University of Washington

Timothy Myers

Joan E Sanders

Ellen L Lee

Kirk Watson Beach

Katheryn J Allyn

Brian Hafner

Daniel C Abrahamson

Santosh Zachariah

Daniel S Harrison

Michael R Severance

George M Turkiyyah

Elizabeth A Sorenson

Parameters related to use of a prosthesis by a patient with a limb amputation are monitored using a tool that includes one or more piezoelectric force sensors. The resulting data are processed for use both in short and long term management of amputee patients. The sensor is a small modular unit that fits within or between traditional prosthetic components, e.g., below a prosthesis socket. The data produced by the tool are collected, processed, and stored. Optionally, the data are periodically communicated to a remote site via a network, e.g., over the Internet. The device and associated software used to process the data can be used to characterize activities conducted by a prosthesis user, to determine pistoning or threatening interface stress distributions between the limb and socket, mal-alignment of the socket, use of improper components, and other possibly undesired conditions that the amputee patient using the prosthesis may be experiencing.

Prosthetic limb monitoring system

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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Timothy Myers