O’Connor, Kyle

Abstract Introduction: Low-dose computed tomography (CT) has been increasingly utilized in FAI due to its improved ability to characterize the complex and variable hip morphologies of FAI patients, compared to plain radiographs. This study defined FAI morphology between females and males as well as across adolescents, young adults, and older adults. Methods: A multi-center, prospective cohort of FAI patients undergoing primary arthroscopy was performed. Patients 14-45 years of age with idiopathic FAI were included. Low-dose CT was used for preoperative planning. Analysis focused on acetabular and femoral morphology and the differences between females/males and adolescents (A,14-18.9)/young adults (Y,19-24.9)/older adults (O,25+). Adolescents were the reference group during analysis. Results: There were 604 patients with CT data. Mean age was 24.9 years with 55.9% female. Males had more anterosuperior coverage (i.e. 64.2% vs 62.5% at 1:00), lower version (14.1° vs 18.0°), smaller femoral neck-shaft angles (130.9° vs 133.4°), and larger alpha angles (i.e. 72.1° vs 58.6° at 1:00) compared to females. Multivariable analysis demonstrated that females had associations with more femoral anteversion (OR: 1.05,CI: 1.03-1.07) and larger femoral neck-shaft angles (OR: 1.11,CI: 1.06-1.16). Males has associations with larger alpha angles at 1:00 (OR: 1.05,CI: 1.02-1.07) and 1:30 (OR: 1.03,CI: 1.00-1.06) as well as radial coverage at 1:00 (OR: 1.18,CI: 1.11-1.26). For females, adolescents had slightly less radial coverage at 2:00 (49.9%) compared to young (51.2%) and older adults (51.4%). Femoral neck-shaft angle decreased across age groups (A: 134.4°,Y: 133.0°,O: 132.7°). Alpha angles increased at 2:00 with age (A:54.6°,Y:55.3°,O:58.7°). Multivariable analysis had femoral neck-shaft angle decreasing for young (OR: 0.932,CI: 0.87) and older adults (OR:0.92,CI: 0.86-0.98) and it also had alpha angle at 1:15 increasing for young adults (OR: 1.03,CI: 1.00-1.06) and older adults (OR: 1.03,CI: 1.01-1.06). Males did not have any appreciable differences alpha angles, femoral version, or acetabular coverage across age groups. Conclusion: Differences in morphology identified on CT exist between females and males as well as across age groups for females. These differences may offer insight into disease pathomechanics between these patient populations. Further studies should confirm these findings and look at how they affect patient outcomes after treatment.