Defining the patient acceptable symptom state using the forgotten joint score 12 after hip arthroscopy

PURPOSE: To contextualize the Forgotten Joint Score (FJS-12) by identifying a patient acceptable symptomatic state (PASS) threshold for patients undergoing hip arthroscopy and to investigate factors which correlated with postoperative FJS-12 score.

METHODS: All patients who underwent hip arthroscopy for femoroacetabular impingement (FAI) under the care of a single surgeon between January 2018 and November 2019 were prospectively identified and included. Exclusion criteria were Tönnis classification grade 2 or greater. Data (including FJS-12, EuroQol-5 Dimension-5L [EQ-5D-5L], visual analog scale (VAS), and 12-item International Hip Outcome Tool (iHOT-12) scores) were available before surgery and at a minimum of 1 year after surgery. PASS was calculated using an anchor-based approach and receiver operator characteristic curve analysis. Pearson correlation analysis was used to correlate preoperative and postoperative factors with postoperative FJS-12 score.

RESULTS: Seventy-seven patients (54 female, 23 male; mean age 30.3 years [standard deviation {SD} 8.2]) were included. Linked longitudinal follow-up data were available for 65 patients (84%) at a mean of 23.8 months (SD 6.4). Six patients required reoperation. Mean postoperative FJS-12 score was 46.5 (SD 33.1) and mean change in score was 27.2 (SD 30.6, P < .001). The PASS threshold for the FJS-12 was 38.5 (sensitivity 80%, specificity 88%), and the area under the curve was 0.852 (95% confidence interval 0.752-0.951). Overall, 53.8% of patients achieved this score. Postoperative FJS-12 score has moderate correlations with preoperative EQ-5D-5L, iHOT-12, and FJS-12 scores, and strong correlations with EQ-5D-5L, iHOT-12 and VAS scores after surgery.

CONCLUSIONS: We report a postoperative PASS threshold of 38.5 points for the FJS-12 after hip arthroscopy for FAI in a United Kingdom population. This value can act as a quantifiable target for clinicians using the FJS-12 to monitor patient outcomes in practice. FJS-12 has strong correlations with EQ-5D-5L, iHOT-12, and VAS at a minimum 12 months after surgery.

CLINICAL RELEVANCE: We have calculated the patient acceptable symptomatic state of the Forgotten Joint Score to be 38.5 points at short-term follow-up. This can assist clinicians in determining whether surgical interventions related to hip arthroscopy for FAI are meaningful to the patient.