PROSTHESES FOR RECREATIONAL AND ELITE SPORTS: BIOMECHANICAL REQUIREMENTS AND TECHNICAL FULFILMENTS

In the past the focus of technical improvements of artificial limbs was on performance enhancement mainly in running or sprinting. Little attention was given to technical aids and devices for recreational sports and other activities than straight running. A more comprehensive understanding of the biomechanics and the energetic contribution under different prosthetic conditions and in different sports activities is essential for the development of technical aids and protection devices. In running of double amputees the role of artificial limbs has been intensively analyzed and revealed evident mechanical differences between double transtibial amputee sprinting and sprinting of able-bodied athletes. The energy contribution to the joints of the lower extremities in the symmetric runners is inverted in single amputee runners. When running at about 7 m/s the sound ankle does about two to three times more mechanical work than the sound knee or the sound hip joint. (Buckley, 2000). These biomechanical differences will lead to different requirements of the prostheses. Unilateral and bilateral transtibial or transfemoral amputees especially in recreational sports will not reduce their activities to straight running. Posture control and body balance in standing, walking, running and hiking, cutting or even pivoting maneuvers increase the requirement of sport prostheses. The technical requirements can be directly derived from the biomechanical demands of these activities. However, a critical review of recent technical fulfillments finds mainly solutions for straight running and related track and field disciplines. The most recent technical solutions allow a differentiation of beginners and advanced athletes through modification of the alignment of the knee rotation axis or the anterior-posterior placement of the prosthetic foot to the artificial knee. Different stiffness of the foot gives the opportunity to adapt the prosthesis to different body weights and different biomechanical requirements of running or jumping at different intensity. Recent swing phase control mechanisms are focused on running and gives free knee movement up to 60° knee flexion and a progressive hydraulic deceleration to a maximum flexion angle of 135°. The prosthetic feet or carbon blades are equipped with running surface related outer soles or even spikes. In summary the technical fulfillments of lower leg prostheses for recreational and elite sports partly meet the biomechanical requirement but have a great potential of further enhancement allowing the amputee to participate in sports and physical activity. Brueggemann, G.-P. et al. 2008. Biomechanics of double transtibial amputee sprinting using dedicated sprinting prostheses. Sports Technol. 2008, 1, No. 4–5, 220–227. Weyand, P. G. et al. 2009 The fastest runner on artificial legs: different limbs, similar function? J. Appl. Physiol. 107, 903–911. Buckley, J. G. 2000. Biomechanical adaptations of transtibial amputee sprinting in athletes using dedicated prostheses.