Amputee residual limb size will increase and decrease throughout the day as the soft tissue is compressed during gait and fluid is forced out. The leg will also change volume over the course of months and years primarily from long term muscular atrophy.
Poor fit of the prosthetic is the leading complaint of amputees and that problem can create skin breakdown and bruising. When they feel discomfort, amputees currently manage volume changes on an hour by hour basis by adding and removing socks (ply) to the residual limb. Exacerbating the problem, most amputees, up to 80%, suffer from sensation loss (neuropathy) in the residual limb making it difficult to maintain an appropriate ply within the prosthetic.
Our adaptive socket interface system continuously measures socket pressure changes due to the daily and long term limb volume change and adjusts to appropriate pressures accordingly. We also detect the activity state of the amputee and reduce pressure while sitting. This allows the limb to recover fluid volume while sitting which has been shown to be important for limb health. In addition to eliminating the hassle of changing sock layers, we anticipate our device will improve amputee quality of life due to improved limb health.
Prototype 1. Initial Proof-of-Concept System
Prototype 2. Funded by Washington State Life Sciences Discovery Fund grant to evolve the system. This version has been used for short term feasibility testing on a variety of patients.
Prototype 3. Significant system update to reduce size, weight and noise while increasing battery life and adding safety features. Testing is in progress across multiple patients at two domestic locations.