FP1.8 Contralateral Hip Disease Progression in Patients with Femoroacetabular Impingement: 10-year follow-up prospective cohort

Background: Femoroacetabular impingement (FAI) morphology is prevalent in the general population, yet only a subset of individuals with this morphology exhibit symptoms, undergo surgery, or develop osteoarthritis. While FAI surgery has been extensively studied, the factors driving symptomatic progression in FAI remain poorly understood. This study aimed to utilize a contralateral FAI hip model to (1) assess rates of symptom development in the contralateral hip of FAI patients over a minimum 10-year period, and (2) identify predictors of disease progression (symptom development and surgical intervention) in the contralateral hip.

Methods: This prospective longitudinal cohort study focused on the contralateral FAI hip in patients presenting for ipsilateral FAI surgery. Ipsilateral surgery was performed between 2011 and 2013, with patients followed for a minimum 10 years. Patients with prior contralateral surgery were excluded. Moderate pain (from modified Harris hip score) in the contralateral hip was considered an endpoint. Patient and imaging characteristics of the contralateral hip were assessed as predictors, including AP-pelvis and 45° Dunn-view radiographic measurements. Statistical analysis included identifying factors significantly associated with symptomatic progression and Kaplan-Meier analysis.

Results: The study cohort comprised 177 hips with 157 patients (88.7%) achieving successful mean 10.9-year follow-up. Baseline data showed 26% experiencing significant contralateral symptoms, increasing to 42% at 5 years and 51% at 10 years. Of initially asymptomatic patients, 33% developed symptoms by the 10-year mark. Overall, 20% of patients underwent contralateral surgery, including 45% of those with symptoms. Univariate analysis revealed a significant association between a lower head-neck offset ratio on AP view and symptom development (p=0.002). Younger age (p=0.006) and contralateral hip Tonnis grade 1 (p=0.04) were also associated with requiring contralateral surgery by 10 years. Rates of symptom development were 31.4%, 21.2%, and 15.7% in patients <18, 18-25, and >25 years of age.

Conclusion: This prospective longitudinal cohort study demonstrated a 51% rate of significant symptomatic development in the contralateral FAI hip at minimum 10-year follow-up, with 26% of patients experiencing symptoms at baseline. Overall, 20% of the contralateral hips underwent surgery by the 10-year mark. Younger age was most strongly associated with a higher risk of contralateral surgery.