Stair-specific algorithms for identification of touch-down and foot-off when descending or ascending a non-instrumented staircase

Abstract

Research HighlightsAlgorithms defining touch-down and foot-off (TD/FO) in stair ambulation are presented Performance of these algorithms was determined by comparison to force defined events TD/ FO were determined with acceptable precision in young and old adultsThe algorithms performed equally well at differing riser heights (85-255 mm)These algorithms can be used when force-instrumented staircases are unavailable AbstractThe present study introduces four event detection algorithms for defining touch-down and foot-off during stair descent and stair ascent using segmental kinematics. For stair descent, vertical velocity minima of the whole body centre-of-mass was used to define touch-down, and foot-off was defined as the instant of trail limb peak knee flexion. For stair ascent, vertical velocity local minima of the lead-limb toe was used to define touch-down, and footoff was defined as the local maxima in vertical displacement between the toe and pelvis. The performance of these algorithms was determined as the agreement in timings of kinematically derived events to those defined kinetically (ground reaction forces). Data were recorded while 17 young and 15 older adults completed stair descent and ascent trials over a four-step instrumented staircase. Trials were repeated for three stair riser height conditions (85 mm, 170 mm, and 255 mm). Kinematically derived touch-down and foot-off events showed good agreement (small 95% limits of agreement) with kinetically derived events for both young and older adults, across all riser heights, and for both ascent and descent. In addition, agreement metrics were better than those returned using existing kinematically derived event detection algorithms developed for overground gait. These results indicate that touch-down and foot-off during stair ascent and descent of non-instrumented staircases can be determined with acceptable precision using segmental kinematic data.

Centre of mass control is reduced in older people when descending stairs at an increased riser height

“…Previous reports based on aspects of this data are currently available in the literature [1,22,2,8,9]. This is the first study on the differences in CoM control and contribution of specific lower limb joints between young and older adults when descending stairs with increased versus standard stair riser-heights, using a step-over-step strategy, and focusing on two distinct phases of stance (landing and lowering).…”

Lower limb kinematics improvement after genicular nerve blockade in patients with knee osteoarthritis: a milestone study using inertial sensors

“…2). We cannot distinguish if the speed increase was mainly in the stance or swing phase of stairs negotiation as we did not record the foot-off events [30]. One can assume that patients lowered their body faster during the stance phase because the subjects increased their joint angular speed at the knee in the sagittal plane and at the hip in the frontal plane when descending stairs [44].…”

“…A cycle lasts from the time point a foot touches the ground until the next contact of the same foot. A combination of vertical shank acceleration and hip and knee angular movement were used to detect those events [29,30].…”

Intermediate addition multifocals provide safe stair ambulation with adequate ‘short‐term’ reading

“…Existing stair ascent and descent marker-based event detection algorithms were used to determine instants of foot-contact and foot-off in each trial. 18 Trials were completed using a 'step-over-step gait', thus the 'leading limb' on each staircase step alternated between left and right limbs. As transitions from stair to floor have been shown to involve slightly different limb kinematics, 16 heel clearance for the bottom step in descent was not assessed.…”

“…Marker trajectories were labelled in Vicon Nexus (http://www.vicon.com/software/nexus) and the resultant C3D files uploaded to Visual 3D (http://www.c-motion.com/products/visual3d/) for further analysis. Existing stair ascent and descent marker‐based event detection algorithms were used to determine instants of foot‐contact and foot‐off in each trial . Trials were completed using a ‘step‐over‐step gait’, thus the ‘leading limb’ on each staircase step alternated between left and right limbs.…”