Review on the Biomechanics and Functional Performance of Lower-Limb Prosthetic Devices

Abstract

Lower limb prostheses play a crucial role in restoring mobility, balance, and quality of life for individuals with lower limb amputations. Practical prosthetic function depends on how well artificial joints replicate the biomechanical roles of natural human joints, particularly the ankle, knee, and hip, during gait. This review synthesises biomechanical principles and recent technological advances in prosthetic limb design, with a particular emphasis on prosthetic knees and ankle–foot systems. Natural joints play a crucial role in walking by supporting body weight, absorbing shock, storing and returning energy, and facilitating smooth limb trajectories during both the stance and swing phases. Replicating these functions in prosthetic devices remains challenging due to limitations in force distribution, energy management, adaptability, and user device integration. Current prosthetic solutions range from passive systems, such as energy storage and return (ESAR) feet and mechanical knees, to quasi-passive microprocessor-controlled devices and fully powered prostheses. Passive designs offer simplicity and reliability, but they are limited in terms of adaptability and energy return. Microprocessor-controlled knees enhance stability, gait symmetry, and safety by adjusting damping in real-time. At the same time, powered prostheses can deliver net positive work, enabling more natural propulsion and improved performance on stairs and slopes. However, these advanced systems introduce trade-offs in terms of weight, power consumption, and complexity. A critical factor influencing comfort and performance is force distribution at the socket–residual limb interface, where poor load transfer can lead to pain, tissue damage, and altered gait patterns. Despite significant progress, challenges remain in achieving consistent energy efficiency, robust terrain adaptability, and intuitive control. Continued multidisciplinary research in materials, sensing, control algorithms, and clinical socket design is crucial to narrowing the gap between artificial and biological limb biomechanics and enhancing real-world functional outcomes for prosthetic users.