516486
article2014
POI0010.1177/0309364613516486Prosthetics and Orthotics InternationalEddison et al.
INTERNATIONAL SOCIETY FOR PROSTHETICS AND ORTHOTICS
Original Research Report
Ankle foot orthosis–footwear combination tuning: An investigation into common clinical practice in the United Kingdom
Prosthetics and Orthotics International 2015, Vol. 39(2) 126–133 © The International Society for Prosthetics and Orthotics 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0309364613516486 poi.sagepub.com
Nicola Eddison1, Nachiappan Chockalingam2 and Stephen Osborne2
Abstract Background: Ankle foot orthoses are used to treat a wide variety of gait pathologies. Ankle foot orthosis–footwear combination tuning should be routine clinical practice when prescribing an ankle foot orthosis. Current research suggests that failure to tune ankle foot orthosis–footwear combinations can lead to immediate detrimental effect on function, and in the longer term, it may actually contribute to deterioration. Objectives: The purpose of this preliminary study was to identify the current level of knowledge clinicians have in the United Kingdom regarding ankle foot orthosis–footwear combination tuning and to investigate common clinical practice regarding ankle foot orthosis–footwear combination tuning among UK orthotists. Study design: Cross-sectional survey. Methods: A prospective study employing a multi-item questionnaire was sent out to registered orthotists and uploaded on to the official website of British Association of Prosthetists and Orthotists to be accessed by their members. Results: A total of 41 completed questionnaires were received. The results demonstrate that only 50% of participants use ankle foot orthosis–footwear combination tuning as standard clinical practice. The most prevalent factors preventing participants from carrying out ankle foot orthosis–footwear combination tuning are a lack of access to three-dimensional gait analysis equipment (37%) and a lack of time available in their clinics (27%). Clinical relevance Although, ankle foot orthosis–footwear combination tuning has been identified as an essential aspect of the prescription of ankle foot orthoses, the results of this study show a lack of understanding of the key principles behind ankle foot orthosis–footwear combination tuning. Keywords Ankle foot orthosis–footwear combination tuning, ankle foot orthosis, gait analysis Date received: 5 October 2013; accepted: 13 November 2013
Background Ankle foot orthoses (AFOs) are orthoses that encompass the ankle joint and the whole or part of the foot.1 AFOs are normally intended to control motion, correct deformity and/or compensate for weakness.2 Although a detailed description of the variation and efficacy of AFOs is beyond the scope of this article, it is described widely within the published literature.3–5
Ankle foot orthosis–footwear combination tuning People with pathological gait have abnormal lower limb kinematics particularly at the shank segment. Attempting
to normalise the shank kinematics offers a greater chance of optimum thigh and trunk kinematics and knee and hip kinetics.6 This is often achieved by the use of a solid AFO. However, the footwear that is worn with an AFO is integral in determining the overall biomechanical control 1Royal
Wolverhampton NHS Trust, Wolverhampton, UK Faculty of Health Sciences, Staffordshire University, Stoke on Trent, UK
2CSHER,
Corresponding Author: Nachiappan Chockalingam, Staffordshire University, Leek Road, Stokeon-Trent, ST4 2DF, UK. Email: [email protected]
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Eddison et al. provided, so the AFO and footwear have been termed ankle foot orthosis–footwear combination (AFO-FC).7 AFO-FC tuning has been recognised as an essential aspect of clinical practice when prescribing AFOs.5,8,9 It is recommended that AFO-FC tuning should be standard clinical practice when issuing an AFO.9 Issuing a suboptimal AFO-FC may have an immediate detrimental effect on function, and in the longer term, it may actually contribute to deterioration of gait and physical function.8 AFO-FC tuning can be defined as the process whereby fine adjustments such as the foot–shank angle are made to the design of the AFO-FC in order to optimise its performance during a particular activity (Owen E, 16 April 2012, Paediatric gait analysis and orthotic management with AFO footwear combinations (Course Manual), personal communication).The term biomechanical optimisation is used to encompass the whole process of designing, aligning and tuning the AFO-FC (Owen E, 16 April 2012, Paediatric gait analysis and orthotic management with AFO footwear combinations (Course Manual), personal communication). As a first step, it is essential to have the most appropriate AFO design and material stiffness to control the foot and ankle in all three planes as the gait pathology necessitates.10–13 In addition to this, the length of gastrocnemius must also be assessed. This should include the passive length of gastrocnemius with the knee in extension and the tone of the triceps surae. Following this, the correct angle of the ankle in the AFO (AAAFO) should be selected to ensure that gastrocnemius is fully accommodated in the subsequent AFO. The AAAFO can be described as the angle of the foot relative to the shank in the sagittal plane in the AFO. It could be in terms of dorsiflexion or plantar flexion, with plantigrade describing a neutral position.6,8 Failing to accommodate the length of gastrocnemius in the AFO will prevent successful AFO-FC tuning. This is due to the stretching of gastrocnemius at the ankle beyond its range which will in turn prevent knee extension when required at midstance (MST), terminal stance (TST) and terminal swing (TS).6 Furthermore, the muscles will not be able to produce power when the sarcomeres are stretched to their maximal length.14
vertical. It is described in degrees, with vertical being 0°,6 and is measured during standing. Owen7 indicated that anthropometric measures dictate that an SVA of 10° inclined from the vertical brings the knee joint centre over the middle of the foot during MST in normal subjects. The AAAFO and the pitch of the HSD will determine the SVA. Detailed information on the tuning process has previously been described.6,7,15
Tuning the AFO-FC
Objectives
Once the designs of the AFO and AAAFO have been decided, the heel sole differential (HSD) can be adjusted in an attempt to produce optimum kinematics and kinetics during gait. The aim of this is to achieve extension at the hip and the knee at terminal stance and terminal swing as per ‘normal’ gait. This is normally done by manipulating the shank to vertical angle (SVA) via the HSD. The SVA can be defined as the angle of the shank relative to the vertical, measured in the sagittal plane. The SVA is described as inclined if the shank is inclined forward from the vertical and reclined if it is reclined backward from the
The aim of this study is to identify what knowledge orthotists in the United Kingdom have regarding the key principles of AFO-FC tuning and to scope the current practice among UK orthotists with regard to AFO-FC tuning. A further aim was to identify any factors which prevent clinicians from using AFO-FC tuning as routine clinical practice. However, it is not the intention of this investigation to (a) explore the international clinical practice on AFO-FC tuning, (b) look at the material science aspects of AFOs and (c) analyse the efficacy or the clinical effectiveness of AFO-FC tuning.
