Anja Desomer

Prosthetic feet: State-of-the-art review and the importance of mimicking human ankle–foot biomechanics

Numerous prosthetic feet are currently on the market for individuals with a transtibial amputation, each device aimed at raising the 3C-level (control, comfort and cosmetics) with slightly different characteristics. In general, prosthetic feet can be classified into three categories. These are, following the time line: conventional feet (CF), energy-storing-and-returning (ESR) feet and the recent so-called ‘bionic’ feet. Researchers have shown enhanced performance properties of ESR feet compared with early CF. However, even with the advanced technology, none of the ESR feet is capable of significantly reducing energy cost of walking or enhancing prosthetic gait (Nielsen et al. J Prosthet Orthotics 1989;1:24–31; Waters et al. J Bone Joint Surg Am 1976;58:42–46; Torburn et al. J Rehabil Res Dev 1990;27:369–384). From the 1990s, gradually more attention has been paid to the incorporation of active elements in prosthetic feet as the passive devices are not capable of providing the individual with sufficient ankle power during gait. Most part of the ‘bionic’ devices are still on the research level nowadays but one can expect that they will become available on the market soon. In this article, the evolution of prosthetic feet over the last two decades is reflected. The importance of mimicking human ankle–foot biomechanics with prosthetic feet is briefly discussed. Prior work in both objective and subjective evaluation of prosthetic gait is reported.

A biomechatronical transtibial prosthesis powered by pleated pneumatic artificial muscles

Due to its high power-to-weight ratio, a pleated pneumatic artificial muscle (PPAM) offers an interesting alternative actuation source for robotic devices. Its inherent compliant behaviour excites another broad field of interest: assistive clinical devices such as powered exoskeletons and prosthetics. In this paper, the design of a pneumatically powered transtibial prosthetic device is presented. A first prototype has been built and provides a preliminary test bed for control algorithm development and testing with able-bodied subjects in laboratory conditions. The characteristics and working principle of a PPAM are described. The design specifications and the mechanical model of the prosthesis are discussed. The mechanical design and the control structure are outlined. Furthermore, some initial walking trials with an able-bodied subject wearing the prosthesis prototype are presented and discussed.

Successful Preliminary Walking Experiments on a Transtibial Amputee Fitted with a Powered Prosthesis

This paper presents the results of preliminary walking experiments on a transtibial amputee wearing a powered prosthesis. The prosthesis prototype serves as a proof-of-concept implementation for investigating the potential of pleated pneumatic artificial muscles to power a transtibial prosthesis. The device is equipped with pleated pneumatic artificial muscles, and tethered to a laboratory pressure source. The prosthesis is capable of providing the amputee with 100% of the required push-off torque and it can adapt its joint stiffness to the walking speed. This study supports the hypothesis that a powered transtibial prosthesis with adaptable stiffness might be beneficial to the amputee.

On the development of a powered prosthesis for transtibial amputees

This paper reports on the development of a powered transtibial prosthesis. The initial prosthesis prototype is a pneumatically powered system, which serves as test bed for proof-of-concept and evaluating control algorithms in laboratory conditions. The characteristics and working principle of the actuators are described. The control approach is discussed. First experimental results with an amputee are presented that demonstrate the promising performance properties of the powered prosthesis.