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Individuals with lower extremity amputation must adapt the mechanical interactions between the feet and ground to account for musculoskeletal function loss. However, it is currently unknown how individuals with amputation modulate three-dimensional ground reaction forces (GRFs) when running. This study aimed to understand how running with running-specific prostheses influences three-dimensional support forces from the ground. Eight individuals with unilateral transtibial amputations and 8 control subjects ran overground at 2.5, 3.0, and 3.5 m/s. Ten force plates measured GRFs at 1000 Hz. Peak and average GRFs and impulses in each plane were compared between limbs and groups. Prosthetic limbs generated reduced vertical impulses, braking forces and impulses, and mediolateral forces while generating similar propulsive impulses compared with intact and control limbs. Intact limbs generated greater peak and average vertical forces and average braking forces than control subjects’ limbs. These data indicate that the nonamputated limb experiences elevated mechanical loading compared with prosthetic and control limbs. This may place individuals with amputation at greater risk of acute injury or joint degeneration in their intact limb. Individuals with amputation adapted to running-specific prosthesis force production limitations by generating longer periods of positive impulse thus producing propulsive impulses equivalent to intact and control limbs.
Brian S. Baum is with the School of Physical Therapy, Regis University, Denver, CO; and the Department of Kinesiology, University of Maryland, College Park, MD. Hiroaki Hobara is with the National Institute of Advanced Industrial Science and Technology, Tokyo, Japan. Yoon Hyuk Kim is with the Department of Mechanical Engineering, Kyung Hee University, Seoul, South Korea. Jae Kun Shim is with the Department of Kinesiology, University of Maryland, College Park, MD; the Department of Mechanical Engineering, Kyung Hee University, Seoul, South Korea; the Neuroscience and Cognitive Science Program, University of Maryland, College Park, MD; and the Fischell Department of Bioengineering, University of Maryland, College Park, MD.