International scientific consensus on medical plantar pressure measurement devices: technical requirements and performance
Consenso scientifico internazionale sui dispositivi medici per la misura delle pressioni plantari: requisiti tecnici e prestazioni
Claudia GiacomozziI; Noel KeijsersII; Todd PatakyIII; Dieter RosenbaumIV
IDipartimento di Tecnologie e Salute, Istituto Superiore di Sanità, Rome, Italy ]]>
IIDepartment of Research, Development and Education, Sint Maartenskliniek, Nijmegen, The Netherlands
IIIYoung Researchers Empowerment Project, Department of Bioengineering, Shinshu University, Ueda, Japan
IVInstitute for Experimental Musculoskeletal Medicine, Movement analysis Lab, University Hospital Münster, Germany
ABSTRACT
BACKGROUND: Since 2006, the Italian National Institute of Health (ISS) has been conducting independent scientific activities to standardize the technical assessment of plantar pressure measurement devices (PMDs).
MATERIAL AND METHODS: On the basis of the ISS results, in 2010 the Pedobarographic Group of the International Foot and Ankle Biomechanics community (i-FAB-PG) promoted a consensus activity about the main technical requirements for the appropriate use of PMDs. The activity relied on a moodlebased on-line forum, documents exchange, discussions, reviews, meetings and a final survey.
RESULTS: The participation of clinical and technical researchers, users, and manufacturers, contributed to the delivery of the hereby reported recommendations which specifically regard Medical PMDs in the form of platforms. ]]>
CONCLUSIONS: The i-FAB-PG community reached overall agreement on the recommendations, with a few minor objections which are reported and commented in the document.
RELEVANCE: The present document, the highest result achievable within a small scientific community, will hopefully represent the starting point of the wider process of establishing official international guidelines or standards, within scientific communities and standardization organizations.
Key words: baropodometry, pressure measurement devices, technical assessment, accuracy, COP estimation.
RIASSUNTO
BACKGROUND: A partire dal 2006, l'Istituto Superiore di Sanità (ISS) ha condotto attività scientifiche indipendenti mirate alla standardizzazione della valutazione tecnica di dispositivi per la misura della pressione plantare (PMDs).
MATERIALI E METODI: A partire dai risultati dell'ISS, nel 2010 il Gruppo Pedobarografico della International Foot and Ankle Biomechanics community (i-FAB-PG) ha lanciato un'attività di consensus relativa ai requisiti tecnici essenziali per un uso appropriato dei PMD. L'attività si è basata su; un forum su piattaforma moodle; scambio, discussione e revisione di documenti; incontri finalizzati; verifica finale di agreement.
RISULTATI: La partecipazione di ricercatori, utilizzatori clinici e tecnici, e produttori, ha contribuito alla definizione delle raccomandazioni qui di seguito riportate, che si riferiscono nello specifico a PMD utilizzati in ambito clinico, in forma di piattaforme.
CONCLUSIONI: La comunità i-FAB-PG ha raggiunto un accordo generale sul documento, con solo qualche residua minore obiezione, riportata e commentata nel documento.
RILEVANZA: È auspicabile che il documento, che costituisce il massimo risultato raggiungibile all'interno di una piccola comunità scientifica, possa rappresentare il punto di partenza di un più ampio processo per la definizione di linee guida ufficiali e di standard, nell'ambito di società scientifiche e di enti normatori.
Parole chiave: baropodometria, dispositivi di misura di pressione, valutazione tecnica, accuratezza, stima centro di pressione (COP).
INTRODUCTION
Plantar pressure measurement devices (PMDs) are widespread:
- in the biomechanical research, where they are mainly used to acquire kinetic parameters of foot-floor interaction during gait, running and standing, even though few experimental studies are currently conducted to use PMD outputs as input for finite element models (FEMs) or in general for biomechanical models;
- in the clinical context, as a support to diagnosis, early detection of pathologies, and monitoring during the treatment of not only orthopaedic diseases, but also degenerative, metabolic and systemic diseases, i.e., diabetes and rheumatoid arthritis;
- as a key instrument for the prescription, design and construction of plantar orthoses, in some cases directly linked to CAD/cAM systems (CAD: computer-aided design: cAM: computer-aided manufacturing), and for the assessment of their efficacy.
