Affiliations: [a] Biomechanics Laboratory, Department of Sport and Movement Sciences, University of Duisburg-Essen, Essen, Germany | [b] Department of Orthopaedic Surgery, Physical Medicine and Rehabilitation, University Hospital of Munich, Munich, Germany | [c] Department of Orthopaedic Surgery, Ruhr-University Bochum, St. Josef-Hospital, Bochum, Germany
Correspondence:
[*]
Corresponding author: Marco Hagen, Biomechanics Laboratory, Institute of Sport and Movement Sciences, University of Duisburg-Essen, Gladbecker Str. 182, 45141 Essen, Germany. Tel.: +49 201 183 7386; Fax: +49 201 183 7309; E-mail: marco.hagen@uni-due.de.
Abstract: Background:Femoroacetabular impingement (FAI) is accompanied by increased hip alpha angles, in particular in athletes with high impact sports. Objective:The aim of our study was to investigate the dynamic function of the foot during walking in male soccer players with increased versus normal alpha angles. Methods:Plantar pressures of 20 injury-free male soccer players were recorded during barefoot walking at 1.6 m/s. Ten subjects had bilaterally increased (>55°) (IA) and ten subjects normal (<50°) hip alpha angles (NA). Both standing and kicking leg were analyzed. Results:Compared to NA, IA showed lower force-time-integrals (−23%; p < 0.01), pressure-time-integrals (−29%; p < 0.001) and relative loads (p < 0.05) under the heel. In IA contact area of the hallux is about 13% (p < 0.05) reduced. In IA relative loads are increased under the lateral midfoot (p < 0.05) and the second toe (p < 0.05). Higher loading of the lateral midfoot is also reflected in the increased force-time integral (+33%; p < 0.001). No differences between legs and no interactions, indicating a specifity in kicking or standing leg, are found. Conclusions:Compared to NA, soccer players with IA show a forward shifting of the center of pressure which indicates a compensatory mechanism of the foot during walking.
