Translation, cross-cultural adaptation, and validation of the Italian language Forgotten Joint Score-12 (FJS-12) as an outcome measure for total knee arthroplasty in an Italian population

Abstract

Background: With ever-increasing numbers of patients undergoing elective total knee arthroplasty (TKA) and as TKA is performed in increasingly younger patients, patient demands and expectations have also increased. With improved patient outcomes, new PROMs with heightened discriminatory power in well-performing patients are needed. The present study aimed to translate and validate the Italian version of the Forgotten Joint Score (FJS-12) as a tool for evaluating pre-operative through longitudinal post-operative outcomes in an Italian population. Methods: In this prospective study, patients with unilateral osteoarthritis, undergoing TKA surgery between May 2015 and December 2017 were recruited to participate in the study. The FJS-12 and WOMAC were collected pre-operatively and at six and 12 months post-operatively. According to the COSMIN checklist, reliability, internal consistency, validity, responsiveness, effect size, and ceiling effects and floor effects were evaluated.Results: One hundred twenty patients completed the study, 66 of which participated in the evaluation of test-retest reliability. Good test-retest reliability was found (ICC = 0.90). The FJS-12 also showed excellent internal consistency (Cronbach α = 0.81). Construct validity with the WOMAC, as a measure of the Pearson correlation coefficient, was moderate (r = 0.45 pre-operatively; r = 0.46 at 6 months and r = 0.42 at 12 months post-operatively). From six to 12 months, the change was slightly greater for the WOMAC than for the FJS-12 patients (effect size d = 0.94; d = 0.75, respectively). At 12-months follow-up, the ceiling effects reflecting the maximum score were 12% for the FJS-12 and 6% for the WOMAC; however, scores within 10% of the maximum score were comprised 30% of the FJS-12 scores and 59% for the WOMAC.

Unicompartmental Knee Arthroplasty: Minimal Important Difference and Patient Acceptable Symptom State for the Forgotten Joint Score

“…The Forgotten Joint Score-12 is a PROM scale designed to assess prosthesis awareness during daily activities (i.e., the patient’s ability to forget the presence of a prosthesis) [ 14 ]. This consists of 12 questions, with a five-point Likert response format, which are summed to obtain scores ranging from 12 to 60.…”

“…A priori power analysis was performed for sample size estimation. A sample size of 15 patients provides 80% power (alpha = 0.05, two-sided) to detect a difference with a large effect size (Cohen’s d = 0.8) in FJS-12 in the preoperative period to the 6-month postoperative follow-up, as in the literature [ 14 , 28 ]. Data normality for the FJS-12 was assessed using the Shapiro–Wilk test of normality.…”

“…In other words, many patients could report the highest possible score on the PROM scale [ 5 ]. The Forgotten Joint Score (FJS-12) is a valid and responsive PROMs scale created to evaluate prosthesis awareness during daily activities [ 14 , 15 ]. Developed by Behrend et al in 2012, it assesses the degree of awareness of the prosthetic joint with a low ceiling effect [ 15 , 16 ].…”

“…They defined the MCID as “the smallest difference in score in the domain of interest which patients perceive as beneficial and which would mandate, in the absence of troublesome side effects and high cost, a change in the patient’s management”. Similar concepts to the MCID are the Minimum Important Change (MIC) and the minimal important difference (MID) [ 14 , 21 , 22 ]. These parameters are always used interchangeably with MCID, causing ambiguity [ 23 ].…”

“…Despite that the validity and reliability of the FJS-12 has already been demonstrated [ 14 ], the MCID of this score remains unknown for UKA. Moreover, only one study assessed the PASS of FJS-12 for UKA [ 5 ].…”