Table 1 AAOS inclusion/exclusion criteria [9]

• Study was of osteoarthritis of the knee

• Study reported on 80% of the patient population of interest

• Article provided full report of a clinical study

• Study was published in a peer-reviewed journal

• Study had a sample of 30 or more patients per treatment group

• Study was of humans

• Study was published in English

• Study was published during or after 1966

• Study results were presented quantitatively

• Study treatment follow up period was at least 4 weeks

• At least 80% of the enrolled study population were 19 years of age or older

• For any included study that used “paper-and-pencil” outcome measures (e.g. SF-36), only those that were validated were included [unless the outcome was identified a priori by the work group in the critical outcomes Delphi round]

• Retrospective non-comparative case series, medical records review, meeting abstracts, historical articles, editorials, letters, and commentaries

• Case series studies that gave patients the treatment of interest AND another treatment

• Case series studies that had non-consecutive enrollment of patients were excluded

• Controlled trials in which patients were not stochastically assigned to groups AND in which there was heterogeneity in patient characteristics or outcomes at baseline AND where the authors did not statistically adjust for these differences when analyzing the results

• All studies of “Very Limited” evidence strength

• Composite measures or outcomes even if they were patient-oriented

• Case series studies with no baseline values

• “Paper and pencil” outcomes (e.g. SF-36) reported by a single group of investigators

• Study performed on cadavers

• In vitro study