Kinematic and kinetic comparisons of transfemoral amputee gait using C-Leg and Mauch SNS prosthetic knees

Abstract

The C-Leg ® (Otto Bock, Duderstadt, Germany) is a microprocessor-controlled prosthetic knee that may enhance amputee gait. This intrasubject randomized study compared the gait biomechanics of transfemoral amputees wearing the C-Leg ® with those wearing a common noncomputerized prosthesis, the Mauch SNS ® (Ossur, Reykjavik, Iceland). After subjects had a 3-month acclimation period with each prosthetic knee, typical gait biomechanical data were collected in a gait laboratory. At a controlled walking speed (CWS), peak swing phase knee-flexion angle decreased for the C-Leg ® group compared with the Mauch SNS ® group (55.2° ± 6.5° vs 64.41° ± 5.8°, respectively; p = 0.005); the C-Leg ® group was similar to control subjects' peak swing knee-flexion angle (56.0° ± 3.4°). Stance knee-flexion moment increased for the C-Leg ® group compared with the Mauch SNS ® group (0.142 ± 0.05 vs 0.067 ± 0.07 N•m, respectively; p = 0.01), but remained significantly reduced compared with control subjects (0.477 ± 0.1 N•m). Prosthetic limb step length at CWS was less for the C-Leg ® group compared with the Mauch SNS ® group (0.66 ± 0.04 vs 0.70 ± 0.06 m, respectively; p = 0.005), which resulted in increased symmetry between limbs for the C-Leg ® group. Subjects also walked faster with the C-Leg ® versus the Mauch SNS ® (1.30 ± 0.1 vs 1.21 ± 0.1 m/s, respectively; p = 0.004). The C-Leg ® prosthetic limb vertical ground reaction force decreased compared with the Mauch SNS ® (96.3 ± 4.7 vs 100.3 ± 7.5 % body weight, respectively; p = 0.0092).

Transtibial amputee gait efficiency: Energy storage and return versus solid ankle cushioned heel prosthetic feet

“…Studies of amputee gait highlight the fact that passive prosthetic feet of all types (including ESR feet) provide a small fraction of the push-off power generated by an intact foot and ankle [22][23][24]. The reduced push-off power of passive ESR feet is likely because the neutral (zero moment) ankle angle of a passive prosthesis corresponds to normal standing, which means that once the prosthesis moves into plantar flexion, it will always produce a dorsiflexion moment (acting to return it to neutral), the opposite of what is required during push-off.…”

“…The reduced push-off power of passive ESR feet is likely because the neutral (zero moment) ankle angle of a passive prosthesis corresponds to normal standing, which means that once the prosthesis moves into plantar flexion, it will always produce a dorsiflexion moment (acting to return it to neutral), the opposite of what is required during push-off. This greatly reduces push-off at the end of stance compared with nondisabled intact ankles [23][24]. As a result, subjects with amputation using ESR feet have to compensate for the lack of push-off power using more proximal joints and their sound limb.…”

Designs and performance of microprocessor-controlled knee joints

“…Their complex interaction of various functional principles used for generating joint resistances are implemented by control algorithms and sensor technology that directly affect movement and safety outcomes for lower-limb amputees [2][3][4]. For the patient, the resultant functional quality [2,5,8,12,17,18,24,[30][31][32], and the reduction in falls some MPKs provide [3,7,11,16], is of central importance. The challenge for prosthetic practitioners and patients alike is how to select the appropriate MPK to meet the functional needs of the lower-limb amputee.…”

Adapting to change : influence if a microprocessor-controlled prosthetic knee on gait adaptations

“…However, previous studies showed that individuals with an amputation exhibit no early stance prosthetic knee flexion while walking with the Mauch SNS. 11,12 The reason of the lack of early stance prosthetic knee flexion while walking with the Mauch SNS is not known. A possible explanation could be that the knee has to be moved towards extension during mid stance.…”

“…12,16 It is thought that this is related to the limited prosthetic knee flexion during stance, which causes a higher vertical position of the center of mass. 17,18 This higher position means that the center of mass covers a larger vertical trajectory during the loading response of the intact leg, potentially leading to a higher loading of the intact leg.…”