Single-center Comparative Study of Variation in Acetabular Anteversion According to Pelvic Tilt in Patients With Femoro-acetabular Impingement and Healthy Volunteers.

The study will be presented to a population of symptomatic DWI patients who are offered hip arthroscopy. As these measurements have never been performed before in a control population, the study will also be proposed to a population of healthy volunteers, matched by age, sex, BMI and level of sports activity, in order to have comparative reference values.

The study consisted of cross-sectional imaging and 3D reconstruction to measure and compare acetabular anteversion in 4 functional pelvic positions in both groups.

• Group 1: Symptomatic DWI patients
• Group 2: Healthy volunteers

For symptomatic patients, the preoperative workup will be the same as in routine practice and will include an X-ray as well as a CT scan. Low-dose EOS imaging of the pelvis in profile in 3 positions (standing sagittal tilt, sitting, maximum hip flexion) will complete this workup in the context of the study, to know the sacral slope associated with each of these positions. If the preoperative workup does not include a CT or arthroscan scan with measurement of femoral anteversion, it will be requested in the low-dose protocol.

The control group will perform a CT scan and EOS imaging in the same 3 positions as the patient group.

From the CT scan, a 3D reconstruction with the BoneMetrix software to calculate the superior acetabular anteversion plane will be performed, giving the anteversion for a supine patient. The software also allows to modify the orientation of the pelvis, according to the results of the sacral slope obtained from the EOS assessment for the calculation of the superior acetabular anteversion in the 3 requested positions. Finally, this 3D reconstruction will allow us to search for the impingement dynamically after pelvis-femur segmentation and to measure the position (degree of femoral flexion) in which it occurs.

As these measurements have never been performed before, a control population is needed to obtain reference values for acetabular behavior that does not lead to symptomatic CFA. This population will be matched by age, sex, BMI and sports activity to the study population.

The results obtained from the 2 populations will be compared. For the operated DWI patients in the cohort, the clinical scores will be evaluated at 6 months and 2 years postoperatively to search for a correlation between these scores and the superior acetabular version angles obtained.

This monocentric study will take place at the Clinique de la Sauvegarde. Patients will be seen in consultation by Dr Bonin or Dr Guicherd. They will be included during the pre-operative consultation during which they will be presented with the examinations to be performed, as well as the study. Their consent will be sought before any preliminary procedure. Imaging will be performed at the Clinique du Parc, as is already done for these patients, outside of any study.