Prospective, multicenter, non-randomized study.

Primary endpoint : to confirm the proper functioning of the device in vivo by analyzing intra and interobserver reproducibility of repeated measurements on healthy controls.

Secondary endpoint : to describe the values of pelvic inclination while standing, sitting and lying in patients with severe hip osteoarthritis before and after total hip arthroplasty

After signing the inform consent form:

For the first endpoint (, 3 healthy volunteers of different morphotypes will have one consultation comprising :

• a medical examination
• 10 measurements of pelvic inclination in sitting position, 10 measurements of pelvic inclination in supine position and 10 measurements of pelvic inclination in standing position, each realized per three different operators. These measurements will be carried out with navigated ultrasound.

For the secondary endpoint, 30 patients awaiting for a hip replacement surgical intervention will realized one consultation the day before the intervention, and one consultation at 2 months after surgery, each comprising :

• a medical examination
• 3 measurements of pelvic inclination (1 standing, 1 sitting and 1 supine). These measurements will be carried out with navigated ultrasound.

Inclusion Criteria:

For primary endpoint

• No medical or surgical history

• Major healthy voluntary topic with

  • Body Mass Index (BMI) <20 for a subject
  • 24 <BMI <26 for a subject
  • BMI> 30 for a subject

• Subject having signed an informed consent

For the secondary endpoint

• Adult patient requiring total hip arthroplasty for severe hip osteoarthritis
• Patient having signed an informed consent

Exclusion Criteria:

• Minor subject
• Resumption of total hip prosthesis
• Subject who can not express their consent to research
• Presence of medical or surgical history for healthy volunteers