Limiting factors to successful AFO-FC tuning The success of tuning an AFO-FC will be limited if there is excessively increased musculotendinous stiffness, an inability to achieve full or nearly full passive extension at the knee and hip during gait due to insufficient musculotendinous length or joint range, an inability to achieve fully or nearly full extension at fast angular velocity at the knee and hip and an excessively rotated foot progression angle.8 Therefore, the physical presentation of the patient will have an impact on the success of AFO-FC tuning.
Methods for tuning AFO-FC Although the visual assessment of gait is important in clinical decision-making, accurate assessment of gait is difficult by eye alone. This could be attributed to the complexity and the speed at which the phases of the gait cycle change, especially when assessing patients with neurological disorders. It has also been suggested that accurate estimation of the kinetics cannot be assumed from observation of the kinematics and thus kinetic information can only be obtained by using instrumented gait analysis systems.6,8 In order for AFO-FC tuning to be carried out regularly within a clinical setting, the ease of use of these instrumented gait analysis systems is paramount. There are various simple methods of instrumented gait analysis available to the clinician, such as the use of superimposing a force vector on a video sequence, negating the need to use an expensive gait laboratory. However, it is not known whether clinicians are aware of which methods are appropriate for AFO-FC tuning.
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Methods A questionnaire was devised, which included both closed and open-ended questions, to investigate current knowledge and clinical practice of tuning AFO-FCs in the United Kingdom. The questionnaire was sent via post and email and issued in person to approximately 150 orthotists. The questionnaire was also uploaded on to the British Association of Prosthetists and Orthotists (BAPO) website, where it could easily be accessed by BAPO members. BAPO have 333 members who stipulate that their practice includes orthotics.
Participants The intended target population was UK registered orthotists currently working for a commercial company or in private practice. Ethical approval was sought and given by the University Ethics Committee. Due to the nature of ethical approval, the National Health Service (NHS) employees could only answer in their capacity as a private practitioner. Since orthotists are the main group of people who are responsible for the assessment, design and issue of AFOs, they were deemed the most appropriate participants for this study. The Health and Care Professions Council, with which all practising orthotists must be registered, reported that there were 890 registered prosthetists/orthotists in the United Kingdom as of May 2012,16 of which it is estimated that approximately 55% are practising orthotists. The total number of orthotists who completed the questionnaire was 41. This represents approximately 9% of the target population. Although this does not appear to be a large number, this response rate exceeded most of previously published studies in the area of AFO-FC tuning.17–20 Although the questionnaire employed within this study was not validated by any previous studies, the authors of the current study who are either experienced clinicians or researchers felt that these were appropriate. The questionnaire was discussed between the authors and the extended clinical group within the academic/ clinical departments of the authors before conducting the study. The questions covered a wide range of issues relating to the prescription or the use of AFO-FC tuning.
Results The results of this study are detailed in Table 1. A total of 95% of participants stated that they understood AFO-FC tuning, but their responses to individual questions show this is incorrect, as they could not name the contraindications of AFO-FC tuning. As indicated earlier, to successfully tune an AFO-FC, one needs to consider (a) the designs of AFO and AAAFO, (b) the physical characteristics of the patient and (c) SVA. From the results, it is clearly indicated that the participants do not understand
these, although they believed they understood AFO-FC tuning. Some of the headline results indicate that 87% of the participants tune by visual inspection alone. Only 50% of participants report that they use AFO-FC tuning as standard clinical practice. Furthermore, there was confusion about how participants were deciding who would be a candidate for AFO-FC tuning, with 49% reporting they follow set criteria, 46% reporting they tune all the AFOFCs they prescribe and 42% stating it depends on whether they have enough time. Similar issues are highlighted in Table 1. The most prevalent factor stated for not tuning AFOFCs routinely was a lack of access to three-dimensional (3D) gait analysis, and the second most prevalent reason (27%) was lack of time. Of the participants, 49% reported that they do not take the design of the AFO into consideration when deciding to tune the AFO-FC; furthermore, 26% state that they also do not take the physical characteristics of the patient into consideration when deciding to tune their AFO-FCs.
Discussion AFO-FC tuning is an essential aspect of clinical treatment when prescribing AFOs. Therefore, it is essential that the prescribing clinician has the knowledge and skills to carry out AFO-FC tuning in order to prevent issuing a suboptimal AFO-FC, which may have an immediate detrimental effect on function and in the longer term potentially contribute to deterioration. The results of the questionnaire show that all participants of this study were aware of AFO-FC tuning, of which only 5% reported that they did not fully understand AFO-FC tuning. However, 50% of the participants reported that they do not use AFO-FC tuning as standard practice on their patients as shown in Table 1. When asked to state which factors are preventing them using AFO-FC tuning as standard clinical practice, the most prevalent reason stated (34%) was a lack of access to 3D gait analysis, although 3D gait analysis is not essential to successfully tune AFO-FCs. Other methods of augmented gait assessment have been recommended as being suitable; they include video recording to enable slow motion and freeze frame qualitative kinematic analysis and two-dimensional video vector systems to enable a combination of qualitative kinematic and kinetic analysis.8 The second most prevalent response (27%) was because respondents felt AFO-FC tuning was too time-consuming, as shown in Figure 1. This highlights the fact that there is a clear need to simplify the tuning process described within the current published and unpublished literature. The majority (51%) stated that they do not have a set criterion for deciding who would benefit from AFO-FC
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Eddison et al. Table 1. Results from questionnaire on AFO-FC tuning, issued to UK orthotists. Question
Response item
Question 1: Are you aware of AFO-FC tuning?
