A Proof of Concept for a Wireless Ambulatory Weight Bearing Measurement System in Rehabilitation and Telerehabilitation Applications

Weight bearing is an important clinical variable for rehabilitation specialists. The objectives of this proof of concept study were to design and build a wireless system for weight bearing measurement that would provide accurate dynamic and static measurements of plantar forces from multiple sites. The proposed system consists of two shoes instrumented with miniature load cells connected to ankle modules for wireless communication to a computer and signal conditioning. Force plates were used as the gold standard to evaluate the accuracy of the proposed system during quiet standing, walking and weight-shifting tasks in 30 young subjects. The performance of the system was characterized for each task using the following variables: percentage of body weight (PBW), heel-strike (HS) peak force value, stance time (ST), double support time (DST), excursion of center of pressure (COP) in the anteroposterior axis (ACOPx). For the measurement of the PBW, the standard deviation of errors in comparison to data obtained from forces plates during quiet-standing and weight-shifting activities was between 3.96% and 5.13%. With respect to gait parameters, the standard deviation of errors for the measurement of the peak forces during walking was between 6.10% and 8.82% for both shoes, and errors on timing variables during gait cycles were small (less than 18 msec for one standard deviation). For the ACOPx during a front weight-shifting trial, the standard deviation of errors was 19.20% for the right foot. The accuracy of the proposed system offers acceptable performances in the context of its proposed clinical applications. The envisioned embodiment and use of the system are instrumented shoes individually calibrated to assess in combination with real time video from videoconferencing codecs weight bearing capabilities in the context of telerehabilitation care. Work on the integration of the system with a clinical system for telerehabilitation is on-going.

[1]  H J Stam,et al.  Techniques for measuring weight bearing during standing and walking. , 2003, Clinical biomechanics.

[2]  J. Winters,et al.  Wearable sensors and telerehabilitation , 2003, IEEE Engineering in Medicine and Biology Magazine.

[3]  S. Brauer,et al.  A prospective study of laboratory and clinical measures of postural stability to predict community-dwelling fallers. , 2000, The journals of gerontology. Series A, Biological sciences and medical sciences.

[4]  V. L. Nickel,et al.  Gait parameters following stroke: a practical assessment. , 1995, Journal of rehabilitation research and development.

[5]  Ari Pääkkönen,et al.  Gait Characteristics and Functional Ambulation Profile in Patients with Chronic Unilateral Stroke , 2003, American journal of physical medicine & rehabilitation.

[6]  E. Roth,et al.  Hemiplegic gait. Relationships between walking speed and other temporal parameters. , 1997, American journal of physical medicine & rehabilitation.

[7]  Strategies for clinical motion analysis based on functional decomposition of the gait cycle. , 2002, Physical medicine and rehabilitation clinics of North America.

[8]  H J Stam,et al.  Accuracy and repeatability of the Pedar Mobile system in long-term vertical force measurements. , 2006, Gait & posture.

[9]  H. Handoll,et al.  Mobilisation strategies after hip fracture surgery in adults. , 2007, The Cochrane database of systematic reviews.

[10]  M Lord,et al.  Time-Dependent Behaviour of a Force-Sensitive Resistor Plantar Pressure Measurement Insole , 1996, Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine.

[11]  L. Feiwell,et al.  A Method for Measuring Foot Pressures Using a High Resolution, Computerized Insole Sensor: The Effect of Heel Wedges on Plantar Pressure Distribution and Center of Force , 1992, Foot & ankle.

[12]  F. Zajac,et al.  Gait differences between individuals with post-stroke hemiparesis and non-disabled controls at matched speeds. , 2005, Gait & posture.

[13]  J Kärrholm,et al.  Low effectiveness of prescribed partial weight bearing. Continuous recording of vertical loads using a new pressure-sensitive insole. , 2001, Journal of Rehabilitation Medicine.

[14]  N. Paik,et al.  Quantification of the path of center of pressure (COP) using an F-scan in-shoe transducer. , 1999, Gait & posture.

[15]  J. Woodburn,et al.  Observations on the F-Scan in-shoe pressure measuring system. , 1996, Clinical biomechanics.

[16]  I. Melzer,et al.  Postural stability in the elderly: a comparison between fallers and non-fallers. , 2004, Age and ageing.

[17]  H. Handoll,et al.  Mobilisation strategies after hip fracture surgery in adults. , 2007, The Cochrane database of systematic reviews.

[18]  T. Mittlmeier,et al.  Partial weight bearing after surgery for fractures of the lower extremity--is it achievable? , 2006, Gait & posture.

[19]  Holt,et al.  How Accurate Is Partial Weightbearing? , 2004, Clinical orthopaedics and related research.

[20]  Jack M Winters,et al.  A telehomecare model for optimizing rehabilitation outcomes. , 2004, Telemedicine journal and e-health : the official journal of the American Telemedicine Association.

[21]  Hongwei Hsiao,et al.  Accuracy and precision of two in-shoe pressure measurement systems , 2002, Ergonomics.

[22]  F. Tang,et al.  Symmetrical body-weight distribution training in stroke patients and its effect on fall prevention. , 2001, Archives of physical medicine and rehabilitation.

[23]  J. Raymakers,et al.  The assessment of body sway and the choice of the stability parameter(s). , 2005, Gait & posture.

[24]  Richard K. Jones,et al.  Reproducibilty of partial weight bearing. , 2005, Injury.

[25]  Richard W. Bohannon,et al.  Accuracy of Weightbearing Estimation by Stroke versus Healthy Subjects , 1991, Perceptual and motor skills.

[26]  J. Cunningham,et al.  A comparison of vertical force and temporal parameters produced by an in-shoe pressure measuring system and a force platform. , 2000, Clinical biomechanics.

[27]  Heidi Nadollek,et al.  Outcomes after trans-tibial amputation: the relationship between quiet stance ability, strength of hip abductor muscles and gait. , 2002, Physiotherapy research international : the journal for researchers and clinicians in physical therapy.

[28]  G M Bashford,et al.  Weight bearing and velocity in trans-tibial and trans-femoral amputees , 1997, Prosthetics and orthotics international.