Over the years, the use of large diameter femoral heads has become increasingly common in orthopaedics due to the decreased risk of dislocation due to increased jumping distance and range of motion. The history of total hip arthroplasty does not favour large diameter heads, especially as conventional polyethylene has a high risk of wear. The development of hard-on-hard bearings (CoC) with a second generation ceramic material and the introduction of cross-linked PE have led to the reintroduction of this concept. The Mpact 3D Metal MonoCER cup was developed to offer the advantages of accommodating large diameter heads with an external metal cup with a pre-assembled system that avoids the surgical step of insert-cotile coupling.

All patients candidated to receive a total hip arthroplasty under 75 years old, who will receive a Mpact 3D Metal cup will be proposed to take part to the study. They will receive the same treatment in case they will not partecipate; the study is an observational study according to standard practice. The study aim to assess the long term peformance of the cup at 10 years after surgery. The patients will be visited at 6 months, 1, 5 and 10 years after surgery.

Inclusion Criteria:

1. Patients undergoing total hip arthroplasty who will receive the Mpact 3D Metal MonoCER acetabular component according to the instructions for use
2. Patients who have signed the informed consent to participate in the study

Exclusion Criteria:

1. Minor patients, patients over 75 years of age at the time of primary surgery;
2. Any patient who is unable or unwilling to give informed consent to participate in the study.

Patients listed for a Total Hip Arthroplasty (THA) with Mpact 3D Metal MONOCER cup, meeting all inclusion/exclusion criteria, at the research site, will be proposed to take part to the current study during the preoperative visit.

The investigator will explain to each participant the nature of the study, its purpose, the procedures involved, the expected duration, the potential risks and benefits and any discomfort it may entail