Yes No Total responses Question 2: Do you fully understand AFOYes FC tuning? No Total responses Question 3: Do you use AFO-FC tuning as Yes standard practice on all patients who are No prescribed with an AFO? Total responses Question 4: If no, what is preventing you I don’t fully understand it from using AFO-FC tuning? I don’t have access to 3D It’s too time-consuming It’s too costly I’m unaware of AFO-FC tuning There’s not enough quality research Tried it but didn’t see any benefit Total responses Question 5: How do you decide which patients will benefit from AFO-FC tuning? (a) I have set criteria Yes No Total responses (b) If yes name set criteria (open-ended Ability to ambulate question) Good gait pattern Compliance Contractures Stability Cognitive status All patients with a solid AFO Consider jointed AFOs when patient does a lot of sitting to standing Angle of AFO is set at 90° Patients who have problems normally Patients who meet objectives Total responses (c) I tune all patients who are prescribed Yes with an AFO No Total responses (d) It depends whether I have enough time Yes No Total responses Question 6: Do you use 3D gait analysis to Yes tune AFO-FCs? No Total responses Question 6.1: Do you use video analysis? Yes No Total responses Question 6.2: Do you tune by eye alone? Yes No Total number of responses Question 6.3: Do you use any other 2D gait analysis method? (open-ended question) Static goniometers Scan force plate Line of progression Timing Total number of responses
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Frequency
Percentage
41 0 41 39 2 41 20 20 40 3 14 11 8 1 4 0 41
100 0 100 95 5 100 50 50 100 7 34 27 20 2 10 0 100
18 19 37 7 1 3 1 1 1 3 1
49 51 100 33 5 14 5 5 5 14 5
1 1 1 21 17 20 37 15 21 36 6 30 36 17 20 37 33 5 38 2 2 1 1 1 7
5 5 5 100 46 54 100 42 58 100 17 83 100 46 54 100 87 13 100 29 29 14 14 14 100
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Table 1. (Continued) Question
Response item
Frequency
Percentage
Question 7: Do you take AFO design into consideration when deciding whether to tune an AFO-FC?
Yes No Total responses Angle of AFO Hinged Fixed PLS AFO Flexible AFO Inadequate AFO stiffness Inadequate AAAFO Inadequate AFO Total number of responses Yes No Total number of responses Significant hip contractures Hip adduction High tone Quad weakness Non ambulant Gross knee instability Offloading a forefoot ulcer Patient has dorsiflexion Blindness Ataxia Significant knee contractures Significant rotational deformity Athetosis Dyskinesia When tuning one segment adversely affects another segment Instability Plantar flexion contracture of 12°–15° Bilateral need for AFOs Significant contractures Total number of responses
20 19 39 1 5 1 4 4 1 1 1 18 29 10 39 4 1 1 3 7 1 1 1 1 1 4 2 1 1 2
51 49 100 6 28 6 22 22 6 6 6 100 74 26 100 10 3 3 8 18 3 3 3 3 3 10 5 3 3 5
5 1 1 2 40
13 3 3 5 100
Question 7.1: If yes, please state the design criteria which would prevent you from tuning the AFO-FC? (open-ended question)
Question 8: Do you take physical ability of the patient into account when deciding whether the AFO-FC should be tuned? Question 8.1: If yes please state physical criteria which would prevent you from tuning an AFO-FC (open-ended question)
AFO: ankle foot orthosis; AAAFO: angle of the ankle in the AFO; AFO-FC: ankle foot orthosis–footwear combination; PLS: posterior leaf spring; 3D: three-dimensional.
Not enough quality research 10%
Don’t see the benefit of AFO-FC tuning 0%
Unaware of AFO-FC tuning 2%
Don’t understand AFO-FC Tuning 7% Don’t have access to 3D Gait analysis 34%
Too costly 20%
Too time consuming 27%
Figure 1. Factors preventing orthotists using AFO-FC tuning.
AFO-FC: ankle foot orthosis–footwear combination; 3D: three-dimensional.
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Eddison et al. Paents who have AFOs set at 90 problems normally Paents who meet degrees 5% 5% objecves, 5% Jointed AFOs for sit - stand 5%
Ability to ambulate, 33%
Paents with solid AFO's 14%
Cognive status 5% Stability 5%
Contractures 5%
Compliance 14%
Good gait paern, 5%
Figure 2. Criteria used to determine which patients will benefit from AFO-FC tuning. AFO-FC: ankle foot orthosis–footwear combination.
tuning; of the 49% of participants who do have set criteria, the ability to ambulate was the most common (33%) criterion used to decide whether a patient should have their AFO-FC tuned, as shown in Figure 2. This indicates a lack of understanding of the process and aims of AFO-FC tuning as tuning is indicated for walking, stepping and standing (Owen E, 16 April 2012, Paediatric gait analysis and orthotic management with AFO footwear combinations (Course Manual), personal communication). As shown in Table 1, although 49% of participants indicated that they have set criteria when deciding who would benefit from AFO-FC tuning, 46% of participants stated that they tune all the AFO-FCs they prescribe, and in the following question, 42% stated that time was the deciding factor on whether they tune the AFO-FCs they prescribe. This indicates some possible confusion regarding how the participants are deciding to tune the AFO-FCs they prescribe. Previous research has stated that the designs of the AFO and the AAAFO are crucial elements of successful AFO-FC tuning, and if the angle of the AFO does not correctly accommodate the length of the patient’s gastrocnemius, optimum AFO-FC tuning will not be possible.6,21 However, 49% of participants stated that they do not take the design of the AFO into account when deciding to tune an AFO-FC. Of 51% who stated that they do take the design of the AFO into account, only 1 participant correctly identified inadequate stiffness, incorrect AAAFO and a hinged AFO as being factors which would prevent successful tuning. Previous research states that there are clear physical presentations which will limit the success of AFO-FC tuning.6,8 However, 26% of respondents reported that they do not take the physical ability of the patient into account when deciding whether to tune an AFO-FC. Of the respondents who reported that they do take physical ability of the patient into account, the most common physical
31-35 years 7% 26-30 years, 7% 21-25 years, 2% 1-5 years 41%
16-20 years, 15%
11-15 years, 17% 6-10 years, 10%
Figure 3. Number of years of clinical experience of participants.
