Introduction: The development of chronic ankle instability (CAI) is the primary residual deficit after ankle joint sprain. It has been proposed that CAI is characterized by two entities, namely, mechanical instability and functional instability. Each of these entities in turn is composed of various insufficiencies. Research of functional insufficiencies to date has shown large variances in results. One particular reason for this could be discrepancies in inclusion criteria and definitions between CAI, mechanical instability, and functional instability used in the literature. Thus, we endeavored to undertake a systematic investigation of those studies published in the area of CAI to identify if there is a large discrepancy in inclusion criteria across studies.
Methods: A systematic search of the following databases was undertaken to identify relevant studies: Cochrane Central Register of Controlled Trials, PubMed, CINAHL, SportDiscus, PEDro, and AMED.
Results: The results of this study indicate that there is a lack of consensus across studies regarding what actually constitutes ankle instability. Furthermore, it is evident that the majority of studies use very different inclusion criteria, which leads to a nonhomogenous population and to difficulties when comparing results across studies.
Conclusions: Future studies should endeavor to be specific with regard to the exact inclusion criteria being used. Particular emphasis should be given to issues such as the number of previous ankle sprains reported by each subject and how often and during which activities episodes of "giving way" occur as well as the presence of concomitant symptoms such as pain and weakness. We recommend that authors use one of the validated tools for discriminating the severity of CAI. Furthermore, we have provided a list of operational definitions and key criteria to be specified when reporting on studies with CAI subjects.
1School of Public Health, Physiotherapy and Population Science, University College Dublin, Dublin, IRELAND; 2Institute for Sport and Health, University College Dublin, Dublin, IRELAND; 3Discipline of Physiotherapy, Faculty of Health Sciences, University of Sydney, Sydney, AUSTRALIA; and 4Musculoskeletal Division, The George Institute for International Health, University of Sydney, Sydney, AUSTRALIA
Address for correspondence: Eamonn Delahunt, Ph.D., School of Physiotherapy and Performance Science, Health Sciences Centre, University College Dublin, Belfield, Dublin 4, Ireland; E-mail: firstname.lastname@example.org.
Submitted for publication September 2009.
Accepted for publication March 2010.