Whenever a PMD is used for analysing a patient, it should be referred to as "Medical PMD".
Besides the increasing use of PMDs and the increasing number of peer-reviewed, scientific publications discussing PMDs, the lack of standardisation is clearly evident in terms of both instrumentation and methodologies, which renders any comparison and data sharing very difficult and of uncertain validity. The major difficulties to cope with when discussing about PMD technical performance are related to significant differences in sensor technology, matrix spatial resolution, pressure range, sampling rate, calibration procedures, raw data pre-processing. In addition, critical practical issues interfere with the appropriate use of PMDs, i.e. problems associated with patient behaviour, experimental protocol and data post-processing [1].
]]> At least three fundamental steps have to be followed towards standardisation in the use of PMDs:1. definition and standardisation of tools and protocols for the technical assessment of PMD hardware performance;
2. definition and standardisation of pressure acquisition protocols;
3. definition and standardisation of data processing and reporting.
The present document only deals with the first step. More specifically, it constitutes the final output of a dedicated consensus Activity ("Agreement on PMD hardware performance"), which has been conducted by the Pedobarographic Group (i-FAB-PG) of the International Foot and Ankle Biomechanics community (moodle.i-fab.org). Before the community reaches full agreement, just a few minor questions remain to be discussed, mostly related to specific aspects raised by some manufacturers. These aspects are fully reported and commented in the document.
All the statements, recommendations, technical and methodological suggestions hereby reported are the result of: i) preliminary activities at the ISS regarding this specific issue [2, 3]; ii) online activities within the i-FAB-PG moodle-based forum; iii) background/working material found in the literature [2-18]; iv) document revision, and final on-line survey.
The content of this final i-FAB-PG Consensus Document addresses PMDs, in the form of PLATFORMS intended to be used as Medical PMD for barefoot walking analysis and, optionally, for stabilometric analysis. It may also be applied to different sensor arrangements - e.g., wearable or flexible equipment - to perform a partial assessment with the sensor horizontally placed on a plane. In any case, further specification and agreement is needed for sensor performance assessment under flexed conditions.
The i-FAB-PG Consensus Document should be seen in terms of pure scientific consensus, obtained through the joint effort of researchers and manufacturers. The manufacturers and users who will agree to follow the recommendations contained in the document will do so on a purely voluntary basis, without any regulatory constraint. In fact, even though the recommendations are in agreement with the requirements of EU Directives for Medical Devices, - i.e. they aim at preserving the safety of users and the achievement of the intended use - in no case do they constitute an instrument by which to claim compliance, or demonstrate lack of compliance, with the EU Regulations.
Finally, the present i-FAB-PG Consensus Document, which represents the highest result achievable within the above scientific community, aims to be a starting point for the onset of the complex process of defining official international guidelines and standards, which are expected by wider scientific societies and international standardization organizations.
]]>MATERIALS AND METHODS
Sequence of actions towards consensus
Since 2006, the Department of Technology and Health of ISS, the Italian National Institute of Health, has been conducting a scientific project and several related activities aimed to design, validate and implement dedicated testing methods and recommendations for PMD technical assessment [2, 4].
In 2010, ISS organized and hosted the workshop "Assessment of pressure measurement devices (PMDs) for their appropriate use in biomechanical research and in the clinical practice" [5]. A first proposal document was presented at the workshop, dealing with methodological issues and some important recommendations to PMD manufacturers and end users, with special focus on the assessment of PMD hardware performance. A full explanation of the rationale behind each recommendation was also given in the document [2].
The feedback from users and manufacturers who participated in the workshop was used to prepare a second Proposal Document which: i) was disseminated by ISS at the ESM2010 Scientific Meeting. (ESM is the acronym for Emed Scientific Meeting, being Emed the capacitive PMD provided by the Manufacturer novel gmbh, Munich, Germany. ESM is a scientific event focussed on foot loading and biomechanics, which takes place every two years, inaugurated and organized by the above Manufacturer and hosted by research and clinical centers all over the world. The 2010 ESM was held in Providence, Rhode Island, USA, on August 14-17 2010, hosted by the Brown University, The center for Restorative and Regenerative Medicine, in cooperation with the University of Rhode Island); ii) was successively finalized through the ISS moodle-based interactive Forum on PMDs (ISS is hosting the moodle-based interactive web page "ISS-PMDs", which is the ISS forum on hardware performance of plantar pressure measurement devices (PMDs). The page can be found at http://vcms.iss.it/moodle19. A free registration needed to navigate the page can be requested by e-mail message with name and affiliation to claudia.giacomozzi@iss.it). In September 2010 the ISS-ESM2010 consensus proposal was ready and published in the Forum [19].
