2.2. Exclusion criteria

In the first instance, all articles retrieved and collected were examined for the title and the abstract by one of the authors. In order to reach our original goal, we excluded the following categories: non-English articles, postgraduate dissertations, doctoral dissertations, studies not involving people with knee osteoarthritis and studies using traditional technical statistics. All the selected articles have been presented either in journal papers or conferences. Finally, the rest of the authors reviewed again the titles and abstracts to ensure that they met the membership criteria.