title: Balance failure in single limb stance due to ankle sprain injury: an analysis of center of pressure using the fractal dimension method.
abstract: Instrumented postural control analysis plays an important role in evaluating the effects of injury on dynamic stability during balance tasks, and is often conveyed with measures based on the displacement of the center-of-pressure (COP) assessed with a force platform. However, the desired outcome of the task is frequently characterized by a loss of dynamic stability, secondary to injury. Typically, these failed trials are discarded during research investigations, with the potential loss of informative data pertaining to task success. The novelty of the present study is that COP characteristics of failed trials in injured participants are compared to successful trial data in another injured group, and a control group of participants, using the fractal dimension (FD) method. Three groups of participants attempted a task of eyes closed single limb stance (SLS): twenty-nine participants with acute ankle sprain successfully completed the task on their non-injured limb (successful injury group); twenty eight participants with acute ankle sprain failed their attempt on their injured limb (failed injury group); sixteen participants with no current injury successfully completed the task on their non-dominant limb (successful non-injured group). Between trial analyses of these groups revealed significant differences in COP trajectory FD (successful injury group: 1.58±0.06; failed injury group: 1.54±0.07; successful non-injured group: 1.64±0.06) with a large effect size (0.27). These findings demonstrate that successful eyes-closed SLS is characterized by a larger FD of the COP path when compared to failed trials, and that injury causes a decrease in COP path FD.
authors.affiliation: School of Public Health, Physiotherapy and Population Science, University College Dublin, Dublin, Ireland. Electronic address: cailbhe.doherty@ucdconnect.ie.
authors.forename: Cailbhe
authors.initials: C
authors.lastname: Doherty
authors.affiliation: Sport and Exercise Sciences Research Institute, Ulster Sports Academy, University of Ulster, Newtownabbey, Co. Antrim, Northern Ireland, United Kingdom.
authors.forename: Chris
authors.initials: C
authors.lastname: Bleakley
authors.affiliation: Department of Kinesiology, University of Virginia, Charlottesville, VA, United States.
authors.forename: Jay
authors.initials: J
authors.lastname: Hertel
authors.affiliation: School of Public Health, Physiotherapy and Population Science, University College Dublin, Dublin, Ireland.
authors.forename: Brian
authors.initials: B
authors.lastname: Caulfield
authors.affiliation: St. Vincent's University Hospital, Dublin, Ireland.
authors.forename: John
authors.initials: J
authors.lastname: Ryan
authors.affiliation: School of Public Health, Physiotherapy and Population Science, University College Dublin, Dublin, Ireland; Institute for Sport and Health, University College Dublin, Dublin, Ireland.
authors.forename: Eamonn
authors.initials: E
authors.lastname: Delahunt
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000842:Ankle / Q000503:physiopathology; D016512:Ankle Injuries / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D005081:Exercise Therapy / Q000379:methods; D005260:Female; D017709:Fractals; D006801:Humans; D008297:Male; D004856:Postural Balance; D011312:Pressure; D013180:Sprains and Strains / Q000503:physiopathology* / Q000534:rehabilitation; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Ankle joint; Biomechanics; Kinetics; Postural balance