presentation which was identified as being the factor which would prevent tuning of an AFO-FC was an inability to ambulate (18%). The majority (54%) of responses named physical characteristics which have not been identified in current literature as preventing successful AFO-FC tuning, with 94% of participants failing to name all the four physical characteristics identified in research as being potential limiting factors of successful AFO-FC tuning. As shown in Figure 3, all respondents were qualified orthotists; the majority (41%) had 1–5 years post-graduate experience in orthotics. When asked about the exact methodology they employ to tune AFO-FCs, 87% of participants stated that they tune by eye alone and do not use any other method of gait assessment. However, it has been suggested that for a successful tuning, it is necessary to utilise some form of augmentative clinical gait assessment. While it was not the intention of this preliminary study to focus on the international clinical practice, the results from the United Kingdom highlight a clear need for further training which could be reflected within the professional
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practice in other countries. One of the limitations of this study could be that it represents only 9% of the practising orthotists, which could be attributed to the recruitment method. However, the results indicate that there is strong need to conduct such a study in other countries and develop a consensus in terms of processes and procedures related to AFO-FC tuning.
AFO-FC tuning among UK orthotists in the current literature with which to compare the results of this study. Conflict of interest None declared.
Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
Conclusion The results of the study indicate a clear lack of understanding regarding the key principles of AFO-FC tuning among the UK orthotists who participated in this study. While the majority of participants indicated that they understood the principles behind AFO-FC tuning, the subsequent questions revealed their limited knowledge. AFO-FC tuning is not yet standard clinical practice among the UK orthotists who participated in this study; the main reasons cited were a lack of access to 3D gait analysis and a lack of time. However, the study also seems to indicate that AFO-FC tuning principles are not well understood by the participants of this study. The 3D gait analysis is not essential to tune AFO-FCs, and the designs of the AFO and the AAAFO and the physical presentation of the patient are essential factors of AFO-FC tuning. However, the most prevalent factor identified as being key to AFO-FC tuning by participants was the patient’s ability to ambulate. Furthermore, of all responses (N = 41), the number of participants who named all the contraindications to AFO-FC tuning was 1. The majority of participants who took part in this study were relatively newly qualified; this may indicate a need to expand training on AFO-FC tuning in the current undergraduate programmes or as a part of post-graduate curriculum. While one could argue that some of the questions relate to the use of equipment and the individual interpretation of AFO-FC tuning, in the authors’ opinion, these are directly linked to various aspects of knowledge regarding AFO-FC tuning. It is possible that participants may have been using their own understanding and definition of AFO-FC tuning and not that of which is in the literature as the definition is yet to be standardised. The authors also recognise that this study has a relatively small subject group and this may have a bearing on the results. However, this study may indicate one important reason why AFO-FC tuning is not yet standard clinical practice, in that the basic principles are not fully understood by clinicians; this may be due to a lack of access to AFO-FC training at both undergraduate and post-graduate levels or the process of AFO-FC tuning may need to be simplified in the literature and made more accessible and easily understood. This study provides an important insight into common clinical practice among the clinicians who participated in this study and potentially highlights important reasons why AFO-FC tuning is not common clinical practice. There is no other available research into the prevalence of
References 1. ISO 8549–1:1989. Prosthetics and orthotics – vocabulary – part 1: general terms for external limb prostheses and external orthoses. 2. Michael JW. Lower limb orthoses. In: Hsu J, Michael J and Fisk J (eds) AAOS atlas of orthoses and assistive devices. Philadelphia, PA: Mosby Elsevier, 2008, pp. 343–355. 3. Condie DN and Meadows CB. Report on a consensus conference on the lower limb orthotic management of cerebral palsy: held at Duke University, Durham, NC, 10–12 November 1994. Copenhagen, Denmark: International Society for Prosthetics and Orthotics. 4. Morris C. A review of the efficacy of lower-limb orthoses used for cerebral palsy. Dev Med Child Neurol 2002; 44: 205–211. 5. Bowers R and Ross K. A review of the effectiveness of lower limb orthoses used in cerebral palsy. In: Morris C and Condie D (eds) Recent developments in healthcare for cerebral palsy: implications and opportunities for orthotics. Copenhagen: International Society for Prosthetics and Orthotics, 2009, pp. 235–297. 6. Owen E (ed.) Tuning of ankle foot orthosis footwear combinations for children with cerebral palsy, spina bifida and other conditions. In: Proceedings of the European Society of Movement Analysis in Adults and Children (ESMAC) seminars, Warsaw, Poland, 23–25 September 2004. 7. Owen E. Shank angle to floor measures and tuning of ankle foot orthosis footwear combinations for children with cerebral palsy, spina bifida and other conditions. MSc Thesis, The University of Strathclyde, Glasgow, 2004. 8. Owen E, Bowers RJ and Meadows CB (eds) Tuning of AFO-footwear combinations for neurological disorders. In: Symposium of the 11th world congress of the International Society for Prosthetics and Orthotics (Invited Presentation), Hong Kong, 1–6 August 2004. ISPO. 9. Bowers R and Ross K. Development of a best practice statement on the use of ankle-foot orthoses following stroke in Scotland. Prosthet Orthot Int 2010; 34(3): 245–253. 10. Filauer C. A new ankle foot orthosis with a moldable carbon composite insert. Orthotics Prosthet 1981; 35: 13–16. 11. Sumiya T, Suzuki Y and Kasahara T. Stiffness control in posterior type plastic ankle foot orthosis: effect of ankle trim line. Part 2: orthosis characteristics and orthosis patient/ matching. Prosthet Orthot Int 1996; 20: 132–137. 12. Nagaya M. Shoehorn-type ankle-foot orthosis: prediction of flexibility. Arch Phys Med Rehabil 1997; 78: 82–84. 13. McHugh B. Analysis of body-device interfaces in the sagittal plane for patients wearing ankle foot orthoses. Prosthet Orthot Int 1999; 23: 75–81.
