RESUMEN
BACKGROUND: Individuals with lower-limb amputation can use running specific prostheses (RSP) that store and then return elastic energy during stance. However, it is unclear whether varying the stiffness category of the same RSP affects spring-mass behaviour during self-selected, submaximal speed running in individuals with unilateral transtibial amputation. RESEARCH QUESTION: The current study investigates how varying RSP stiffness affects limb stiffness, running performance, and associated joint kinetics in individuals with a unilateral transtibial amputation. METHODS: Kinematic and ground reaction force data were collected from eight males with unilateral transtibial amputation who ran at self-selected submaximal speeds along a 15 m runway in three RSP stiffness conditions; recommended habitual stiffness (HAB) and, following 10-minutes of familiarisation, stiffness categories above (+1) and below (-1) the HAB. Stance-phase centre of mass velocity, contact time, limb stiffness' and joint/RSP work were computed for each limb across RSP stiffness conditions. RESULTS: With increased RSP stiffness, prosthetic limb stiffness increased, whilst intact limb stiffness decreased slightly (p<0.03). Centre of mass forward velocity during stance-phase (p<0.02) and contact time (p<0.04) were higher in the intact limb and lower in the prosthetic limb but were unaffected by RSP stiffness. Intact limb hip joint positive work increased for both the +1 and -1 conditions but remained unchanged across conditions in the prosthetic limb (p<0.02). SIGNIFICANCE: In response to changes in RSP stiffness, there were acute increased mechanical demands on the intact limb, reflecting a reliance on the intact limb during running. However, overall running speed was unaffected, suggesting participants acutely adapted to an RSP of a non-prescribed stiffness.
Asunto(s)
Amputados , Miembros Artificiales , Carrera , Masculino , Humanos , Conducta de Masa , Carrera/fisiología , Amputación Quirúrgica , Fenómenos BiomecánicosRESUMEN
Accurate foot placement is important for dynamic balance during activities of daily living. Disruption of sensory information and prosthetic componentry characteristics may result in increased locomotor task difficulty for individuals with lower limb amputation. This study investigated the accuracy and precision of prosthetic and intact foot placement during a targeted stepping task in individuals with unilateral transtibial amputation (IUTAs; N = 8, 47 ± 13 yrs), compared to the preferred foot of control participant's (N = 8, 33 ± 15 yrs). Participants walked along a 10-metre walkway, placing their foot into a rectangular floor-based target with dimensions normalised to a percentage of participant's foot length and width; 'standard' = 150% x 150%, 'wide' = 150% x 200%, 'long' = 200% x 150%. Foot placement accuracy (relative distance between foot and target centre), precision (between-trial variability), and foot-reach kinematics were determined for each limb and target, using three-dimensional motion capture. A significant foot-by-target interaction revealed less mediolateral foot placement accuracy for IUTAs in the wide target, which was significantly less accurate for the intact (28 ± 12 mm) compared to prosthetic foot (16 ± 14 mm). Intact peak foot velocity (4.6 ± 0.8 m.s-1) was greater than the prosthetic foot (4.5 ± 0.8 m.s-1) for all targets. Controls were more accurate and precise than IUTAs, regardless of target size. Less accurate and precise intact foot placement in IUTAs, coupled with a faster moving intact limb, is likely due to several factors including reduced proprioceptive feedback and active control during prosthetic limb single stance. This could affect activities of daily living where foot placement is critical, such as negotiating cluttered travel paths or obstacles whilst maintaining balance.
Asunto(s)
Amputados , Miembros Artificiales , Actividades Cotidianas , Amputación Quirúrgica , Fenómenos Biomecánicos , Marcha , Humanos , CaminataRESUMEN
A gait cycle is typically defined as being from heel strike or initial contact (IC) to the next ipsilateral IC using kinetic data. When these data are not available other methods of event definition are required. An algorithm based upon sagittal plane kinematics of the hip, which defines IC at contralateral peak hip extension (PHE) is presented. Kinematic and kinetic data were recorded while 10 unimpaired participants each completed a minimum of 25 overground gait cycles. The accuracy of 551 IC events was evaluated by comparing the agreement of PHE to other kinematic and kinetic algorithms. The mean temporal difference in IC between the PHE algorithm and a kinetic algorithm was +0.0006±0.008 s. The 95% Limits of Agreement was ±0.018 s. This new PHE algorithm provides simple to implement and accurate gait events for use when kinetic data are not available.