Powered prostheses are at the forefront of prosthetic technology, improving functionality by providing positive power to joints in the absence of native anatomy. Currently, there is no commercially available powered solution for hip-level amputees, and most hip prostheses are mounted to the front of the prosthetic socket. This thesis designed, fabricated, and tested a novel Laterally Mounted Powered Hip Joint (LMPHJ) that augments user gait to promote improved walking patterns. The LMPHJ attaches to the lateral side of the prosthetic socket, locating the hip centre of rotation closer to the anatomical location while ensuring user safety and stability. The new design locates the motor and all electronics in the thigh area, thereby maintaining a low profile while transmitting the required hip moments to the joint centre of rotation. A prototype was designed and manufactured to evaluate LMPHJ performance. Mechanical testing followed the ISO 15032:2000 standard and successfully demonstrated the joint's resistance to everyday loading conditions. Functional testing involved integrating the LMPHJ, Ossur Rheo Knee, and Ossur Pro-Flex XC with a prosthesis simulator that allowed three able-bodied participants to walk with the powered prosthesis successfully. This validated the mechanical design for walking over level ground and demonstrated that the LMPHJ is ready for next phase evaluation with hip disarticulation amputee participants.

Hip-knee-ankle-foot (HKAF) prostheses are full lower limb devices for people with hip amputations. They are designed to enable individuals to regain their mobility and move freely with little restriction. HKAFs typically have high rejection rates among users, as well as gait asymmetry and increased trunk anterior-posterior lean and pelvic tilt. In this thesis, a novel integrated hip-knee (IHK) unit was designed and evaluated to address the limitations of existing solutions. This IHK combines powered hip and microprocessor controlled knee joints into one structure, with shared electronics, sensors, and batteries. The unit is also adjustable to the user leg length by a prosthetist. ISO-10328 standard mechanical testing demonstrated acceptable structural safety and rigidity. Successful functional testing involved three able-bodied participants walking with the IHK in a hip prosthesis simulator. Hip and knee joint angles and pelvic tilt angles were recorded, gait characteristics were analyzed using video recordings. Testing showed that the participants were able to walk using the IHK, and data showed that participants used different walking strategies. Points of improvement were identified for future development of the thigh unit, including completion of a synergistic gait control system, improved battery holding mechanism, and amputee user testing.