Impact of Femoroacetabular Impingement Morphology on Gait Assessment in Symptomatic Patients

Background: Gait is abnormal in patients with femoroacetabular impingement (FAI). To date, studies have not correlated radiographic FAI morphology with gait abnormalities. Hypothesis: Gait abnormalities in FAI patients will be associated with radiographic FAI morphology. Study Design: Cross-sectional study. Level of Evidence: Level 4. Methods: Patients with symptomatic FAI (n = 20) underwent radiographic and gait analysis. Exclusion criteria included previous injuries or surgeries to the lower extremities or lumbar spine as well as bilateral symptomatic FAI. The alpha angle (AA) and center- edge angle (CEA) were measured on anteroposterior (AP) pelvis, Dunn lateral, and false-profile radiographs, and inter-and intraobserver variability was determined. Motion analysis techniques were used to obtain gait data including 3-dimensional kinematic and kinetic data. Descriptive analysis was performed using Spearman correlations for morphologic measurements. A stepwise regression model was used to examine the association of gait measures with AA and CEA. Results: Intraobserver agreement for the AA and CEA was 0.92 (CI, 0.80- 0.97) and 0.90 (CI, 0.76-0.96), while interobserver agreement for the angles was 0.96 (CI, 0.89-0.98) and 0.96 (CI, 0.90-0.98), respectively. Descriptive analysis suggested correlations between AA and peak external hip and knee external rotation moments, maximum ankle flexion angle, and ankle range of motion (range, - 0.51 to 0.42; P < 0.0001). The CEA correlated with stride, peak external ankle eversion and inversion moments, peak external knee extension moment, and peak external hip flexion moment (range, - 0.44 to 0.51; P < 0.0001). We found that gait variables accounted for a large amount of variation in AA (8 variables accounted for 87% variation) and in CEA (7 variables accounted for 82% variation). Conclusion: Lower extremity gait parameters correlate highly with radiographic FAI morphology in symptomatic FAI patients.