Quantifying Differences in Femoral Head and Neck Asphericity in the Common Hip Conditions of Femoroacetabular Impingement (FAI) and Hip Dysplasia Versus Controls Using Radial 3DCT Imaging and Volumetric Segmentation

AIM: 3DCT analysis of femoral head and bump anatomy in quantifying pathology in common hip conditions of FAI and hip dysplasia versus controls. Material and Methods: Consecutive patients who obtained 3DCT imaging for hip dysplasia or FAI were compared to asymptomatic controls. Alpha angles on radial CT and 3D volumetric femoral head and bump segmentations were obtained by two readers. Inter- and intra-patient comparisons were performed including inter-reader and ROC analyses. RESULTS: 25 FAI patients, 16 hip dysplasia patients and 38 controls were analyzed. FAI and dysplasia patients exhibited higher alpha angles and higher bump-head volume ratios than the controls (p<0.05). FAI patients exhibited larger bumps than dysplasia and the contralateral hips of FAI were also different than the controls. Alpha angle at 2 oﾒclock and bump to head ratio showed the highest area under the curve for cases versus controls. The reader reliability was better for volumetric segmentation (ICC= 0.35-0.84) as compared to the alpha angles (ICC= 0.11-0.44). CONCLUSION: Patients with both FAI and dysplasia exhibit different femoral head anatomy than the asymptomatic controls. Volumetric segmentation of femoral head and bump is more reliable and better demonstrates the bilateral femoral head anatomy differences of cases versus controls.