Pelvic rotation in femoroacetabular impingement is decreased compared to other symptomatic hip conditions

STUDY DESIGN: Cross-sectional, case-control design.BACKGROUND: Pelvic movement has been considered a possible discriminating parameter associated with femoroacetabular impingement (FAI) symptom onset. Decreased pelvic rotation has been found during squatting in people with FAI when compared to people with healthy hips.However, it is possible that changes in pelvic movement may occur in other hip conditions because of pain and may not be specific to FAI.OBJECTIVES: To compare sagittal pelvic rotation during hip flexion and in sitting between people with FAI and people with other symptomatic hip conditions. METHODS: Thirty people with symptomatic FAI,30 people with other symptomatic hip conditions,and 20 people with healthy hips participated in the study. Sagittal pelvic rotation was calculated based on measures of pelvic alignment in standing, hip flexion to 45° and 90°, and sitting. RESULTS: There were significant differences in sagittal pelvic rotation among the 3 groups in all conditions (P<.05). Post hoc analyses revealed that participants in the symptomatic FAI group had less pelvic rotation during hip flexion to 45° and 90° compared to participants in the other symptomatic hip conditions group and the hip-healthy group (mean difference, 1.2°-1.9°). In sitting, participants in the other symptomatic hip conditions group had less posterior pelvic rotation compared to those in the hip-healthy group (mean difference, 3.9°). CONCLUSION: People with symptomatic FAI have less posterior pelvic rotation during hip flexion when compared to people with other symptomatic hip conditions and those with healthy hips.