Abstract
Background:
Femoroacetabular impingement (FAI) is as prevalent in adolescents as in adults, yet few studies have analyzed treatment outcomes in the adolescent population. The purpose of this study was to determine the clinical outcomes of FAI surgery in adolescent patients and to identify predictors of treatment failure.
Methods:
A cohort of 126 adolescent patients (<18 years) undergoing surgery for symptomatic FAI were prospectively assessed among a larger multicenter cohort. The adolescent subgroup included 74 (58.7%) males and 52 (41.3%) females, had a mean age of 16.1 years (range 11.3-18.0), and a mean follow-up of 3.7 years. Mild cam FAI was defined by an alpha angle less than 55 degrees. Clinical outcomes were analyzed with the mHHS, HOOS (5 domains), and UCLA activity score. Failure was defined as revision surgery or clinical failure (failure to reach MCID (minimally clinically important difference) or PASS (patient acceptable symptoms state) for modified Harris Hip score. Statistical analysis was performed to identify factors significantly associated with failure.
Results:
There was clinically important improvement in all PROs (mHHS, all HOOS domains) for the overall cohort and 81% of patients met criteria for a successful outcome. The failure rate (revision surgery or clinical failure) of the overall cohort was 19%, including revision surgery in 8.7%. Female patients were significantly more likely than male patients to be classified as a failure (25.7% vs. 9.1%, p=0.017, OR 2.6), in part because of a lower preoperative mHHS (59.1 vs. 67.0, p<0.001). Mild cam FAI (alpha less than 55 degrees) was present in 31.5% of cases including 39.1% of females and 14.5% of males. Maximal alpha angle was significantly inversely associated with the failure rate (37.5% for alpha<55, 19.2% for alpha 55-63, and 6.8% for alpha>63, p<0.005). Non-athletes were at a significantly greater risk of failure compared to athletes (26.5% vs. 10.3%, p=0.043, OR 2.3). Multivariable logistic regression identified mild cam FAI and lack of participation in sports as predictive of failure (p=0.005 and p=0.04), while gender was no longer significantly associated with failure after controlling for other variables.
Conclusions:
Adolescent patients undergoing surgical treatment of FAI demonstrate significant improvement at early followup. However, mild cam FAI deformities (which are common in adolescent female patients) and lack of participation in sports are independently associated with higher rates of treatment failure. These factors associated with treatment failure should be considered in surgical treatment decision-making and patient counseling.