Energy storage and release of prosthetic feet

This paper is the second part of a study on biomechanical and functional properties of prosthetic feet. The first part dealt with a biomechanical analysis related to user benefits. This part deals with subjective ratings and deciding factors for trans-tibia] amputees using 2 energy storing feet (ESF) and 2 conventional feet (CF). The Otto Bock Dynamic Pro and Hanger Quantum feet were used as ESF and the Otto Bock Multi Axial and Otto Bock Lager feet were used as CF. Ten trans-tibial amputees, active walkers, without stump problems, were selected (mean age: 49 years old). The study was designed as a double-blind, randomised trial and for each foot there was a habituation period of 2 weeks. Two questionnaires were designed. (A) concerned information about the preference of the subjects and (B) concerned the order of importance of difference aspects concerning a prosthesis. Results indicated that no clear preference for either the ESF or the CF existed and that the individual preference is not related to age. The items 'ability to walk fast' and 'no fatigue during walking' , score statistically significantly worse for the CF2. With the small contrast between the ESF and CF, in relation to energy All correspondence to be addressed to K. Postema, Research and Development, St. Maartenskliniek, Postbus 9011 , 6500 GM Nijmegen, The Netherlands. storing capacities, the subjects cannot distinguish between the ESF and CF. The 'absence of stump pain' and 'stability while walking' are ranked as most important aspects concerning a prosthesis. The perception of stability is likely to be related to the level and kind of activities the subject performs. Introduction More and more leg amputations are performed mainly due to the growing number of the elderly. In the Netherlands a steady increase is seen in the number of leg amputations (SIG, 1995). Between 1991 and 1994 the incidence increased from 0.16 to 0.17 per thousand inhabitants (2,457 amputations in 1991 and 2,618 in 1994). A further increase is expected. Up to now in the Netherlands a prosthetist and a doctor together make the total prescription for the prosthesis. But it is realised more and more that amputees have to be involved in this decision because their demands on function, comfort and cosmesis of the prosthesis ought to weigh heavily in the choice of different parts of the prosthesis. Therefore not only are rates of satisfaction about function, comfort and cosmesis of amputees required, but also an insight into which aspects concerning the prosthesis amputees rate as important. In the literature scant attention is given to subjective ratings of various feet, personal choice of foot and deciding factors concerning that choice. Prosthetic Profile of the Amputee (PPA) Questionnaire is a validated questionnaire about