At this point, while still maintaining its PMD-related activities with a constant update and interaction on its own dedicated Forum, ISS brought the consensus Activity to a wider level: in September 2010 the Pedobarographic Group named i-FAB-PG was created and launched at the meeting of the International Foot and Ankle Biomechanics community (2nd i-FAB meeting, Seattle, US, Sept 2010). Work was done interactively through the online Forum across 2011, and a first draft of the iFAB-PG Consensus Document on PMD technical performance was disseminated immediately before, and presented during, the dedicated i-FAB-PG session at the ISB meeting in Bruxelles, on July 5th 2011.
Following the general agreement on the Document, a final Agreement Survey was kept open until the end of July 2011 to give all participants the opportunity to make a final revision and comment on the Document. On the basis of the last 10 comments received, the i-FAB-PG Consensus Document was finalised as is reported here. Where agreement could not be reached - mainly due to residual comments or concerns by the manufacturers - a detailed explanation is given in the Document.
For the sake of readability, many technical details proposed and discussed in the drafts of the Document have not been included in this final version, but they are still available on the Forum or may be directly obtained by the leader of the associated consensus Activity, c. Giacomozzi.
Methodology for document revision and finalisation within i-FAB-PG
]]> Starting from September 2010, background working material and draft documents were uploaded and made available for consultation and downloading at any time by i-FAB-PG Forum participants. Several invitations were sent out to all interested researchers, clinical users and manufacturers through several internet dissemination channels and mailing lists. e-mailing was encouraged through the moodle page of the Forum on the proposed discussion topics.Each time a new document was uploaded on the Forum page, or a new on-line activity was launched, an e-mail message was sent out to all Forum Participants. ISS gave its support also through its own PMDs Forum, by uploading a pdf version of the i-FAB-PG working documents and by alerting its Forum Participants about the i-FAB-PG on-going activities.
Some specific on-line activities were activated for limited time periods, which are briefly summarised here below:
- January 28th - February 11th 2011. A daily open online discussion was "tutored" on the Consensus Document Draft0: it was a constructive phase of the consensus process, even though there was not a true daily on-line discussion among participants for most of them preferred an off-line way of contributing.
- March 1st - June 9th 2011. The revised Draft1 of the Consensus Document was uploaded and open for comments through the page. As no relevant comments were posted, the Final Document was written with only few minor editorial changes.
- June 10th - July 5th 2011. The Final complete Consensus Document was uploaded and remained available for comments until its discussion during the i-FAB-PG general meeting in Brussels (July 5th, 2011), open to all ISB participants;
- July 6th - July 31st 2011. The Final Survey was launched and kept open to ask for a Final Agreement on the Final Consensus Document; quick questions were delivered to ask whether participants had any residual objection regarding each Table in particular or the entire Document as a whole.
For the general revision procedure, the concept was followed of taking into account each general comment providing a good explanation, contributed at any stage of the revision process, and with a general applicability to Medical PMDs. Each revision was shared and agreed by the PG leaders - i.e. the authors of the present Document - before dissemination. More in detail:
]]> - from Draft0 to Draft1. Seventeen users actively navigated the page during the period; 5 researchers and 3 manufacturers sent back their comments; some other researchers and manufacturers sent their informal comments through private email to activity leaders. None of the points suggested in Draft0 was rebutted; few points were raised for clarification, and proper explanations were added at the beginning or in the core of Draft1; other points were added as suggested by participants. comments were not added to the document when they were too specific or regarded the performance of specific commercial products. In any case, individual answers were sent to each participant if specifically requested;- from Draft1 to the Final Document. No comments were posted on the i-FAB-PG Forum; another positive answer was received through the ISS PMD Forum from another manufacturer who requested no changes at all. Only minor editorial changes were shared among the PG leaders, and implemented in the Revised version, which was presented at the i-FAB-PG meeting on July 5th 2011 and uploaded to the Forum for the Final Survey;
- from Final Document to i-FAB-PG Consensus Document on PMD Technical Assessment - i.e. the present Document -. Ten comments were received in all, with 3 containing suggestions for further specifications rather than changes. As for the remaining comments, they mainly regarded commercial experiences from Manufacturers: a short explanation accounts for them in the consensus Tables. Whenever high-level specifications led to disagreement/discussions deserving further investigation, a more general level was maintained for this final Consensus Document with respect to the working documents, whose validity had been implicitly agreed upon by all Participants.
