Knee Swing Phase Flexion Resistance Affects Several Key Features of Leg Swing Important to Safe Transfemoral Prosthetic Gait

Abstract

We systematically investigate in-vivo the effect of increasing prosthetic knee flexion damping on key features of the swing phase of individuals with transfemoral amputation during walking. Five experienced prosthesis users walked using a prototype device in a motion capture laboratory. A range of interchangeable hydraulic rotary dampers was used to progressively modify swing phase flexion resistance in isolation. Toe clearance (TC; vertical distance toe to floor), effective leg length (ELL; distance hip to toe), and knee flexion angle during swing phase were computed, alongside the sensitivities of vertical toe position to angular displacements at the hip, knee and ankle. Key features of these profiles were compared across 5 damping conditions. With higher damping, knee extension occurred earlier in swing phase, promoting greater symmetry. However, with implications for toe catch, minimum TC reduced, and minimum TC and maximum ELL occurred earlier; temporally closer to mid-swing, when the limb must pass the stance limb. Further, TC became less sensitive to changes in hip flexion, suggesting a lesser ability to control toe clearance without employing proximal or contralateral compensations. There is a trade-off between key features related to gait safety when selecting an appropriate resistance for a mechanical prosthetic knee. In addition to highlighting broader implications surrounding swing phase damping selection for the optimization of mechanical knees, this work reveals design considerations that may be of utility in the formulation of control strategies for computerized devices.

Biomechanical Comparison of Novel Adaptive Swing-Phase Control Mechanical Knee Prostheses with 3R60 and 3R15 in Trans-Femoral Amputees

“…Conversely, by increasing walking speed, the heel-rise and the swing extension time is reduced in the novel mechanical joint. The other studies [20,21,35] confirmed these results. In the present study, in fast walking speed, the 3R60 knee has a longer swing time extension due to the higher heel rise.…”

“…Microprocessors and active knee joints have been developed, including sensors to detect the knee joint's speed, angle, and a motor and drive system [6,[17][18][19]. These joints can reduce the peak knee swing flexion by increasing speed and subsequently reduce the swing extension time; accordingly, greater adaptability has been achieved [20][21][22]. Despite these advantages, compared to non-adaptive mechanical knee joints, these joints are large, heavy, and noisy with a higher maintenance cost.…”

Effect Of Quadriceps Inhibition And Hamstring Facilitation On Knee Control In Hemiplegic Gait.

“…In contrast, achieving full or nearly full extension at terminal swing creates an extension moment upon loading, preventing buckling and ensuring a safe transition from swing to the stance phase of gait. [12] The most common cause of gait abnormalities in hemiplegic gait is quadriceps overactivity. [8,13] During normal gait, the locomotor centre of the Central Nervous System (CNS) maintains balanced coactivation of the agonist quadriceps and antagonist hamstring muscles in order to stabilise the knee joint during mid-stance.…”