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Patient specific ankle-foot orthoses using rapid prototyping

Constantinos Mavroidis1*, Richard G Ranky1, Mark L Sivak1, Benjamin L Patritti2, Joseph DiPisa1, Alyssa Caddle1, Kara Gilhooly1, Lauren Govoni1, Seth Sivak1, Michael Lancia3, Robert Drillio4 and Paolo Bonato25*

Author Affiliations

1 Department of Mechanical & Industrial Engineering, Northeastern University, 360 Huntington Avenue, Boston, MA, 02115, USA

2 Department of Physical Medicine and Rehabilitation, Harvard Medical School, Spaulding Rehabilitation Hospital, 125 Nashua Street, Boston, MA, 02114, USA

3 Polymesh LLC, 163 Waterman Street Providence, RI 02906-3109

4 IAM Orthotics & Prosthetics, Inc., 400 West Cummings Park, Suite 4950, Woburn, MA, 01801, USA

5 Harvard-MIT Division of Health Sciences and Technology, 77 Massachusetts Ave., Cambridge, MA, 02139, USA

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Journal of NeuroEngineering and Rehabilitation 2011, 8:1  doi:10.1186/1743-0003-8-1

Published: 12 January 2011

Abstract

Background

Prefabricated orthotic devices are currently designed to fit a range of patients and therefore they do not provide individualized comfort and function. Custom-fit orthoses are superior to prefabricated orthotic devices from both of the above-mentioned standpoints. However, creating a custom-fit orthosis is a laborious and time-intensive manual process performed by skilled orthotists. Besides, adjustments made to both prefabricated and custom-fit orthoses are carried out in a qualitative manner. So both comfort and function can potentially suffer considerably. A computerized technique for fabricating patient-specific orthotic devices has the potential to provide excellent comfort and allow for changes in the standard design to meet the specific needs of each patient.

Methods

In this paper, 3D laser scanning is combined with rapid prototyping to create patient-specific orthoses. A novel process was engineered to utilize patient-specific surface data of the patient anatomy as a digital input, manipulate the surface data to an optimal form using Computer Aided Design (CAD) software, and then download the digital output from the CAD software to a rapid prototyping machine for fabrication.

Results

Two AFOs were rapidly prototyped to demonstrate the proposed process. Gait analysis data of a subject wearing the AFOs indicated that the rapid prototyped AFOs performed comparably to the prefabricated polypropylene design.

Conclusions

The rapidly prototyped orthoses fabricated in this study provided good fit of the subject's anatomy compared to a prefabricated AFO while delivering comparable function (i.e. mechanical effect on the biomechanics of gait). The rapid fabrication capability is of interest because it has potential for decreasing fabrication time and cost especially when a replacement of the orthosis is required.