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Eddison et al. 14. Lieber RL. Skeletal muscle structure, function and plasticity: the physiological basis of rehabilitation. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins, 2002. 15. Owen E. A clinical algorithm for the design and tuning of ankle-foot orthosis footwear combinations (AFOFCs) based on shank kinematics. Gait Posture 2005; 22S: S36–S37. 16. Health Professions Council. http://www.hpc-uk.org/ aboutregistration/professions/index.asp?id=9#profDetails (accessed 15 May 2012). 17. Butler PB, Thompson N and Major RE. Improvement in walking performance of children with cerebral palsy: preliminary results. Dev Med Child Neurol 1992; 34(7): 567–576. 18. Owen E. The point of ‘point-loading rockers’ in ankle foot orthosis footwear combinations used with children with cer-
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article2014
POI0010.1177/0309364613516486Prosthetics and Orthotics InternationalEddison et al.
INTERNATIONAL SOCIETY FOR PROSTHETICS AND ORTHOTICS
Original Research Report
Ankle foot orthosis–footwear combination tuning: An investigation into common clinical practice in the United Kingdom
Prosthetics and Orthotics International 2015, Vol. 39(2) 126–133 © The International Society for Prosthetics and Orthotics 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0309364613516486 poi.sagepub.com
Nicola Eddison1, Nachiappan Chockalingam2 and Stephen Osborne2
Abstract Background: Ankle foot orthoses are used to treat a wide variety of gait pathologies. Ankle foot orthosis–footwear combination tuning should be routine clinical practice when prescribing an ankle foot orthosis. Current research suggests that failure to tune ankle foot orthosis–footwear combinations can lead to immediate detrimental effect on function, and in the longer term, it may actually contribute to deterioration. Objectives: The purpose of this preliminary study was to identify the current level of knowledge clinicians have in the United Kingdom regarding ankle foot orthosis–footwear combination tuning and to investigate common clinical practice regarding ankle foot orthosis–footwear combination tuning among UK orthotists. Study design: Cross-sectional survey. Methods: A prospective study employing a multi-item questionnaire was sent out to registered orthotists and uploaded on to the official website of British Association of Prosthetists and Orthotists to be accessed by their members. Results: A total of 41 completed questionnaires were received. The results demonstrate that only 50% of participants use ankle foot orthosis–footwear combination tuning as standard clinical practice. The most prevalent factors preventing participants from carrying out ankle foot orthosis–footwear combination tuning are a lack of access to three-dimensional gait analysis equipment (37%) and a lack of time available in their clinics (27%). Clinical relevance Although, ankle foot orthosis–footwear combination tuning has been identified as an essential aspect of the prescription of ankle foot orthoses, the results of this study show a lack of understanding of the key principles behind ankle foot orthosis–footwear combination tuning. Keywords Ankle foot orthosis–footwear combination tuning, ankle foot orthosis, gait analysis Date received: 5 October 2013; accepted: 13 November 2013
Background Ankle foot orthoses (AFOs) are orthoses that encompass the ankle joint and the whole or part of the foot.1 AFOs are normally intended to control motion, correct deformity and/or compensate for weakness.2 Although a detailed description of the variation and efficacy of AFOs is beyond the scope of this article, it is described widely within the published literature.3–5
Ankle foot orthosis–footwear combination tuning People with pathological gait have abnormal lower limb kinematics particularly at the shank segment. Attempting
to normalise the shank kinematics offers a greater chance of optimum thigh and trunk kinematics and knee and hip kinetics.6 This is often achieved by the use of a solid AFO. However, the footwear that is worn with an AFO is integral in determining the overall biomechanical control 1Royal
Wolverhampton NHS Trust, Wolverhampton, UK Faculty of Health Sciences, Staffordshire University, Stoke on Trent, UK
2CSHER,
Corresponding Author: Nachiappan Chockalingam, Staffordshire University, Leek Road, Stokeon-Trent, ST4 2DF, UK. Email: [email protected]
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Eddison et al. provided, so the AFO and footwear have been termed ankle foot orthosis–footwear combination (AFO-FC).7 AFO-FC tuning has been recognised as an essential aspect of clinical practice when prescribing AFOs.5,8,9 It is recommended that AFO-FC tuning should be standard clinical practice when issuing an AFO.9 Issuing a suboptimal AFO-FC may have an immediate detrimental effect on function, and in the longer term, it may actually contribute to deterioration of gait and physical function.8 AFO-FC tuning can be defined as the process whereby fine adjustments such as the foot–shank angle are made to the design of the AFO-FC in order to optimise its performance during a particular activity (Owen E, 16 April 2012, Paediatric gait analysis and orthotic management with AFO footwear combinations (Course Manual), personal communication).The term biomechanical optimisation is used to encompass the whole process of designing, aligning and tuning the AFO-FC (Owen E, 16 April 2012, Paediatric gait analysis and orthotic management with AFO footwear combinations (Course Manual), personal communication). As a first step, it is essential to have the most appropriate AFO design and material stiffness to control the foot and ankle in all three planes as the gait pathology necessitates.10–13 In addition to this, the length of gastrocnemius must also be assessed. This should include the passive length of gastrocnemius with the knee in extension and the tone of the triceps surae. Following this, the correct angle of the ankle in the AFO (AAAFO) should be selected to ensure that gastrocnemius is fully accommodated in the subsequent AFO. The AAAFO can be described as the angle of the foot relative to the shank in the sagittal plane in the AFO. It could be in terms of dorsiflexion or plantar flexion, with plantigrade describing a neutral position.6,8 Failing to accommodate the length of gastrocnemius in the AFO will prevent successful AFO-FC tuning. This is due to the stretching of gastrocnemius at the ankle beyond its range which will in turn prevent knee extension when required at midstance (MST), terminal stance (TST) and terminal swing (TS).6 Furthermore, the muscles will not be able to produce power when the sarcomeres are stretched to their maximal length.14
