-900000000-99919

PFA in children• Small numbers – 2/31 (6%) of PFA identified at Roehampampton [2]• Currently almost no data on functional outcomes in children with PFA.• General management guidelines and prosthetic / orthotic designs [3-5], case

series without objective outcome measures [6].• One study gives subjective description of gait pattern and walking speed, without

+/- device comparison [7]

Biomechanics in PFA

Extending CoP past end of residual foot requires an orthosis extending proximal to the ankle [8]. In adults, PFA does not consistently reduce speed. Speed appears to be reduced in the presence of co-morbidities only, such as DM [9-12]:

• Normal walking velocity = 1.4 m/s• Partial foot & no concurrent disease = 1.18 1.46 m/s• Partial foot & concurrent disease = 0.85 m/s

Fig. 17

Fig. 18

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Summary DiscussionFollowing the presentations and considering some of the questions and observations made by the delegates, a series of short questions were tendered by the chair to try to encapsulate the feeling of the meeting and therefore act as a degree of informal verbal consensus on the day.

Dependant on the needs of the pathologies presented, it was generally felt that the mobility of foot / ankle joints should be maintained and the use of orthoses with a variety of ankle joint mechanisms or free foot control, such as the Allard AFO range should be considered before fixing anatomical joints that would otherwise function normally.

Inter disciplinary understanding and communication was felt to be vitally important and was perceived as where some systems break down. It was suggested that goals and assessment be the criteria when requesting referrals are sent in, and that use of the NHS Net for interdisciplinary communication could play a role in overcoming some of the communication difficulties. It was also expressed that Orthotists should try to keep prescriptions simple and not overcomplicated and that the need to feel they must have an intervention solution was not always the case, advice could be as valuable as a device. There was some debate about understanding the different competencies of the members of the Multidisciplinary Team (MDT), however there was not unanimous agreement on this.

Did the delegates feel that cost could be a barrier to prescription, and therefore promoting dispensing rather than problem solving? Cost also could relate to material choices. Overall the feeling was cost was not a constraint on the choice of material. Evidence of the use of the devices relative to cost was heavily debated. Orthoses were often seen as a commodity and as such were purchased along these lines. Universities have a role in organising good practical research, and ethics and time to be granted often resulted in literature studies being conducted over hard practical evidence. Integrated pathways led by consensus leading to multicentre studies would also be useful in producing evidence. Holistic cost benefit should be encouraged in the treatment models.

Data collection on outcome measures and the use of new technology such as 3D printing and production of customised laminates in conjunction with prosthetic technology were also seen as issues to be addressed. The use of Functional Electrical Stimulation in conjunction with lower limb devices was discussed and the need to keep a safe open mind on who could benefit from the mix of these techniques was felt to be worth exploring

ConclusionCommunication and understanding of multidisciplinary roles are paramount in delivering quality of service, and therefore quality of life experience to the patients. Published evidence as well as clinical experiences driving materials and cost benefits to the service in a holistic way was fundamentally important in providing integrated care.

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Speaker Profiles

Mr Robert Freeman is Consultant Paediatric Orthopaedic Surgeon at Robert Jones & Agnes Hunt (RJAH), Orthopaedic Hospital, with specialist interest in cerebral palsy and gait analysis. He has been working in Oswestry since 2010 as part of a team of three surgeons treating the full spectrum of children’s orthopaedic conditions, while in the gait lab, he works as part of an MDT of physiotherapists, orthotists and engineers to try and enable patients to achieve their maximum potential.

William A Munro Dip OTC, MBAPO, FFPM RCPS (GLAS), Is a HCPC Registered Orthotist. Specialist in Diabetic Foot Management who has practiced in Neurological, Spinal and Polio pathology management. Honorary Clinical Research Fellow, University of Strathclyde, Department of Biomedical Engineering.

Tom Woods is one of the senior orthotists at Robert Jones and Agnes Hunt Orthopaedic Hospital in Oswestry. As part of that role, Tom spends time at the Orthotic Research and Locomotor Assessment Unit (ORLAU) where he is involved with ensuring that patients have the most optimal orthoses for their particular presentation, with his specialist interests being gait analysis and KAFO prescription.

Sarah Jarvis is a senior Physiotherapist and Clinical Services Lead, at the Orthotic Research and Locomotor Assessment Unit (ORLAU) at Robert Jones & Agnes Hunt Orthopaedic Hospital in Oswestry. Sarah has gained a master’s in applied Biomechanics from Strathclyde University and her interests have focused around the use of both 3D and 2D video vector focus to improve patient’s gait and orthotic management.

Gordon Steel is the Professional Lead in Orthotics, leading a team of seven orthotists from their base at the Specialist Mobility Rehabilitation Centre of Lancashire Teaching Hospitals NHS Foundation Trust. Gordon has taken a leading role in service and clinical development in both commercial and NHS settings, establishing and embedding an MDT approach to patient care in many Trusts in England. Gordon is a qualified orthotist and holds a BSc in Health and Sports Studies and a master’s degree in Education.

Tom Ramsay has 15 years’ experience as an Orthotist, holding a number of unique roles in his career to date including a position in orthopaedic triage assessing front of list foot and ankle patients. Tom has a specialist interest in custom design and the application of composite materials and emerging technologies in orthotic design.

Graham Nuttall is shared clinical Lead at East Lancashire Hospitals Trust, Blackburn. Graham graduated in Prosthetics and Orthotics from the University of Salford in 2001. He has worked within the paediatric team in East Lancashire for the past 17 years and has had research published in York Consortium and Orthopeadica Belgica.

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Emma Loader graduated from the University of Salford in 2013 from the four-year Prosthetics and Orthotics degree course. Since Graduating, she has worked as an Orthotist at East Lancashire Hospitals NHS Trust, Blackburn, where she undertakes a variety work with Paediatric patients, at both inpatient and outpatient orthotic clinics. Emma has also presented her research paper in 2018 at BAPO.

Gunilla Ström is the Research and Development Director at Allard INT (Camp Scandinavia), in Helsingborg, Sweden, from where she has been directing the R&D activities of the Composite AFO product development team for the past number of years. Gunilla is a Certified Orthotist and Prosthetist and holds a Master of Science in Business Administration and Economics.

Joshua Young is an orthotist practising at centres including Great Ormond Street Hospital for Children and The Evelina London Children's Hospital, with John Florence Limited. He was previously senior orthotist at the Douglas Bader Rehabilitation Centre, Roehampton, where he conducted various specialist clinics in addition to a non-medical imaging referrer. He has work published in journals including Prosthetics and Orthotics International and the Journal of Prosthetics and Orthotics.