| Summary: | Reduction in residuum volume during periods of upright mobility is a common problem in lower limb amputees. A vacuum pump to reduce the in-socket air pressure has been shown to conserve residuum volume, but is expensive and not widely available. In this thesis an alternative (passive) approach to reducing pressures within the socket during gait is proposed, based on building in a distal void into the socket, thereby exploiting Boyles’ Law. The aims of this thesis were to: 1) develop a test prosthesis, allowing for testing of passive, modified passive, and active systems and, 2) compare the performance of these systems in terms of residuum volume changes, comfort, and gait kinematics and ground reaction forces. For the first aim, an Instrumented Trans-tibial Prosthesis (ITTP) was developed. The socket was designed with a configurable distal void and could also be used in conjunction with a commercially available pump. For the second aim and prior to conducting the main study, the repeatability of a laser-based scanner system to measure residuum volume, as well as gait measures, were evaluated in five trans-tibial amputee subjects. The methods proved to be highly repeatable. In the main study, five trans-tibial amputee participants were cast and fitted with bespoke ITTP. Residuum volume was measured before and after walking across 3 test-conditions (passive – conventional; passive plus distal void; and active). Participants were asked to rest for 20 minutes between test-conditions to allow the residuum volume to return to steady-state. Gait kinematics and GRFs were collected during the walking trials and comfort assessed after each set of trials. Following resting, the residuum volume decreased, relative to the baseline volume, by 4.2% for the conventional passive system and less than 2% for both the passive plus distal void and active system. The results suggest the proposed approach shows promise and further work is merited.
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