Gait asymmetry of transfemoral amputees using mechanical and microprocessor-controlled prosthetic knees

Abstract

Background: Amputees walk with an asymmetrical gait, which may lead to future musculoskeletal degenerative changes. The purpose of this study was to compare the gait asymmetry of active transfemoral amputees while using a passive mechanical knee joint or a microprocessor-controlled knee joint.

Methods: Objective 3D gait measurements were obtained in 15 subjects (12 men and 3 women; age 42, range 26-57). Research participants were longtime users of a mechanical prosthesis (mean 20 years, range 3-36 years). Joint symmetry was calculated using a novel method that includes the entire waveform throughout the gait cycle.

Findings: There was no significant difference in hip, knee and ankle kinematics symmetry when using the different knee prostheses. In contrast, the results demonstrated a significant improvement in lower extremity joint kinetics symmetry when using the microprocessor-controlled knee.

Interpretation: Use of the microprocessor-controlled knee joint resulted in improved gait symmetry. These improvements may lead to a reduction in the degenerative musculoskeletal changes often experienced by amputees.

Figure 1

Symmetry index for kinematics in the sagittal plane for three joints (hip, knee, ankle) and two different prostheses. There were no significant differences between the MPK and NMPK. There was a significant difference between stance and swing phase gait symmetry.

Figure 2

Sagittal plane kinematics of the intact leg (solid line) versus the prosthetic leg (dashed line) of a representative subject for the three joints (hip, knee, ankle). The subject is wearing a NMPK knee in the first row and a MPK in the second row. Graphs are plotted as percentage of gait cycle (% Gait Cycle), where 0% is heel strike and 100% is subsequent heel strike. A positive value indicates hip flexion, knee flexion, and ankle dorsiflexion.

Figure 3

Symmetry index for kinetics in the sagittal plane for three joints (hip, knee, ankle) and two different prostheses. There was a significant improvement in the symmetry index for all joints when the MPK was used. There was also a significant difference in the symmetry index between stance and swing.

Figure 4

Sagittal plane Kinetics of the intact leg (solid line) versus the prosthetic leg (dashed line) for a representative subject at the three joints (hip, knee, ankle). The subject is wearing a NMPK knee in the first row and a MPK in the second row. Graphs are plotted as percentage of gait cycle (% Gait Cycle), where 0% is heel strike and 100% is subsequent heel strike. A positive value represents an internal hip extensor, knee extensor, and ankle plantarflexor moment.