Design and Evaluation of a Microprocessor-Controlled Powered Hip Prosthesis

Abstract

Hip disarticulations and hemipelvectomies are the highest level of lower limb amputations. As such, these amputations create ambulation difficulties and current prosthetic solutions are limited. Powered prosthetic joints have successfully improved lower limb amputee gait; however, no powered hip joints are available on the market. This thesis presents the design and evaluation of a microprocessor-controlled powered hip joint for hip-level amputees. A rope and pulley system was used to transmit power from an actuator located at the prosthetic thigh to rotate the prosthetic leg around an anteriorly-located prosthetic hip joint. The pulley system features an innovative tensioning system using multiple keyways, allowing the system to be tensioned without external tensioning devices. The powered hip prosthesis passed ISO 15032:2000 mechanical strength tests that simulated 100 kg user loads. The joint was also tested by able-bodied individuals using a hip disarticulation simulator to walk with the powered hip-knee-ankle-foot prosthesis. Though the participants had asymmetrical gait with shorter intact-side swing time, the device successfully allowed the participants to ambulate. The final device weighed 3.9 kg and respected geometric design constraints to fit comfortably under pants. Future work is needed to implement a gait control system, resolve a rope slack issue, and test the device with hip-level amputees.