Does use of a powered ankle-foot prosthesis restore whole-body angular momentum during walking at different speeds?
BACKGROUND
Whole-body angular momentum (H) influences fall risk, is tightly regulated during walking, and is primarily controlled by muscle force generation. People with transtibial amputations using passive-elastic prostheses typically have greater H compared with nonamputees.


OBJECTIVE
(1) Do people with unilateral transtibial amputations using passive-elastic prostheses have greater sagittal and frontal plane H ranges of motion during walking compared with nonamputees and compared with using powered prostheses? (2) Does use of powered ankle-foot prostheses result in equivalent H ranges in all planes of motion compared with nonamputees during walking as a result of normative prosthetic ankle power generation?


METHODS
Eight patients with a unilateral transtibial amputation and eight nonamputees walked 0.75, 1.00, 1.25, 1.50, and 1.75 m/s while we measured kinematics and ground reaction forces. We calculated H for participants using their passive-elastic prosthesis and a powered ankle-foot prosthesis and for nonamputees at each speed.


RESULTS
Patients using passive-elastic prostheses had 32% to 59% greater sagittal H ranges during the affected leg stance phase compared with nonamputees at 1.00 to 1.75 m/s (p < 0.05). Patients using passive-elastic prostheses had 5% and 9% greater sagittal H ranges compared with using powered prostheses at 1.25 and 1.50 m/s, respectively (p < 0.05). Participants using passive-elastic prostheses had 29% and 17% greater frontal H ranges at 0.75 and 1.50 m/s, respectively, compared with nonamputees (p < 0.05). Surprisingly, patients using powered prostheses had 26% to 50% greater sagittal H ranges during the affected leg stance phase compared with nonamputees at 1.00 to 1.75 m/s (p < 0.05). Patients using powered prostheses also had 26% greater frontal H range compared with nonamputees at 0.75 m/s (p < 0.05).


CONCLUSIONS
People with a transtibial amputation may more effectively regulate H at two specific walking speeds when using powered compared with passive-elastic prostheses.


CONCLUSIONS
Our results support the hypothesis that an ankle-foot prosthesis capable of providing net positive work during the stance phase of walking reduces sagittal plane H; future studies are needed to validate our biomechanical findings with larger numbers of patients and should determine whether powered prostheses can decrease the risk of falls in patients with a transtibial amputation.
Department of Veterans Affairs, Providence VA Medical Center, Providence, RI, USA.
Susan
S
D'Andrea
Natalie
N
Wilhelm
Anne K
AK
Silverman
Alena M
AM
Grabowski
D000328:Adult; D000671:Amputation, Surgical / Q000534:rehabilitation*; D000674:Amputees; D000843:Ankle Joint / Q000503:physiopathology / Q000601:surgery*; D001186:Artificial Limbs; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D004548:Elasticity; D005684:Gait; D006801:Humans; D007869:Leg Injuries / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D020127:Recovery of Function; D013977:Tibia / Q000293:injuries / Q000503:physiopathology / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome; D014728:Veterans; D014741:Video Recording; D016138:Walking