UNCORRECTED PROOF Gait & Posture xxx (2017) xxx-xxx Contents lists available at ScienceDirect Gait & Posture journal homepage: www.elsevier.com Speed dependent efects of laterally wedged insoles on gait biomechanics in healthy subjects Felix Kluge a, c, ⁎ , Sebastian Krinner b , Matthias Lochmann c , Bjoern M. Eskofer a a Digital Sports Group, Pattern Recognition Lab, Department of Computer Science, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Martensstrasse 3, 91058 Erlangen, Germany b Department of Trauma Surgery, University Hospital Erlangen, Krankenhausstraße 12, 91054 Erlangen, Germany c Institute of Sport Science and Sport, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Gebbertstraße 123B, 91058 Erlangen, Germany ARTICLE INFO Keywords: Walking speed Kinematics Kinetics Orthotic device Joint loading Knee osteoarthritis ABSTRACT Laterally wedged insoles have been shown to be effective for the reduction of the knee adduction moment and other biomechanical variables that are associated with the pathogenesis of knee osteoarthritis. However, incon- clusive results such as adverse effects in individual subjects or even no group-wise wedge effects have been pre- sented in different studies and it has been suggested to identify variables that potentially confound the wedge effect. The main objective of this study was the investigation of interaction effects of lateral wedges with walking speed, as different self-select speeds have mainly been used in previous studies. Twenty-two healthy subjects completed gait analysis trials on an instrumented treadmill. They walked in dif- ferent speed conditions (0.9, 1.1, 1.3, 1.5 m/s) with a neutral and a laterally wedged insole. Kinematics were ac- quired using infrared cinematography with refective markers attached to the lower body. From the stance phase we extracted biomechanical parameters that are associated with knee joint loading and osteoarthritis severity. No interaction effect of lateral wedges and speed was observed for most biomechanical parameters except for the ankle eversion range of motion. The main effects of wedges were reductions of the external knee adduction moment and of the knee adduction angular impulse. All biomechanical variables changed with increasing speed. Only the lateral ofset of the center of pressure did not respond to wedge or to speed changes. Our results suggest that different self-selected speeds do not confound the effect of laterally wedged insoles. 1. Introduction Knee osteoarthritis (OA) is a progressive musculoskeletal disorder with high prevalence of 12% in adults aged 60 and older [1]. Its patho- genesis has been associated with biomechanical factors such as in- creased medial knee compartment load which results from the ground reaction force (GRF) passing medially to the knee joint during gait giv- ing rise to the external knee adduction moment (EKAM) [2–5]. Laterally wedged insoles have been proposed as a non-invasive method for the treatment of early stage OA by reducing knee joint loading [4,6]. By ap- plying lateral wedges, the frontal plane lower limb alignment is altered towards a more valgus alignment, resulting in a reduction of knee joint moment arm, a more vertical alignment of the GRF and thus a decreased EKAM [7]. While many studies have shown evidence for biomechanical lateral wedge effcacy with EKAM reductions of up to 10% [8], single sub- jects showed no or adverse reactions and some studies demonstrated no or little group effects of wedges on some biomechanically relevant parameters [5,7,9–11]. Additionally, studies on the clinical benefts are still inconclusive [12]. This indicates that clinical and biomechanical re- sponses are not universal and may depend on other variables that po- tentially confound the effect of insoles. Gait speed has an effect on kinematic and kinetic variables [13] and it has been suggested that it might infuence the biomechanical effect of wedged insoles when comparing subjects walking at different self-se- lected speeds [10]. The purpose of this study was therefore to systematically investi- gate the effect of gait speed on wedge effcacy for biomechanically rel- evant parameters such as the knee adduction moment in a population ⁎ Corresponding author at: Martensstrasse 3, 91058, Erlangen, Germany. Email addresses: felix.kluge@fau.de (F. Kluge); sebastian.krinner@uk-erlangen.de (S. Krinner); matthias.lochmann@fau.de (M. Lochmann); bjoern.eskofer@fau.de (B.M. Eskofer) http://dx.doi.org/10.1016/j.gaitpost.2017.04.012 Received 18 February 2017; Received in revised form 29 March 2017; Accepted 7 April 2017 Available online xxx 0966-6362/ © 2016 Published by Elsevier Ltd. Full length article