Case Control Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. Apr 18, 2017; 8(4): 322-328
Published online Apr 18, 2017. doi: 10.5312/wjo.v8.i4.322
Abnormal ground reaction forces lead to a general decline in gait speed in knee osteoarthritis patients
Anatole Vilhelm Wiik, Adeel Aqil, Mads Brevadt, Gareth Jones, Justin Cobb
Anatole Vilhelm Wiik, MSk Lab, Department of Surgery and Cancer, Charing Cross Hospital, London W68RF, United Kingdom
Anatole Vilhelm Wiik, Adeel Aqil, Mads Brevadt, Gareth Jones, Justin Cobb, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
Author contributions: Wiik AV and Cobb J designed the study; Wiik AV collected the clinical data; Wiik AV and Brevadt M analysed the data; Wiik AV, Aqil A, Brevadt M, Jones G and Cobb J interpreted and wrote the report.
Institutional review board statement: Ethical approval was sought and gained prior to commencement of the trial through the research ethics committee (10/H0807/101). All investigations were conducted in conformity with ethical principles of research, and informed consent for participation in the study was obtained. This work was performed at, Imperial College London, Charing Cross Campus, United Kingdom.
Informed consent statement: All study participants provided informed written consent prior to study enrolment.
Conflict-of-interest statement: No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.
Data sharing statement: Extended dataset available from the corresponding author.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Correspondence to: Dr. Anatole Vilhelm Wiik, MSk Lab, Department of Surgery and Cancer, Charing Cross Hospital, Fulham Place Road, London W68RF, United Kingdom.
Telephone: +44-20-33130970 Fax: +44-20-33115218
Received: June 17, 2016
Peer-review started: June 17, 2016
First decision: August 16, 2016
Revised: January 1, 2017
Accepted: January 16, 2017
Article in press: January 18, 2017
Published online: April 18, 2017

To analyse ground reaction forces at higher speeds using another method to be more sensitive in assessing significant gait abnormalities.


A total of 44 subjects, consisting of 24 knee osteoarthritis (OA) patients and 20 healthy controls were analysed. The knee OA patients were recruited from an orthopaedic clinic that were awaiting knee replacement. All subjects had their gait patterns during stance phase at top walking speed assessed on a validated treadmill instrumented with tandem force plates. Temporal measurements and ground reaction forces (GRFs) along with a novel impulse technique were collected for both limbs and a symmetry ratio was applied to all variables to assess inter-limb asymmetry. All continuous variables for each group were compared using a student t-test and χ2 analysis for categorical variables with significance set at α = 0.05. Receiver operator characteristics curves were utilised to determine best discriminating ability.


The knee OA patients were older (66 ± 7 years vs 53 ± 9 years, P = 0.01) and heavier (body mass index: 31 ± 6 vs 23 ± 7, P < 0.001) but had a similar gender ratio when compared to the control group. Knee OA patients were predictably slower at top walking speed (1.37 ± 0.23 m/s vs 2.00 ± 0.20 m/s, P < 0.0001) with shorter mean step length (79 ± 12 cm vs 99 ± 8 cm, P < 0.0001) and broader gait width (14 ± 5 cm vs 11 ± 3 cm, P = 0.015) than controls without any known lower-limb joint disease. At a matched mean speed (1.37 ± 0.23 vs 1.34 ± 0.07), ground reaction results revealed that push-off forces and impulse were significantly (P < 0.0001) worse (18% and 12% respectively) for the knee OA patients when compared to the controls. Receiver operating characteristic curves analysis demonstrated total impulse to be the best discriminator of asymmetry, with an area under the curve of 0.902, with a cut-off of -3% and a specificity of 95% and sensitivity of 88%.


Abnormal GRFs in knee osteoarthritis are clearly evident at higher speeds. Analysing GRFs with another method may explain the general decline in knee OA patient’s gait.

Keywords: Gait, Treadmill, Ground reaction forces, Symmetry, Osteoarthritis, Knee

Core tip: Top walking speed may unmask significant abnormalities which would not be seen at slower walking speeds. The use of impulse rather than solitary peaks in the analysis of ground reaction forces may be more sensitive in detecting significant abnormalities in gait.