2021 ISAKOS Biennial Congress Paper
Alpha Angle More Useful Than Femoral Head-Neck Offset to Predict Intra-Articular Damage in Patients with FAI Undergoing Hip Arthroscopy
Jacob Shapira, MD, Des Plaines UNITED STATES
Jade S Owens, BS, Des Plaines, Illinois UNITED STATES
David R. Maldonado, MD, Houston, TX UNITED STATES
Philip Joseph Rosinsky, MD, Skokie, IL UNITED STATES
Hari Krishna Ankem, MD, Louisville, KENTUCKY UNITED STATES
Bezalel Peskin, MD, En Ayyla POB 57 ISRAEL
Ajay C. Lall, MD, MS, FAAOS, Paramus, New Jersey UNITED STATES
Benjamin G. Domb, MD, Chicago, IL UNITED STATES
American Hip Institute Research Foundation, Des Plaines, Illinois, UNITED STATES
FDA Status Cleared
Summary
In a multivariate analysis, factors identified as preoperative predictors of intra-articular cartilage damage in patients with FAI were age, sex, ACEA, and alpha angle.
Abstract
Purpose
To identify radiographic measurements and demographics that are predictive of intra-articular cartilage damage in patients with femoroacetabular impingement (FAI) undergoing hip arthroscopy. More specifically, to compare the predictive value of alpha angle and femoral head-neck offset in determining the preoperative likelihood and severity of intra-articular cartilage damage.
Methods
Patients were included if they underwent primary hip arthroscopy between February 2008 and June 2020. A total of 13 variables were assessed in a bivariate comparison and analyzed in a multivariate logistic model. The Acetabular Labrum Articular Disruption (ALAD) and Outerbridge (OB) classifications were used to define acetabular cartilage defects. Those without damage or those with mild acetabular cartilage damage belonged to the ALAD/OB = 2 group and those with severe acetabular cartilage damage belonged to the ALAD/OB = 3 group.
Results
The multivariate logistic regression selected age, sex, anterior center-edge angle (ACEA), and alpha angle. Every additional degree in the alpha angle was associated with a 6% increase in the odds of severe acetabular cartilage damage defined as ALAD/OB = 3 (OR, 1.06 [95% CI, 0.12-8.11]). The multivariate analysis did not identify femoral head-neck offset as a predictor. The odds of severe acetabular cartilage damage were 3.73 times higher in males than females (OR, 3.73 [95% CI, 0.01-1705.96]). Higher age (per log 10 unit) was found to increase the likelihood of ALAD/OB = 3 (OR, 1.04 [95% CI, 0.13-7.75]).
Conclusions
In a multivariate analysis, factors identified as preoperative predictors of intra-articular cartilage damage in patients with FAI were age, sex, ACEA, and alpha angle. Femoral head-neck offset was not predictive, suggesting alpha angle may take precedence as a predictor of intra-articular cartilage damage. These findings may be helpful to the clinician’s efficient utilization and selection of radiographic predictors of intra-articular cartilage damage in patients with FAI undergoing hip arthroscopy.