vertical. It is described in degrees, with vertical being 0°,6 and is measured during standing. Owen7 indicated that anthropometric measures dictate that an SVA of 10° inclined from the vertical brings the knee joint centre over the middle of the foot during MST in normal subjects. The AAAFO and the pitch of the HSD will determine the SVA. Detailed information on the tuning process has previously been described.6,7,15
Tuning the AFO-FC
Objectives
Once the designs of the AFO and AAAFO have been decided, the heel sole differential (HSD) can be adjusted in an attempt to produce optimum kinematics and kinetics during gait. The aim of this is to achieve extension at the hip and the knee at terminal stance and terminal swing as per ‘normal’ gait. This is normally done by manipulating the shank to vertical angle (SVA) via the HSD. The SVA can be defined as the angle of the shank relative to the vertical, measured in the sagittal plane. The SVA is described as inclined if the shank is inclined forward from the vertical and reclined if it is reclined backward from the
The aim of this study is to identify what knowledge orthotists in the United Kingdom have regarding the key principles of AFO-FC tuning and to scope the current practice among UK orthotists with regard to AFO-FC tuning. A further aim was to identify any factors which prevent clinicians from using AFO-FC tuning as routine clinical practice. However, it is not the intention of this investigation to (a) explore the international clinical practice on AFO-FC tuning, (b) look at the material science aspects of AFOs and (c) analyse the efficacy or the clinical effectiveness of AFO-FC tuning.
Limiting factors to successful AFO-FC tuning The success of tuning an AFO-FC will be limited if there is excessively increased musculotendinous stiffness, an inability to achieve full or nearly full passive extension at the knee and hip during gait due to insufficient musculotendinous length or joint range, an inability to achieve fully or nearly full extension at fast angular velocity at the knee and hip and an excessively rotated foot progression angle.8 Therefore, the physical presentation of the patient will have an impact on the success of AFO-FC tuning.
Methods for tuning AFO-FC Although the visual assessment of gait is important in clinical decision-making, accurate assessment of gait is difficult by eye alone. This could be attributed to the complexity and the speed at which the phases of the gait cycle change, especially when assessing patients with neurological disorders. It has also been suggested that accurate estimation of the kinetics cannot be assumed from observation of the kinematics and thus kinetic information can only be obtained by using instrumented gait analysis systems.6,8 In order for AFO-FC tuning to be carried out regularly within a clinical setting, the ease of use of these instrumented gait analysis systems is paramount. There are various simple methods of instrumented gait analysis available to the clinician, such as the use of superimposing a force vector on a video sequence, negating the need to use an expensive gait laboratory. However, it is not known whether clinicians are aware of which methods are appropriate for AFO-FC tuning.
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Methods A questionnaire was devised, which included both closed and open-ended questions, to investigate current knowledge and clinical practice of tuning AFO-FCs in the United Kingdom. The questionnaire was sent via post and email and issued in person to approximately 150 orthotists. The questionnaire was also uploaded on to the British Association of Prosthetists and Orthotists (BAPO) website, where it could easily be accessed by BAPO members. BAPO have 333 members who stipulate that their practice includes orthotics.
Participants The intended target population was UK registered orthotists currently working for a commercial company or in private practice. Ethical approval was sought and given by the University Ethics Committee. Due to the nature of ethical approval, the National Health Service (NHS) employees could only answer in their capacity as a private practitioner. Since orthotists are the main group of people who are responsible for the assessment, design and issue of AFOs, they were deemed the most appropriate participants for this study. The Health and Care Professions Council, with which all practising orthotists must be registered, reported that there were 890 registered prosthetists/orthotists in the United Kingdom as of May 2012,16 of which it is estimated that approximately 55% are practising orthotists. The total number of orthotists who completed the questionnaire was 41. This represents approximately 9% of the target population. Although this does not appear to be a large number, this response rate exceeded most of previously published studies in the area of AFO-FC tuning.17–20 Although the questionnaire employed within this study was not validated by any previous studies, the authors of the current study who are either experienced clinicians or researchers felt that these were appropriate. The questionnaire was discussed between the authors and the extended clinical group within the academic/ clinical departments of the authors before conducting the study. The questions covered a wide range of issues relating to the prescription or the use of AFO-FC tuning.
