Colloquia

Summary

Microprocessor-controlled prosthetic knees (MPK) are prostheses in which the flexion and extension of the knee are controlled throughout stance- and swing phases of the gait cycle, in order to give the best possible support to simulate healthy knee function for transfemoral amputees. MPKs can be divided into two categories: passive (P-MPKs) and active (A-MPKs). Unilateral transfemoral amputees walking with P-MPKs load their sound leg more than their prosthetic leg, placing more stress on their intact limb. The increased joint loading could lead to osteoarthritis and related pain in this limb, while osteoporosis occurs on the amputated side. In addition, the asymmetric movement patterns caused by the use of a P-MPK result in a number of other long term problems, for example back pain.  In 2018, Reboocon Bionics brought a new powered knee prosthesis to the market: the Intuy knee (IK), being only the second commercially available A-MPK.  It is expected that transfemoral amputees will benefit from this knee compared to passive knees since the IK injects energy into the knee joint, possibly leading to more symmetry in joint angles, torques, and muscle activation.

This research describes an evaluation of the Intuy knee. The IK was evaluated by analysing joint kinematics, muscle activation, and GRF’s, using musculoskeletal modelling. Data was collected while the two subjects performed three different movements: level-walking, stepping over an object, and rising from a chair, using the IK. This data was then compared to that of the subject’s daily use prosthesis, P-MPKs. A secondary goal of this research was to explore the possibility of using personalized instructions and prosthesis fine-tuning to optimize the use of the IK.

Based on the spatio-temporal gait parameters the IK showed promising results, though based on the symmetry in joint kinematics neither the IK or P-MPKs seemed superior over the other in level-walking. The IK supports the user during step-over-object movements, however this requires more practise than the subjects in this study received. For one subjects the IK lowered sound limb loading during the sit-to-stand movement, while for the other subject no significant difference was found. Based on the data alone it cannot be stated whether the IK is superior to passive knee prostheses, however taking the subjects' personal experiences into account the IK shows potential.