Table 2.

Method of extracting percentage satisfied.

Study reporting method	Approach to extract percentage satisfied
Means and SD, or proportion values of categorical satisfaction scales	Percentage satisfied was derived from the sample size
Visual analogue scales reported	A satisfaction threshold was chosen based on the ‘smile face’ scale, where the point at which the face begins to smile was considered to be ‘satisfied’ (see Fig. 1); in a 1–10 scale, a score of 7 or more was chosen; in a 1–5 scale, 4 or more was chosen. The percentage of satisfied people was derived by calculating the number of people in the sample who had scores above the appropriate threshold for the data reported. This was achieved by converting the difference between the sample mean and the threshold into a z-score (the number of SD the threshold was away from the mean). The z-score was then converted to a percentile using the NORMDIST function in Excel v16.11 (Microsoft Corp, Redmond, WA, USA)
Only medians reported	An approximation of mean values was derived from the median range and sample size using the method of Hozo [18] to attain the percentage satisfied
Likert Scales	Outcomes of ‘satisfied’ or ‘very satisfied’ was regarded as a satisfied outcome
Knee Society Knee Score Satisfaction scale [19]. Total score of 40 from 5 items each with a maximum score of 8	A threshold of 28 was selected to indicate satisfaction. This represented a minimum of 4 satisfied answers and 1 neutral answer across the 5 satisfaction items.
The Self-Administered Patient Satisfaction Scale for Primary Hip and Knee Arthroplasty [20]. The items are scored on a 4-point Likert scale, with 4 response options: 25 pts (very dissatisfied), 50 pts (somewhat dissatisfied), 75 pts (somewhat satisfied), or 100 pts (very satisfied), which are averaged to give a total score.	A threshold of 68 was selected. The sum score of 68 represented 3 somewhat satisfied and 1 somewhat dissatisfied responses.
Multiple satisfaction questions under the one questionnaire	Where possible, these were individually reported as well as reporting a composite score
Papers reporting multiple follow-ups	The time point closest to twelve months was selected to be included in the review, based on evidence that this is when maximum improvement in pain and function is attained [21].
Papers only reporting satisfaction outcomes for subgroups of the sample	These subgroup scores were combined into one total group summary score.