The purpose of this study is to collect clinical and radiological data from the case series of patients surgically treated with total hip arthroplasty at the Rizzoli Orthopaedic Institute.

The primary objective is to evaluate in terms of safety and efficacy the reduction of legs dysmetria and proper acetabular cup inclination intraoperatively when comparing anterior, direct lateral, and postero-lateral hip approaches conducted via traditional or navigation-assisted surgery.

The secondary objectives of the study are to evaluate, by comparing navigation-assisted and non-navigation-assisted hip approaches, intraoperatively the correct positioning of the prosthesis by analyzing the acetabular cup version; surgical timing; and number of intraoperative radiographs taken. In addition, the accuracy of preoperative planning will be assessed and a clinical evaluation performed during a follow-up of one year.

Inclusion Criteria:

1. Age between 50 and 80 years;
2. Signs and symptoms of hip osteoarthritis (pain intensity of at least 6 points of visual analogic scale pain - 0-10 scale in the previous week);
3. Radiographic signs of hip osteoarthritis (Grade 3-4 according to Tonnis classification);

Exclusion Criteria:

1. Patients unable to express consent;
2. Patients undergoing previous ipsilateral hip surgery;
3. Patients undergoing lower limb surgery to be treated in the previous 12 months;
4. Patients with malignant neoplasms;
5. Patients with rheumatic diseases;
6. Patients with uncontrolled diabetes;
7. Patients with uncontrolled thyroid metabolic disorders;
8. Patients abusing alcoholic beverages, drugs or medications;
9. Body Mass Index > 35;
10. Pregnant and/or fertile women.
11. Pain intensity less than 6 points in accordance with the visual analogic scale scale.
12. Patients with the presence of excessive deformity resulting from acetabular or femoral head dysplasia
13. Patients who have already undergone total hip arthroplasty surgery on the affected hip.
14. Previous extensive surgery of the reference joint (osteotomy around the hip, open or arthroscopic osteochondroplasty for femoral-acetabular conflict).