University of Washington

Ellen L Lee

Joan E Sanders

Timothy Myers

Kirk Watson Beach

Katheryn J Allyn

Santosh Zachariah

Daniel S Harrison

Daniel C Abrahamson

Michael R Severance

George M Turkiyyah

Elizabeth A Sorenson

Changes in the volume of residual limbs on which prosthetic sockets are worn can be measured based on bioimpedance measurements along one or more segments of the limb. A current at an appropriate frequency (e.g., in the range from 1 kHz to 1 MHz) is injected at two current electrodes that contact the skin of the residual limb. The voltage at the voltage electrodes disposed between the current electrodes is measured and using an appropriate model, the change in the segmented volume of the limb can be determined during periods of different activity and at different times during the day. This information can be used for assessing the fit of the socket and can also provide a feedback signal for automatically controlling volume management devices, to ensure a more comfortable fit when the volume of the limb is changing.

Measurement and use of in-socket residual limb volume change data for prosthetic fitting

For use in connection with evaluating prosthetic sockets (and other objects) designed and fabricated with computer aided design and manufacturing software, the shape of a socket is accurately scanned and digitized. The scanned data are then compared to either an electronic shape data file, or to the shape of another socket, a positive model of a residual limb (or socket), or a residual limb. Differences detected during the comparison can then be applied to revise the design or fabrication of the socket, to more accurately achieve a desired shape that properly fits the residual limb of a patient and can be used to solve the inverse problem by correcting for observed errors of a specific fabricator before a socket is produced. The digitizing process is implemented using a stylus ball that contacts a surface of the socket to produce data indicating the three-dimensional shape of the socket.

Computer aided design and manufacturing of transtibial prosthetic sockets

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Corvallis, OR, United States of America

Ellen L Lee