Pressure Imaging

Pedobarography is the study of pressure fields acting between the plantar surface of the foot and a supporting surface. Used most often for biomechanical analysis of gait and posture, pedobarography is employed in a wide range of applications including sports biomechanics and gait biometrics. The term 'pedobarography' is derived from the Latin: ''pedes'', referring to the foot (as in: pedometer, pedestrian, etc.), and the Greek: ''baros'' meaning 'weight' and also 'pressure' (as in: barometer, barograph).

History

The first documented pedobarographic study was published in 1882 and used rubber and ink to record foot pressures. Numerous studies using similar apparatus were conducted in the early- and mid-twentieth century, but it was not until the advent of the personal computer that electronic apparatus were developed and that pedobarography became practical for routine clinical use. It is now used widely to assess and correct a variety of biomechanical and neuropathic disorders.

Hardware

Devices fall into two main categories: (i) floor-based, and (ii) in-shoe. The underlying technology is diverse, ranging from piezoelectric sensor arrays to light refraction,




but the ultimate form of the data generated by all modern technologies is either a 2D image or a 2D image time series of the pressures acting under the plantar surface of the foot. From these data other variables may be calculated (see Data analysis).

There are a few differences between the types of information you will received from these two systems, so depending on the application one system might be a better fit. For example, a floor-based system will provide spatial temporal information, like stride length that an in-shoe system cannot provide. Platform systems (or floor-based systems) will also allow for testing of patients with walking aids for assistive devices. However, there is some controversy about evaluating natural gait with a platform system due to patients potentially targeting the platform when walking. This is where an in-shoe system provides an advantage as it reduces the risk of targeting. Users should evaluate carefully the differences between the systems, the patients they will be evaluating and the type of data they are interested in when selecting a system.

The spatial and temporal resolutions of the images generated by commercial pedobarographic systems range from approximately 3 to 10 mm and 25 to 500 Hz, respectively. Finer resolution is limited by sensor technology. Such resolutions yield a contact area of approximately 500 sensors (for a typical adult human foot with surface area of approximately 100 cm²). For a stance phase duration of approximately 0.6 seconds during normal walking, approximately 150,000 pressure values, depending on the hardware specifications, are recorded for each step.

Data analysis

To deal with the large volume of data contained in each pedobarographic record, traditional analyses reduce the data to a more manageable size in three stages: (1) produce anatomical or regional masks, (2) extract regional data, and (3) run statistical tests. Results are typically reported in tabular or bar graph formats. There are also a number of alternative analysis techniques derived from digital image processing methodology. These techniques have also been found to be clinically and biomechanically useful, but traditional regional analyses are most common.

The most commonly analyzed pedobarographic variable is 'peak pressure', or the maximum pressure experienced at each sensor (or pixel, if the sensors fall on a regular square grid) over the duration of the step. Other variables like contact duration, pressure-time integral, center of pressure trajectory, for example, are also relevant to the biomechanical function of the foot.

Clinical use

The most widely researched clinical application of pedobarography is diabetic foot ulceration, a condition which can lead to amputation in extreme cases but for which even mild-to-moderate cases are associated with substantial health care expenditure. Pedobarography is also used in a variety of other clinical situations including: post-surgery biomechanical assessment, intra-operative assessment, orthotics design and assessment of drop-foot surgery. In addition to clinical applications, pedobarography continues to be used in the laboratory to understand the mechanisms governing human gait and posture.

The use of pedobarographs in clinical settings is supported by researchers. According to Bowen, et al., "Pediobarograph measurements can be used to monitor and quantitatively assess the progressive changes of foot deformity over time. Pedobarograph is a reliable measurement that shows little variability between measurements at the same occasion and between measurements on different days."

Terminology

*''Dynamic pedobarography'' refers to the collection and analysis of time series pedobarographic data during dynamic activities like gait.
*''Static pedobarography'' refers to the collection and analysis of time series pedobarographic data during postural (i.e. quasi-static) activities.

References

{{Reflist, refs=

{{cite journal , vauthors = Alexander IJ, Chao EY, Johnson KA , title = The assessment of dynamic foot-to-ground contact forces and plantar pressure distribution: a review of the evolution of current techniques and clinical applications , journal = Foot & Ankle , volume = 11 , issue = 3 , pages = 152–67 , date = December 1990 , doi = 10.1177/107110079001100306 , pmid = 2074083 , s2cid = 28350803

{{cite journal , vauthors = Blanc Y, Balmer C, Landis T, Vingerhoets F , title = Temporal parameters and patterns of the foot roll over during walking: normative data for healthy adults , journal = Gait & Posture , volume = 10 , issue = 2 , pages = 97–108 , date = October 1999 , pmid = 10502643 , doi = 10.1016/S0966-6362(99)00019-3

{{cite journal , vauthors = Birtane M, Tuna H , title = The evaluation of plantar pressure distribution in obese and non-obese adults , journal = Clinical Biomechanics (Bristol, Avon) , volume = 19 , issue = 10 , pages = 1055–9 , date = December 2004 , pmid = 15531056 , doi = 10.1016/j.clinbiomech.2004.07.008

