Socket Pressure Monitoring System

The goal of this Phase 1 project is to identify changes in residual limb volume in amputees and to warn the user when these changes may lead to potential problems. One cause of residual limb pain in amputees is improper prosthetic socket fit, causing a range of mild to unbearable pressures. Residual limbs can change shape over long timeframes which can change the interface between the socket and skin. The volume changes may be due to inactivity, weight gain or loss, medications, vascular conditions, or other medical complications. Additionally, the residual limb may have reduced sensation due to neuropathy related to diabetes. This project uses sensors embedded in the socket to monitor pressure in transfemoral amputees as residual limb volume change is simulated. Volume change is mimicked by testing amputees wearing prosthetic sockets that are slightly larger and smaller than usual, and then measuring the corresponding pressures. Pressure is recorded at two locations in the socket in three different simulated conditions: (1) decreased limb volume, (2) reference limb volume, and (3) increased limb volume. The two locations are at the distal end of the residual limb and at the ischium. From this data, the percent change in pressure from the reference pressure is calculated for the increased limb volume and the decreased limb volume conditions. This data is used to determine pressure thresholds which, when exceeded, can be used to alert the user that they have a compromised fit. Users can then intervene before the limb’s skin is damaged, thus increasing their ability to use their prosthesis, improving their quality of life, and reducing healthcare costs.