Results The results of this study are detailed in Table 1. A total of 95% of participants stated that they understood AFO-FC tuning, but their responses to individual questions show this is incorrect, as they could not name the contraindications of AFO-FC tuning. As indicated earlier, to successfully tune an AFO-FC, one needs to consider (a) the designs of AFO and AAAFO, (b) the physical characteristics of the patient and (c) SVA. From the results, it is clearly indicated that the participants do not understand
these, although they believed they understood AFO-FC tuning. Some of the headline results indicate that 87% of the participants tune by visual inspection alone. Only 50% of participants report that they use AFO-FC tuning as standard clinical practice. Furthermore, there was confusion about how participants were deciding who would be a candidate for AFO-FC tuning, with 49% reporting they follow set criteria, 46% reporting they tune all the AFOFCs they prescribe and 42% stating it depends on whether they have enough time. Similar issues are highlighted in Table 1. The most prevalent factor stated for not tuning AFOFCs routinely was a lack of access to three-dimensional (3D) gait analysis, and the second most prevalent reason (27%) was lack of time. Of the participants, 49% reported that they do not take the design of the AFO into consideration when deciding to tune the AFO-FC; furthermore, 26% state that they also do not take the physical characteristics of the patient into consideration when deciding to tune their AFO-FCs.
Discussion AFO-FC tuning is an essential aspect of clinical treatment when prescribing AFOs. Therefore, it is essential that the prescribing clinician has the knowledge and skills to carry out AFO-FC tuning in order to prevent issuing a suboptimal AFO-FC, which may have an immediate detrimental effect on function and in the longer term potentially contribute to deterioration. The results of the questionnaire show that all participants of this study were aware of AFO-FC tuning, of which only 5% reported that they did not fully understand AFO-FC tuning. However, 50% of the participants reported that they do not use AFO-FC tuning as standard practice on their patients as shown in Table 1. When asked to state which factors are preventing them using AFO-FC tuning as standard clinical practice, the most prevalent reason stated (34%) was a lack of access to 3D gait analysis, although 3D gait analysis is not essential to successfully tune AFO-FCs. Other methods of augmented gait assessment have been recommended as being suitable; they include video recording to enable slow motion and freeze frame qualitative kinematic analysis and two-dimensional video vector systems to enable a combination of qualitative kinematic and kinetic analysis.8 The second most prevalent response (27%) was because respondents felt AFO-FC tuning was too time-consuming, as shown in Figure 1. This highlights the fact that there is a clear need to simplify the tuning process described within the current published and unpublished literature. The majority (51%) stated that they do not have a set criterion for deciding who would benefit from AFO-FC
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Eddison et al. Table 1. Results from questionnaire on AFO-FC tuning, issued to UK orthotists. Question
Response item
Question 1: Are you aware of AFO-FC tuning?
Yes No Total responses Question 2: Do you fully understand AFOYes FC tuning? No Total responses Question 3: Do you use AFO-FC tuning as Yes standard practice on all patients who are No prescribed with an AFO? Total responses Question 4: If no, what is preventing you I don’t fully understand it from using AFO-FC tuning? I don’t have access to 3D It’s too time-consuming It’s too costly I’m unaware of AFO-FC tuning There’s not enough quality research Tried it but didn’t see any benefit Total responses Question 5: How do you decide which patients will benefit from AFO-FC tuning? (a) I have set criteria Yes No Total responses (b) If yes name set criteria (open-ended Ability to ambulate question) Good gait pattern Compliance Contractures Stability Cognitive status All patients with a solid AFO Consider jointed AFOs when patient does a lot of sitting to standing Angle of AFO is set at 90° Patients who have problems normally Patients who meet objectives Total responses (c) I tune all patients who are prescribed Yes with an AFO No Total responses (d) It depends whether I have enough time Yes No Total responses Question 6: Do you use 3D gait analysis to Yes tune AFO-FCs? No Total responses Question 6.1: Do you use video analysis? Yes No Total responses Question 6.2: Do you tune by eye alone? Yes No Total number of responses Question 6.3: Do you use any other 2D gait analysis method? (open-ended question) Static goniometers Scan force plate Line of progression Timing Total number of responses
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Frequency
Percentage
41 0 41 39 2 41 20 20 40 3 14 11 8 1 4 0 41
100 0 100 95 5 100 50 50 100 7 34 27 20 2 10 0 100
18 19 37 7 1 3 1 1 1 3 1
49 51 100 33 5 14 5 5 5 14 5
1 1 1 21 17 20 37 15 21 36 6 30 36 17 20 37 33 5 38 2 2 1 1 1 7
5 5 5 100 46 54 100 42 58 100 17 83 100 46 54 100 87 13 100 29 29 14 14 14 100
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Table 1. (Continued) Question
Response item
Frequency
Percentage
Question 7: Do you take AFO design into consideration when deciding whether to tune an AFO-FC?
Yes No Total responses Angle of AFO Hinged Fixed PLS AFO Flexible AFO Inadequate AFO stiffness Inadequate AAAFO Inadequate AFO Total number of responses Yes No Total number of responses Significant hip contractures Hip adduction High tone Quad weakness Non ambulant Gross knee instability Offloading a forefoot ulcer Patient has dorsiflexion Blindness Ataxia Significant knee contractures Significant rotational deformity Athetosis Dyskinesia When tuning one segment adversely affects another segment Instability Plantar flexion contracture of 12°–15° Bilateral need for AFOs Significant contractures Total number of responses
20 19 39 1 5 1 4 4 1 1 1 18 29 10 39 4 1 1 3 7 1 1 1 1 1 4 2 1 1 2
51 49 100 6 28 6 22 22 6 6 6 100 74 26 100 10 3 3 8 18 3 3 3 3 3 10 5 3 3 5
5 1 1 2 40
13 3 3 5 100
Question 7.1: If yes, please state the design criteria which would prevent you from tuning the AFO-FC? (open-ended question)
Question 8: Do you take physical ability of the patient into account when deciding whether the AFO-FC should be tuned? Question 8.1: If yes please state physical criteria which would prevent you from tuning an AFO-FC (open-ended question)
AFO: ankle foot orthosis; AAAFO: angle of the ankle in the AFO; AFO-FC: ankle foot orthosis–footwear combination; PLS: posterior leaf spring; 3D: three-dimensional.