RESULTS
The i-FAB-PG consensus document
The outcomes of the described consensus activity have been collected in eight tables. Briefly: Table 1 resumes the basic principles over which agreement has been reached, and which represent the basis for the PMD technical assessment approach; Table 2 describes the parameters which should be included in the minimum set of parameters to be assessed in factory; Table 3 reports the technical requirements a proper test system should have to deliver the parameters listed in Table 2; Table 4 deals with a suggestion for implementing in factory testing protocols; Table 5 gives some recommendations in terms of minimum requirements for Medical PMDs addressed to barefoot gait analysis; Table 6 contains a proposal for the Manufacturer's technical report to be associated with the commercial PMD; Table 7 deals with on-site, periodical assessment of PMDs; Table 8 contains a sort of checklist for Authors, Reviewers and Editors to properly judge the consistency of data scientific papers rely on. In each Table comments and explanations are reported when a full agreement had not been reached with respect to the specific point.
DISCUSSION AND CONCLUSIONS
The i-FAB-PG Consensus Document hereby reported is the first attempt of a Scientific community at having users and manufacturers work together for the definition of recommendations to standardise the assessment of PMD hardware performance. Notwithstanding the effort and the time devoted to discussing and finding agreement on several issues, and the valuable results obtained up to now, the Document should still be reckoned as a merely scientific initiative of only a part of the entire world scientific community involved in PMD research and applications.
]]> At a more general level, at least another three project lines should stem from this first experience, namely:- the preparation of official guidelines as a result of a worldwide consensus activity. ISS is deeply involved in the formulation of official guidelines at national level in the field of Public Health, and is thus ready to start and lead such an initiative at the International level. The process should be based on an active collaboration with the dedicated scientific societies all over the world; the activities ISS is conducting within the Italian Society of Movement Analysis in clinics (SIAMOC) already represents a first step in this direction. Equally important in this sense are all the dissemination activities aimed at sharing a deeper knowledge of PMDs technology, potentialities and criticalities with users at different levels and in different scenarios;
- the definition of a clearer regulatory scenario: an issue of particular relevance in clinical environments, where PMDs are to be intended as Medical Devices. ISS has already started a regulatory activity in this direction within the Italian Institutes for Standards, for the submission of a PMD-specific Standard; hopefully, this activity will be eventually taken to the European level;
- continuous research and technology develop ment to design and validate innovative and valuable methods and instruments for PMD testing, both on the bench and in the field;
After this Consensus Document, i-FAB-PG will hopefully continue the discussion and investigation of the other issues relevant to the appropriate use of PMDs: those strictly related to measurement protocols, and data extraction and interpretation.
Acknowledgements
The authors thank all i-FAB-PG and i-FAB participants who gave their best and rendered consensus activity a success; special thanks are due to the following researchers and manufacturers who actively contributed to the preparation and revision of the documents (some of them, external to the i-FAB-PG, gave their contribution through the ISS-PMDs Forum): i) researchers: Bus SA; D'Amico M; Davenport c; Evans A; Gapeyeva H; Lau Hc; Mickle K; Murphy N; Roberts A; Russell J; Sawacha Z; Segers V; ii) manufacturers: AMcUBE; MEDILOGIc; NOVEL; RSSCAN, TEKSCAN. The authors are also grateful to Monica Brocco for the English editing of the manuscript.
Conflict of interest statement
There are no potential conflicts of interest or any financial or personal relationships with other people or organizations that could inappropriately bias conduct and findings of this study. Manufacturers' indications and suggestions have been taken into account only when based on a strong scientific rationale, and having general applicability.
]]>References
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Address for correspondence: Received on 5 May 2012.
Accepted on 11 June 2012.