Effect of Early Postoperative Gait Parameters After Total Hip Arthroplasty on Forgotten Joint Score-12 at 2-Year Follow-Up.

Purpose: This study aimed to elucidate the relationship between early postoperative gait parameters after total hip arthroplasty (THA) and the Forgotten Joint Score-12 (FJS-12) score at the 2-year follow-up after surgery. In addition, the cutoff gait parameter values for predicting discomfort using specific FJS-12 subitems were evaluated. Methods: Among 313 patients who underwent THA between April and December 2019, 44 (14.0%) who responded to the FJS-12 questionnaire at 2 years postoperatively were included in this study. Gait parameters, including walking speed, stride length, and their coefficients of variation (CVs), were measured at 13.8 ± 3.6 (mean ± standard deviation) days postoperatively. The FJS-12 was used to evaluate patients at 2 years after surgery. The correlation between the FJS-12 score and gait parameters was analyzed using Spearman's rank correlation coefficient. To determine the significant predictors of the FJS-12 score, multiple regression analysis was performed after adjusting for age as a covariate. Furthermore, receiver operating characteristic curves were used to determine the cutoff gait parameter values for predicting discomfort using specific FJS-12 subitems. Results: The FJS-12 score was significantly positively correlated with walking speed (r_s = 0.38, p < 0.05) and stride length (r_s = 0.51, p < 0.01). Meanwhile, the FJS-12 score was significantly negatively correlated with the CVs of walking speed (r_s = -0.34, p < 0.05) and stride length (r_s = -0.35, p < 0.05). Based on multiple regression analysis, stride length was a significant predictor of discomfort assessed using the FJS-12 score (β = 0.48, p < 0.01). According to the receiver operating characteristic curves, the cutoff stride length values for predicting discomfort using the FJS-12 subitems 9, 10, 11, and 12 showed moderate accuracy (area under the curve > 0.7). Conclusions: Improved walking ability of patients who underwent THA through early rehabilitation is linked to joint discomfort and patient satisfaction in daily life 2 years postoperatively.