{{cite journal , vauthors = Chu WC, Lee SH, Chu W, Wang TJ, Lee MC , title = The use of arch index to characterize arch height: a digital image processing approach , journal = IEEE Transactions on Bio-Medical Engineering , volume = 42 , issue = 11 , pages = 1088–93 , date = November 1995 , pmid = 7498912 , doi = 10.1109/10.469375 , s2cid = 20181495

{{cite journal , vauthors = Cobb J, Claremont DJ , title = Transducers for foot pressure measurement: survey of recent developments , journal = Medical & Biological Engineering & Computing , volume = 33 , issue = 4 , pages = 525–32 , date = July 1995 , pmid = 7475382 , doi = 10.1007/BF02522509 , s2cid = 19670853

{{cite journal , vauthors = Gefen A , title = Pressure-sensing devices for assessment of soft tissue loading under bony prominences: technological concepts and clinical utilization , journal = Wounds: A Compendium of Clinical Research and Practice , volume = 19 , issue = 12 , pages = 350–62 , date = December 2007 , pmid = 25942685 , url = https://www.woundsresearch.com/article/8106

{{ cite journal , vauthors = Lord M , date = 1981 , title = Foot pressure measurement: a review of methodology. , journal = J Biomed Eng , volume = 3 , issue = 2 , pages = 91–9 , doi = 10.1016/0141-5425(81)90001-7 , pmid = 7230763

{{cite journal , vauthors = Rosenbaum D, Becker HP , date = 1997 , title = Plantar pressure distribution measurements: technical background and clinical applications. , journal = J Foot Ankle Surg , volume = 3 , pages = 1–14 , doi = 10.1046/j.1460-9584.1997.00043.x

{{cite journal , vauthors = Orlin MN, McPoil TG , title = Plantar pressure assessment , journal = Physical Therapy , volume = 80 , issue = 4 , pages = 399–409 , date = April 2000 , pmid = 10758524 , doi = 10.1093/ptj/80.4.399 , doi-access = free

{{cite journal , vauthors = Hahn F, Maiwald C, Horstmann T, Vienne P , title = Changes in plantar pressure distribution after Achilles tendon augmentation with flexor hallucis longus transfer , journal = Clinical Biomechanics (Bristol, Avon) , volume = 23 , issue = 1 , pages = 109–16 , date = January 2008 , pmid = 17949866 , doi = 10.1016/j.clinbiomech.2007.08.015

{{cite journal , vauthors = Hodge MC, Bach TM, Carter GM , title = novel Award First Prize Paper. Orthotic management of plantar pressure and pain in rheumatoid arthritis , journal = Clinical Biomechanics (Bristol, Avon) , volume = 14 , issue = 8 , pages = 567–75 , date = October 1999 , pmid = 10521640 , doi = 10.1016/S0268-0033(99)00034-0

{{cite book , vauthors = Klenerman L, Wood B , year = 2006 , title = The Human Foot: A Companion to Medical Studies , location = Berlin , publisher = Springer

{{cite journal , vauthors = Prabhu KG, Patil KM, Srinivasan S , title = Diabetic feet at risk: a new method of analysis of walking foot pressure images at different levels of neuropathy for early detection of plantar ulcers , journal = Medical & Biological Engineering & Computing , volume = 39 , issue = 3 , pages = 288–93 , date = May 2001 , pmid = 11465882 , doi = 10.1007/BF02345282 , s2cid = 25342386

{{ cite journal , vauthors = Richter M, Frink M, Zech S, Geerling J, Droste P, Knobloch K, Krettek C , author-link1 = Martinus Richter , date = 2006 , title = Technique for intraoperative use of pedobarography. , journal = Tech Foot Ankle Surg , volume = 5 , pages = 88–100 , doi = 10.1097/00132587-200606000-00006 , s2cid = 72699538

{{cite journal , vauthors = Reiber GE , title = Diabetic foot care. Financial implications and practice guidelines , journal = Diabetes Care , volume = 15 Suppl 1 , pages = 29–31 , date = March 1992 , pmid = 1559416 , doi = 10.2337/diacare.15.1.S29 , s2cid = 20148896

v{{cite journal , vauthors = van Schie CH , title = A review of the biomechanics of the diabetic foot , journal = The International Journal of Lower Extremity Wounds , volume = 4 , issue = 3 , pages = 160–70 , date = September 2005 , pmid = 16100097 , doi = 10.1177/1534734605280587

{{cite book , vauthors = Shah SR, Patil KM , year = 2005 , chapter = Processing of foot pressure images and display of an advanced clinical parameter PR in diabetic neuropathy. , title = Proc 9th Intl Conf Rehab Robotics , pages = 414–417 , doi = 10.1109/ICORR.2005.1501131 , isbn = 0-7803-9003-2 , s2cid = 47541236

{{cite book , vauthors = Parmar B , year = 2009 , chapter = Assessment of Foot Drop Surgery in Leprosy Subjects Using Frequency Domain Analysis of Foot Pressure Distribution Images. , title = 13th International Conference on Biomedical Engineering, IFMBE Proceedings , series = IFMBE Proceedings , volume = 23 , pages = 1107–1111 , doi = 10.1007/978-3-540-92841-6_272 , isbn = 978-3-540-92840-9

Podiatry
Walking
Anthropometry
Biomechanics