Not enough quality research 10%
Don’t see the benefit of AFO-FC tuning 0%
Unaware of AFO-FC tuning 2%
Don’t understand AFO-FC Tuning 7% Don’t have access to 3D Gait analysis 34%
Too costly 20%
Too time consuming 27%
Figure 1. Factors preventing orthotists using AFO-FC tuning.
AFO-FC: ankle foot orthosis–footwear combination; 3D: three-dimensional.
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Eddison et al. Paents who have AFOs set at 90 problems normally Paents who meet degrees 5% 5% objecves, 5% Jointed AFOs for sit - stand 5%
Ability to ambulate, 33%
Paents with solid AFO's 14%
Cognive status 5% Stability 5%
Contractures 5%
Compliance 14%
Good gait paern, 5%
Figure 2. Criteria used to determine which patients will benefit from AFO-FC tuning. AFO-FC: ankle foot orthosis–footwear combination.
tuning; of the 49% of participants who do have set criteria, the ability to ambulate was the most common (33%) criterion used to decide whether a patient should have their AFO-FC tuned, as shown in Figure 2. This indicates a lack of understanding of the process and aims of AFO-FC tuning as tuning is indicated for walking, stepping and standing (Owen E, 16 April 2012, Paediatric gait analysis and orthotic management with AFO footwear combinations (Course Manual), personal communication). As shown in Table 1, although 49% of participants indicated that they have set criteria when deciding who would benefit from AFO-FC tuning, 46% of participants stated that they tune all the AFO-FCs they prescribe, and in the following question, 42% stated that time was the deciding factor on whether they tune the AFO-FCs they prescribe. This indicates some possible confusion regarding how the participants are deciding to tune the AFO-FCs they prescribe. Previous research has stated that the designs of the AFO and the AAAFO are crucial elements of successful AFO-FC tuning, and if the angle of the AFO does not correctly accommodate the length of the patient’s gastrocnemius, optimum AFO-FC tuning will not be possible.6,21 However, 49% of participants stated that they do not take the design of the AFO into account when deciding to tune an AFO-FC. Of 51% who stated that they do take the design of the AFO into account, only 1 participant correctly identified inadequate stiffness, incorrect AAAFO and a hinged AFO as being factors which would prevent successful tuning. Previous research states that there are clear physical presentations which will limit the success of AFO-FC tuning.6,8 However, 26% of respondents reported that they do not take the physical ability of the patient into account when deciding whether to tune an AFO-FC. Of the respondents who reported that they do take physical ability of the patient into account, the most common physical
31-35 years 7% 26-30 years, 7% 21-25 years, 2% 1-5 years 41%
16-20 years, 15%
11-15 years, 17% 6-10 years, 10%
Figure 3. Number of years of clinical experience of participants.
presentation which was identified as being the factor which would prevent tuning of an AFO-FC was an inability to ambulate (18%). The majority (54%) of responses named physical characteristics which have not been identified in current literature as preventing successful AFO-FC tuning, with 94% of participants failing to name all the four physical characteristics identified in research as being potential limiting factors of successful AFO-FC tuning. As shown in Figure 3, all respondents were qualified orthotists; the majority (41%) had 1–5 years post-graduate experience in orthotics. When asked about the exact methodology they employ to tune AFO-FCs, 87% of participants stated that they tune by eye alone and do not use any other method of gait assessment. However, it has been suggested that for a successful tuning, it is necessary to utilise some form of augmentative clinical gait assessment. While it was not the intention of this preliminary study to focus on the international clinical practice, the results from the United Kingdom highlight a clear need for further training which could be reflected within the professional
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practice in other countries. One of the limitations of this study could be that it represents only 9% of the practising orthotists, which could be attributed to the recruitment method. However, the results indicate that there is strong need to conduct such a study in other countries and develop a consensus in terms of processes and procedures related to AFO-FC tuning.
AFO-FC tuning among UK orthotists in the current literature with which to compare the results of this study. Conflict of interest None declared.
Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
Conclusion The results of the study indicate a clear lack of understanding regarding the key principles of AFO-FC tuning among the UK orthotists who participated in this study. While the majority of participants indicated that they understood the principles behind AFO-FC tuning, the subsequent questions revealed their limited knowledge. AFO-FC tuning is not yet standard clinical practice among the UK orthotists who participated in this study; the main reasons cited were a lack of access to 3D gait analysis and a lack of time. However, the study also seems to indicate that AFO-FC tuning principles are not well understood by the participants of this study. The 3D gait analysis is not essential to tune AFO-FCs, and the designs of the AFO and the AAAFO and the physical presentation of the patient are essential factors of AFO-FC tuning. However, the most prevalent factor identified as being key to AFO-FC tuning by participants was the patient’s ability to ambulate. Furthermore, of all responses (N = 41), the number of participants who named all the contraindications to AFO-FC tuning was 1. The majority of participants who took part in this study were relatively newly qualified; this may indicate a need to expand training on AFO-FC tuning in the current undergraduate programmes or as a part of post-graduate curriculum. While one could argue that some of the questions relate to the use of equipment and the individual interpretation of AFO-FC tuning, in the authors’ opinion, these are directly linked to various aspects of knowledge regarding AFO-FC tuning. It is possible that participants may have been using their own understanding and definition of AFO-FC tuning and not that of which is in the literature as the definition is yet to be standardised. The authors also recognise that this study has a relatively small subject group and this may have a bearing on the results. However, this study may indicate one important reason why AFO-FC tuning is not yet standard clinical practice, in that the basic principles are not fully understood by clinicians; this may be due to a lack of access to AFO-FC training at both undergraduate and post-graduate levels or the process of AFO-FC tuning may need to be simplified in the literature and made more accessible and easily understood. This study provides an important insight into common clinical practice among the clinicians who participated in this study and potentially highlights important reasons why AFO-FC tuning is not common clinical practice. There is no other available research into the prevalence of
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