Preliminary Prediction Model for Fear-Induced Activity Limitation After Total Knee Arthroplasty in People 60 Years and Older: Prospective Cohort Study

OBJECTIVES: To assess the presence of fear-induced activity limitation (FIAL) in a sample of patients 1 year after total knee arthroplasty (TKA), and to develop a preliminary prediction model to predict the risk of FIAL. DESIGN: Prospective cohort study. SETTING: A tertiary teaching hospital. PARTICIPANTS: Patients (N=72; mean age, 70±6y) undergoing primary, unilateral TKA participated. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Preoperative candidate predictors were age, sex, body mass index, previous falls history, number of comorbidities, self-report physical function, gait speed, knee range of motion, knee pain, and standing balance. Outcome measure at 1-year follow-up was the level of FIAL, measured by the Survey of Activities and Fear of Falling in the Elderly. RESULTS: Thirty-one patients (41%; 95% confidence interval, .31-.55) had FIAL, of whom 15 had moderate to severe FIAL. Multivariable predictors of FIAL included preoperative habitual gait speed and velocity of postural sway in the anterior-posterior axis. A 2-variable nomogram-based prediction model was constructed, and this model showed moderately good discrimination (optimism-corrected c-index, .76) and adequate calibration. CONCLUSIONS: In our sample of patients with TKA, FIAL is common, and early identification of patients at risk of FIAL would bring them into appropriate modes of preventive care. Our prediction model shows some promise in identifying patients with FIAL, but prospective validation studies are needed.