Amputee gait

Pushoff Work is Increased Following Prosthesis Adaptation

The purpose of this study was to quantify adaptation to a new prosthesis in terms of mechanical work profiles. Currently, there is a lack of knowledge on how individuals adapt to a new prosthesis, with many studies investigating different prosthetic feet but not adaptation over time. Thus, there is a need for objective measures to quantify the process of adaptation. Mechanical power and work profiles are a prime subject for modern energy-storage-and-return type prostheses, as the amount of energy a prosthesis stores and returns (i.e., positive and negative work) during stance is directly related to how a user loads and unloads the limb. 22 individuals with unilateral, transtibial amputation were given a new prosthesis at their current mobility level (K3 or above) and wore it for a three-week adaptation period. Kinematic and kinetic measures were recorded from walking on overground force plates at 0, 1.5, and 3 weeks into the adaptation period. Positive and negative work done by the prosthesis and intact ankle-foot was calculated using a unified deformable segment model. Positive work from the prosthesis side increased by 6.1% and intact side by 5.7% after 3 weeks (p = .041, .036). No significant changes were seen in negative power from prosthesis or intact side (p = .115, .192). Analyzing work done by a prosthesis may be desirable for tracking a patient’s gait rehabilitation over time. Future work may analyze how mechanical work profiles relate to more traditional clinical measures.

Listed In: Biomechanics, Gait, Physical Therapy

Joint loading during graded walking with different prostheses - a case study

For lower limb amputees graded walking imposes a high level of motor ability, due to the missing proprioceptive feedback of the limb, and the necessary compensation mechanisms. In order to facilitate gait a focus in prosthesis research is the development of the prostheses ankle joints from rigid to moveable. Therefore, the aim of this case study was to analyse the effects of three different prostheses with a rigid and a moveable ankle joint during graded walking of a unilateral amputee. One male unilateral transfemoral amputee was recruited for this study and a comparison of following three prostheses (endolite, Germany) was performed: Elan (movable ankle joint with flexible resistance), Echelon (movable ankle joint with steady resistance) and Esprit (rigid ankle joint). Kinematic (12 cameras, Vicon, UK, 250 Hz) and kinetic (2 force plates, AMTI, MA, 1000 Hz) data were recorded during self-paced walking on a 6 m ramp, which was set to the inclinations of -12°, -4°, 0°, 4° and 12°. Following gait parameters, ground reaction forces, joint angles and joint moments were calculated. Gait parameters, ground reaction forces and joint angles were marginally influenced by the different prosthetic designs, but major changes occurred on the joint moment level. The use of the rigid ankle prosthesis Esprit induced up to 10 times higher joint moments compared to the moveable ankle joint prostheses. This case study showed that a moveable ankle joint can reduce the joint moments during graded walking, which might be advantageous to use for transfemoral amputees in graded walking.
Listed In: Biomechanics, Gait

Improved Prosthetic Gait Following Amputee-Specific Physical Therapy.

Following amputation, an amputee must learn to walk again using a prosthesis. A goal of prosthetic rehabilitation is to reduce and eliminate asymmetries between the prosthetic leg and sound leg which may decrease the negative effects of long term force and work demands on the sound leg. An amputee-specific physical therapy program provides structured motor learning to aid in developing proper gait mechanics. However, physical therapy is not standard of care for all individuals receiving their first prosthesis due to limited evidence showing improved gait. Thus, the purpose of this study was to determine whether amputees receiving physical therapy have better gait mechanics than those that do not. It was hypothesized that those who underwent an amputee-specific physical therapy program would display a more symmetrical gait pattern. Transtibial amputees walked overground at self-selected pace while kinetic (600Hz) and kinematic (60Hz) data were collected. The therapy group had previously received 2-3 therapy sessions per week for 3 months. Asymmetries were determined through dependent t-tests (α=0.05) comparing sound leg and prosthetic leg kinetic variables. Of the 23 kinetic variables tested, 17 variables showed significant difference between the sound leg and prosthetic leg for the group that did not receive the amputee-specific physical therapy. For the group that had previously received the therapy, only 4 variables showed differences between the sound and prosthetic leg. Thus, we showed that individuals partaking in amputee-specific physical therapy have a more symmetrical gait which results on less force and energy demands on the sound leg.
Listed In: Biomechanics, Gait, Physical Therapy