VALIDATION DATA

The values of Chronbach’s alpha for the satisfaction construct were 0.90 for preoperative data and 0.95 for postoperative data. Slightly lower values were observed for the expectation construct (preoperative: 0.79; postoperative: 0.92). Values for the individual subscales of the functional activities subscale ranged from 0.68 to 0.95, which suggests an acceptable level of internal consistency.

Ten activities were correlated with the TKFQ (p < 0.001), and the inclusion of additional items did not lead to a substantial improvement in prediction of outcome.

Exploratory factor analysis was performed to assess whether all of the items (questions) within each domain elicited internally consistent responses (construct validity). The results showed the underlying constructs of the expectation and function instruments (both pre- and postoperative) responded unidimensionality and thus gave internally consistent responses. Moreover, each subscale of the function instrument (ie, walking and standing, standard activities, advanced activities, and discretionary activities) had construct validity, both pre- and postoperatively.