O0809 Oct.3: 3:20pm - Larger Alpha Angle is associated with Severity of Labral Disease in the Adolescent Patient

Background:
Femoroacetabular Impingement (FAI) is a common cause of hip pain in adolescent patients. Clinical exam and radiographic markers, such as alpha angle and lateral center edge angle (LCEA), are commonly used to aid in the diagnosis of this condition. The purpose of this study was to correlate these radiographic parameters in the adolescent patient to preoperative symptoms, intraoperative disease, and post-operative patient reported outcomes (PROs).

Methods:
A retrospective analysis of prospectively collected data was conducted for all patients who underwent operative intervention for FAI at an academic institution over a 10-year period. Pre-operative AP pelvis and Dunn 45 radiographs were obtained and measured for LCEA and alpha angle. PROs (modified Harris Hip Score [mHHS], Hip Disability and Osteoarthritis Outcome Score [HOOS], and UCLA Score) were collected pre-operatively, as well as 1, 2, and 5 years post-operatively. Operative intervention was either open surgical hip dislocation or arthroscopic, and intraoperative disease was graded using the Beck Classification system. Mann-Whitney-U test and Spearman’s correlation were used to assess association between variables. Patients with minimum one-year follow-up were included in statistical analysis.

Results:
This study includes 86 hips (64 female hips) with an average age of 16.3 yrs (range 10.4-20.5), with an average of 3.1 years of follow up. 77% of patients had an isolated cam lesion, 22% with mixed, and 1% pincer-only. There was no correlation between severity of preoperative symptoms or difference between pre and post-operative patient reported outcomes for both alpha angle and LCEA. Overall, significant average improvement was noted in all PRO, mHHS 23.5 (p<0.0001), HOOS 28.1 (p<0.0001), UCLA Score 1.4 (p<0.0001). Independent of pre-operative symptoms, increased alpha angle correlated with more severe intraoperative labral disease (as defined by the Beck Classification system) (p<0.001), and longer length of labral tear (p<0.01). Femoral head and acetabular articular cartilage damage did not correlate with alpha angle or LCEA, nor did overall severity of disease.

Conclusion:
In adolescent patients with FAI, increased alpha angle was found to significantly correlate with labral pathology, including increased length of tear and severity of disease, irrespective of preoperative symptoms or post-operative patient reported outcomes.