Assessment of transfemoral amputees using C-Leg and Power Knee for ascending and descending inclines and steps

Abstract

Abstract-Adding active power to a prosthetic knee unit may improve function and reduce the potential for overuse injuries in persons with transfemoral amputation (TFA). Servicemembers who have sustained a TFA are often young and motivated to perform at high functional levels. The goal of this article is to compare the biomechanics of ramp and stair descent and ascent for participants using the C-Leg and the Power Knee (PK). Subjects were asked to ascend and descend an instrumented staircase and 12 degree ramp at their comfortable pace while equipped with retroreflective markers. Temporal-spatial and kinetic data were collected. Knee power generated by the nondisabled limb during stair ascent for subjects wearing the C-Leg was significantly greater than for those wearing the PK. Knee power generated by prosthetic knee units was significantly greater for subjects while wearing the PK. Although the PK reduced the power required from the nondisabled knee during stair climbing, it does not appear to be superior to the CLeg for other tasks. Adding power to a prosthetic knee may reduce wear on the nondisabled limb; however, there are still limitations that require improvement.

Metabolic effects of using a variable impedance prosthetic knee

“…The work of Sup et al has resulted in a combined knee-ankle powered prosthesis that can approximate the kinematics of nondisabled walking over level ground and up-slope ambulation using onboard sensors to control prosthesis gait [21][22]. Commercially, Össur hf is marketing the Power Knee, a direct-drive, servo-controlled device that uses motion of the soundside leg to determine prosthetic knee position [23][24]. These earlier attempts to restore knee function, while allowing for powered walking, have largely not fully leveraged the benefits of energy conservation (storage and controlled release) that can be afforded by passive, elastic elements incorporated into the design of the device.…”

Kinematic differences exist between transtibial amputee fallers and non-fallers during downwards step transitioning

“…Powers (13) and 0.48 m/s (15) , respectively, for their transtibial 0.45 m/s for transfemoral amputees using a Power Knee and C-Leg, respectively (16) . In 200 the current study, the amputee fallers walked more than 0.2 m/s faster than these 201 previous studies (13,15) , whereas the non-fallers' speeds were virtually the same as 202 reported for other transtibial amputees (13,15) .…”

Feasibility of enhanced user control and feedback in upper leg prostheses

“…Wolf et al (2012) showed that the prosthetic stance phase (60%) is reduced compared to the stance phase of the intact limb (70%) [117]. In addition, several changes in kinematics are seen [116].…”

“…Wolf et al [117] found that in slope descent the prosthetic stance phase is also shorter (57%) compared to the stance phase of the intact leg (70%) using a C-leg (Otto Bock). Compared to level walking hip flexion at IC is reduced, whereas knee flexion is increased.…”

“…For slope ascent and descent in amputees similar kinematic changes are seen when compared to level walking [23,117], but little information is available on muscle activity in amputee slope walking. In addition, few studies have looked at stair ascent and descent in TFA, and mostly at step-over-step (SOS) [41,[118][119][120][121].…”