The "Forgotten Joint" as the Ultimate Goal in Joint Arthroplasty Validation of a New Patient-Reported Outcome Measure

With improving patient outcome after joint arthroplasty, new assessment tools with increased discriminatory power especially in well-performing patients are desirable. The goal of the present study was to develop and validate a new score ("Forgotten Joint Score," or FJS) introducing a new aspect of patient-reported outcome: the patient's ability to forget the artificial joint in everyday life. After a pilot study, the FJS was validated and showed high internal consistency (Cronbach alpha = .95). Ceiling effects were considerably lower for the FJS (9.2%) compared with the Western Ontario and McMaster Universities subscales (16.7%-46.7%). Known-group comparisons proved the FJS to be highly discriminative in a validation sample of 243 patients. The FJS not only reflects differences between "good" and "bad" but also between "good," "very good," and "excellent" outcomes. This concise score is appealing for its more adequate measurement range and because it measures the new, promising concept of the "forgotten joint."